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[rsync.git] / main.c

/*
 * The startup routines, including main(), for rsync.
 *
 * Copyright (C) 1996-2001 Andrew Tridgell <tridge@samba.org>
 * Copyright (C) 1996 Paul Mackerras
 * Copyright (C) 2001, 2002 Martin Pool <mbp@samba.org>
 * Copyright (C) 2003-2008 Wayne Davison
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, visit the http://fsf.org website.
 */

#include "rsync.h"
#include "ifuncs.h"
#include "io.h"
#if defined CONFIG_LOCALE && defined HAVE_LOCALE_H
#include <locale.h>
#endif

extern int verbose;
extern int dry_run;
extern int list_only;
extern int am_root;
extern int am_server;
extern int am_sender;
extern int am_generator;
extern int am_daemon;
extern int inc_recurse;
extern int blocking_io;
extern int remove_source_files;
extern int need_messages_from_generator;
extern int kluge_around_eof;
extern int do_stats;
extern int got_xfer_error;
extern int module_id;
extern int copy_links;
extern int copy_dirlinks;
extern int copy_unsafe_links;
extern int keep_dirlinks;
extern int preserve_hard_links;
extern int protocol_version;
extern int file_total;
extern int recurse;
extern int xfer_dirs;
extern int protect_args;
extern int relative_paths;
extern int sanitize_paths;
extern int curr_dir_depth;
extern int curr_dir_len;
extern int module_id;
extern int rsync_port;
extern int whole_file;
extern int read_batch;
extern int write_batch;
extern int batch_fd;
extern int filesfrom_fd;
extern int connect_timeout;
extern pid_t cleanup_child_pid;
extern unsigned int module_dirlen;
extern struct stats stats;
extern char *filesfrom_host;
extern char *partial_dir;
extern char *dest_option;
extern char *basis_dir[];
extern char *rsync_path;
extern char *shell_cmd;
extern char *batch_name;
extern char *password_file;
extern char curr_dir[MAXPATHLEN];
extern struct file_list *first_flist;
extern struct filter_list_struct daemon_filter_list;

uid_t our_uid;
int local_server = 0;
int daemon_over_rsh = 0;
mode_t orig_umask = 0;
int batch_gen_fd = -1;

/* There's probably never more than at most 2 outstanding child processes,
 * but set it higher, just in case. */
#define MAXCHILDPROCS 7

#ifdef HAVE_SIGACTION
# ifdef HAVE_SIGPROCMASK
#  define SIGACTMASK(n,h) SIGACTION(n,h), sigaddset(&sigmask,(n))
# else
#  define SIGACTMASK(n,h) SIGACTION(n,h)
# endif
static struct sigaction sigact;
#endif

struct pid_status {
        pid_t pid;
        int status;
} pid_stat_table[MAXCHILDPROCS];

static time_t starttime, endtime;
static int64 total_read, total_written;

static void show_malloc_stats(void);

/* Works like waitpid(), but if we already harvested the child pid in our
 * remember_children(), we succeed instead of returning an error. */
pid_t wait_process(pid_t pid, int *status_ptr, int flags)
{
        pid_t waited_pid;
        
        do {
                waited_pid = waitpid(pid, status_ptr, flags);
        } while (waited_pid == -1 && errno == EINTR);

        if (waited_pid == -1 && errno == ECHILD) {
                /* Status of requested child no longer available:  check to
                 * see if it was processed by remember_children(). */
                int cnt;
                for (cnt = 0; cnt < MAXCHILDPROCS; cnt++) {
                        if (pid == pid_stat_table[cnt].pid) {
                                *status_ptr = pid_stat_table[cnt].status;
                                pid_stat_table[cnt].pid = 0;
                                return pid;
                        }
                }
        }

        return waited_pid;
}

/* Wait for a process to exit, calling io_flush while waiting. */
static void wait_process_with_flush(pid_t pid, int *exit_code_ptr)
{
        pid_t waited_pid;
        int status;

        while ((waited_pid = wait_process(pid, &status, WNOHANG)) == 0) {
                msleep(20);
                io_flush(FULL_FLUSH);
        }

        /* TODO: If the child exited on a signal, then log an
         * appropriate error message.  Perhaps we should also accept a
         * message describing the purpose of the child.  Also indicate
         * this to the caller so that they know something went wrong. */
        if (waited_pid < 0) {
                rsyserr(FERROR, errno, "waitpid");
                *exit_code_ptr = RERR_WAITCHILD;
        } else if (!WIFEXITED(status)) {
#ifdef WCOREDUMP
                if (WCOREDUMP(status))
                        *exit_code_ptr = RERR_CRASHED;
                else
#endif
                if (WIFSIGNALED(status))
                        *exit_code_ptr = RERR_TERMINATED;
                else
                        *exit_code_ptr = RERR_WAITCHILD;
        } else
                *exit_code_ptr = WEXITSTATUS(status);
}

/* This function gets called from all 3 processes.  We want the client side
 * to actually output the text, but the sender is the only process that has
 * all the stats we need.  So, if we're a client sender, we do the report.
 * If we're a server sender, we write the stats on the supplied fd.  If
 * we're the client receiver we read the stats from the supplied fd and do
 * the report.  All processes might also generate a set of debug stats, if
 * the verbose level is high enough (this is the only thing that the
 * generator process and the server receiver ever do here). */
static void handle_stats(int f)
{
        endtime = time(NULL);

        /* Cache two stats because the read/write code can change it. */
        total_read = stats.total_read;
        total_written = stats.total_written;

        if (do_stats && verbose > 1) {
                /* These come out from every process */
                show_malloc_stats();
                show_flist_stats();
        }

        if (am_generator)
                return;

        if (am_daemon) {
                if (f == -1 || !am_sender)
                        return;
        }

        if (am_server) {
                if (am_sender) {
                        write_varlong30(f, total_read, 3);
                        write_varlong30(f, total_written, 3);
                        write_varlong30(f, stats.total_size, 3);
                        if (protocol_version >= 29) {
                                write_varlong30(f, stats.flist_buildtime, 3);
                                write_varlong30(f, stats.flist_xfertime, 3);
                        }
                }
                return;
        }

