devname.c revision 18a1444b4f1e6a0948fd38fa0de382d86cfe04de 
1/*
2 * devname.c - get a dev by its device inode name
3 *
4 * Copyright (C) Andries Brouwer
5 * Copyright (C) 1999, 2000, 2001, 2002, 2003 Theodore Ts'o
6 * Copyright (C) 2001 Andreas Dilger
7 *
8 * %Begin-Header%
9 * This file may be redistributed under the terms of the
10 * GNU Lesser General Public License.
11 * %End-Header%
12 */
13
14#define _GNU_SOURCE 1
15
16#include <stdio.h>
17#include <string.h>
18#include <limits.h>
19#if HAVE_UNISTD_H
20#include <unistd.h>
21#endif
22#include <stdlib.h>
23#include <string.h>
24#include <ctype.h>
25#if HAVE_SYS_TYPES_H
26#include <sys/types.h>
27#endif
28#include <dirent.h>
29#if HAVE_SYS_STAT_H
30#include <sys/stat.h>
31#endif
32#if HAVE_ERRNO_H
33#include <errno.h>
34#endif
35#if HAVE_SYS_MKDEV_H
36#include <sys/mkdev.h>
37#endif
38#include <time.h>
39
40#include "blkidP.h"
41
42/*
43 * Find a dev struct in the cache by device name, if available.
44 *
45 * If there is no entry with the specified device name, and the create
46 * flag is set, then create an empty device entry.
47 */
48blkid_dev blkid_get_dev(blkid_cache cache, const char *devname, int flags)
49{
50	blkid_dev dev = NULL, tmp;
51	struct list_head *p, *pnext;
52
53	if (!cache || !devname)
54		return NULL;
55
56	list_for_each(p, &cache->bic_devs) {
57		tmp = list_entry(p, struct blkid_struct_dev, bid_devs);
58		if (strcmp(tmp->bid_name, devname))
59			continue;
60
61		DBG(DEBUG_DEVNAME,
62		    printf("found devname %s in cache\n", tmp->bid_name));
63		dev = tmp;
64		break;
65	}
66
67	if (!dev && (flags & BLKID_DEV_CREATE)) {
68		if (access(devname, F_OK) < 0)
69			return NULL;
70		dev = blkid_new_dev();
71		if (!dev)
72			return NULL;
73		dev->bid_time = INT_MIN;
74		dev->bid_name = blkid_strdup(devname);
75		dev->bid_cache = cache;
76		list_add_tail(&dev->bid_devs, &cache->bic_devs);
77		cache->bic_flags |= BLKID_BIC_FL_CHANGED;
78	}
79
80	if (flags & BLKID_DEV_VERIFY) {
81		dev = blkid_verify(cache, dev);
82		if (!dev || !(dev->bid_flags & BLKID_BID_FL_VERIFIED))
83			return dev;
84		/*
85		 * If the device is verified, then search the blkid
86		 * cache for any entries that match on the type, uuid,
87		 * and label, and verify them; if a cache entry can
88		 * not be verified, then it's stale and so we remove
89		 * it.
