/*
* read.c - read the blkid cache from disk, to avoid scanning all devices
*
* Copyright (C) 2001, 2003 Theodore Y. Ts'o
* Copyright (C) 2001 Andreas Dilger
*
* %Begin-Header%
* This file may be redistributed under the terms of the
* GNU Lesser General Public License.
* %End-Header%
*/
#include <stdio.h>
#include <ctype.h>
#include <string.h>
#include <time.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#ifdef HAVE_ERRNO_H
#include <errno.h>
#endif
#include "blkidP.h"
#ifdef HAVE_STDLIB_H
# ifndef _XOPEN_SOURCE
# define _XOPEN_SOURCE 600 /* for inclusion of strtoull */
# endif
# include <stdlib.h>
#endif
#ifdef HAVE_STRTOULL
#define STRTOULL strtoull /* defined in stdlib.h if you try hard enough */
#else
/* FIXME: need to support real strtoull here */
#define STRTOULL strtoul
#endif
#ifdef TEST_PROGRAM
#define blkid_debug_dump_dev(dev) (debug_dump_dev(dev))
static void debug_dump_dev(blkid_dev dev);
#endif
/*
* File format:
*
* <device [<NAME="value"> ...]>device_name</device>
*
* The following tags are required for each entry:
* <ID="id"> unique (within this file) ID number of this device
* <TIME="sec.usec"> (time_t and suseconds_t) time this entry was last
* read from disk
* <TYPE="type"> (detected) type of filesystem/data for this partition
*
* The following tags may be present, depending on the device contents
* <LABEL="label"> (user supplied) label (volume name, etc)
* <UUID="uuid"> (generated) universally unique identifier (serial no)
*/
static char *skip_over_blank(char *cp)
{
while (*cp && isspace(*cp))
cp++;
return cp;
}
static char *skip_over_word(char *cp)
{
char ch;
while ((ch = *cp)) {
/* If we see a backslash, skip the next character */
if (ch == '\\') {
cp++;
if (*cp == '\0')
break;
cp++;
continue;
}
if (isspace(ch) || ch == '<' || ch == '>')
break;
cp++;
}
return cp;
}
static char *strip_line(char *line)
{
char *p;
line = skip_over_blank(line);
p = line + strlen(line) - 1;
while (*line) {
if (isspace(*p))
*p-- = '\0';
else
break;
}
return line;
}
#if 0
static char *parse_word(char **buf)
{
char *word, *next;
word = *buf;
if (*word == '\0')
return NULL;
word = skip_over_blank(word);
next = skip_over_word(word);
if (*next) {
char *end = next - 1;
if (*end == '"' || *end == '\'')
*end = '\0';
*next++ = '\0';
}
*buf = next;
if (*word == '"' || *word == '\'')
word++;
return word;
}
#endif
/*
* Start parsing a new line from the cache.
*
* line starts with "<device" return 1 -> continue parsing line
* line starts with "<foo", empty, or # return 0 -> skip line
* line starts with other, return -BLKID_ERR_CACHE -> error
*/
static int parse_start(char **cp)
{
char *p;
p = strip_line(*cp);
/* Skip comment or blank lines. We can't just NUL the first '#' char,
* in case it is inside quotes, or escaped.