        /* this is the client */

        if (f < 0 && !am_sender) /* e.g. when we got an empty file list. */
                ;
        else if (!am_sender) {
                /* Read the first two in opposite order because the meaning of
                 * read/write swaps when switching from sender to receiver. */
                total_written = read_varlong30(f, 3);
                total_read = read_varlong30(f, 3);
                stats.total_size = read_varlong30(f, 3);
                if (protocol_version >= 29) {
                        stats.flist_buildtime = read_varlong30(f, 3);
                        stats.flist_xfertime = read_varlong30(f, 3);
                }
        } else if (write_batch) {
                /* The --read-batch process is going to be a client
                 * receiver, so we need to give it the stats. */
                write_varlong30(batch_fd, total_read, 3);
                write_varlong30(batch_fd, total_written, 3);
                write_varlong30(batch_fd, stats.total_size, 3);
                if (protocol_version >= 29) {
                        write_varlong30(batch_fd, stats.flist_buildtime, 3);
                        write_varlong30(batch_fd, stats.flist_xfertime, 3);
                }
        }
}

static void output_summary(void)
{
        if (do_stats) {
                rprintf(FCLIENT, "\n");
                rprintf(FINFO,"Number of files: %d\n", stats.num_files);
                rprintf(FINFO,"Number of files transferred: %d\n",
                        stats.num_transferred_files);
                rprintf(FINFO,"Total file size: %s bytes\n",
                        human_num(stats.total_size));
                rprintf(FINFO,"Total transferred file size: %s bytes\n",
                        human_num(stats.total_transferred_size));
                rprintf(FINFO,"Literal data: %s bytes\n",
                        human_num(stats.literal_data));
                rprintf(FINFO,"Matched data: %s bytes\n",
                        human_num(stats.matched_data));
                rprintf(FINFO,"File list size: %s\n",
                        human_num(stats.flist_size));
                if (stats.flist_buildtime) {
                        rprintf(FINFO,
                                "File list generation time: %.3f seconds\n",
                                (double)stats.flist_buildtime / 1000);
                        rprintf(FINFO,
                                "File list transfer time: %.3f seconds\n",
                                (double)stats.flist_xfertime / 1000);
                }
                rprintf(FINFO,"Total bytes sent: %s\n",
                        human_num(total_written));
                rprintf(FINFO,"Total bytes received: %s\n",
                        human_num(total_read));
        }

        if (verbose || do_stats) {
                rprintf(FCLIENT, "\n");
                rprintf(FINFO,
                        "sent %s bytes  received %s bytes  %s bytes/sec\n",
                        human_num(total_written), human_num(total_read),
                        human_dnum((total_written + total_read)/(0.5 + (endtime - starttime)), 2));
                rprintf(FINFO, "total size is %s  speedup is %.2f%s\n",
                        human_num(stats.total_size),
                        (double)stats.total_size / (total_written+total_read),
                        write_batch < 0 ? " (BATCH ONLY)" : dry_run ? " (DRY RUN)" : "");
        }

        fflush(stdout);
        fflush(stderr);
}


/**
 * If our C library can get malloc statistics, then show them to FINFO
 **/
static void show_malloc_stats(void)
{
#ifdef HAVE_MALLINFO
        struct mallinfo mi;

        mi = mallinfo();

        rprintf(FCLIENT, "\n");
        rprintf(FINFO, RSYNC_NAME "[%d] (%s%s%s) heap statistics:\n",
                getpid(), am_server ? "server " : "",
                am_daemon ? "daemon " : "", who_am_i());
        rprintf(FINFO, "  arena:     %10ld   (bytes from sbrk)\n",
                (long)mi.arena);
        rprintf(FINFO, "  ordblks:   %10ld   (chunks not in use)\n",
                (long)mi.ordblks);
        rprintf(FINFO, "  smblks:    %10ld\n",
                (long)mi.smblks);
        rprintf(FINFO, "  hblks:     %10ld   (chunks from mmap)\n",
                (long)mi.hblks);
        rprintf(FINFO, "  hblkhd:    %10ld   (bytes from mmap)\n",
                (long)mi.hblkhd);
        rprintf(FINFO, "  allmem:    %10ld   (bytes from sbrk + mmap)\n",
                (long)mi.arena + mi.hblkhd);
        rprintf(FINFO, "  usmblks:   %10ld\n",
                (long)mi.usmblks);
        rprintf(FINFO, "  fsmblks:   %10ld\n",
                (long)mi.fsmblks);
        rprintf(FINFO, "  uordblks:  %10ld   (bytes used)\n",
                (long)mi.uordblks);
        rprintf(FINFO, "  fordblks:  %10ld   (bytes free)\n",
                (long)mi.fordblks);
        rprintf(FINFO, "  keepcost:  %10ld   (bytes in releasable chunk)\n",
                (long)mi.keepcost);
#endif /* HAVE_MALLINFO */
}


/* Start the remote shell.   cmd may be NULL to use the default. */
static pid_t do_cmd(char *cmd, char *machine, char *user, char **remote_argv, int remote_argc,
                    int *f_in_p, int *f_out_p)
{
        int i, argc = 0;
        char *args[MAX_ARGS];
        pid_t pid;
        int dash_l_set = 0;

        if (!read_batch && !local_server) {
                char *t, *f, in_quote = '\0';
                char *rsh_env = getenv(RSYNC_RSH_ENV);
                if (!cmd)
                        cmd = rsh_env;
                if (!cmd)
                        cmd = RSYNC_RSH;
                cmd = strdup(cmd); /* MEMORY LEAK */
                if (!cmd)
                        goto oom;

                for (t = f = cmd; *f; f++) {
                        if (*f == ' ')
                                continue;
                        /* Comparison leaves rooms for server_options(). */
                        if (argc >= MAX_ARGS - MAX_SERVER_ARGS)
                                goto arg_overflow;
                        args[argc++] = t;
                        while (*f != ' ' || in_quote) {
                                if (!*f) {
                                        if (in_quote) {
                                                rprintf(FERROR,
                                                    "Missing trailing-%c in remote-shell command.\n",
                                                    in_quote);
                                                exit_cleanup(RERR_SYNTAX);
                                        }
                                        f--;
                                        break;
                                }
                                if (*f == '\'' || *f == '"') {
                                        if (!in_quote) {
                                                in_quote = *f++;
                                                continue;
                                        }
                                        if (*f == in_quote && *++f != in_quote) {
                                                in_quote = '\0';
                                                continue;
                                        }
                                }
                                *t++ = *f++;
                        }
                        *t++ = '\0';
                }

