fsync.c

   1 #include "compat-util.h"
   2 #include <dirent.h>
   3 #include <libgen.h>
   4 #include <dlfcn.h>
   5
   6 #if defined(_POSIX_SYNCHRONIZED_IO) && _POSIX_SYNCHRONIZED_IO > 0
   7 static int have_fdatasync = 1;
   8 #else
   9 static int have_fdatasync;
  10 #endif
  11
  12 /* TODO: sync_file_range() if on Linux */
  13
  14 static int usage(const char * argv0)
  15 {
  16         fprintf(stderr, "Usage: %s [-d] [-D] FILE...\n", argv0);
  17         return 1;
  18 }
  19
  20 #define FN_NOT_FOUND ((void *)(1))
  21
  22 static int fs_sync(const char *path)
  23 {
  24         int rc = 0;
  25 #if defined(__linux__) && defined(RTLD_NEXT)
  26         static int (*syncfs_fn)(int);
  27
  28         if (syncfs_fn == NULL) {
  29                 syncfs_fn = dlsym(RTLD_DEFAULT, "syncfs");
  30                 if (syncfs_fn == NULL || dlerror())
  31                         syncfs_fn = FN_NOT_FOUND;
  32         }
  33         if (syncfs_fn != NULL && syncfs_fn != FN_NOT_FOUND) {
  34                 int fd = open(path, O_RDONLY|O_NOATIME);
  35
  36                 if (fd >= 0) {
  37                         int err;
  38                         rc = syncfs_fn(fd);
  39                         err = errno;
  40                         close(fd);
  41
  42                         /*
  43                          * if glibc has syncfs(2) but we're running an
  44                          * old kernel, fall back to sync(2) below
  45                          */
  46                         if (err != ENOSYS)
  47                                 return rc;
  48                         rc = 0;
  49                 }
  50         }
  51 #endif /* ! __linux__ */
  52         sync();
  53         return rc;
  54 }
  55
  56 static int do_sync(const char *path, int data_only, int directory)
  57 {
  58         int fd;
  59         const char *errfunc = "";
  60
  61         if ((fd = open(path, O_RDWR|O_NOATIME)) < 0) {
  62                 if (errno == EISDIR) {
  63                         directory = 1;
  64                         goto sync_dir;
  65                 }
  66                 errfunc = "open";
  67                 goto err;
  68         }
  69
  70         if (data_only && have_fdatasync) {
  71                 if (fdatasync(fd) < 0) {
  72                         errfunc = "fdatasync";
  73                         goto err;
  74                 }
  75         } else {
  76                 if (fsync(fd) < 0) {
  77                         errfunc = "fsync";
  78                         goto err;
  79                 }
  80         }
  81
  82         if (close(fd) < 0) {
  83                 errfunc = "close";
  84                 goto err;
  85         }
  86
  87 sync_dir:
  88         if (directory) {
  89                 char *dpath;
  90                 DIR *dir;
  91
  92                 if (!(dpath = strdup(path))){
  93                         errfunc = "strdup";
  94                         goto err;
  95                 }
  96                 if (!(dir = opendir(dirname(dpath)))) {
  97                         errfunc = "opendir";
  98                         goto err;
  99                 }
 100                 if (fsync(dirfd(dir)) < 0) {
 101                         errfunc = "(directory) fsync";
 102                         goto err;
 103                 }
 104                 if (closedir(dir) < 0) {
 105                         errfunc = "closedir";
 106                         goto err;
 107                 }
 108                 free(dpath);
 109         }
 110
 111         return 0;
 112 err:
 113         fprintf(stderr, "%s: %s(): %s\n", path, errfunc, strerror(errno));
 114         return -1;
 115 }
 116
 117 int main(int argc, char * const argv[])
 118 {
 119         int data_only = 0;
 120         int fs = 0;
 121         int directory = 0;
 122         int opt;
 123         int argi = 1;
 124
 125         while ((opt = getopt(argc, argv, "dDf")) != -1) {
 126                 ++argi;
 127                 switch(opt) {
 128                 case 'd':
 129                         data_only = 1;
 130                         break;
 131                 case 'D':
 132                         directory = 1;
 133                         break;
 134                 case 'f':
 135                         fs = 1;
 136                         break;
 137                 default:
 138                         return usage(argv[0]);
 139                 }
 140         }
 141
 142         if (argi >= argc)
 143                 return usage(argv[0]);
 144
 145         for (; argi < argc; ++argi) {
 146                 if (fs) {
 147                         if (fs_sync(argv[argi]) < 0)
 148                                 return 1;
 149                 } else {
 150                         if (do_sync(argv[argi], data_only, directory) < 0)
 151                                 return 1;
 152                 }
 153         }
 154
 155         return 0;
 156 }