svlogd: fix compat problem: svlogd -tt should timestanp stderr too

[busybox.git] / util-linux / mount.c

/* vi: set sw=4 ts=4: */
/*
 * Mini mount implementation for busybox
 *
 * Copyright (C) 1995, 1996 by Bruce Perens <bruce@pixar.com>.
 * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
 * Copyright (C) 2005-2006 by Rob Landley <rob@landley.net>
 *
 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
 */

/* Design notes: There is no spec for mount.  Remind me to write one.

   mount_main() calls singlemount() which calls mount_it_now().

   mount_main() can loop through /etc/fstab for mount -a
   singlemount() can loop through /etc/filesystems for fstype detection.
   mount_it_now() does the actual mount.
*/

#include <mntent.h>
#include "libbb.h"

/* Needed for nfs support only... */
#include <syslog.h>
#include <sys/utsname.h>
#undef TRUE
#undef FALSE
#include <rpc/rpc.h>
#include <rpc/pmap_prot.h>
#include <rpc/pmap_clnt.h>

#ifndef MS_SILENT
#define MS_SILENT       (1 << 15)
#endif

#if defined(__dietlibc__)
/* 16.12.2006, Sampo Kellomaki (sampo@iki.fi)
 * dietlibc-0.30 does not have implementation of getmntent_r() */
struct mntent *getmntent_r(FILE* stream, struct mntent* result, char* buffer, int bufsize)
{
        struct mntent* ment = getmntent(stream);
        memcpy(result, ment, sizeof(struct mntent));
        return result;
}
#endif

#define getmntent_buf bb_common_bufsiz1


// Not real flags, but we want to be able to check for this.
enum {
        MOUNT_USERS  = (1<<28)*ENABLE_DESKTOP,
        MOUNT_NOAUTO = (1<<29),
        MOUNT_SWAP   = (1<<30),
};
// TODO: more "user" flag compatibility.
// "user" option (from mount manpage):
// Only the user that mounted a filesystem can unmount it again.
// If any user should be able to unmount, then use users instead of user
// in the fstab line.  The owner option is similar to the user option,
// with the restriction that the user must be the owner of the special file.
// This may be useful e.g. for /dev/fd if a login script makes
// the console user owner of this device.

/* Standard mount options (from -o options or --options), with corresponding
 * flags */

static const struct {
        const char *name;
        long flags;
} mount_options[] = {
        // MS_FLAGS set a bit.  ~MS_FLAGS disable that bit.  0 flags are NOPs.

        USE_FEATURE_MOUNT_LOOP(
                {"loop", 0},
        )

        USE_FEATURE_MOUNT_FSTAB(
                {"defaults", 0},
                /* {"quiet", 0}, - do not filter out, vfat wants to see it */
                {"noauto", MOUNT_NOAUTO},
                {"sw", MOUNT_SWAP},
                {"swap", MOUNT_SWAP},
                USE_DESKTOP({"user",  MOUNT_USERS},)
                USE_DESKTOP({"users", MOUNT_USERS},)
        )

        USE_FEATURE_MOUNT_FLAGS(
                // vfs flags
                {"nosuid", MS_NOSUID},
                {"suid", ~MS_NOSUID},
                {"dev", ~MS_NODEV},
                {"nodev", MS_NODEV},
                {"exec", ~MS_NOEXEC},
                {"noexec", MS_NOEXEC},
                {"sync", MS_SYNCHRONOUS},
                {"async", ~MS_SYNCHRONOUS},
                {"atime", ~MS_NOATIME},
                {"noatime", MS_NOATIME},
                {"diratime", ~MS_NODIRATIME},
                {"nodiratime", MS_NODIRATIME},
                {"loud", ~MS_SILENT},

                // action flags

                {"bind", MS_BIND},
                {"move", MS_MOVE},
                {"shared", MS_SHARED},
                {"slave", MS_SLAVE},
                {"private", MS_PRIVATE},
                {"unbindable", MS_UNBINDABLE},
                {"rshared", MS_SHARED|MS_RECURSIVE},
                {"rslave", MS_SLAVE|MS_RECURSIVE},
                {"rprivate", MS_SLAVE|MS_RECURSIVE},
                {"runbindable", MS_UNBINDABLE|MS_RECURSIVE},
        )

        // Always understood.

        {"ro", MS_RDONLY},        // vfs flag
        {"rw", ~MS_RDONLY},       // vfs flag
        {"remount", MS_REMOUNT},  // action flag
};


/* Append mount options to string */
static void append_mount_options(char **oldopts, const char *newopts)
{
        if (*oldopts && **oldopts) {
                /* do not insert options which are already there */
                while (newopts[0]) {
                        char *p;
                        int len = strlen(newopts);
                        p = strchr(newopts, ',');
                        if (p) len = p - newopts;
                        p = *oldopts;
                        while (1) {
                                if (!strncmp(p, newopts, len)
                                 && (p[len]==',' || p[len]==0))
                                        goto skip;
                                p = strchr(p,',');
                                if (!p) break;
                                p++;
                        }
                        p = xasprintf("%s,%.*s", *oldopts, len, newopts);
                        free(*oldopts);
                        *oldopts = p;
skip:
                        newopts += len;
                        while (newopts[0] == ',') newopts++;
                }
        } else {
                if (ENABLE_FEATURE_CLEAN_UP) free(*oldopts);
                *oldopts = xstrdup(newopts);
        }
}

/* Use the mount_options list to parse options into flags.
 * Also return list of unrecognized options if unrecognized!=NULL */
static int parse_mount_options(char *options, char **unrecognized)
{
        int flags = MS_SILENT;

        // Loop through options
        for (;;) {
                int i;
                char *comma = strchr(options, ',');

                if (comma) *comma = 0;

                // Find this option in mount_options
                for (i = 0; i < ARRAY_SIZE(mount_options); i++) {
                        if (!strcasecmp(mount_options[i].name, options)) {
                                long fl = mount_options[i].flags;
                                if (fl < 0) flags &= fl;
                                else flags |= fl;
                                break;
                        }
                }
                // If unrecognized not NULL, append unrecognized mount options */
                if (unrecognized && i == ARRAY_SIZE(mount_options)) {
                        // Add it to strflags, to pass on to kernel
                        i = *unrecognized ? strlen(*unrecognized) : 0;
                        *unrecognized = xrealloc(*unrecognized, i+strlen(options)+2);

                        // Comma separated if it's not the first one
                        if (i) (*unrecognized)[i++] = ',';
                        strcpy((*unrecognized)+i, options);
                }

                if (!comma)
                        break;
                // Advance to next option
                *comma = ',';
                options = ++comma;
        }

        return flags;
}

// Return a list of all block device backed filesystems

static llist_t *get_block_backed_filesystems(void)
{
        static const char filesystems[2][sizeof("/proc/filesystems")] = {
                "/etc/filesystems",
                "/proc/filesystems",
        };
        char *fs, *buf;
        llist_t *list = 0;
        int i;
        FILE *f;

        for (i = 0; i < 2; i++) {
                f = fopen(filesystems[i], "r");
                if (!f) continue;

                while ((buf = xmalloc_getline(f)) != 0) {
                        if (!strncmp(buf, "nodev", 5) && isspace(buf[5]))
                                continue;
                        fs = skip_whitespace(buf);
                        if (*fs=='#' || *fs=='*' || !*fs) continue;