90		 */
91		list_for_each_safe(p, pnext, &cache->bic_devs) {
92			blkid_dev dev2;
93			if (!p)
94				break;
95			dev2 = list_entry(p, struct blkid_struct_dev, bid_devs);
96			if (dev2->bid_flags & BLKID_BID_FL_VERIFIED)
97				continue;
98			if (!dev->bid_type || !dev2->bid_type ||
99			    strcmp(dev->bid_type, dev2->bid_type))
100				continue;
101			if (dev->bid_label && dev2->bid_label &&
102			    strcmp(dev->bid_label, dev2->bid_label))
103				continue;
104			if (dev->bid_uuid && dev2->bid_uuid &&
105			    strcmp(dev->bid_uuid, dev2->bid_uuid))
106				continue;
107			if ((dev->bid_label && !dev2->bid_label) ||
108			    (!dev->bid_label && dev2->bid_label) ||
109			    (dev->bid_uuid && !dev2->bid_uuid) ||
110			    (!dev->bid_uuid && dev2->bid_uuid))
111				continue;
112			dev2 = blkid_verify(cache, dev2);
113			if (dev2 && !(dev2->bid_flags & BLKID_BID_FL_VERIFIED))
114				blkid_free_dev(dev2);
115		}
116	}
117	return dev;
118}
119
120/* Directories where we will try to search for device names */
121static const char *dirlist[] = { "/dev", "/devfs", "/devices", NULL };
122
123static int is_dm_leaf(const char *devname)
124{
125	struct dirent	*de, *d_de;
126	DIR		*dir, *d_dir;
127	char		path[256];
128	int		ret = 1;
129
130	if ((dir = opendir("/sys/block")) == NULL)
131		return 0;
132	while ((de = readdir(dir)) != NULL) {
133		if (!strcmp(de->d_name, ".") || !strcmp(de->d_name, "..") ||
134		    !strcmp(de->d_name, devname) ||
135		    strncmp(de->d_name, "dm-", 3) ||
136		    strlen(de->d_name) > sizeof(path)-32)
137			continue;
138		sprintf(path, "/sys/block/%s/slaves", de->d_name);
139		if ((d_dir = opendir(path)) == NULL)
140			continue;
141		while ((d_de = readdir(d_dir)) != NULL) {
142			if (!strcmp(d_de->d_name, devname)) {
143				ret = 0;
144				break;
145			}
146		}
147		closedir(d_dir);
148		if (!ret)
149			break;
150	}
151	closedir(dir);
152	return ret;
153}
154
155/*
156 * Since 2.6.29 (patch 784aae735d9b0bba3f8b9faef4c8b30df3bf0128) kernel sysfs
157 * provides the real DM device names in /sys/block/<ptname>/dm/name
158 */
159static char *get_dm_name(const char *ptname)
160{
161	FILE	*f;
162	size_t	sz;
163	char	path[256], name[256], *res = NULL;
164
165	snprintf(path, sizeof(path), "/sys/block/%s/dm/name", ptname);
166	if ((f = fopen(path, "r")) == NULL)
167		return NULL;
168
169	/* read "<name>\n" from sysfs */
170	if (fgets(name, sizeof(name), f) && (sz = strlen(name)) > 1) {
171		name[sz - 1] = '\0';
172		snprintf(path, sizeof(path), "/dev/mapper/%s", name);
173		res = blkid_strdup(path);
174	}
175	fclose(f);
176	return res;
177}
178
179/*
180 * Probe a single block device to add to the device cache.
181 */
182static void probe_one(blkid_cache cache, const char *ptname,
183		      dev_t devno, int pri, int only_if_new)
184{
185	blkid_dev dev = NULL;
186	struct list_head *p, *pnext;
187	const char **dir;
188	char *devname = NULL;
189
190	/* See if we already have this device number in the cache. */
191	list_for_each_safe(p, pnext, &cache->bic_devs) {
192		blkid_dev tmp = list_entry(p, struct blkid_struct_dev,
193					   bid_devs);
194		if (tmp->bid_devno == devno) {
195			if (only_if_new && !access(tmp->bid_name, F_OK))
196				return;
197			dev = blkid_verify(cache, tmp);
198			if (dev && (dev->bid_flags & BLKID_BID_FL_VERIFIED))
199				break;
200			dev = 0;
201		}
202	}
203	if (dev && dev->bid_devno == devno)
204		goto set_pri;
205
206	/* Try to translate private device-mapper dm-<N> names
207	 * to standard /dev/mapper/<name>.
208	 */
209	if (!strncmp(ptname, "dm-", 3) && isdigit(ptname[3])) {
210		devname = get_dm_name(ptname);
211		if (!devname)
212			blkid__scan_dir("/dev/mapper", devno, 0, &devname);
213		if (devname)
214			goto get_dev;
215	}
216
217	/*
218	 * Take a quick look at /dev/ptname for the device number.  We check
219	 * all of the likely device directories.  If we don't find it, or if
220	 * the stat information doesn't check out, use blkid_devno_to_devname()
221	 * to find it via an exhaustive search for the device major/minor.
