1/* vi: set sw=4 ts=4: */
2/*
3 * Utility routines.
4 *
5 * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
6 *
7 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
8 */
9
10#include "libbb.h"
11
12/* Find block device /dev/XXX which contains specified file
13 * We handle /dev/dir/dir/dir too, at a cost of ~80 more bytes code */
14
15/* Do not reallocate all this stuff on each recursion */
16enum { DEVNAME_MAX = 256 };
17struct arena {
18	struct stat st;
19	dev_t dev;
20	/* Was PATH_MAX, but we recurse _/dev_. We can assume
21	 * people are not crazy enough to have mega-deep tree there */
22	char devpath[DEVNAME_MAX];
23};
24
25static char *find_block_device_in_dir(struct arena *ap)
26{
27	DIR *dir;
28	struct dirent *entry;
29	char *retpath = NULL;
30	int len, rem;
31
32	dir = opendir(ap->devpath);
33	if (!dir)
34		return NULL;
35
36	len = strlen(ap->devpath);
37	rem = DEVNAME_MAX-2 - len;
38	if (rem <= 0)
39		return NULL;
40	ap->devpath[len++] = '/';
41
42	while ((entry = readdir(dir)) != NULL) {
43		safe_strncpy(ap->devpath + len, entry->d_name, rem);
44		/* lstat: do not follow links */
45		if (lstat(ap->devpath, &ap->st) != 0)
46			continue;
47		if (S_ISBLK(ap->st.st_mode) && ap->st.st_rdev == ap->dev) {
48			retpath = xstrdup(ap->devpath);
49			break;
50		}
51		if (S_ISDIR(ap->st.st_mode)) {
52			/* Do not recurse for '.' and '..' */
53			if (DOT_OR_DOTDOT(entry->d_name))
54				continue;
55			retpath = find_block_device_in_dir(ap);
56			if (retpath)
57				break;
58		}
59	}
60	closedir(dir);
61
62	return retpath;
63}
64
65char* FAST_FUNC find_block_device(const char *path)
66{
67	struct arena a;
68
69	if (stat(path, &a.st) != 0)
70		return NULL;
71	a.dev = S_ISBLK(a.st.st_mode) ? a.st.st_rdev : a.st.st_dev;
72	strcpy(a.devpath, "/dev");
73	return find_block_device_in_dir(&a);
74}
75