                /* check to see if we've already been given '-l user' in
                 * the remote-shell command */
                for (i = 0; i < argc-1; i++) {
                        if (!strcmp(args[i], "-l") && args[i+1][0] != '-')
                                dash_l_set = 1;
                }

#ifdef HAVE_REMSH
                /* remsh (on HPUX) takes the arguments the other way around */
                args[argc++] = machine;
                if (user && !(daemon_over_rsh && dash_l_set)) {
                        args[argc++] = "-l";
                        args[argc++] = user;
                }
#else
                if (user && !(daemon_over_rsh && dash_l_set)) {
                        args[argc++] = "-l";
                        args[argc++] = user;
                }
                args[argc++] = machine;
#endif

                args[argc++] = rsync_path;

                if (blocking_io < 0) {
                        char *cp;
                        if ((cp = strrchr(cmd, '/')) != NULL)
                                cp++;
                        else
                                cp = cmd;
                        if (strcmp(cp, "rsh") == 0 || strcmp(cp, "remsh") == 0)
                                blocking_io = 1;
                }

                server_options(args,&argc);

                if (argc >= MAX_ARGS - 2)
                        goto arg_overflow;
        }

        args[argc++] = ".";

        if (!daemon_over_rsh) {
                while (remote_argc > 0) {
                        if (argc >= MAX_ARGS - 1) {
                          arg_overflow:
                                rprintf(FERROR, "internal: args[] overflowed in do_cmd()\n");
                                exit_cleanup(RERR_SYNTAX);
                        }
                        args[argc++] = *remote_argv++;
                        remote_argc--;
                }
        }

        args[argc] = NULL;

        if (verbose > 3) {
                for (i = 0; i < argc; i++)
                        rprintf(FCLIENT, "cmd[%d]=%s ", i, args[i]);
                rprintf(FCLIENT, "\n");
        }

        if (read_batch) {
                int from_gen_pipe[2];
                set_allow_inc_recurse();
                if (fd_pair(from_gen_pipe) < 0) {
                        rsyserr(FERROR, errno, "pipe");
                        exit_cleanup(RERR_IPC);
                }
                batch_gen_fd = from_gen_pipe[0];
                *f_out_p = from_gen_pipe[1];
                *f_in_p = batch_fd;
                pid = (pid_t)-1; /* no child pid */
#ifdef ICONV_CONST
                setup_iconv();
#endif
        } else if (local_server) {
                /* If the user didn't request --[no-]whole-file, force
                 * it on, but only if we're not batch processing. */
                if (whole_file < 0 && !write_batch)
                        whole_file = 1;
                set_allow_inc_recurse();
                pid = local_child(argc, args, f_in_p, f_out_p, child_main);
#ifdef ICONV_CONST
                setup_iconv();
#endif
        } else {
                pid = piped_child(args, f_in_p, f_out_p);
#ifdef ICONV_CONST
                setup_iconv();
#endif
                if (protect_args)
                        send_protected_args(*f_out_p, args);
        }

        return pid;

  oom:
        out_of_memory("do_cmd");
        return 0; /* not reached */
}

/* The receiving side operates in one of two modes:
 *
 * 1. it receives any number of files into a destination directory,
 * placing them according to their names in the file-list.
 *
 * 2. it receives a single file and saves it using the name in the
 * destination path instead of its file-list name.  This requires a
 * "local name" for writing out the destination file.
 *
 * So, our task is to figure out what mode/local-name we need.
 * For mode 1, we change into the destination directory and return NULL.
 * For mode 2, we change into the directory containing the destination
 * file (if we aren't already there) and return the local-name. */
static char *get_local_name(struct file_list *flist, char *dest_path)
{
        STRUCT_STAT st;
        int statret;
        char *cp;

        if (verbose > 2) {
                rprintf(FINFO, "get_local_name count=%d %s\n",
                        file_total, NS(dest_path));
        }

        if (!dest_path || list_only)
                return NULL;

        if (daemon_filter_list.head) {
                char *slash = strrchr(dest_path, '/');
                if (slash && slash[1] == '\0')
                        *slash = '\0';
                else
                        slash = NULL;
                if (check_filter(&daemon_filter_list, FLOG, dest_path, 0) < 0
                 || check_filter(&daemon_filter_list, FLOG, dest_path, 1) < 0) {
                        rprintf(FERROR, "skipping daemon-excluded destination \"%s\"\n",
                                dest_path);
                        exit_cleanup(RERR_FILESELECT);
                }
                if (slash)
                        *slash = '/';
        }

        /* See what currently exists at the destination. */
        if ((statret = do_stat(dest_path, &st)) == 0) {
                /* If the destination is a dir, enter it and use mode 1. */
                if (S_ISDIR(st.st_mode)) {
                        if (!change_dir(dest_path, CD_NORMAL)) {
                                rsyserr(FERROR, errno, "change_dir#1 %s failed",
                                        full_fname(dest_path));
                                exit_cleanup(RERR_FILESELECT);
                        }
                        return NULL;
                }
                if (file_total > 1) {
                        rprintf(FERROR,
                                "ERROR: destination must be a directory when"
                                " copying more than 1 file\n");
                        exit_cleanup(RERR_FILESELECT);
                }
                if (file_total == 1 && S_ISDIR(flist->files[0]->mode)) {
                        rprintf(FERROR,
                                "ERROR: cannot overwrite non-directory"
                                " with a directory\n");
                        exit_cleanup(RERR_FILESELECT);
                }
        } else if (errno != ENOENT) {
                /* If we don't know what's at the destination, fail. */
                rsyserr(FERROR, errno, "ERROR: cannot stat destination %s",
                        full_fname(dest_path));
                exit_cleanup(RERR_FILESELECT);
        }

        cp = strrchr(dest_path, '/');