*/
if (*p == '\0' || *p == '#')
return 0;
if (!strncmp(p, "<device", 7)) {
DBG(READ, ul_debug("found device header: %8s", p));
p += 7;
*cp = p;
return 1;
}
if (*p == '<')
return 0;
return -BLKID_ERR_CACHE;
}
/* Consume the remaining XML on the line (cosmetic only) */
static int parse_end(char **cp)
{
*cp = skip_over_blank(*cp);
if (!strncmp(*cp, "</device>", 9)) {
DBG(READ, ul_debug("found device trailer %9s", *cp));
*cp += 9;
return 0;
}
return -BLKID_ERR_CACHE;
}
/*
* Allocate a new device struct with device name filled in. Will handle
* finding the device on lines of the form:
* <device foo=bar>devname</device>
* <device>devname<foo>bar</foo></device>
*/
static int parse_dev(blkid_cache cache, blkid_dev *dev, char **cp)
{
char *start, *tmp, *end, *name;
int ret;
if ((ret = parse_start(cp)) <= 0)
return ret;
start = tmp = strchr(*cp, '>');
if (!start) {
DBG(READ, ul_debug("blkid: short line parsing dev: %s", *cp));
return -BLKID_ERR_CACHE;
}
start = skip_over_blank(start + 1);
end = skip_over_word(start);
DBG(READ, ul_debug("device should be %*s",
(int)(end - start), start));
if (**cp == '>')
*cp = end;
else
(*cp)++;
*tmp = '\0';
if (!(tmp = strrchr(end, '<')) || parse_end(&tmp) < 0) {
DBG(READ, ul_debug("blkid: missing </device> ending: %s", end));
} else if (tmp)
*tmp = '\0';
if (end - start <= 1) {
DBG(READ, ul_debug("blkid: empty device name: %s", *cp));
return -BLKID_ERR_CACHE;
}
name = strndup(start, end - start);
if (name == NULL)
return -BLKID_ERR_MEM;
DBG(READ, ul_debug("found dev %s", name));
if (!(*dev = blkid_get_dev(cache, name, BLKID_DEV_CREATE))) {
free(name);
return -BLKID_ERR_MEM;
}
free(name);
return 1;
}
/*
* Extract a tag of the form NAME="value" from the line.
*/
static int parse_token(char **name, char **value, char **cp)
{
char *end;
if (!name || !value || !cp)
return -BLKID_ERR_PARAM;
if (!(*value = strchr(*cp, '=')))
return 0;
**value = '\0';
*name = strip_line(*cp);
*value = skip_over_blank(*value + 1);
if (**value == '"') {
char *p = end = *value + 1;
/* convert 'foo\"bar' to 'foo"bar' */
while (*p) {
if (*p == '\\') {
p++;
*end = *p;
} else {
*end = *p;
if (*p == '"')
break;
}
p++;
end++;
}
if (*end != '"') {
DBG(READ, ul_debug("unbalanced quotes at: %s", *value));
*cp = *value;
return -BLKID_ERR_CACHE;
}
(*value)++;
*end = '\0';
end = ++p;
} else {
end = skip_over_word(*value);
if (*end) {
*end = '\0';
end++;
}
}
*cp = end;
return 1;
}
/*
* Extract a tag of the form <NAME>value</NAME> from the line.
*/
/*
static int parse_xml(char **name, char **value, char **cp)
{
char *end;
if (!name || !value || !cp)
return -BLKID_ERR_PARAM;
*name = strip_line(*cp);
if ((*name)[0] != '<' || (*name)[1] == '/')
return 0;
FIXME: finish this.
}
*/
/*
* Extract a tag from the line.
*
* Return 1 if a valid tag was found.
* Return 0 if no tag found.
* Return -ve error code.
*/
static int parse_tag(blkid_cache cache, blkid_dev dev, char **cp)
{
char *name = NULL;
char *value = NULL;
int ret;
if (!cache || !dev)
return -BLKID_ERR_PARAM;
if ((ret = parse_token(&name, &value, cp)) <= 0 /* &&
(ret = parse_xml(&name, &value, cp)) <= 0 */)
return ret;
/* Some tags are stored directly in the device struct */
if (!strcmp(name, "DEVNO"))
dev->bid_devno = STRTOULL(value, 0, 0);
else if (!strcmp(name, "PRI"))
dev->bid_pri = strtol(value, 0, 0);
else if (!strcmp(name, "TIME")) {
char *end = NULL;
dev->bid_time = STRTOULL(value, &end, 0);
if (end && *end == '.')
dev->bid_utime = STRTOULL(end + 1, 0, 0);
} else
ret = blkid_set_tag(dev, name, value, strlen(value));
DBG(READ, ul_debug(" tag: %s=\"%s\"", name, value));
return ret < 0 ? ret : 1;
}
/*
* Parse a single line of data, and return a newly allocated dev struct.
* Add the new device to the cache struct, if one was read.
*
* Lines are of the form <device [TAG="value" ...]>/dev/foo</device>
*
* Returns -ve value on error.
* Returns 0 otherwise.
* If a valid device was read, *dev_p is non-NULL, otherwise it is NULL
* (e.g. comment lines, unknown XML content, etc).