                        llist_add_to_end(&list, xstrdup(fs));
                        free(buf);
                }
                if (ENABLE_FEATURE_CLEAN_UP) fclose(f);
        }

        return list;
}

static llist_t *fslist;

#if ENABLE_FEATURE_CLEAN_UP
static void delete_block_backed_filesystems(void)
{
        llist_free(fslist, free);
}
#else
void delete_block_backed_filesystems(void);
#endif

#if ENABLE_FEATURE_MTAB_SUPPORT
static int useMtab = 1;
static int fakeIt;
#else
#define useMtab 0
#define fakeIt 0
#endif

// Perform actual mount of specific filesystem at specific location.
// NB: mp->xxx fields may be trashed on exit
static int mount_it_now(struct mntent *mp, int vfsflags, char *filteropts)
{
        int rc = 0;

        if (fakeIt) goto mtab;

        // Mount, with fallback to read-only if necessary.

        for (;;) {
                rc = mount(mp->mnt_fsname, mp->mnt_dir, mp->mnt_type,
                                vfsflags, filteropts);
                if (!rc || (vfsflags&MS_RDONLY) || (errno!=EACCES && errno!=EROFS))
                        break;
                if (!(vfsflags & MS_SILENT))
                        bb_error_msg("%s is write-protected, mounting read-only",
                                                mp->mnt_fsname);
                vfsflags |= MS_RDONLY;
        }

        // Abort entirely if permission denied.

        if (rc && errno == EPERM)
                bb_error_msg_and_die(bb_msg_perm_denied_are_you_root);

        /* If the mount was successful, and we're maintaining an old-style
         * mtab file by hand, add the new entry to it now. */
 mtab:
        if (ENABLE_FEATURE_MTAB_SUPPORT && useMtab && !rc && !(vfsflags & MS_REMOUNT)) {
                char *fsname;
                FILE *mountTable = setmntent(bb_path_mtab_file, "a+");
                int i;

                if (!mountTable) {
                        bb_error_msg("no %s",bb_path_mtab_file);
                        goto ret;
                }

                // Add vfs string flags

                for (i=0; mount_options[i].flags != MS_REMOUNT; i++)
                        if (mount_options[i].flags > 0 && (mount_options[i].flags & vfsflags))
                                append_mount_options(&(mp->mnt_opts), mount_options[i].name);

                // Remove trailing / (if any) from directory we mounted on

                i = strlen(mp->mnt_dir) - 1;
                if (i > 0 && mp->mnt_dir[i] == '/') mp->mnt_dir[i] = 0;

                // Convert to canonical pathnames as needed

                mp->mnt_dir = bb_simplify_path(mp->mnt_dir);
                fsname = 0;
                if (!mp->mnt_type || !*mp->mnt_type) { /* bind mount */
                        mp->mnt_fsname = fsname = bb_simplify_path(mp->mnt_fsname);
                        mp->mnt_type = (char*)"bind";
                }
                mp->mnt_freq = mp->mnt_passno = 0;

                // Write and close.

                addmntent(mountTable, mp);
                endmntent(mountTable);
                if (ENABLE_FEATURE_CLEAN_UP) {
                        free(mp->mnt_dir);
                        free(fsname);
                }
        }
 ret:
        return rc;
}

#if ENABLE_FEATURE_MOUNT_NFS

/*
 * Linux NFS mount
 * Copyright (C) 1993 Rick Sladkey <jrs@world.std.com>
 *
 * Licensed under GPLv2, see file LICENSE in this tarball for details.
 *
 * Wed Feb  8 12:51:48 1995, biro@yggdrasil.com (Ross Biro): allow all port
 * numbers to be specified on the command line.
 *
 * Fri, 8 Mar 1996 18:01:39, Swen Thuemmler <swen@uni-paderborn.de>:
 * Omit the call to connect() for Linux version 1.3.11 or later.
 *
 * Wed Oct  1 23:55:28 1997: Dick Streefland <dick_streefland@tasking.com>
 * Implemented the "bg", "fg" and "retry" mount options for NFS.
 *
 * 1999-02-22 Arkadiusz Mi¶kiewicz <misiek@misiek.eu.org>
 * - added Native Language Support
 *
 * Modified by Olaf Kirch and Trond Myklebust for new NFS code,
 * plus NFSv3 stuff.
 */

/* This is just a warning of a common mistake.  Possibly this should be a
 * uclibc faq entry rather than in busybox... */
#if defined(__UCLIBC__) && ! defined(__UCLIBC_HAS_RPC__)
#error "You need to build uClibc with UCLIBC_HAS_RPC for NFS support."
#endif

#define MOUNTPORT 635
#define MNTPATHLEN 1024
#define MNTNAMLEN 255
#define FHSIZE 32
#define FHSIZE3 64

typedef char fhandle[FHSIZE];

typedef struct {
        unsigned int fhandle3_len;
        char *fhandle3_val;
} fhandle3;

enum mountstat3 {
        MNT_OK = 0,
        MNT3ERR_PERM = 1,
        MNT3ERR_NOENT = 2,
        MNT3ERR_IO = 5,
        MNT3ERR_ACCES = 13,
        MNT3ERR_NOTDIR = 20,
        MNT3ERR_INVAL = 22,
        MNT3ERR_NAMETOOLONG = 63,
        MNT3ERR_NOTSUPP = 10004,
        MNT3ERR_SERVERFAULT = 10006,
};
typedef enum mountstat3 mountstat3;

struct fhstatus {
        unsigned int fhs_status;
        union {
                fhandle fhs_fhandle;
        } fhstatus_u;
};
typedef struct fhstatus fhstatus;

struct mountres3_ok {
        fhandle3 fhandle;
        struct {
                unsigned int auth_flavours_len;
                char *auth_flavours_val;
        } auth_flavours;
};
typedef struct mountres3_ok mountres3_ok;

struct mountres3 {
        mountstat3 fhs_status;
        union {
                mountres3_ok mountinfo;
        } mountres3_u;
};
typedef struct mountres3 mountres3;

typedef char *dirpath;

typedef char *name;

typedef struct mountbody *mountlist;

struct mountbody {
        name ml_hostname;
        dirpath ml_directory;
        mountlist ml_next;
};
typedef struct mountbody mountbody;

typedef struct groupnode *groups;

struct groupnode {
        name gr_name;
        groups gr_next;
};
typedef struct groupnode groupnode;

typedef struct exportnode *exports;

struct exportnode {
        dirpath ex_dir;
        groups ex_groups;
        exports ex_next;
};
typedef struct exportnode exportnode;

struct ppathcnf {
        int pc_link_max;
        short pc_max_canon;
        short pc_max_input;
        short pc_name_max;
        short pc_path_max;
        short pc_pipe_buf;
        uint8_t pc_vdisable;
        char pc_xxx;
        short pc_mask[2];
};
typedef struct ppathcnf ppathcnf;

#define MOUNTPROG 100005
#define MOUNTVERS 1

#define MOUNTPROC_NULL 0
#define MOUNTPROC_MNT 1
#define MOUNTPROC_DUMP 2
#define MOUNTPROC_UMNT 3
#define MOUNTPROC_UMNTALL 4
#define MOUNTPROC_EXPORT 5
#define MOUNTPROC_EXPORTALL 6

