1 files changed, 468 insertions, 0 deletions
diff --git a/libblkid/src/read.c b/libblkid/src/read.c
new file mode 100644
index 0000000..89adf11
--- /dev/null
+++ b/libblkid/src/read.c
@@ -0,0 +1,468 @@
+/*
+ * 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
+
+/*
+ * 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;
+
+	DBG(READ, ul_debug("tag: %s=\"%s\"", name, value));
+
+	/* Some tags are stored directly in the device struct */
+	if (!strcmp(name, "DEVNO"))
+		dev->bid_devno = strtoull(value, NULL, 0);
+	else if (!strcmp(name, "PRI"))
+		dev->bid_pri = strtol(value, NULL, 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, NULL, 0);
+	} else
+		ret = blkid_set_tag(dev, name, value, strlen(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;
+	}
+
+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 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
+
+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