222	 */
223	for (dir = dirlist; *dir; dir++) {
224		struct stat st;
225		char device[256];
226
227		sprintf(device, "%s/%s", *dir, ptname);
228		if ((dev = blkid_get_dev(cache, device, BLKID_DEV_FIND)) &&
229		    dev->bid_devno == devno)
230			goto set_pri;
231
232		if (stat(device, &st) == 0 && S_ISBLK(st.st_mode) &&
233		    st.st_rdev == devno) {
234			devname = blkid_strdup(device);
235			goto get_dev;
236		}
237	}
238	/* Do a short-cut scan of /dev/mapper first */
239	if (!devname)
240		devname = get_dm_name(ptname);
241	if (!devname)
242		blkid__scan_dir("/dev/mapper", devno, 0, &devname);
243	if (!devname) {
244		devname = blkid_devno_to_devname(devno);
245		if (!devname)
246			return;
247	}
248get_dev:
249	dev = blkid_get_dev(cache, devname, BLKID_DEV_NORMAL);
250	free(devname);
251set_pri:
252	if (dev) {
253		if (pri)
254			dev->bid_pri = pri;
255		else if (!strncmp(dev->bid_name, "/dev/mapper/", 11)) {
256			dev->bid_pri = BLKID_PRI_DM;
257			if (is_dm_leaf(ptname))
258				dev->bid_pri += 5;
259		} else if (!strncmp(ptname, "md", 2))
260			dev->bid_pri = BLKID_PRI_MD;
261 	}
262	return;
263}
264
265#define PROC_PARTITIONS "/proc/partitions"
266#define VG_DIR		"/proc/lvm/VGs"
267
268/*
269 * This function initializes the UUID cache with devices from the LVM
270 * proc hierarchy.  We currently depend on the names of the LVM
271 * hierarchy giving us the device structure in /dev.  (XXX is this a
272 * safe thing to do?)
273 */
274#ifdef VG_DIR
275static dev_t lvm_get_devno(const char *lvm_device)
276{
277	FILE *lvf;
278	char buf[1024];
279	int ma, mi;
280	dev_t ret = 0;
281
282	DBG(DEBUG_DEVNAME, printf("opening %s\n", lvm_device));
283	if ((lvf = fopen(lvm_device, "r")) == NULL) {
284		DBG(DEBUG_DEVNAME, printf("%s: (%d) %s\n", lvm_device, errno,
285					  strerror(errno)));
286		return 0;
287	}
288
289	while (fgets(buf, sizeof(buf), lvf)) {
290		if (sscanf(buf, "device: %d:%d", &ma, &mi) == 2) {
291			ret = makedev(ma, mi);
292			break;
293		}
294	}
295	fclose(lvf);
296
297	return ret;
298}
299
300static void lvm_probe_all(blkid_cache cache, int only_if_new)
301{
302	DIR		*vg_list;
303	struct dirent	*vg_iter;
304	int		vg_len = strlen(VG_DIR);
305	dev_t		dev;
306
307	if ((vg_list = opendir(VG_DIR)) == NULL)
308		return;
309
310	DBG(DEBUG_DEVNAME, printf("probing LVM devices under %s\n", VG_DIR));
311
312	while ((vg_iter = readdir(vg_list)) != NULL) {
313		DIR		*lv_list;
314		char		*vdirname;
315		char		*vg_name;
316		struct dirent	*lv_iter;
317
318		vg_name = vg_iter->d_name;
319		if (!strcmp(vg_name, ".") || !strcmp(vg_name, ".."))
320			continue;
321		vdirname = malloc(vg_len + strlen(vg_name) + 8);
322		if (!vdirname)
323			goto exit;
324		sprintf(vdirname, "%s/%s/LVs", VG_DIR, vg_name);
325
326		lv_list = opendir(vdirname);
327		free(vdirname);
328		if (lv_list == NULL)
329			continue;
330
331		while ((lv_iter = readdir(lv_list)) != NULL) {
332			char		*lv_name, *lvm_device;
333
334			lv_name = lv_iter->d_name;
335			if (!strcmp(lv_name, ".") || !strcmp(lv_name, ".."))