#define MOUNTVERS_POSIX 2

#define MOUNTPROC_PATHCONF 7

#define MOUNT_V3 3

#define MOUNTPROC3_NULL 0
#define MOUNTPROC3_MNT 1
#define MOUNTPROC3_DUMP 2
#define MOUNTPROC3_UMNT 3
#define MOUNTPROC3_UMNTALL 4
#define MOUNTPROC3_EXPORT 5

enum {
#ifndef NFS_FHSIZE
        NFS_FHSIZE = 32,
#endif
#ifndef NFS_PORT
        NFS_PORT = 2049
#endif
};

/*
 * We want to be able to compile mount on old kernels in such a way
 * that the binary will work well on more recent kernels.
 * Thus, if necessary we teach nfsmount.c the structure of new fields
 * that will come later.
 *
 * Moreover, the new kernel includes conflict with glibc includes
 * so it is easiest to ignore the kernel altogether (at compile time).
 */

struct nfs2_fh {
        char                    data[32];
};
struct nfs3_fh {
        unsigned short          size;
        unsigned char           data[64];
};

struct nfs_mount_data {
        int             version;                /* 1 */
        int             fd;                     /* 1 */
        struct nfs2_fh  old_root;               /* 1 */
        int             flags;                  /* 1 */
        int             rsize;                  /* 1 */
        int             wsize;                  /* 1 */
        int             timeo;                  /* 1 */
        int             retrans;                /* 1 */
        int             acregmin;               /* 1 */
        int             acregmax;               /* 1 */
        int             acdirmin;               /* 1 */
        int             acdirmax;               /* 1 */
        struct sockaddr_in addr;                /* 1 */
        char            hostname[256];          /* 1 */
        int             namlen;                 /* 2 */
        unsigned int    bsize;                  /* 3 */
        struct nfs3_fh  root;                   /* 4 */
};

/* bits in the flags field */
enum {
        NFS_MOUNT_SOFT = 0x0001,        /* 1 */
        NFS_MOUNT_INTR = 0x0002,        /* 1 */
        NFS_MOUNT_SECURE = 0x0004,      /* 1 */
        NFS_MOUNT_POSIX = 0x0008,       /* 1 */
        NFS_MOUNT_NOCTO = 0x0010,       /* 1 */
        NFS_MOUNT_NOAC = 0x0020,        /* 1 */
        NFS_MOUNT_TCP = 0x0040,         /* 2 */
        NFS_MOUNT_VER3 = 0x0080,        /* 3 */
        NFS_MOUNT_KERBEROS = 0x0100,    /* 3 */
        NFS_MOUNT_NONLM = 0x0200        /* 3 */
};


/*
 * We need to translate between nfs status return values and
 * the local errno values which may not be the same.
 *
 * Andreas Schwab <schwab@LS5.informatik.uni-dortmund.de>: change errno:
 * "after #include <errno.h> the symbol errno is reserved for any use,
 *  it cannot even be used as a struct tag or field name".
 */

#ifndef EDQUOT
#define EDQUOT  ENOSPC
#endif

// Convert each NFSERR_BLAH into EBLAH

static const struct {
        int stat;
        int errnum;
} nfs_errtbl[] = {
        {0,0}, {1,EPERM}, {2,ENOENT}, {5,EIO}, {6,ENXIO}, {13,EACCES}, {17,EEXIST},
        {19,ENODEV}, {20,ENOTDIR}, {21,EISDIR}, {22,EINVAL}, {27,EFBIG},
        {28,ENOSPC}, {30,EROFS}, {63,ENAMETOOLONG}, {66,ENOTEMPTY}, {69,EDQUOT},
        {70,ESTALE}, {71,EREMOTE}, {-1,EIO}
};

static char *nfs_strerror(int status)
{
        int i;

        for (i = 0; nfs_errtbl[i].stat != -1; i++) {
                if (nfs_errtbl[i].stat == status)
                        return strerror(nfs_errtbl[i].errnum);
        }
        return xasprintf("unknown nfs status return value: %d", status);
}

static bool_t xdr_fhandle(XDR *xdrs, fhandle objp)
{
        if (!xdr_opaque(xdrs, objp, FHSIZE))
                 return FALSE;
        return TRUE;
}

static bool_t xdr_fhstatus(XDR *xdrs, fhstatus *objp)
{
        if (!xdr_u_int(xdrs, &objp->fhs_status))
                 return FALSE;
        switch (objp->fhs_status) {
        case 0:
                if (!xdr_fhandle(xdrs, objp->fhstatus_u.fhs_fhandle))
                         return FALSE;
                break;
        default:
                break;
        }
        return TRUE;
}

static bool_t xdr_dirpath(XDR *xdrs, dirpath *objp)
{
        if (!xdr_string(xdrs, objp, MNTPATHLEN))
                 return FALSE;
        return TRUE;
}

static bool_t xdr_fhandle3(XDR *xdrs, fhandle3 *objp)
{
        if (!xdr_bytes(xdrs, (char **)&objp->fhandle3_val, (unsigned int *) &objp->fhandle3_len, FHSIZE3))
                 return FALSE;
        return TRUE;
}

static bool_t xdr_mountres3_ok(XDR *xdrs, mountres3_ok *objp)
{
        if (!xdr_fhandle3(xdrs, &objp->fhandle))
                return FALSE;
        if (!xdr_array(xdrs, &(objp->auth_flavours.auth_flavours_val), &(objp->auth_flavours.auth_flavours_len), ~0,
                                sizeof (int), (xdrproc_t) xdr_int))
                return FALSE;
        return TRUE;
}

static bool_t xdr_mountstat3(XDR *xdrs, mountstat3 *objp)
{
        if (!xdr_enum(xdrs, (enum_t *) objp))
                 return FALSE;
        return TRUE;
}

static bool_t xdr_mountres3(XDR *xdrs, mountres3 *objp)
{
        if (!xdr_mountstat3(xdrs, &objp->fhs_status))
                return FALSE;
        switch (objp->fhs_status) {
        case MNT_OK:
                if (!xdr_mountres3_ok(xdrs, &objp->mountres3_u.mountinfo))
                         return FALSE;
                break;
        default:
                break;
        }
        return TRUE;
}

#define MAX_NFSPROT ((nfs_mount_version >= 4) ? 3 : 2)

static smalluint nfs_mount_version;

