qmail/syncdir.c

   1 /* syncdir -- emulate synchronous directories
   2     Copyright (C) 1998 Bruce Guenter
   3
   4     This program is free software; you can redistribute it and/or modify
   5     it under the terms of the GNU General Public License as published by
   6     the Free Software Foundation; either version 2 of the License, or
   7     (at your option) any later version.
   8
   9     This program is distributed in the hope that it will be useful,
  10     but WITHOUT ANY WARRANTY; without even the implied warranty of
  11     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12     GNU General Public License for more details.
  13
  14     You should have received a copy of the GNU General Public License
  15     along with this program; if not, write to the Free Software
  16     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  17
  18     You can reach me at bruce.guenter@qcc.sk.ca
  19 */
  20
  21 #include <sys/types.h>
  22 #include <sys/stat.h>
  23 #define open XXX_open
  24 #include <fcntl.h>
  25 #undef open
  26 #include <unistd.h>
  27 #include <string.h>
  28 #include <syscall.h>
  29 #include <stdio.h>
  30 #include <errno.h>
  31 #include <bits/syscall.h>
  32
  33 #define SYS_OPEN(FILE,FLAG,MODE) syscall(SYS_open, FILE, FLAG, MODE)
  34 #define SYS_CLOSE(FD) syscall(SYS_close, FD)
  35 #define SYS_LINK(OLD,NEW) syscall(SYS_link, OLD, NEW)
  36 #define SYS_UNLINK(PATH) syscall(SYS_unlink, PATH)
  37 #define SYS_RENAME(OLD,NEW) syscall(SYS_rename, OLD, NEW)
  38 #define SYS_FSYNC(FD) syscall(SYS_fsync, FD)
  39
  40 static int fdirsync(const char* filename, unsigned length)
  41 {
  42   char dirname[length+1];
  43   /* This could also be:
  44    * char* dirname = alloca(length+1); */
  45   int dirfd;
  46   int retval;
  47   memcpy(dirname, filename, length);
  48   dirname[length] = 0;
  49   if((dirfd = SYS_OPEN(dirname,O_RDONLY,0)) == -1)
  50     return -1;
  51   retval = (SYS_FSYNC(dirfd) == -1 && errno == EIO) ? -1 : 0;
  52   SYS_CLOSE(dirfd);
  53   return retval;
  54 }
  55
  56 static int fdirsyncfn(const char *filename)
  57 {
  58    const char *slash = filename+strlen(filename)-1;
  59
  60    /* Skip over trailing slashes, which would be ignored by some
  61     * operations */
  62    while(slash > filename && *slash == '/')
  63      --slash;
  64
  65    /* Skip back to the next slash */
  66    while(slash > filename && *slash != '/')
  67      --slash;
  68
  69    /* slash now either points to a '/' character, or no slash was found */
  70    if(*slash == '/')
  71       return fdirsync(filename,
  72                       (slash == filename) ? 1 : slash-filename);
  73    else
  74      return fdirsync(".", 1);
  75 }
  76
  77 int open(const char *file,int oflag,mode_t mode)
  78 {
  79   int fd = SYS_OPEN(file, oflag, mode);
  80   if(fd == -1)
  81     return fd;
  82   if (oflag & O_CREAT)
  83     if (fdirsyncfn(file) == -1) {
  84       SYS_CLOSE(fd);
  85       return -1;
  86     }
  87   return fd;
  88 }
  89
  90 int link(const char *oldpath,const char *newpath)
  91 {
  92    if(SYS_LINK(oldpath,newpath) == -1)
  93      return -1;
  94    return fdirsyncfn(newpath);
  95 }
  96
  97 int unlink(const char *path)
  98 {
  99    if(SYS_UNLINK(path) == -1)
 100      return -1;
 101    return fdirsyncfn(path);
 102 }
 103
 104 int rename(const char *oldpath,const char *newpath)
 105 {
 106    if (SYS_RENAME(oldpath,newpath) == -1)
 107      return -1;
 108    if (fdirsyncfn(newpath) == -1)
 109      return -1;
 110    return fdirsyncfn(oldpath);
 111 }