        /* If we need a destination directory because the transfer is not
         * of a single non-directory or the user has requested one via a
         * destination path ending in a slash, create one and use mode 1. */
        if (file_total > 1 || (cp && !cp[1])) {
                /* Lop off the final slash (if any). */
                if (cp && !cp[1])
                        *cp = '\0';

                if (statret == 0) {
                        rprintf(FERROR,
                            "ERROR: destination path is not a directory\n");
                        exit_cleanup(RERR_SYNTAX);
                }

                if (mkdir_defmode(dest_path) != 0) {
                        rsyserr(FERROR, errno, "mkdir %s failed",
                                full_fname(dest_path));
                        exit_cleanup(RERR_FILEIO);
                }

                if (flist->high >= flist->low
                 && strcmp(flist->files[flist->low]->basename, ".") == 0)
                        flist->files[0]->flags |= FLAG_DIR_CREATED;

                if (verbose)
                        rprintf(FINFO, "created directory %s\n", dest_path);

                if (dry_run) {
                        /* Indicate that dest dir doesn't really exist. */
                        dry_run++;
                }

                if (!change_dir(dest_path, dry_run > 1 ? CD_SKIP_CHDIR : CD_NORMAL)) {
                        rsyserr(FERROR, errno, "change_dir#2 %s failed",
                                full_fname(dest_path));
                        exit_cleanup(RERR_FILESELECT);
                }

                return NULL;
        }

        /* Otherwise, we are writing a single file, possibly on top of an
         * existing non-directory.  Change to the item's parent directory
         * (if it has a path component), return the basename of the
         * destination file as the local name, and use mode 2. */
        if (!cp)
                return dest_path;

        if (cp == dest_path)
                dest_path = "/";

        *cp = '\0';
        if (!change_dir(dest_path, CD_NORMAL)) {
                rsyserr(FERROR, errno, "change_dir#3 %s failed",
                        full_fname(dest_path));
                exit_cleanup(RERR_FILESELECT);
        }
        *cp = '/';

        return cp + 1;
}

/* This function checks on our alternate-basis directories.  If we're in
 * dry-run mode and the destination dir does not yet exist, we'll try to
 * tweak any dest-relative paths to make them work for a dry-run (the
 * destination dir must be in curr_dir[] when this function is called).
 * We also warn about any arg that is non-existent or not a directory. */
static void check_alt_basis_dirs(void)
{
        STRUCT_STAT st;
        char **dir_p, *slash = strrchr(curr_dir, '/');

        for (dir_p = basis_dir; *dir_p; dir_p++) {
                if (dry_run > 1 && **dir_p != '/') {
                        int len = curr_dir_len + 1 + strlen(*dir_p) + 1;
                        char *new = new_array(char, len);
                        if (!new)
                                out_of_memory("check_alt_basis_dirs");
                        if (slash && strncmp(*dir_p, "../", 3) == 0) {
                            /* We want to remove only one leading "../" prefix for
                             * the directory we couldn't create in dry-run mode:
                             * this ensures that any other ".." references get
                             * evaluated the same as they would for a live copy. */
                            *slash = '\0';
                            pathjoin(new, len, curr_dir, *dir_p + 3);
                            *slash = '/';
                        } else
                            pathjoin(new, len, curr_dir, *dir_p);
                        *dir_p = new;
                }
                if (do_stat(*dir_p, &st) < 0) {
                        rprintf(FWARNING, "%s arg does not exist: %s\n",
                                dest_option, *dir_p);
                } else if (!S_ISDIR(st.st_mode)) {
                        rprintf(FWARNING, "%s arg is not a dir: %s\n",
                                dest_option, *dir_p);
                }
        }
}

/* This is only called by the sender. */
static void read_final_goodbye(int f_in)
{
        int i, iflags, xlen;
        uchar fnamecmp_type;
        char xname[MAXPATHLEN];

        if (protocol_version < 29)
                i = read_int(f_in);
        else {
                i = read_ndx_and_attrs(f_in, &iflags, &fnamecmp_type,
                                       xname, &xlen);
        }

        if (i != NDX_DONE) {
                rprintf(FERROR, "Invalid packet at end of run (%d) [%s]\n",
                        i, who_am_i());
                exit_cleanup(RERR_PROTOCOL);
        }
}

static void do_server_sender(int f_in, int f_out, int argc, char *argv[])
{
        struct file_list *flist;
        char *dir = argv[0];

        if (verbose > 2) {
                rprintf(FINFO, "server_sender starting pid=%ld\n",
                        (long)getpid());
        }

        if (am_daemon && lp_write_only(module_id)) {
                rprintf(FERROR, "ERROR: module is write only\n");
                exit_cleanup(RERR_SYNTAX);
                return;
        }
        if (am_daemon && lp_read_only(module_id) && remove_source_files) {
                rprintf(FERROR,
                    "ERROR: --remove-%s-files cannot be used with a read-only module\n",
                    remove_source_files == 1 ? "source" : "sent");
                exit_cleanup(RERR_SYNTAX);
                return;
        }

        if (!relative_paths) {
                if (!change_dir(dir, CD_NORMAL)) {
                        rsyserr(FERROR, errno, "change_dir#3 %s failed",
                                full_fname(dir));
                        exit_cleanup(RERR_FILESELECT);
                }
        }
        argc--;
        argv++;

        if (argc == 0 && (recurse || xfer_dirs || list_only)) {
                argc = 1;
                argv--;
                argv[0] = ".";
        }

        flist = send_file_list(f_out,argc,argv);
        if (!flist || flist->used == 0)
                exit_cleanup(0);

        io_start_buffering_in(f_in);

        send_files(f_in, f_out);
        io_flush(FULL_FLUSH);
        handle_stats(f_out);
        if (protocol_version >= 24)
                read_final_goodbye(f_in);
        io_flush(FULL_FLUSH);
        exit_cleanup(0);
}


static int do_recv(int f_in, int f_out, char *local_name)
{
        int pid;
        int exit_code = 0;
        int error_pipe[2];

        /* The receiving side mustn't obey this, or an existing symlink that
         * points to an identical file won't be replaced by the referent. */
        copy_links = copy_dirlinks = copy_unsafe_links = 0;