/*
 * Unfortunately, the kernel prints annoying console messages
 * in case of an unexpected nfs mount version (instead of
 * just returning some error).  Therefore we'll have to try
 * and figure out what version the kernel expects.
 *
 * Variables:
 *      KERNEL_NFS_MOUNT_VERSION: kernel sources at compile time
 *      NFS_MOUNT_VERSION: these nfsmount sources at compile time
 *      nfs_mount_version: version this source and running kernel can handle
 */
static void
find_kernel_nfs_mount_version(void)
{
        int kernel_version;

        if (nfs_mount_version)
                return;

        nfs_mount_version = 4; /* default */

        kernel_version = get_linux_version_code();
        if (kernel_version) {
                if (kernel_version < KERNEL_VERSION(2,1,32))
                        nfs_mount_version = 1;
                else if (kernel_version < KERNEL_VERSION(2,2,18) ||
                                (kernel_version >= KERNEL_VERSION(2,3,0) &&
                                 kernel_version < KERNEL_VERSION(2,3,99)))
                        nfs_mount_version = 3;
                /* else v4 since 2.3.99pre4 */
        }
}

static void
get_mountport(struct pmap *pm_mnt,
        struct sockaddr_in *server_addr,
        long unsigned prog,
        long unsigned version,
        long unsigned proto,
        long unsigned port)
{
        struct pmaplist *pmap;

        server_addr->sin_port = PMAPPORT;
/* glibc 2.4 (still) has pmap_getmaps(struct sockaddr_in *).
 * I understand it like "IPv6 for this is not 100% ready" */
        pmap = pmap_getmaps(server_addr);

        if (version > MAX_NFSPROT)
                version = MAX_NFSPROT;
        if (!prog)
                prog = MOUNTPROG;
        pm_mnt->pm_prog = prog;
        pm_mnt->pm_vers = version;
        pm_mnt->pm_prot = proto;
        pm_mnt->pm_port = port;

        while (pmap) {
                if (pmap->pml_map.pm_prog != prog)
                        goto next;
                if (!version && pm_mnt->pm_vers > pmap->pml_map.pm_vers)
                        goto next;
                if (version > 2 && pmap->pml_map.pm_vers != version)
                        goto next;
                if (version && version <= 2 && pmap->pml_map.pm_vers > 2)
                        goto next;
                if (pmap->pml_map.pm_vers > MAX_NFSPROT ||
                    (proto && pm_mnt->pm_prot && pmap->pml_map.pm_prot != proto) ||
                    (port && pmap->pml_map.pm_port != port))
                        goto next;
                memcpy(pm_mnt, &pmap->pml_map, sizeof(*pm_mnt));
 next:
                pmap = pmap->pml_next;
        }
        if (!pm_mnt->pm_vers)
                pm_mnt->pm_vers = MOUNTVERS;
        if (!pm_mnt->pm_port)
                pm_mnt->pm_port = MOUNTPORT;
        if (!pm_mnt->pm_prot)
                pm_mnt->pm_prot = IPPROTO_TCP;
}

#if BB_MMU
static int daemonize(void)
{
        int fd;
        int pid = fork();
        if (pid < 0) /* error */
                return -errno;
        if (pid > 0) /* parent */
                return 0;
        /* child */
        fd = xopen(bb_dev_null, O_RDWR);
        dup2(fd, 0);
        dup2(fd, 1);
        dup2(fd, 2);
        while (fd > 2) close(fd--);
        setsid();
        openlog(applet_name, LOG_PID, LOG_DAEMON);
        logmode = LOGMODE_SYSLOG;
        return 1;
}
#else
static inline int daemonize(void) { return -ENOSYS; }
#endif

// TODO
static inline int we_saw_this_host_before(const char *hostname)
{
        return 0;
}

/* RPC strerror analogs are terminally idiotic:
 * *mandatory* prefix and \n at end.
 * This hopefully helps. Usage:
 * error_msg_rpc(clnt_*error*(" ")) */
static void error_msg_rpc(const char *msg)
{
        int len;
        while (msg[0] == ' ' || msg[0] == ':') msg++;
        len = strlen(msg);
        while (len && msg[len-1] == '\n') len--;
        bb_error_msg("%.*s", len, msg);
}

// NB: mp->xxx fields may be trashed on exit
static int nfsmount(struct mntent *mp, int vfsflags, char *filteropts)
{
        CLIENT *mclient;
        char *hostname;
        char *pathname;
        char *mounthost;
        struct nfs_mount_data data;
        char *opt;
        struct hostent *hp;
        struct sockaddr_in server_addr;
        struct sockaddr_in mount_server_addr;
        int msock, fsock;
        union {
                struct fhstatus nfsv2;
                struct mountres3 nfsv3;
        } status;
        int daemonized;
        char *s;
        int port;
        int mountport;
        int proto;
#if BB_MMU
        int bg = 0;
#else
        enum { bg = 0 };
#endif
        int soft;
        int intr;
        int posix;
        int nocto;
        int noac;
        int nolock;
        int retry;
        int tcp;
        int mountprog;
        int mountvers;
        int nfsprog;
        int nfsvers;
        int retval;

        find_kernel_nfs_mount_version();

        daemonized = 0;
        mounthost = NULL;
        retval = ETIMEDOUT;
        msock = fsock = -1;
        mclient = NULL;

        /* NB: hostname, mounthost, filteropts must be free()d prior to return */

        filteropts = xstrdup(filteropts); /* going to trash it later... */

        hostname = xstrdup(mp->mnt_fsname);
        /* mount_main() guarantees that ':' is there */
        s = strchr(hostname, ':');
        pathname = s + 1;
        *s = '\0';
        /* Ignore all but first hostname in replicated mounts
           until they can be fully supported. (mack@sgi.com) */
        s = strchr(hostname, ',');
        if (s) {
                *s = '\0';
                bb_error_msg("warning: multiple hostnames not supported");
        }

        server_addr.sin_family = AF_INET;
        if (!inet_aton(hostname, &server_addr.sin_addr)) {
                hp = gethostbyname(hostname);
                if (hp == NULL) {
                        bb_herror_msg("%s", hostname);
                        goto fail;
                }
                if (hp->h_length > sizeof(struct in_addr)) {
                        bb_error_msg("got bad hp->h_length");
                        hp->h_length = sizeof(struct in_addr);
                }
                memcpy(&server_addr.sin_addr,
                                hp->h_addr, hp->h_length);
        }

        memcpy(&mount_server_addr, &server_addr, sizeof(mount_server_addr));

        /* add IP address to mtab options for use when unmounting */

        if (!mp->mnt_opts) { /* TODO: actually mp->mnt_opts is never NULL */
                mp->mnt_opts = xasprintf("addr=%s", inet_ntoa(server_addr.sin_addr));
        } else {
                char *tmp = xasprintf("%s%saddr=%s", mp->mnt_opts,
                                        mp->mnt_opts[0] ? "," : "",
                                        inet_ntoa(server_addr.sin_addr));
                free(mp->mnt_opts);
                mp->mnt_opts = tmp;
        }

        /* Set default options.
         * rsize/wsize (and bsize, for ver >= 3) are left 0 in order to
         * let the kernel decide.
         * timeo is filled in after we know whether it'll be TCP or UDP. */
        memset(&data, 0, sizeof(data));
        data.retrans    = 3;
        data.acregmin   = 3;
        data.acregmax   = 60;
        data.acdirmin   = 30;
        data.acdirmax   = 60;
        data.namlen     = NAME_MAX;

        soft = 0;
        intr = 0;
        posix = 0;
        nocto = 0;
        nolock = 0;
        noac = 0;
        retry = 10000;          /* 10000 minutes ~ 1 week */
        tcp = 0;

        mountprog = MOUNTPROG;
        mountvers = 0;
        port = 0;
        mountport = 0;
        nfsprog = 100003;
        nfsvers = 0;

