compat/fsmonitor/fsm-path-utils-darwin.c

   1 #include "fsmonitor.h"
   2 #include "fsmonitor-path-utils.h"
   3 #include "gettext.h"
   4 #include <dirent.h>
   5 #include <errno.h>
   6 #include <fcntl.h>
   7 #include <sys/param.h>
   8 #include <sys/mount.h>
   9
  10 int fsmonitor__get_fs_info(const char *path, struct fs_info *fs_info)
  11 {
  12         struct statfs fs;
  13         if (statfs(path, &fs) == -1) {
  14                 int saved_errno = errno;
  15                 trace_printf_key(&trace_fsmonitor, "statfs('%s') failed: %s",
  16                                  path, strerror(saved_errno));
  17                 errno = saved_errno;
  18                 return -1;
  19         }
  20
  21         trace_printf_key(&trace_fsmonitor,
  22                          "statfs('%s') [type 0x%08x][flags 0x%08x] '%s'",
  23                          path, fs.f_type, fs.f_flags, fs.f_fstypename);
  24
  25         if (!(fs.f_flags & MNT_LOCAL))
  26                 fs_info->is_remote = 1;
  27         else
  28                 fs_info->is_remote = 0;
  29
  30         fs_info->typename = xstrdup(fs.f_fstypename);
  31
  32         trace_printf_key(&trace_fsmonitor,
  33                                 "'%s' is_remote: %d",
  34                                 path, fs_info->is_remote);
  35         return 0;
  36 }
  37
  38 int fsmonitor__is_fs_remote(const char *path)
  39 {
  40         struct fs_info fs;
  41         if (fsmonitor__get_fs_info(path, &fs))
  42                 return -1;
  43
  44         free(fs.typename);
  45
  46         return fs.is_remote;
  47 }
  48
  49 /*
  50  * Scan the root directory for synthetic firmlinks that when resolved
  51  * are a prefix of the path, stopping at the first one found.
  52  *
  53  * Some information about firmlinks and synthetic firmlinks:
  54  * https://eclecticlight.co/2020/01/23/catalina-boot-volumes/
  55  *
  56  * macOS no longer allows symlinks in the root directory; any link found
  57  * there is therefore a synthetic firmlink.
  58  *
  59  * If this function gets called often, will want to cache all the firmlink
  60  * information, but for now there is only one caller of this function.
  61  *
  62  * If there is more than one alias for the path, that is another
  63  * matter altogether.
  64  */
  65 int fsmonitor__get_alias(const char *path, struct alias_info *info)
  66 {
  67         DIR *dir;
  68         int retval = -1;
  69         const char *const root = "/";
  70         struct stat st;
  71         struct dirent *de;
  72         struct strbuf alias;
  73         struct strbuf points_to = STRBUF_INIT;
  74
  75         dir = opendir(root);
  76         if (!dir)
  77                 return error_errno(_("opendir('%s') failed"), root);
  78
  79         strbuf_init(&alias, 256);
  80
  81         while ((de = readdir(dir)) != NULL) {
  82                 strbuf_reset(&alias);
  83                 strbuf_addf(&alias, "%s%s", root, de->d_name);
  84
  85                 if (lstat(alias.buf, &st) < 0) {
  86                         error_errno(_("lstat('%s') failed"), alias.buf);
  87                         goto done;
  88                 }
  89
  90                 if (!S_ISLNK(st.st_mode))
  91                         continue;
  92
  93                 if (strbuf_readlink(&points_to, alias.buf, st.st_size) < 0) {
  94                         error_errno(_("strbuf_readlink('%s') failed"), alias.buf);
  95                         goto done;
  96                 }
  97
  98                 if (!strncmp(points_to.buf, path, points_to.len) &&
  99                         (path[points_to.len] == '/')) {
 100                         strbuf_addbuf(&info->alias, &alias);
 101                         strbuf_addbuf(&info->points_to, &points_to);
 102                         trace_printf_key(&trace_fsmonitor,
 103                                 "Found alias for '%s' : '%s' -> '%s'",
 104                                 path, info->alias.buf, info->points_to.buf);
 105                         retval = 0;
 106                         goto done;
 107                 }
 108         }
 109         retval = 0; /* no alias */
 110
 111 done:
 112         strbuf_release(&alias);
 113         strbuf_release(&points_to);
 114         if (closedir(dir) < 0)
 115                 return error_errno(_("closedir('%s') failed"), root);
 116         return retval;
 117 }
 118
 119 char *fsmonitor__resolve_alias(const char *path,
 120         const struct alias_info *info)
 121 {
 122         if (!info->alias.len)
 123                 return NULL;
 124
 125         if ((!strncmp(info->alias.buf, path, info->alias.len))
 126                 && path[info->alias.len] == '/') {
 127                 struct strbuf tmp = STRBUF_INIT;
 128                 const char *remainder = path + info->alias.len;
 129
 130                 strbuf_addbuf(&tmp, &info->points_to);
 131                 strbuf_add(&tmp, remainder, strlen(remainder));
 132                 return strbuf_detach(&tmp, NULL);
 133         }
 134
 135         return NULL;
 136 }