#ifdef SUPPORT_HARD_LINKS
        if (preserve_hard_links && !inc_recurse)
                match_hard_links(first_flist);
#endif

        if (fd_pair(error_pipe) < 0) {
                rsyserr(FERROR, errno, "pipe failed in do_recv");
                exit_cleanup(RERR_IPC);
        }

        io_flush(NORMAL_FLUSH);

        if ((pid = do_fork()) == -1) {
                rsyserr(FERROR, errno, "fork failed in do_recv");
                exit_cleanup(RERR_IPC);
        }

        if (pid == 0) {
                close(error_pipe[0]);
                if (f_in != f_out)
                        close(f_out);

                /* we can't let two processes write to the socket at one time */
                io_end_multiplex_out();

                /* set place to send errors */
                set_msg_fd_out(error_pipe[1]);
                io_start_buffering_out(error_pipe[1]);

                recv_files(f_in, local_name);
                io_flush(FULL_FLUSH);
                handle_stats(f_in);

                send_msg(MSG_DONE, "", 1, 0);
                write_varlong(error_pipe[1], stats.total_read, 3);
                io_flush(FULL_FLUSH);

                /* Handle any keep-alive packets from the post-processing work
                 * that the generator does. */
                if (protocol_version >= 29) {
                        int iflags, xlen;
                        uchar fnamecmp_type;
                        char xname[MAXPATHLEN];

                        kluge_around_eof = -1;

                        /* This should only get stopped via a USR2 signal. */
                        read_ndx_and_attrs(f_in, &iflags, &fnamecmp_type,
                                           xname, &xlen);

                        rprintf(FERROR, "Invalid packet at end of run [%s]\n",
                                who_am_i());
                        exit_cleanup(RERR_PROTOCOL);
                }

                /* Finally, we go to sleep until our parent kills us with a
                 * USR2 signal.  We sleep for a short time, as on some OSes
                 * a signal won't interrupt a sleep! */
                while (1)
                        msleep(20);
        }

        am_generator = 1;

        io_end_multiplex_in();
        if (write_batch && !am_server)
                stop_write_batch();

        close(error_pipe[1]);
        if (f_in != f_out)
                close(f_in);

        io_start_buffering_out(f_out);

        set_msg_fd_in(error_pipe[0]);
        io_start_buffering_in(error_pipe[0]);

#ifdef SUPPORT_HARD_LINKS
        if (preserve_hard_links && inc_recurse) {
                struct file_list *flist;
                for (flist = first_flist; flist; flist = flist->next)
                        match_hard_links(flist);
        }
#endif

        generate_files(f_out, local_name);

        handle_stats(-1);
        io_flush(FULL_FLUSH);
        if (protocol_version >= 24) {
                /* send a final goodbye message */
                write_ndx(f_out, NDX_DONE);
        }
        io_flush(FULL_FLUSH);

        set_msg_fd_in(-1);
        kill(pid, SIGUSR2);
        wait_process_with_flush(pid, &exit_code);
        return exit_code;
}

static void do_server_recv(int f_in, int f_out, int argc, char *argv[])
{
        int exit_code;
        struct file_list *flist;
        char *local_name = NULL;
        int save_verbose = verbose;

        if (filesfrom_fd >= 0) {
                /* We can't mix messages with files-from data on the socket,
                 * so temporarily turn off verbose messages. */
                verbose = 0;
        }

        if (verbose > 2) {
                rprintf(FINFO, "server_recv(%d) starting pid=%ld\n",
                        argc, (long)getpid());
        }

        if (am_daemon && lp_read_only(module_id)) {
                rprintf(FERROR,"ERROR: module is read only\n");
                exit_cleanup(RERR_SYNTAX);
                return;
        }

        if (argc > 0) {
                char *dir = argv[0];
                argc--;
                argv++;
                if (!am_daemon && !change_dir(dir, CD_NORMAL)) {
                        rsyserr(FERROR, errno, "change_dir#4 %s failed",
                                full_fname(dir));
                        exit_cleanup(RERR_FILESELECT);
                }
        }

        if (protocol_version >= 30)
                io_start_multiplex_in();
        else
                io_start_buffering_in(f_in);
        recv_filter_list(f_in);

        if (filesfrom_fd >= 0) {
                /* We need to send the files-from names to the sender at the
                 * same time that we receive the file-list from them, so we
                 * need the IO routines to automatically write out the names
                 * onto our f_out socket as we read the file-list.  This
                 * avoids both deadlock and extra delays/buffers. */
                io_set_filesfrom_fds(filesfrom_fd, f_out);
                filesfrom_fd = -1;
        }

        flist = recv_file_list(f_in);
        if (!flist) {
                rprintf(FERROR,"server_recv: recv_file_list error\n");
                exit_cleanup(RERR_FILESELECT);
        }
        if (inc_recurse && file_total == 1)
                recv_additional_file_list(f_in);
        verbose = save_verbose;

        if (argc > 0)
                local_name = get_local_name(flist,argv[0]);

        /* Now that we know what our destination directory turned out to be,
         * we can sanitize the --link-/copy-/compare-dest args correctly. */
        if (sanitize_paths) {
                char **dir_p;
                for (dir_p = basis_dir; *dir_p; dir_p++)
                        *dir_p = sanitize_path(NULL, *dir_p, NULL, curr_dir_depth, SP_DEFAULT);
                if (partial_dir)
                        partial_dir = sanitize_path(NULL, partial_dir, NULL, curr_dir_depth, SP_DEFAULT);
        }
        check_alt_basis_dirs();

        if (daemon_filter_list.head) {
                char **dir_p;
                struct filter_list_struct *elp = &daemon_filter_list;

                for (dir_p = basis_dir; *dir_p; dir_p++) {
                        char *dir = *dir_p;
                        if (*dir == '/')
                                dir += module_dirlen;
                        if (check_filter(elp, FLOG, dir, 1) < 0)
                                goto options_rejected;
                }
                if (partial_dir && *partial_dir == '/'
                 && check_filter(elp, FLOG, partial_dir + module_dirlen, 1) < 0) {
                    options_rejected:
                        rprintf(FERROR,
                                "Your options have been rejected by the server.\n");
                        exit_cleanup(RERR_SYNTAX);
                }
        }

        exit_code = do_recv(f_in, f_out, local_name);
        exit_cleanup(exit_code);
}


int child_main(int argc, char *argv[])
{
        start_server(STDIN_FILENO, STDOUT_FILENO, argc, argv);
        return 0;
}


void start_server(int f_in, int f_out, int argc, char *argv[])
{
        set_nonblocking(f_in);
        set_nonblocking(f_out);

        io_set_sock_fds(f_in, f_out);
        setup_protocol(f_out, f_in);

        if (protocol_version >= 23)
                io_start_multiplex_out();

        if (am_sender) {
                keep_dirlinks = 0; /* Must be disabled on the sender. */
                if (need_messages_from_generator)
                        io_start_multiplex_in();
                recv_filter_list(f_in);
                do_server_sender(f_in, f_out, argc, argv);
        } else
                do_server_recv(f_in, f_out, argc, argv);
        exit_cleanup(0);
}