        /* parse options */
        if (filteropts) for (opt = strtok(filteropts, ","); opt; opt = strtok(NULL, ",")) {
                char *opteq = strchr(opt, '=');
                if (opteq) {
                        static const char options[] ALIGN1 =
                                /* 0 */ "rsize\0"
                                /* 1 */ "wsize\0"
                                /* 2 */ "timeo\0"
                                /* 3 */ "retrans\0"
                                /* 4 */ "acregmin\0"
                                /* 5 */ "acregmax\0"
                                /* 6 */ "acdirmin\0"
                                /* 7 */ "acdirmax\0"
                                /* 8 */ "actimeo\0"
                                /* 9 */ "retry\0"
                                /* 10 */ "port\0"
                                /* 11 */ "mountport\0"
                                /* 12 */ "mounthost\0"
                                /* 13 */ "mountprog\0"
                                /* 14 */ "mountvers\0"
                                /* 15 */ "nfsprog\0"
                                /* 16 */ "nfsvers\0"
                                /* 17 */ "vers\0"
                                /* 18 */ "proto\0"
                                /* 19 */ "namlen\0"
                                /* 20 */ "addr\0";
                        int val = xatoi_u(opteq + 1);
                        *opteq = '\0';
                        switch (index_in_strings(options, opt)) {
                        case 0: // "rsize"
                                data.rsize = val;
                                break;
                        case 1: // "wsize"
                                data.wsize = val;
                                break;
                        case 2: // "timeo"
                                data.timeo = val;
                                break;
                        case 3: // "retrans"
                                data.retrans = val;
                                break;
                        case 4: // "acregmin"
                                data.acregmin = val;
                                break;
                        case 5: // "acregmax"
                                data.acregmax = val;
                                break;
                        case 6: // "acdirmin"
                                data.acdirmin = val;
                                break;
                        case 7: // "acdirmax"
                                data.acdirmax = val;
                                break;
                        case 8: // "actimeo"
                                data.acregmin = val;
                                data.acregmax = val;
                                data.acdirmin = val;
                                data.acdirmax = val;
                                break;
                        case 9: // "retry"
                                retry = val;
                                break;
                        case 10: // "port"
                                port = val;
                                break;
                        case 11: // "mountport"
                                mountport = val;
                                break;
                        case 12: // "mounthost"
                                mounthost = xstrndup(opteq+1,
                                                strcspn(opteq+1," \t\n\r,"));
                                break;
                        case 13: // "mountprog"
                                mountprog = val;
                                break;
                        case 14: // "mountvers"
                                mountvers = val;
                                break;
                        case 15: // "nfsprog"
                                nfsprog = val;
                                break;
                        case 16: // "nfsvers"
                        case 17: // "vers"
                                nfsvers = val;
                                break;
                        case 18: // "proto"
                                if (!strncmp(opteq+1, "tcp", 3))
                                        tcp = 1;
                                else if (!strncmp(opteq+1, "udp", 3))
                                        tcp = 0;
                                else
                                        bb_error_msg("warning: unrecognized proto= option");
                                break;
                        case 19: // "namlen"
                                if (nfs_mount_version >= 2)
                                        data.namlen = val;
                                else
                                        bb_error_msg("warning: option namlen is not supported\n");
                                break;
                        case 20: // "addr" - ignore
                                break;
                        default:
                                bb_error_msg("unknown nfs mount parameter: %s=%d", opt, val);
                                goto fail;
                        }
                }
                else {
                        static const char options[] ALIGN1 =
                                "bg\0"
                                "fg\0"
                                "soft\0"
                                "hard\0"
                                "intr\0"
                                "posix\0"
                                "cto\0"
                                "ac\0"
                                "tcp\0"
                                "udp\0"
                                "lock\0";
                        int val = 1;
                        if (!strncmp(opt, "no", 2)) {
                                val = 0;
                                opt += 2;
                        }
                        switch (index_in_strings(options, opt)) {
                        case 0: // "bg"
#if BB_MMU
                                bg = val;
#endif
                                break;
                        case 1: // "fg"
#if BB_MMU
                                bg = !val;
#endif
                                break;
                        case 2: // "soft"
                                soft = val;
                                break;
                        case 3: // "hard"
                                soft = !val;
                                break;
                        case 4: // "intr"
                                intr = val;
                                break;
                        case 5: // "posix"
                                posix = val;
                                break;
                        case 6: // "cto"
                                nocto = !val;
                                break;
                        case 7: // "ac"
                                noac = !val;
                                break;
                        case 8: // "tcp"
                                tcp = val;
                                break;
                        case 9: // "udp"
                                tcp = !val;
                                break;
                        case 10: // "lock"
                                if (nfs_mount_version >= 3)
                                        nolock = !val;
                                else
                                        bb_error_msg("warning: option nolock is not supported");
                                break;
                        default:
                                bb_error_msg("unknown nfs mount option: %s%s", val ? "" : "no", opt);
                                goto fail;
                        }
                }
        }
        proto = (tcp) ? IPPROTO_TCP : IPPROTO_UDP;

        data.flags = (soft ? NFS_MOUNT_SOFT : 0)
                | (intr ? NFS_MOUNT_INTR : 0)
                | (posix ? NFS_MOUNT_POSIX : 0)
                | (nocto ? NFS_MOUNT_NOCTO : 0)
                | (noac ? NFS_MOUNT_NOAC : 0);
        if (nfs_mount_version >= 2)
                data.flags |= (tcp ? NFS_MOUNT_TCP : 0);
        if (nfs_mount_version >= 3)
                data.flags |= (nolock ? NFS_MOUNT_NONLM : 0);
        if (nfsvers > MAX_NFSPROT || mountvers > MAX_NFSPROT) {
                bb_error_msg("NFSv%d not supported", nfsvers);
                goto fail;
        }
        if (nfsvers && !mountvers)
                mountvers = (nfsvers < 3) ? 1 : nfsvers;
        if (nfsvers && nfsvers < mountvers) {
                mountvers = nfsvers;
        }

        /* Adjust options if none specified */
        if (!data.timeo)
                data.timeo = tcp ? 70 : 7;

        data.version = nfs_mount_version;

        if (vfsflags & MS_REMOUNT)
                goto do_mount;

        /*
         * If the previous mount operation on the same host was
         * backgrounded, and the "bg" for this mount is also set,
         * give up immediately, to avoid the initial timeout.
         */
        if (bg && we_saw_this_host_before(hostname)) {
                daemonized = daemonize();
                if (daemonized <= 0) { /* parent or error */
                        retval = -daemonized;
                        goto ret;
                }
        }

        /* create mount daemon client */
        /* See if the nfs host = mount host. */
        if (mounthost) {
                if (mounthost[0] >= '0' && mounthost[0] <= '9') {
                        mount_server_addr.sin_family = AF_INET;
                        mount_server_addr.sin_addr.s_addr = inet_addr(hostname);
                } else {
                        hp = gethostbyname(mounthost);
                        if (hp == NULL) {
                                bb_herror_msg("%s", mounthost);
                                goto fail;
                        } else {
                                if (hp->h_length > sizeof(struct in_addr)) {
                                        bb_error_msg("got bad hp->h_length?");
                                        hp->h_length = sizeof(struct in_addr);
                                }
                                mount_server_addr.sin_family = AF_INET;
                                memcpy(&mount_server_addr.sin_addr,
                                                hp->h_addr, hp->h_length);
                        }
                }
        }

