1 files changed, 227 insertions, 0 deletions

diff --git a/libblkid/save.c b/libblkid/save.c
new file mode 100644
index 000000000..c94cc2a82
--- /dev/null
+++ b/libblkid/save.c
@@ -0,0 +1,227 @@
+/*
+ * save.c - write the cache struct to disk
+ *
+ * Copyright (C) 2001 by Andreas Dilger
+ * Copyright (C) 2003 Theodore Ts'o
+ *
+ * %Begin-Header%
+ * This file may be redistributed under the terms of the
+ * GNU Lesser General Public License.
+ * %End-Header%
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/types.h>
+#ifdef HAVE_SYS_STAT_H
+#include <sys/stat.h>
+#endif
+#ifdef HAVE_ERRNO_H
+#include <errno.h>
+#endif
+#include "blkidP.h"
+
+static int save_dev(blkid_dev dev, FILE *file)
+{
+	struct list_head *p;
+
+	if (!dev || dev->bid_name[0] != '/')
+		return 0;
+
+	DBG(DEBUG_SAVE,
+	    printf("device %s, type %s\n", dev->bid_name, dev->bid_type ?
+		   dev->bid_type : "(null)"));
+
+	fprintf(file, "<device DEVNO=\"0x%04lx\" TIME=\"%ld.%ld\"",
+			(unsigned long) dev->bid_devno,
+			(long) dev->bid_time,
+			(long) dev->bid_utime);
+
+	if (dev->bid_pri)
+		fprintf(file, " PRI=\"%d\"", dev->bid_pri);
+	list_for_each(p, &dev->bid_tags) {
+		blkid_tag tag = list_entry(p, struct blkid_struct_tag, bit_tags);
+		fprintf(file, " %s=\"%s\"", tag->bit_name,tag->bit_val);
+	}
+	fprintf(file, ">%s</device>\n", dev->bid_name);
+
+	return 0;
+}
+
+/*
+ * Write out the cache struct to the cache file on disk.
+ */
+int blkid_flush_cache(blkid_cache cache)
+{
+	struct list_head *p;
+	char *tmp = NULL;
+	char *opened = NULL;
+	char *filename;
+	FILE *file = NULL;
+	int fd, ret = 0;
+	struct stat st;
+
+	if (!cache)
+		return -BLKID_ERR_PARAM;
+
+	if (list_empty(&cache->bic_devs) ||
+	    !(cache->bic_flags & BLKID_BIC_FL_CHANGED)) {
+		DBG(DEBUG_SAVE, printf("skipping cache file write\n"));
+		return 0;
+	}
+
+	filename = cache->bic_filename ? cache->bic_filename :
+					 blkid_get_cache_filename(NULL);
+	if (!filename)
+		return -BLKID_ERR_PARAM;
+
+	if (strncmp(filename,
+	    BLKID_RUNTIME_DIR "/", sizeof(BLKID_RUNTIME_DIR)) == 0) {
+
+		/* default destination, create the directory if necessary */
+		if (stat(BLKID_RUNTIME_DIR, &st)
+		    && errno == ENOENT
+		    && mkdir(BLKID_RUNTIME_DIR, S_IWUSR|
+						S_IRUSR|S_IRGRP|S_IROTH|
+						S_IXUSR|S_IXGRP|S_IXOTH) != 0
+		    && errno != EEXIST) {
+			DBG(DEBUG_SAVE,
+				printf("can't create %s directory for cache file\n",
+					BLKID_RUNTIME_DIR));
+			return 0;
+		}
+	}
+
+	/* If we can't write to the cache file, then don't even try */
+	if (((ret = stat(filename, &st)) < 0 && errno != ENOENT) ||
+	    (ret == 0 && access(filename, W_OK) < 0)) {
+		DBG(DEBUG_SAVE,
+		    printf("can't write to cache file %s\n", filename));
+		return 0;
+	}
+
+	/*
+	 * Try and create a temporary file in the same directory so
+	 * that in case of error we don't overwrite the cache file.
+	 * If the cache file doesn't yet exist, it isn't a regular
+	 * file (e.g. /dev/null or a socket), or we couldn't create
+	 * a temporary file then we open it directly.
+	 */
+	if (ret == 0 && S_ISREG(st.st_mode)) {
+		tmp = malloc(strlen(filename) + 8);
+		if (tmp) {
+			sprintf(tmp, "%s-XXXXXX", filename);
+			fd = mkstemp(tmp);
+			if (fd >= 0) {
+				if (fchmod(fd, 0644) != 0)
+					DBG(DEBUG_SAVE,	printf("%s: fchmod failed\n", filename));
+				else if ((file = fdopen(fd, "w")))
+					opened = tmp;
+				if (!file)
+					close(fd);
+			}
+		}
+	}
+
+	if (!file) {
+		file = fopen(filename, "w");
+		opened = filename;
+	}
+
+	DBG(DEBUG_SAVE,
+	    printf("writing cache file %s (really %s)\n",
+		   filename, opened));
+
+	if (!file) {
+		ret = errno;
+		goto errout;
+	}
+
+	list_for_each(p, &cache->bic_devs) {
+		blkid_dev dev = list_entry(p, struct blkid_struct_dev, bid_devs);
+		if (!dev->bid_type || (dev->bid_flags & BLKID_BID_FL_REMOVABLE))
+			continue;
+		if ((ret = save_dev(dev, file)) < 0)
+			break;
+	}
+
+	if (ret >= 0) {
+		cache->bic_flags &= ~BLKID_BIC_FL_CHANGED;
+		ret = 1;
+	}
+
+	fclose(file);
+	if (opened != filename) {
+		if (ret < 0) {
+			unlink(opened);
+			DBG(DEBUG_SAVE,
+			    printf("unlinked temp cache %s\n", opened));
+		} else {
+			char *backup;
+
+			backup = malloc(strlen(filename) + 5);
+			if (backup) {
+				sprintf(backup, "%s.old", filename);
+				unlink(backup);
+				if (link(filename, backup)) {
+					DBG(DEBUG_SAVE,
+						printf("can't link %s to %s\n",
+							filename, backup));
+				}
+				free(backup);
+			}
+			if (rename(opened, filename)) {
+				ret = errno;
+				DBG(DEBUG_SAVE,
+					printf("can't rename %s to %s\n",
+						opened, filename));
+			} else {
+				DBG(DEBUG_SAVE,
+				    printf("moved temp cache %s\n", opened));
+			}
+		}
+	}
+
+errout:
+	free(tmp);
+	if (filename != cache->bic_filename)
+		free(filename);
+	return ret;
+}
+
+#ifdef TEST_PROGRAM
+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 loading/saving a cache (filename)\n", argv[0]);
+		exit(1);
+	}
+
+	if ((ret = blkid_get_cache(&cache, "/dev/null")) != 0) {
+		fprintf(stderr, "%s: error creating cache (%d)\n",
+			argv[0], ret);
+		exit(1);
+	}
+	if ((ret = blkid_probe_all(cache)) < 0) {
+		fprintf(stderr, "error (%d) probing devices\n", ret);
+		exit(1);
+	}
+	cache->bic_filename = strdup(argv[1]);
+
+	if ((ret = blkid_flush_cache(cache)) < 0) {
+		fprintf(stderr, "error (%d) saving cache\n", ret);
+		exit(1);
+	}
+
+	blkid_put_cache(cache);
+
+	return ret;
+}
+#endif