/*
 * This is called once the connection has been negotiated.  It is used
 * for rsyncd, remote-shell, and local connections.
 */
int client_run(int f_in, int f_out, pid_t pid, int argc, char *argv[])
{
        struct file_list *flist = NULL;
        int exit_code = 0, exit_code2 = 0;
        char *local_name = NULL;

        cleanup_child_pid = pid;
        if (!read_batch) {
                set_nonblocking(f_in);
                set_nonblocking(f_out);
        }

        io_set_sock_fds(f_in, f_out);
        setup_protocol(f_out,f_in);

        /* We set our stderr file handle to blocking because ssh might have
         * set it to non-blocking.  This can be particularly troublesome if
         * stderr is a clone of stdout, because ssh would have set our stdout
         * to non-blocking at the same time (which can easily cause us to lose
         * output from our print statements).  This kluge shouldn't cause ssh
         * any problems for how we use it.  Note also that we delayed setting
         * this until after the above protocol setup so that we know for sure
         * that ssh is done twiddling its file descriptors.  */
        set_blocking(STDERR_FILENO);

        if (am_sender) {
                keep_dirlinks = 0; /* Must be disabled on the sender. */
                if (protocol_version >= 30)
                        io_start_multiplex_out();
                else
                        io_start_buffering_out(f_out);
                if (!filesfrom_host)
                        set_msg_fd_in(f_in);
                send_filter_list(f_out);
                if (filesfrom_host)
                        filesfrom_fd = f_in;

                if (write_batch && !am_server)
                        start_write_batch(f_out);
                flist = send_file_list(f_out, argc, argv);
                set_msg_fd_in(-1);
                if (verbose > 3)
                        rprintf(FINFO,"file list sent\n");

                if (protocol_version >= 23)
                        io_start_multiplex_in();

                io_flush(NORMAL_FLUSH);
                send_files(f_in, f_out);
                io_flush(FULL_FLUSH);
                handle_stats(-1);
                if (protocol_version >= 24)
                        read_final_goodbye(f_in);
                if (pid != -1) {
                        if (verbose > 3)
                                rprintf(FINFO,"client_run waiting on %d\n", (int) pid);
                        io_flush(FULL_FLUSH);
                        wait_process_with_flush(pid, &exit_code);
                }
                output_summary();
                io_flush(FULL_FLUSH);
                exit_cleanup(exit_code);
        }

        if (!read_batch) {
                if (protocol_version >= 23)
                        io_start_multiplex_in();
                if (need_messages_from_generator)
                        io_start_multiplex_out();
        }

        send_filter_list(read_batch ? -1 : f_out);

        if (filesfrom_fd >= 0) {
                io_set_filesfrom_fds(filesfrom_fd, f_out);
                filesfrom_fd = -1;
        }

        if (write_batch && !am_server)
                start_write_batch(f_in);
        flist = recv_file_list(f_in);
        if (inc_recurse && file_total == 1)
                recv_additional_file_list(f_in);

        if (flist && flist->used > 0) {
                local_name = get_local_name(flist, argv[0]);

                check_alt_basis_dirs();

                exit_code2 = do_recv(f_in, f_out, local_name);
        } else {
                handle_stats(-1);
                output_summary();
        }

        if (pid != -1) {
                if (verbose > 3)
                        rprintf(FINFO,"client_run2 waiting on %d\n", (int) pid);
                io_flush(FULL_FLUSH);
                wait_process_with_flush(pid, &exit_code);
        }

        return MAX(exit_code, exit_code2);
}

static int copy_argv(char *argv[])
{
        int i;

        for (i = 0; argv[i]; i++) {
                if (!(argv[i] = strdup(argv[i]))) {
                        rprintf (FERROR, "out of memory at %s(%d)\n",
                                 __FILE__, __LINE__);
                        return RERR_MALLOC;
                }
        }

        return 0;
}


/**
 * Start a client for either type of remote connection.  Work out
 * whether the arguments request a remote shell or rsyncd connection,
 * and call the appropriate connection function, then run_client.
 *
 * Calls either start_socket_client (for sockets) or do_cmd and
 * client_run (for ssh).
 **/
static int start_client(int argc, char *argv[])
{
        char *p, *shell_machine = NULL, *shell_user = NULL;
        char **remote_argv;
        int remote_argc;
        int f_in, f_out;
        int ret;
        pid_t pid;

        /* Don't clobber argv[] so that ps(1) can still show the right
         * command line. */
        if ((ret = copy_argv(argv)) != 0)
                return ret;

        if (!read_batch) { /* for read_batch, NO source is specified */
                char *path = check_for_hostspec(argv[0], &shell_machine, &rsync_port);
                if (path) { /* source is remote */
                        char *dummy_host;
                        int dummy_port = 0;
                        *argv = path;
                        remote_argv = argv;
                        remote_argc = argc;
                        argv += argc - 1;
                        if (argc == 1 || **argv == ':')
                                argc = 0; /* no dest arg */
                        else if (check_for_hostspec(*argv, &dummy_host, &dummy_port)) {
                                rprintf(FERROR,
                                        "The source and destination cannot both be remote.\n");
                                exit_cleanup(RERR_SYNTAX);
                        } else {
                                remote_argc--; /* don't count dest */
                                argc = 1;
                        }
                        if (filesfrom_host && *filesfrom_host
                            && strcmp(filesfrom_host, shell_machine) != 0) {
                                rprintf(FERROR,
                                        "--files-from hostname is not the same as the transfer hostname\n");
                                exit_cleanup(RERR_SYNTAX);
                        }
                        am_sender = 0;
                        if (rsync_port)
                                daemon_over_rsh = shell_cmd ? 1 : -1;
                } else { /* source is local, check dest arg */
                        am_sender = 1;