        /*
         * The following loop implements the mount retries. When the mount
         * times out, and the "bg" option is set, we background ourself
         * and continue trying.
         *
         * The case where the mount point is not present and the "bg"
         * option is set, is treated as a timeout. This is done to
         * support nested mounts.
         *
         * The "retry" count specified by the user is the number of
         * minutes to retry before giving up.
         */
        {
                struct timeval total_timeout;
                struct timeval retry_timeout;
                struct pmap pm_mnt;
                time_t t;
                time_t prevt;
                time_t timeout;

                retry_timeout.tv_sec = 3;
                retry_timeout.tv_usec = 0;
                total_timeout.tv_sec = 20;
                total_timeout.tv_usec = 0;
                timeout = time(NULL) + 60 * retry;
                prevt = 0;
                t = 30;
retry:
                /* be careful not to use too many CPU cycles */
                if (t - prevt < 30)
                        sleep(30);

                get_mountport(&pm_mnt, &mount_server_addr,
                                mountprog,
                                mountvers,
                                proto,
                                mountport);
                nfsvers = (pm_mnt.pm_vers < 2) ? 2 : pm_mnt.pm_vers;

                /* contact the mount daemon via TCP */
                mount_server_addr.sin_port = htons(pm_mnt.pm_port);
                msock = RPC_ANYSOCK;

                switch (pm_mnt.pm_prot) {
                case IPPROTO_UDP:
                        mclient = clntudp_create(&mount_server_addr,
                                                 pm_mnt.pm_prog,
                                                 pm_mnt.pm_vers,
                                                 retry_timeout,
                                                 &msock);
                        if (mclient)
                                break;
                        mount_server_addr.sin_port = htons(pm_mnt.pm_port);
                        msock = RPC_ANYSOCK;
                case IPPROTO_TCP:
                        mclient = clnttcp_create(&mount_server_addr,
                                                 pm_mnt.pm_prog,
                                                 pm_mnt.pm_vers,
                                                 &msock, 0, 0);
                        break;
                default:
                        mclient = NULL;
                }
                if (!mclient) {
                        if (!daemonized && prevt == 0)
                                error_msg_rpc(clnt_spcreateerror(" "));
                } else {
                        enum clnt_stat clnt_stat;
                        /* try to mount hostname:pathname */
                        mclient->cl_auth = authunix_create_default();

                        /* make pointers in xdr_mountres3 NULL so
                         * that xdr_array allocates memory for us
                         */
                        memset(&status, 0, sizeof(status));

                        if (pm_mnt.pm_vers == 3)
                                clnt_stat = clnt_call(mclient, MOUNTPROC3_MNT,
                                              (xdrproc_t) xdr_dirpath,
                                              (caddr_t) &pathname,
                                              (xdrproc_t) xdr_mountres3,
                                              (caddr_t) &status,
                                              total_timeout);
                        else
                                clnt_stat = clnt_call(mclient, MOUNTPROC_MNT,
                                              (xdrproc_t) xdr_dirpath,
                                              (caddr_t) &pathname,
                                              (xdrproc_t) xdr_fhstatus,
                                              (caddr_t) &status,
                                              total_timeout);

                        if (clnt_stat == RPC_SUCCESS)
                                goto prepare_kernel_data; /* we're done */
                        if (errno != ECONNREFUSED) {
                                error_msg_rpc(clnt_sperror(mclient, " "));
                                goto fail;      /* don't retry */
                        }
                        /* Connection refused */
                        if (!daemonized && prevt == 0) /* print just once */
                                error_msg_rpc(clnt_sperror(mclient, " "));
                        auth_destroy(mclient->cl_auth);
                        clnt_destroy(mclient);
                        mclient = NULL;
                        close(msock);
                        msock = -1;
                }

                /* Timeout. We are going to retry... maybe */

                if (!bg)
                        goto fail;
                if (!daemonized) {
                        daemonized = daemonize();
                        if (daemonized <= 0) { /* parent or error */
                                retval = -daemonized;
                                goto ret;
                        }
                }
                prevt = t;
                t = time(NULL);
                if (t >= timeout)
                        /* TODO error message */
                        goto fail;

                goto retry;
        }

prepare_kernel_data:

        if (nfsvers == 2) {
                if (status.nfsv2.fhs_status != 0) {
                        bb_error_msg("%s:%s failed, reason given by server: %s",
                                hostname, pathname,
                                nfs_strerror(status.nfsv2.fhs_status));
                        goto fail;
                }
                memcpy(data.root.data,
                                (char *) status.nfsv2.fhstatus_u.fhs_fhandle,
                                NFS_FHSIZE);
                data.root.size = NFS_FHSIZE;
                memcpy(data.old_root.data,
                                (char *) status.nfsv2.fhstatus_u.fhs_fhandle,
                                NFS_FHSIZE);
        } else {
                fhandle3 *my_fhandle;
                if (status.nfsv3.fhs_status != 0) {
                        bb_error_msg("%s:%s failed, reason given by server: %s",
                                hostname, pathname,
                                nfs_strerror(status.nfsv3.fhs_status));
                        goto fail;
                }
                my_fhandle = &status.nfsv3.mountres3_u.mountinfo.fhandle;
                memset(data.old_root.data, 0, NFS_FHSIZE);
                memset(&data.root, 0, sizeof(data.root));
                data.root.size = my_fhandle->fhandle3_len;
                memcpy(data.root.data,
                                (char *) my_fhandle->fhandle3_val,
                                my_fhandle->fhandle3_len);

                data.flags |= NFS_MOUNT_VER3;
        }

        /* create nfs socket for kernel */

        if (tcp) {
                if (nfs_mount_version < 3) {
                        bb_error_msg("NFS over TCP is not supported");
                        goto fail;
                }
                fsock = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
        } else
                fsock = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
        if (fsock < 0) {
                bb_perror_msg("nfs socket");
                goto fail;
        }
        if (bindresvport(fsock, 0) < 0) {
                bb_perror_msg("nfs bindresvport");
                goto fail;
        }
        if (port == 0) {
                server_addr.sin_port = PMAPPORT;
                port = pmap_getport(&server_addr, nfsprog, nfsvers,
                                        tcp ? IPPROTO_TCP : IPPROTO_UDP);
                if (port == 0)
                        port = NFS_PORT;
        }
        server_addr.sin_port = htons(port);

        /* prepare data structure for kernel */

        data.fd = fsock;
        memcpy((char *) &data.addr, (char *) &server_addr, sizeof(data.addr));
        strncpy(data.hostname, hostname, sizeof(data.hostname));

        /* clean up */

        auth_destroy(mclient->cl_auth);
        clnt_destroy(mclient);
        close(msock);
        msock = -1;

        if (bg) {
                /* We must wait until mount directory is available */
                struct stat statbuf;
                int delay = 1;
                while (stat(mp->mnt_dir, &statbuf) == -1) {
                        if (!daemonized) {
                                daemonized = daemonize();
                                if (daemonized <= 0) { /* parent or error */
        // FIXME: parent doesn't close fsock - ??!
                                        retval = -daemonized;
                                        goto ret;
                                }
                        }
                        sleep(delay);   /* 1, 2, 4, 8, 16, 30, ... */
                        delay *= 2;
                        if (delay > 30)
                                delay = 30;
                }
        }

do_mount: /* perform actual mount */

        mp->mnt_type = (char*)"nfs";
        retval = mount_it_now(mp, vfsflags, (char*)&data);
        goto ret;

fail:   /* abort */

        if (msock >= 0) {
                if (mclient) {
                        auth_destroy(mclient->cl_auth);
                        clnt_destroy(mclient);
                }
                close(msock);
        }
        if (fsock >= 0)
                close(fsock);

ret:
        free(hostname);
        free(mounthost);
        free(filteropts);
        return retval;
}