336				continue;
337
338			lvm_device = malloc(vg_len + strlen(vg_name) +
339					    strlen(lv_name) + 8);
340			if (!lvm_device) {
341				closedir(lv_list);
342				goto exit;
343			}
344			sprintf(lvm_device, "%s/%s/LVs/%s", VG_DIR, vg_name,
345				lv_name);
346			dev = lvm_get_devno(lvm_device);
347			sprintf(lvm_device, "%s/%s", vg_name, lv_name);
348			DBG(DEBUG_DEVNAME, printf("LVM dev %s: devno 0x%04X\n",
349						  lvm_device,
350						  (unsigned int) dev));
351			probe_one(cache, lvm_device, dev, BLKID_PRI_LVM,
352				  only_if_new);
353			free(lvm_device);
354		}
355		closedir(lv_list);
356	}
357exit:
358	closedir(vg_list);
359}
360#endif
361
362#define PROC_EVMS_VOLUMES "/proc/evms/volumes"
363
364static int
365evms_probe_all(blkid_cache cache, int only_if_new)
366{
367	char line[100];
368	int ma, mi, sz, num = 0;
369	FILE *procpt;
370	char device[110];
371
372	procpt = fopen(PROC_EVMS_VOLUMES, "r");
373	if (!procpt)
374		return 0;
375	while (fgets(line, sizeof(line), procpt)) {
376		if (sscanf (line, " %d %d %d %*s %*s %[^\n ]",
377			    &ma, &mi, &sz, device) != 4)
378			continue;
379
380		DBG(DEBUG_DEVNAME, printf("Checking partition %s (%d, %d)\n",
381					  device, ma, mi));
382
383		probe_one(cache, device, makedev(ma, mi), BLKID_PRI_EVMS,
384			  only_if_new);
385		num++;
386	}
387	fclose(procpt);
388	return num;
389}
390
391/*
392 * Read the device data for all available block devices in the system.
393 */
394static int probe_all(blkid_cache cache, int only_if_new)
395{
396	FILE *proc;
397	char line[1024];
398	char ptname0[128], ptname1[128], *ptname = 0;
399	char *ptnames[2];
400	dev_t devs[2];
401	int ma, mi;
402	unsigned long long sz;
403	int lens[2] = { 0, 0 };
404	int which = 0, last = 0;
405	struct list_head *p, *pnext;
406
407	ptnames[0] = ptname0;
408	ptnames[1] = ptname1;
409
410	if (!cache)
411		return -BLKID_ERR_PARAM;
412
413	if (cache->bic_flags & BLKID_BIC_FL_PROBED &&
414	    time(0) - cache->bic_time < BLKID_PROBE_INTERVAL)
415		return 0;
416
417	blkid_read_cache(cache);
418	evms_probe_all(cache, only_if_new);
419#ifdef VG_DIR
420	lvm_probe_all(cache, only_if_new);
421#endif
422
423	proc = fopen(PROC_PARTITIONS, "r");
424	if (!proc)
425		return -BLKID_ERR_PROC;
426
427	while (fgets(line, sizeof(line), proc)) {
428		last = which;
429		which ^= 1;
430		ptname = ptnames[which];
431
432		if (sscanf(line, " %d %d %llu %128[^\n ]",
433			   &ma, &mi, &sz, ptname) != 4)
434			continue;
435		devs[which] = makedev(ma, mi);
436
437		DBG(DEBUG_DEVNAME, printf("read partition name %s\n", ptname));
438
439		/* Skip whole disk devs unless they have no partitions.
440		 * If base name of device has changed, also
441		 * check previous dev to see if it didn't have a partn.
442		 * heuristic: partition name ends in a digit, & partition
443		 * names contain whole device name as substring.
