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-rw-r--r--libblkid/read.c500
1 files changed, 500 insertions, 0 deletions
diff --git a/libblkid/read.c b/libblkid/read.c
new file mode 100644
index 000000000..8914cad69
--- /dev/null
+++ b/libblkid/read.c
@@ -0,0 +1,500 @@
+/*
+ * 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(DEBUG_READ, printf("found device header: %8s\n", 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(DEBUG_READ, printf("found device trailer %9s\n", *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(DEBUG_READ,
+ printf("blkid: short line parsing dev: %s\n", *cp));
+ return -BLKID_ERR_CACHE;
+ }
+ start = skip_over_blank(start + 1);
+ end = skip_over_word(start);
+
+ DBG(DEBUG_READ, printf("device should be %*s\n",
+ (int)(end - start), start));
+
+ if (**cp == '>')
+ *cp = end;
+ else
+ (*cp)++;
+
+ *tmp = '\0';
+
+ if (!(tmp = strrchr(end, '<')) || parse_end(&tmp) < 0) {
+ DBG(DEBUG_READ,
+ printf("blkid: missing </device> ending: %s\n", end));
+ } else if (tmp)
+ *tmp = '\0';
+
+ if (end - start <= 1) {
+ DBG(DEBUG_READ, printf("blkid: empty device name: %s\n", *cp));
+ return -BLKID_ERR_CACHE;
+ }
+
+ name = strndup(start, end - start);
+ if (name == NULL)
+ return -BLKID_ERR_MEM;
+
+ DBG(DEBUG_READ, printf("found dev %s\n", 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 == '"') {
+ end = strchr(*value + 1, '"');
+ if (!end) {
+ DBG(DEBUG_READ,
+ printf("unbalanced quotes at: %s\n", *value));
+ *cp = *value;
+ return -BLKID_ERR_CACHE;
+ }
+ (*value)++;
+ *end = '\0';
+ end++;
+ } 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(DEBUG_READ, printf(" tag: %s=\"%s\"\n", 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(DEBUG_READ, printf("line: %s\n", 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(DEBUG_READ,
+ printf("blkid: device %s has no TYPE\n",dev->bid_name));
+ blkid_free_dev(dev);
+ goto done;
+ }
+
+ DBG(DEBUG_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(DEBUG_CACHE, printf("skipping re-read of %s\n",
+ cache->bic_filename));
+ goto errout;
+ }
+
+ DBG(DEBUG_CACHE, printf("reading cache file %s\n",
+ cache->bic_filename));
+
+ file = fdopen(fd, "r");
+ 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(DEBUG_READ,
+ printf("blkid: bad format on line %d\n", 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(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
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