#else /* !ENABLE_FEATURE_MOUNT_NFS */

/* Never called. Call should be optimized out. */
int nfsmount(struct mntent *mp, int vfsflags, char *filteropts);

#endif /* !ENABLE_FEATURE_MOUNT_NFS */

// Mount one directory.  Handles CIFS, NFS, loopback, autobind, and filesystem
// type detection.  Returns 0 for success, nonzero for failure.
// NB: mp->xxx fields may be trashed on exit
static int singlemount(struct mntent *mp, int ignore_busy)
{
        int rc = -1, vfsflags;
        char *loopFile = 0, *filteropts = 0;
        llist_t *fl = 0;
        struct stat st;

        vfsflags = parse_mount_options(mp->mnt_opts, &filteropts);

        // Treat fstype "auto" as unspecified.

        if (mp->mnt_type && strcmp(mp->mnt_type,"auto") == 0)
                mp->mnt_type = 0;

        // Might this be a virtual filesystem?

        if (ENABLE_FEATURE_MOUNT_HELPERS
         && (strchr(mp->mnt_fsname,'#'))
        ) {
                char *s, *p, *args[35];
                int n = 0;
                for (s = p = mp->mnt_fsname; *s && n < 35-3; ++s) {
                        if (s[0] == '#' && s[1] != '#') {
                                *s = '\0';
                                args[n++] = p;
                                p = s + 1;
                        }
                }
                args[n++] = p;
                args[n++] = mp->mnt_dir;
                args[n] = NULL;
                rc = wait4pid(xspawn(args));
                goto report_error;
        }

        // Might this be an CIFS filesystem?

        if (ENABLE_FEATURE_MOUNT_CIFS
         && (!mp->mnt_type || strcmp(mp->mnt_type,"cifs") == 0)
         && (mp->mnt_fsname[0]=='/' || mp->mnt_fsname[0]=='\\')
         && mp->mnt_fsname[0]==mp->mnt_fsname[1]
        ) {
                len_and_sockaddr *lsa;
                char *ip, *dotted;
                char *s;

                rc = 1;
                // Replace '/' with '\' and verify that unc points to "//server/share".

                for (s = mp->mnt_fsname; *s; ++s)
                        if (*s == '/') *s = '\\';

                // get server IP

                s = strrchr(mp->mnt_fsname, '\\');
                if (s <= mp->mnt_fsname+1) goto report_error;
                *s = '\0';
                lsa = host2sockaddr(mp->mnt_fsname+2, 0);
                *s = '\\';
                if (!lsa) goto report_error;

                // insert ip=... option into string flags.

                dotted = xmalloc_sockaddr2dotted_noport(&lsa->sa);
                ip = xasprintf("ip=%s", dotted);
                parse_mount_options(ip, &filteropts);

                // compose new unc '\\server-ip\share'
                // (s => slash after hostname)

                mp->mnt_fsname = xasprintf("\\\\%s%s", dotted, s);

                // lock is required
                vfsflags |= MS_MANDLOCK;

                mp->mnt_type = (char*)"cifs";
                rc = mount_it_now(mp, vfsflags, filteropts);
                if (ENABLE_FEATURE_CLEAN_UP) {
                        free(mp->mnt_fsname);
                        free(ip);
                        free(dotted);
                        free(lsa);
                }
                goto report_error;
        }

        // Might this be an NFS filesystem?

        if (ENABLE_FEATURE_MOUNT_NFS
         && (!mp->mnt_type || !strcmp(mp->mnt_type, "nfs"))
         && strchr(mp->mnt_fsname, ':') != NULL
        ) {
                rc = nfsmount(mp, vfsflags, filteropts);
                goto report_error;
        }

        // Look at the file.  (Not found isn't a failure for remount, or for
        // a synthetic filesystem like proc or sysfs.)
        // (We use stat, not lstat, in order to allow
        // mount symlink_to_file_or_blkdev dir)

        if (!stat(mp->mnt_fsname, &st)
         && !(vfsflags & (MS_REMOUNT | MS_BIND | MS_MOVE))
        ) {
                // Do we need to allocate a loopback device for it?

                if (ENABLE_FEATURE_MOUNT_LOOP && S_ISREG(st.st_mode)) {
                        loopFile = bb_simplify_path(mp->mnt_fsname);
                        mp->mnt_fsname = NULL; /* will receive malloced loop dev name */
                        if (set_loop(&(mp->mnt_fsname), loopFile, 0) < 0) {
                                if (errno == EPERM || errno == EACCES)
                                        bb_error_msg(bb_msg_perm_denied_are_you_root);
                                else
                                        bb_perror_msg("cannot setup loop device");
                                return errno;
                        }

                // Autodetect bind mounts

                } else if (S_ISDIR(st.st_mode) && !mp->mnt_type)
                        vfsflags |= MS_BIND;
        }

        /* If we know the fstype (or don't need to), jump straight
         * to the actual mount. */

        if (mp->mnt_type || (vfsflags & (MS_REMOUNT | MS_BIND | MS_MOVE)))
                rc = mount_it_now(mp, vfsflags, filteropts);
        else {
                // Loop through filesystem types until mount succeeds
                // or we run out

                /* Initialize list of block backed filesystems.  This has to be
                 * done here so that during "mount -a", mounts after /proc shows up
                 * can autodetect. */

                if (!fslist) {
                        fslist = get_block_backed_filesystems();
                        if (ENABLE_FEATURE_CLEAN_UP && fslist)
                                atexit(delete_block_backed_filesystems);
                }

                for (fl = fslist; fl; fl = fl->link) {
                        mp->mnt_type = fl->data;
                        rc = mount_it_now(mp, vfsflags, filteropts);
                        if (!rc) break;
                }
        }

        // If mount failed, clean up loop file (if any).

        if (ENABLE_FEATURE_MOUNT_LOOP && rc && loopFile) {
                del_loop(mp->mnt_fsname);
                if (ENABLE_FEATURE_CLEAN_UP) {
                        free(loopFile);
                        free(mp->mnt_fsname);
                }
        }

 report_error:
        if (ENABLE_FEATURE_CLEAN_UP)
                free(filteropts);

        if (errno == EBUSY && ignore_busy)
                return 0;
        if (rc < 0)
                bb_perror_msg("mounting %s on %s failed", mp->mnt_fsname, mp->mnt_dir);
        return rc;
}

// Parse options, if necessary parse fstab/mtab, and call singlemount for
// each directory to be mounted.