444		 *
445		 * Skip extended partitions.
446		 * heuristic: size is 1
447		 *
448		 * FIXME: skip /dev/{ida,cciss,rd} whole-disk devs
449		 */
450
451		lens[which] = strlen(ptname);
452
453		/* ends in a digit, clearly a partition, so check */
454		if (isdigit(ptname[lens[which] - 1])) {
455			DBG(DEBUG_DEVNAME,
456			    printf("partition dev %s, devno 0x%04X\n",
457				   ptname, (unsigned int) devs[which]));
458
459			if (sz > 1)
460				probe_one(cache, ptname, devs[which], 0,
461					  only_if_new);
462			lens[which] = 0;	/* mark as checked */
463		}
464
465		/*
466		 * If last was a whole disk and we just found a partition
467		 * on it, remove the whole-disk dev from the cache if
468		 * it exists.
469		 */
470		if (lens[last] && !strncmp(ptnames[last], ptname, lens[last])) {
471			list_for_each_safe(p, pnext, &cache->bic_devs) {
472				blkid_dev tmp;
473
474				/* find blkid dev for the whole-disk devno */
475				tmp = list_entry(p, struct blkid_struct_dev,
476						 bid_devs);
477				if (tmp->bid_devno == devs[last]) {
478					DBG(DEBUG_DEVNAME,
479						printf("freeing %s\n",
480						       tmp->bid_name));
481					blkid_free_dev(tmp);
482					cache->bic_flags |= BLKID_BIC_FL_CHANGED;
483					break;
484				}
485			}
486			lens[last] = 0;
487		}
488		/*
489		 * If last was not checked because it looked like a whole-disk
490		 * dev, and the device's base name has changed,
491		 * check last as well.
492		 */
493		if (lens[last] && strncmp(ptnames[last], ptname, lens[last])) {
494			DBG(DEBUG_DEVNAME,
495			    printf("whole dev %s, devno 0x%04X\n",
496				   ptnames[last], (unsigned int) devs[last]));
497			probe_one(cache, ptnames[last], devs[last], 0,
498				  only_if_new);
499			lens[last] = 0;
500		}
501	}
502
503	/* Handle the last device if it wasn't partitioned */
504	if (lens[which])
505		probe_one(cache, ptname, devs[which], 0, only_if_new);
506
507	fclose(proc);
508	blkid_flush_cache(cache);
509	return 0;
510}
511
512int blkid_probe_all(blkid_cache cache)
513{
514	int ret;
515
516	DBG(DEBUG_PROBE, printf("Begin blkid_probe_all()\n"));
517	ret = probe_all(cache, 0);
518	cache->bic_time = time(0);
519	cache->bic_flags |= BLKID_BIC_FL_PROBED;
520	DBG(DEBUG_PROBE, printf("End blkid_probe_all()\n"));
521	return ret;
522}
523
524int blkid_probe_all_new(blkid_cache cache)
525{
526	int ret;
527
528	DBG(DEBUG_PROBE, printf("Begin blkid_probe_all_new()\n"));
529	ret = probe_all(cache, 1);
530	DBG(DEBUG_PROBE, printf("End blkid_probe_all_new()\n"));
531	return ret;
532}
533
534
535#ifdef TEST_PROGRAM
536int main(int argc, char **argv)
537{
538	blkid_cache cache = NULL;
539	int ret;
540
541	blkid_debug_mask = DEBUG_ALL;
542	if (argc != 1) {
543		fprintf(stderr, "Usage: %s\n"
544			"Probe all devices and exit\n", argv[0]);
545		exit(1);
546	}
547	if ((ret = blkid_get_cache(&cache, "/dev/null")) != 0) {
548		fprintf(stderr, "%s: error creating cache (%d)\n",
549			argv[0], ret);
550		exit(1);
551	}
552	if (blkid_probe_all(cache) < 0)
553		printf("%s: error probing devices\n", argv[0]);
554
555	blkid_put_cache(cache);
556	return (0);
557}
558#endif
559