*/
static int blkid_parse_line(blkid_cache cache, blkid_dev *dev_p, char *cp)
{
blkid_dev dev;
int ret;
if (!cache || !dev_p)
return -BLKID_ERR_PARAM;
*dev_p = NULL;
DBG(READ, ul_debug("line: %s", cp));
if ((ret = parse_dev(cache, dev_p, &cp)) <= 0)
return ret;
dev = *dev_p;
while ((ret = parse_tag(cache, dev, &cp)) > 0) {
;
}
if (dev->bid_type == NULL) {
DBG(READ, ul_debug("blkid: device %s has no TYPE",dev->bid_name));
blkid_free_dev(dev);
goto done;
}
DBG(READ, blkid_debug_dump_dev(dev));
done:
return ret;
}
/*
* Parse the specified filename, and return the data in the supplied or
* a newly allocated cache struct. If the file doesn't exist, return a
* new empty cache struct.
*/
void blkid_read_cache(blkid_cache cache)
{
FILE *file;
char buf[4096];
int fd, lineno = 0;
struct stat st;
if (!cache)
return;
/*
* If the file doesn't exist, then we just return an empty
* struct so that the cache can be populated.
*/
if ((fd = open(cache->bic_filename, O_RDONLY|O_CLOEXEC)) < 0)
return;
if (fstat(fd, &st) < 0)
goto errout;
if ((st.st_mtime == cache->bic_ftime) ||
(cache->bic_flags & BLKID_BIC_FL_CHANGED)) {
DBG(CACHE, ul_debug("skipping re-read of %s",
cache->bic_filename));
goto errout;
}
DBG(CACHE, ul_debug("reading cache file %s",
cache->bic_filename));
file = fdopen(fd, "r" UL_CLOEXECSTR);
if (!file)
goto errout;
while (fgets(buf, sizeof(buf), file)) {
blkid_dev dev;
unsigned int end;
lineno++;
if (buf[0] == 0)
continue;
end = strlen(buf) - 1;
/* Continue reading next line if it ends with a backslash */
while (end < (sizeof(buf) - 2) && buf[end] == '\\' &&
fgets(buf + end, sizeof(buf) - end, file)) {
end = strlen(buf) - 1;
lineno++;
}
if (blkid_parse_line(cache, &dev, buf) < 0) {
DBG(READ, ul_debug("blkid: bad format on line %d", lineno));
continue;
}
}
fclose(file);
/*
* Initially we do not need to write out the cache file.
*/
cache->bic_flags &= ~BLKID_BIC_FL_CHANGED;
cache->bic_ftime = st.st_mtime;
return;
errout:
close(fd);
return;
}
#ifdef TEST_PROGRAM
static void debug_dump_dev(blkid_dev dev)
{
struct list_head *p;
if (!dev) {
printf(" dev: NULL\n");
return;
}
printf(" dev: name = %s\n", dev->bid_name);
printf(" dev: DEVNO=\"0x%0llx\"\n", (long long)dev->bid_devno);
printf(" dev: TIME=\"%ld.%ld\"\n", (long)dev->bid_time, (long)dev->bid_utime);
printf(" dev: PRI=\"%d\"\n", dev->bid_pri);
printf(" dev: flags = 0x%08X\n", dev->bid_flags);
list_for_each(p, &dev->bid_tags) {
blkid_tag tag = list_entry(p, struct blkid_struct_tag, bit_tags);
if (tag)
printf(" tag: %s=\"%s\"\n", tag->bit_name,
tag->bit_val);
else
printf(" tag: NULL\n");
}
printf("\n");
}
int main(int argc, char**argv)
{
blkid_cache cache = NULL;
int ret;
blkid_init_debug(BLKID_DEBUG_ALL);
if (argc > 2) {
fprintf(stderr, "Usage: %s [filename]\n"
"Test parsing of the cache (filename)\n", argv[0]);
exit(1);
}
if ((ret = blkid_get_cache(&cache, argv[1])) < 0)
fprintf(stderr, "error %d reading cache file %s\n", ret,
argv[1] ? argv[1] : blkid_get_cache_filename(NULL));
blkid_put_cache(cache);
return ret;
}
#endif
