--- /dev/null
+/*
+ * evaluate.c - very high-level API to evaluate LABELs or UUIDs
+ *
+ * This is simular to blkid_get_devname() from resolve.c, but this
+ * API supports udev /dev/disk/by-{label,uuid} links.
+ *
+ * Copyright (C) 2009 Karel Zak <kzak@redhat.com>
+ *
+ * This file may be redistributed under the terms of the
+ * GNU Lesser General Public License.
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <ctype.h>
+#include <sys/types.h>
+#ifdef HAVE_SYS_STAT_H
+#include <sys/stat.h>
+#endif
+#ifdef HAVE_SYS_MKDEV_H
+#include <sys/mkdev.h>
+#endif
+#ifdef HAVE_ERRNO_H
+#include <errno.h>
+#endif
+#include <stdint.h>
+#ifdef HAVE_LIBUUID
+#include <uuid/uuid.h>
+#endif
+#include <stdarg.h>
+
+#include "pathnames.h"
+#include "canonicalize.h"
+
+#include "blkdev.h"
+#include "blkidP.h"
+
+/* returns zero when the device has NAME=value (LABEL/UUID) */
+static int verify_tag(const char *devname, const char *name, const char *value)
+{
+ blkid_probe pr;
+ int fd = -1, rc = -1;
+ size_t len;
+ unsigned char *data;
+
+ pr = blkid_new_probe();
+ if (!pr)
+ return -1;
+
+ blkid_probe_set_request(pr, BLKID_PROBREQ_LABEL | BLKID_PROBREQ_UUID);
+
+ fd = open(devname, O_RDONLY);
+ if (fd < 0)
+ goto done;
+ if (blkid_probe_set_device(pr, fd, 0, 0))
+ goto done;
+ rc = blkid_do_safeprobe(pr);
+ if (rc)
+ goto done;
+ rc = blkid_probe_lookup_value(pr, name, &data, &len);
+ if (!rc)
+ rc = memcmp(value, data, len);
+done:
+ DBG(DEBUG_EVALUATE, printf("%s: %s verification %s\n",
+ devname, name, rc == 0 ? "PASS" : "FAILED"));
+ if (fd >= 0)
+ close(fd);
+ blkid_free_probe(pr);
+ return rc;
+}
+
+/**
+ * blkid_send_uevent:
+ * @devname: absolute path to the device
+ *
+ * Returns -1 in case of failure, or 0 on success.
+ */
+int blkid_send_uevent(const char *devname, const char *action)
+{
+ char uevent[PATH_MAX];
+ struct stat st;
+ FILE *f;
+ int rc = -1;
+
+ DBG(DEBUG_EVALUATE, printf("%s: uevent '%s' requested\n", devname, action));
+
+ if (!devname || !action)
+ return -1;
+ if (stat(devname, &st) || !S_ISBLK(st.st_mode))
+ return -1;
+
+ snprintf(uevent, sizeof(uevent), "/sys/dev/block/%d:%d/uevent",
+ major(st.st_rdev), minor(st.st_rdev));
+
+ f = fopen(uevent, "w");
+ if (f) {
+ rc = 0;
+ if (fputs(action, f) >= 0)
+ rc = 0;
+ fclose(f);
+ }
+ DBG(DEBUG_EVALUATE, printf("%s: send uevent %s\n",
+ uevent, rc == 0 ? "SUCCES" : "FAILED"));
+ return rc;
+}
+
+static char *evaluate_by_udev(const char *token, const char *value, int uevent)
+{
+ char dev[PATH_MAX];
+ char *path = NULL;
+ size_t len;
+ struct stat st;
+
+ DBG(DEBUG_EVALUATE,
+ printf("evaluating by udev %s=%s\n", token, value));
+
+ if (!strcmp(token, "UUID"))
+ strcpy(dev, _PATH_DEV_BYUUID "/");
+ else if (!strcmp(token, "LABEL"))
+ strcpy(dev, _PATH_DEV_BYLABEL "/");
+ else {
+ DBG(DEBUG_EVALUATE,
+ printf("unsupported token %s\n", token));
