#include "libbb.h"
-char *find_block_device(const char *path)
+/* Find block device /dev/XXX which contains specified file
+ * We handle /dev/dir/dir/dir too, at a cost of ~80 more bytes code */
+
+/* Do not reallocate all this stuff on each recursion */
+enum { DEVNAME_MAX = 256 };
+struct arena {
+ struct stat st;
+ dev_t dev;
+ /* Was PATH_MAX, but we recurse _/dev_. We can assume
+ * people are not crazy enough to have mega-deep tree there */
+ char devpath[DEVNAME_MAX];
+};
+
+static char *find_block_device_in_dir(struct arena *ap)
{
DIR *dir;
struct dirent *entry;
- struct stat st;
- dev_t dev;
- char *retpath=NULL;
+ char *retpath = NULL;
+ int len, rem;
+
+ dir = opendir(ap->devpath);
+ if (!dir)
+ return NULL;
- if (stat(path, &st) || !(dir = opendir("/dev")))
+ len = strlen(ap->devpath);
+ rem = DEVNAME_MAX-2 - len;
+ if (rem <= 0)
return NULL;
- dev = (st.st_mode & S_IFMT) == S_IFBLK ? st.st_rdev : st.st_dev;
+ ap->devpath[len++] = '/';
+
while ((entry = readdir(dir)) != NULL) {
- char devpath[PATH_MAX];
- sprintf(devpath,"/dev/%s", entry->d_name);
- if (!stat(devpath, &st) && S_ISBLK(st.st_mode) && st.st_rdev == dev) {
- retpath = xstrdup(devpath);
+ safe_strncpy(ap->devpath + len, entry->d_name, rem);
+ /* lstat: do not follow links */
+ if (lstat(ap->devpath, &ap->st) != 0)
+ continue;
+ if (S_ISBLK(ap->st.st_mode) && ap->st.st_rdev == ap->dev) {
+ retpath = xstrdup(ap->devpath);
break;
}
+ if (S_ISDIR(ap->st.st_mode)) {
+ /* Do not recurse for '.' and '..' */
+ if (DOT_OR_DOTDOT(entry->d_name))
+ continue;
+ retpath = find_block_device_in_dir(ap);
+ if (retpath)
+ break;
+ }
}
closedir(dir);
return retpath;
}
+
+char* FAST_FUNC find_block_device(const char *path)
+{
+ struct arena a;
+
+ if (stat(path, &a.st) != 0)
+ return NULL;
+ a.dev = S_ISBLK(a.st.st_mode) ? a.st.st_rdev : a.st.st_dev;
+ strcpy(a.devpath, "/dev");
+ return find_block_device_in_dir(&a);
+}