static const char must_be_root[] ALIGN1 = "you must be root";

int mount_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int mount_main(int argc, char **argv)
{
        enum { OPT_ALL = 0x10 };

        char *cmdopts = xstrdup(""), *fstype=0, *storage_path=0;
        char *opt_o;
        const char *fstabname;
        FILE *fstab;
        int i, j, rc = 0;
        unsigned opt;
        struct mntent mtpair[2], *mtcur = mtpair;
        SKIP_DESKTOP(const int nonroot = 0;)
        USE_DESKTOP( int nonroot = (getuid() != 0);)

        /* parse long options, like --bind and --move.  Note that -o option
         * and --option are synonymous.  Yes, this means --remount,rw works. */

        for (i = j = 0; i < argc; i++) {
                if (argv[i][0] == '-' && argv[i][1] == '-') {
                        append_mount_options(&cmdopts, argv[i]+2);
                } else argv[j++] = argv[i];
        }
        argv[j] = 0;
        argc = j;

        // Parse remaining options

        opt = getopt32(argv, "o:t:rwanfvsi", &opt_o, &fstype);
        if (opt & 0x1) append_mount_options(&cmdopts, opt_o); // -o
        //if (opt & 0x2) // -t
        if (opt & 0x4) append_mount_options(&cmdopts, "ro"); // -r
        if (opt & 0x8) append_mount_options(&cmdopts, "rw"); // -w
        //if (opt & 0x10) // -a
        if (opt & 0x20) USE_FEATURE_MTAB_SUPPORT(useMtab = 0); // -n
        if (opt & 0x40) USE_FEATURE_MTAB_SUPPORT(fakeIt = 1); // -f
        //if (opt & 0x80) // -v: verbose (ignore)
        //if (opt & 0x100) // -s: sloppy (ignore)
        //if (opt & 0x200) // -i: don't call mount.<fstype> (ignore)
        argv += optind;
        argc -= optind;

        // Three or more non-option arguments?  Die with a usage message.

        if (argc > 2) bb_show_usage();

        // If we have no arguments, show currently mounted filesystems

        if (!argc) {
                if (!(opt & OPT_ALL)) {
                        FILE *mountTable = setmntent(bb_path_mtab_file, "r");

                        if (!mountTable) bb_error_msg_and_die("no %s", bb_path_mtab_file);

                        while (getmntent_r(mountTable, &mtpair[0], getmntent_buf,
                                                                sizeof(getmntent_buf)))
                        {
                                // Don't show rootfs. FIXME: why??
                                // util-linux 2.12a happily shows rootfs...
                                //if (!strcmp(mtpair->mnt_fsname, "rootfs")) continue;

                                if (!fstype || !strcmp(mtpair->mnt_type, fstype))
                                        printf("%s on %s type %s (%s)\n", mtpair->mnt_fsname,
                                                        mtpair->mnt_dir, mtpair->mnt_type,
                                                        mtpair->mnt_opts);
                        }
                        if (ENABLE_FEATURE_CLEAN_UP) endmntent(mountTable);
                        return EXIT_SUCCESS;
                }
        } else storage_path = bb_simplify_path(argv[0]);

        // When we have two arguments, the second is the directory and we can
        // skip looking at fstab entirely.  We can always abspath() the directory
        // argument when we get it.

        if (argc == 2) {
                if (nonroot)
                        bb_error_msg_and_die(must_be_root);
                mtpair->mnt_fsname = argv[0];
                mtpair->mnt_dir = argv[1];
                mtpair->mnt_type = fstype;
                mtpair->mnt_opts = cmdopts;
                rc = singlemount(mtpair, 0);
                goto clean_up;
        }

        i = parse_mount_options(cmdopts, 0);
        if (nonroot && (i & ~MS_SILENT)) // Non-root users cannot specify flags
                bb_error_msg_and_die(must_be_root);

        // If we have a shared subtree flag, don't worry about fstab or mtab.

        if (ENABLE_FEATURE_MOUNT_FLAGS
         && (i & (MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE))
        ) {
                rc = mount("", argv[0], "", i, "");
                if (rc) bb_simple_perror_msg_and_die(argv[0]);
                goto clean_up;
        }

        // Open either fstab or mtab

        fstabname = "/etc/fstab";
        if (i & MS_REMOUNT) {
                fstabname = bb_path_mtab_file;
        }
        fstab = setmntent(fstabname, "r");
        if (!fstab)
                bb_perror_msg_and_die("cannot read %s", fstabname);

        // Loop through entries until we find what we're looking for.

        memset(mtpair, 0, sizeof(mtpair));
        for (;;) {
                struct mntent *mtnext = (mtcur==mtpair ? mtpair+1 : mtpair);

                // Get next fstab entry

                if (!getmntent_r(fstab, mtcur, getmntent_buf
                                        + (mtcur==mtpair ? sizeof(getmntent_buf)/2 : 0),
                                sizeof(getmntent_buf)/2))
                {
                        // Were we looking for something specific?

                        if (argc) {

                                // If we didn't find anything, complain.

                                if (!mtnext->mnt_fsname)
                                        bb_error_msg_and_die("can't find %s in %s",
                                                argv[0], fstabname);

                                mtcur = mtnext;
                                if (nonroot) {
                                        // fstab must have "users" or "user"
                                        if (!(parse_mount_options(mtcur->mnt_opts, 0) & MOUNT_USERS))
                                                bb_error_msg_and_die(must_be_root);
                                }

                                // Mount the last thing we found.

                                mtcur->mnt_opts = xstrdup(mtcur->mnt_opts);
                                append_mount_options(&(mtcur->mnt_opts), cmdopts);
                                rc = singlemount(mtcur, 0);
                                free(mtcur->mnt_opts);
                        }
                        goto clean_up;
                }

                /* If we're trying to mount something specific and this isn't it,
                 * skip it.  Note we must match both the exact text in fstab (ala
                 * "proc") or a full path from root */

                if (argc) {

                        // Is this what we're looking for?

                        if (strcmp(argv[0], mtcur->mnt_fsname) &&
                           strcmp(storage_path, mtcur->mnt_fsname) &&
                           strcmp(argv[0], mtcur->mnt_dir) &&
                           strcmp(storage_path, mtcur->mnt_dir)) continue;

                        // Remember this entry.  Something later may have overmounted
                        // it, and we want the _last_ match.

                        mtcur = mtnext;

                // If we're mounting all.

                } else {
                        // Do we need to match a filesystem type?
                        if (fstype && match_fstype(mtcur, fstype)) continue;

                        // Skip noauto and swap anyway.

                        if (parse_mount_options(mtcur->mnt_opts, 0)
                                & (MOUNT_NOAUTO | MOUNT_SWAP)) continue;

                        // No, mount -a won't mount anything,
                        // even user mounts, for mere humans.

                        if (nonroot)
                                bb_error_msg_and_die(must_be_root);

                        // Mount this thing.

                        // NFS mounts want this to be xrealloc-able
                        mtcur->mnt_opts = xstrdup(mtcur->mnt_opts);
                        if (singlemount(mtcur, 1)) {
                                /* Count number of failed mounts */
                                rc++;
                        }
                        free(mtcur->mnt_opts);
                }
        }
        if (ENABLE_FEATURE_CLEAN_UP) endmntent(fstab);

clean_up:

        if (ENABLE_FEATURE_CLEAN_UP) {
                free(storage_path);
                free(cmdopts);
        }

        return rc;
}