                        if (argc > 1) {
                                p = argv[--argc];
                                remote_argv = argv + argc;
                        } else {
                                static char *dotarg[1] = { "." };
                                p = dotarg[0];
                                remote_argv = dotarg;
                        }
                        remote_argc = 1;

                        path = check_for_hostspec(p, &shell_machine, &rsync_port);
                        if (path && filesfrom_host && *filesfrom_host
                            && strcmp(filesfrom_host, shell_machine) != 0) {
                                rprintf(FERROR,
                                        "--files-from hostname is not the same as the transfer hostname\n");
                                exit_cleanup(RERR_SYNTAX);
                        }
                        if (!path) { /* no hostspec found, so src & dest are local */
                                local_server = 1;
                                if (filesfrom_host) {
                                        rprintf(FERROR,
                                                "--files-from cannot be remote when the transfer is local\n");
                                        exit_cleanup(RERR_SYNTAX);
                                }
                                shell_machine = NULL;
                        } else { /* hostspec was found, so dest is remote */
                                argv[argc] = path;
                                if (rsync_port)
                                        daemon_over_rsh = shell_cmd ? 1 : -1;
                        }
                }
        } else {  /* read_batch */
                local_server = 1;
                if (check_for_hostspec(argv[argc-1], &shell_machine, &rsync_port)) {
                        rprintf(FERROR, "remote destination is not allowed with --read-batch\n");
                        exit_cleanup(RERR_SYNTAX);
                }
                remote_argv = argv + argc - 1;
                remote_argc = 1;
        }

        if (am_sender) {
                char *dummy_host;
                int dummy_port = rsync_port;
                int i;
                /* For local source, extra source args must not have hostspec. */
                for (i = 1; i < argc; i++) {
                        if (check_for_hostspec(argv[i], &dummy_host, &dummy_port)) {
                                rprintf(FERROR, "Unexpected remote arg: %s\n", argv[i]);
                                exit_cleanup(RERR_SYNTAX);
                        }
                }
        } else {
                char *dummy_host;
                int dummy_port = rsync_port;
                int i;
                /* For remote source, any extra source args must have either
                 * the same hostname or an empty hostname. */
                for (i = 1; i < remote_argc; i++) {
                        char *arg = check_for_hostspec(remote_argv[i], &dummy_host, &dummy_port);
                        if (!arg) {
                                rprintf(FERROR, "Unexpected local arg: %s\n", remote_argv[i]);
                                rprintf(FERROR, "If arg is a remote file/dir, prefix it with a colon (:).\n");
                                exit_cleanup(RERR_SYNTAX);
                        }
                        if (*dummy_host && strcmp(dummy_host, shell_machine) != 0) {
                                rprintf(FERROR, "All source args must come from the same machine.\n");
                                exit_cleanup(RERR_SYNTAX);
                        }
                        if (rsync_port != dummy_port) {
                                if (!rsync_port || !dummy_port)
                                        rprintf(FERROR, "All source args must use the same hostspec format.\n");
                                else
                                        rprintf(FERROR, "All source args must use the same port number.\n");
                                exit_cleanup(RERR_SYNTAX);
                        }
                        remote_argv[i] = arg;
                }
        }

        if (daemon_over_rsh < 0)
                return start_socket_client(shell_machine, remote_argc, remote_argv, argc, argv);

        if (password_file && !daemon_over_rsh) {
                rprintf(FERROR, "The --password-file option may only be "
                                "used when accessing an rsync daemon.\n");
                exit_cleanup(RERR_SYNTAX);
        }

        if (connect_timeout) {
                rprintf(FERROR, "The --contimeout option may only be "
                                "used when connecting to an rsync daemon.\n");
                exit_cleanup(RERR_SYNTAX);
        }

        if (shell_machine) {
                p = strrchr(shell_machine,'@');
                if (p) {
                        *p = 0;
                        shell_user = shell_machine;
                        shell_machine = p+1;
                }
        }

        if (verbose > 3) {
                rprintf(FINFO,"cmd=%s machine=%s user=%s path=%s\n",
                        NS(shell_cmd), NS(shell_machine), NS(shell_user),
                        remote_argv ? NS(remote_argv[0]) : "");
        }

        pid = do_cmd(shell_cmd, shell_machine, shell_user, remote_argv, remote_argc,
                     &f_in, &f_out);

        /* if we're running an rsync server on the remote host over a
         * remote shell command, we need to do the RSYNCD protocol first */
        if (daemon_over_rsh) {
                int tmpret;
                tmpret = start_inband_exchange(f_in, f_out, shell_user, remote_argc, remote_argv);
                if (tmpret < 0)
                        return tmpret;
        }

        ret = client_run(f_in, f_out, pid, argc, argv);

        fflush(stdout);
        fflush(stderr);

        return ret;
}


static RETSIGTYPE sigusr1_handler(UNUSED(int val))
{
        exit_cleanup(RERR_SIGNAL1);
}

static RETSIGTYPE sigusr2_handler(UNUSED(int val))
{
        if (!am_server)
                output_summary();
        close_all();
        if (got_xfer_error)
                _exit(RERR_PARTIAL);
        _exit(0);
}

RETSIGTYPE remember_children(UNUSED(int val))
{
#ifdef WNOHANG
        int cnt, status;
        pid_t pid;
        /* An empty waitpid() loop was put here by Tridge and we could never
         * get him to explain why he put it in, so rather than taking it
         * out we're instead saving the child exit statuses for later use.
         * The waitpid() loop presumably eliminates all possibility of leaving
         * zombie children, maybe that's why he did it. */
        while ((pid = waitpid(-1, &status, WNOHANG)) > 0) {
                /* save the child's exit status */
                for (cnt = 0; cnt < MAXCHILDPROCS; cnt++) {
                        if (pid_stat_table[cnt].pid == 0) {
                                pid_stat_table[cnt].pid = pid;
                                pid_stat_table[cnt].status = status;
                                break;
                        }
                }
        }
#endif
#ifndef HAVE_SIGACTION
        signal(SIGCHLD, remember_children);
#endif
}