+ return NULL; /* unsupported tag */
+ }
+
+ len = strlen(dev);
+ if (blkid_encode_string(value, &dev[len], sizeof(dev) - len) != 0)
+ return NULL;
+
+ DBG(DEBUG_EVALUATE,
+ printf("expected udev link: %s\n", dev));
+
+ if (stat(dev, &st))
+ goto failed; /* link or device does not exist */
+
+ if (!S_ISBLK(st.st_mode))
+ return NULL;
+
+ path = canonicalize_path(dev);
+ if (!path)
+ return NULL;
+
+ if (verify_tag(path, token, value))
+ goto failed;
+ return path;
+
+failed:
+ DBG(DEBUG_EVALUATE, printf("failed to evaluate by udev\n"));
+
+ if (uevent && path)
+ blkid_send_uevent(path, "change");
+ free(path);
+ return NULL;
+}
+
+static char *evaluate_by_scan(const char *token, const char *value,
+ blkid_cache *cache, const char *cachefile)
+{
+ blkid_cache c = cache ? *cache : NULL;
+ char *res;
+
+ DBG(DEBUG_EVALUATE,
+ printf("evaluating by blkid scan %s=%s\n", token, value));
+
+ if (!c)
+ blkid_get_cache(&c, cachefile);
+ if (!c)
+ return NULL;
+
+ res = blkid_get_devname(c, token, value);
+
+ if (cache)
+ *cache = c;
+ else
+ blkid_put_cache(c);
+
+ return res;
+}
+
+/**
+ * blkid_evaluate_spec:
+ * @token: token name (e.g "LABEL" or "UUID")
+ * @value: token data
+ * @cache: pointer to cache (or NULL when you don't want to re-use the cache)
+ *
+ * Returns allocated string with device name.
+ */
+char *blkid_evaluate_spec(const char *token, const char *value, blkid_cache *cache)
+{
+ struct blkid_config *conf = NULL;
+ char *t = NULL, *v = NULL;
+ char *ret = NULL;
+ int i;
+
+ if (!token)
+ return NULL;
+
+ if (!cache || !*cache)
+ blkid_debug_init(0);
+
+ DBG(DEBUG_EVALUATE,
+ printf("evaluating %s%s%s\n", token, value ? "=" : "",
+ value ? value : ""));
+
+ if (!value) {
+ if (!strchr(token, '=')) {
+ ret = blkid_strdup(token);
+ goto out;
+ }
+ blkid_parse_tag_string(token, &t, &v);
+ if (!t || !v)
+ goto out;
+ token = t;
+ value = v;
+ }
+
+ conf = blkid_read_config(NULL);
+ if (!conf)
+ goto out;
+
+ for (i = 0; i < conf->nevals; i++) {
+ if (conf->eval[i] == BLKID_EVAL_UDEV)
+ ret = evaluate_by_udev(token, value, conf->uevent);
+ else if (conf->eval[i] == BLKID_EVAL_SCAN)
+ ret = evaluate_by_scan(token, value, cache, conf->cachefile);
+ if (ret)
+ break;
+ }
+
+ DBG(DEBUG_EVALUATE,
+ printf("%s=%s evaluated as %s\n", token, value, ret));
+out:
+ blkid_free_config(conf);
+ free(t);
+ free(v);
+ return ret;
+}
+
+#ifdef TEST_PROGRAM
+int main(int argc, char *argv[])
+{
+ blkid_cache cache = NULL;
+ char *res;
+
+ if (argc < 3) {
+ fprintf(stderr, "usage: %s <token> <value>\n", argv[0]);
+ return EXIT_FAILURE;
+ }
+
+ blkid_debug_init(0);
+
+ res = blkid_evaluate_spec(argv[1], argv[2], &cache);
+ if (res)
+ printf("%s\n", res);
+ if (cache)
+ blkid_put_cache(cache);
+
+ return res ? EXIT_SUCCESS : EXIT_FAILURE;
+}
+#endif
projects / util-linux / commitdiff