minix/servers/vfs/time.c

   1 /* This file takes care of those system calls that deal with time.
   2  *
   3  * The entry points into this file are
   4  *   do_utimens:        perform the UTIMENS system call
   5  */
   6
   7 #include "fs.h"
   8 #include <minix/callnr.h>
   9 #include <minix/com.h>
  10 #include <time.h>
  11 #include <string.h>
  12 #include <sys/stat.h>
  13 #include <fcntl.h>
  14 #include "file.h"
  15 #include "path.h"
  16 #include "vnode.h"
  17 #include <minix/vfsif.h>
  18 #include "vmnt.h"
  19
  20 #define UTIMENS_STYLE   0       /* utimes(2)/utimensat(2) style, named file */
  21 #define FUTIMENS_STYLE  1       /* futimens(2)/futimes(2) style, file desc. */
  22
  23 /*===========================================================================*
  24  *                              do_utimens                                   *
  25  *===========================================================================*/
  26 int do_utimens(void)
  27 {
  28 /* Perform the utimens(name, times, flag) system call, and its friends.
  29  * Implement a very large but not complete subset of the utimensat()
  30  * Posix:2008/XOpen-7 function.
  31  * Are handled all the following cases:
  32  * . utimensat(AT_FDCWD, "/some/absolute/path", , )
  33  * . utimensat(AT_FDCWD, "some/path", , )
  34  * . utimens("anything", ) really special case of the above two
  35  * . lutimens("anything", ) also really special case of the above
  36  * . utimensat(fd, "/some/absolute/path", , ) although fd is useless here
  37  * . futimens(fd, )
  38  * Are not handled the following cases:
  39  * . utimensat(fd, "some/path", , ) path to a file relative to some open fd
  40  */
  41   int r, kind, lookup_flags;
  42   struct vnode *vp;
  43   struct filp *filp = NULL; /* initialization required by clueless GCC */
  44   struct vmnt *vmp;
  45   struct timespec actim, modtim, now, newactim, newmodtim;
  46   char fullpath[PATH_MAX];
  47   struct lookup resolve;
  48   vir_bytes vname;
  49   size_t vname_length;
  50
  51   memset(&now, 0, sizeof(now));
  52
  53   /* The case times==NULL is handled by the caller, replaced with UTIME_NOW */
  54   actim.tv_sec = job_m_in.m_vfs_utimens.atime;
  55   actim.tv_nsec = job_m_in.m_vfs_utimens.ansec;
  56   modtim.tv_sec = job_m_in.m_vfs_utimens.mtime;
  57   modtim.tv_nsec = job_m_in.m_vfs_utimens.mnsec;
  58
  59   if (job_m_in.m_vfs_utimens.name != NULL) {
  60         kind = UTIMENS_STYLE;
  61         if (job_m_in.m_vfs_utimens.flags & ~AT_SYMLINK_NOFOLLOW)
  62                 return EINVAL; /* unknown flag */
  63         /* Temporarily open the file */
  64         vname = (vir_bytes) job_m_in.m_vfs_utimens.name;
  65         vname_length = (size_t) job_m_in.m_vfs_utimens.len;
  66         if (job_m_in.m_vfs_utimens.flags & AT_SYMLINK_NOFOLLOW)
  67                 lookup_flags = PATH_RET_SYMLINK;
  68         else
  69                 lookup_flags = PATH_NOFLAGS;
  70         lookup_init(&resolve, fullpath, lookup_flags, &vmp, &vp);
  71         resolve.l_vmnt_lock = VMNT_READ;
  72         resolve.l_vnode_lock = VNODE_READ;
  73         /* Temporarily open the file */
  74         if (fetch_name(vname, vname_length, fullpath) != OK) return(err_code);
  75         if ((vp = eat_path(&resolve, fp)) == NULL) return(err_code);
  76   }
  77   else {
  78         kind = FUTIMENS_STYLE;
  79         /* Change timestamps on already-opened fd. Is it valid? */
  80         if (job_m_in.m_vfs_utimens.flags != 0)
  81                 return EINVAL; /* unknown flag */
  82         if ((filp = get_filp(job_m_in.m_vfs_utimens.fd, VNODE_READ)) == NULL)
  83                 return err_code;
  84         vp = filp->filp_vno;
  85   }
  86
  87   r = OK;
  88   /* Only the owner of a file or the super user can change timestamps. */
  89   if (vp->v_uid != fp->fp_effuid && fp->fp_effuid != SU_UID) r = EPERM;
  90   /* Need write permission (or super user) to 'touch' the file */
  91   if (r != OK && actim.tv_nsec == UTIME_NOW
  92               && modtim.tv_nsec == UTIME_NOW) r = forbidden(fp, vp, W_BIT);
  93   if (read_only(vp) != OK) r = EROFS; /* Not even su can touch if R/O */
  94
  95   if (r == OK) {
  96         /* Do we need to ask for current time? */
  97         if (actim.tv_nsec == UTIME_NOW
  98          || actim.tv_nsec == UTIME_OMIT
  99          || modtim.tv_nsec == UTIME_NOW
 100          || modtim.tv_nsec == UTIME_OMIT) {
 101                 now = clock_timespec();
 102         }
 103
 104         /* Build the request */
 105         switch (actim.tv_nsec) {
 106         case UTIME_NOW:
 107                 newactim = now;
 108                 break;
 109         case UTIME_OMIT:
 110                 newactim.tv_nsec = UTIME_OMIT;
 111                 /* Be nice with old FS, put a sensible value in
 112                  * otherwise not used field for seconds
 113                  */
 114                 newactim.tv_sec = now.tv_sec;
 115                 break;
 116         default:
 117                 if ( (unsigned)actim.tv_nsec >= 1000000000)
 118                         r = EINVAL;
 119                 else
 120                         newactim = actim;
 121                 break;
 122         }
 123         switch (modtim.tv_nsec) {
 124         case UTIME_NOW:
 125                 newmodtim = now;
 126                 break;
 127         case UTIME_OMIT:
 128                 newmodtim.tv_nsec = UTIME_OMIT;
 129                 /* Be nice with old FS, put a sensible value */
 130                 newmodtim.tv_sec = now.tv_sec;
 131                 break;
 132         default:
 133                 if ( (unsigned)modtim.tv_nsec >= 1000000000)
 134                         r = EINVAL;
 135                 else
 136                         newmodtim = modtim;
 137                 break;
 138         }
 139   }
 140
 141   if (r == OK)
 142         /* Issue request */
 143         r = req_utime(vp->v_fs_e, vp->v_inode_nr, &newactim, &newmodtim);
 144
 145   if (kind == UTIMENS_STYLE) {
 146         /* Close the temporary */
 147         unlock_vnode(vp);
 148         unlock_vmnt(vmp);
 149         put_vnode(vp);
 150   }
 151   else { /* Change timestamps on opened fd. */
 152         unlock_filp(filp);
 153   }
 154   return r;
 155 }