/**
 * This routine catches signals and tries to send them to gdb.
 *
 * Because it's called from inside a signal handler it ought not to
 * use too many library routines.
 *
 * @todo Perhaps use "screen -X" instead/as well, to help people
 * debugging without easy access to X.  Perhaps use an environment
 * variable, or just call a script?
 *
 * @todo The /proc/ magic probably only works on Linux (and
 * Solaris?)  Can we be more portable?
 **/
#ifdef MAINTAINER_MODE
const char *get_panic_action(void)
{
        const char *cmd_fmt = getenv("RSYNC_PANIC_ACTION");

        if (cmd_fmt)
                return cmd_fmt;
        else
                return "xterm -display :0 -T Panic -n Panic "
                        "-e gdb /proc/%d/exe %d";
}


/**
 * Handle a fatal signal by launching a debugger, controlled by $RSYNC_PANIC_ACTION.
 *
 * This signal handler is only installed if we were configured with
 * --enable-maintainer-mode.  Perhaps it should always be on and we
 * should just look at the environment variable, but I'm a bit leery
 * of a signal sending us into a busy loop.
 **/
static RETSIGTYPE rsync_panic_handler(UNUSED(int whatsig))
{
        char cmd_buf[300];
        int ret;

        snprintf(cmd_buf, sizeof cmd_buf, get_panic_action(),
                 getpid(), getpid());

        /* Unless we failed to execute gdb, we allow the process to
         * continue.  I'm not sure if that's right. */
        ret = system(cmd_buf);
        if (ret)
                _exit(ret);
}
#endif


int main(int argc,char *argv[])
{
        int ret;
        int orig_argc = argc;
        char **orig_argv = argv;
#ifdef HAVE_SIGACTION
# ifdef HAVE_SIGPROCMASK
        sigset_t sigmask;

        sigemptyset(&sigmask);
# endif
        sigact.sa_flags = SA_NOCLDSTOP;
#endif
        SIGACTMASK(SIGUSR1, sigusr1_handler);
        SIGACTMASK(SIGUSR2, sigusr2_handler);
        SIGACTMASK(SIGCHLD, remember_children);
#ifdef MAINTAINER_MODE
        SIGACTMASK(SIGSEGV, rsync_panic_handler);
        SIGACTMASK(SIGFPE, rsync_panic_handler);
        SIGACTMASK(SIGABRT, rsync_panic_handler);
        SIGACTMASK(SIGBUS, rsync_panic_handler);
#endif

        starttime = time(NULL);
        our_uid = MY_UID();
        am_root = our_uid == 0;

        memset(&stats, 0, sizeof(stats));

        if (argc < 2) {
                usage(FERROR);
                exit_cleanup(RERR_SYNTAX);
        }

        /* we set a 0 umask so that correct file permissions can be
         * carried across */
        orig_umask = umask(0);

#if defined CONFIG_LOCALE && defined HAVE_SETLOCALE
        setlocale(LC_CTYPE, "");
#endif

        if (!parse_arguments(&argc, (const char ***) &argv)) {
                /* FIXME: We ought to call the same error-handling
                 * code here, rather than relying on getopt. */
                option_error();
                exit_cleanup(RERR_SYNTAX);
        }

        SIGACTMASK(SIGINT, sig_int);
        SIGACTMASK(SIGHUP, sig_int);
        SIGACTMASK(SIGTERM, sig_int);
#if defined HAVE_SIGACTION && HAVE_SIGPROCMASK
        sigprocmask(SIG_UNBLOCK, &sigmask, NULL);
#endif

        /* Ignore SIGPIPE; we consistently check error codes and will
         * see the EPIPE. */
        SIGACTION(SIGPIPE, SIG_IGN);
#ifdef SIGXFSZ
        SIGACTION(SIGXFSZ, SIG_IGN);
#endif

        /* Initialize change_dir() here because on some old systems getcwd
         * (implemented by forking "pwd" and reading its output) doesn't
         * work when there are other child processes.  Also, on all systems
         * that implement getcwd that way "pwd" can't be found after chroot. */
        change_dir(NULL, CD_NORMAL);

        init_flist();

        if ((write_batch || read_batch) && !am_server) {
                if (write_batch)
                        write_batch_shell_file(orig_argc, orig_argv, argc);

                if (read_batch && strcmp(batch_name, "-") == 0)
                        batch_fd = STDIN_FILENO;
                else {
                        batch_fd = do_open(batch_name,
                                   write_batch ? O_WRONLY | O_CREAT | O_TRUNC
                                   : O_RDONLY, S_IRUSR | S_IWUSR);
                }
                if (batch_fd < 0) {
                        rsyserr(FERROR, errno, "Batch file %s open error",
                                full_fname(batch_name));
                        exit_cleanup(RERR_FILEIO);
                }
                if (read_batch)
                        read_stream_flags(batch_fd);
                else
                        write_stream_flags(batch_fd);
        }
        if (write_batch < 0)
                dry_run = 1;

        if (am_server) {
#ifdef ICONV_CONST
                setup_iconv();
#endif
        } else if (am_daemon)
                return daemon_main();

        if (am_server && protect_args) {
                char buf[MAXPATHLEN];
                protect_args = 2;
                read_args(STDIN_FILENO, NULL, buf, sizeof buf, 1, &argv, &argc, NULL);
                if (!parse_arguments(&argc, (const char ***) &argv)) {
                        option_error();
                        exit_cleanup(RERR_SYNTAX);
                }
        }

        if (argc < 1) {
                usage(FERROR);
                exit_cleanup(RERR_SYNTAX);
        }

        if (am_server) {
                set_nonblocking(STDIN_FILENO);
                set_nonblocking(STDOUT_FILENO);
                if (am_daemon)
                        return start_daemon(STDIN_FILENO, STDOUT_FILENO);
                start_server(STDIN_FILENO, STDOUT_FILENO, argc, argv);
        }

        ret = start_client(argc, argv);
        if (ret == -1)
                exit_cleanup(RERR_STARTCLIENT);
        else
                exit_cleanup(ret);

        return ret;
}