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

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