X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?a=blobdiff_plain;f=extras%2Fvolume_id%2Flib%2Fvolume_id.c;h=48bfd88624d323b7922370d9b68950bee41f54b5;hb=c807ad918c7c61a8af3fcc930cc2a5ad4c978ea1;hp=8f22509ca6be6ab718780dda3e4c428c4cbc0a9a;hpb=b29a5e4ab98f460d2f79a11d1969858640e897e6;p=elogind.git

diff --git a/extras/volume_id/lib/volume_id.c b/extras/volume_id/lib/volume_id.c
index 8f22509ca..48bfd8862 100644
--- a/extras/volume_id/lib/volume_id.c
+++ b/extras/volume_id/lib/volume_id.c
@@ -219,6 +219,19 @@ int volume_id_get_uuid_raw(struct volume_id *id, const uint8_t **uuid, size_t *l
 	return 1;
 }
 
+int volume_id_get_uuid_sub(struct volume_id *id, const char **uuid)
+{
+	if (id == NULL)
+		return 0;
+	if (uuid == NULL)
+		return 0;
+	if (id->usage_id == VOLUME_ID_UNUSED)
+		return 0;
+
+	*uuid = id->uuid_sub;
+	return 1;
+}
+
 /**
  * volume_id_get_usage:
  * @id: Probing context.
@@ -369,9 +382,12 @@ int volume_id_probe_raid(struct volume_id *id, uint64_t off, uint64_t size)
 
 	info("probing at offset 0x%" PRIx64 ", size 0x%" PRIx64 "\n", off, size);
 
-	for (i = 0; i < ARRAY_SIZE(prober_raid); i++)
-		if (prober_raid[i].prober(id, off, size) == 0)
+	for (i = 0; i < ARRAY_SIZE(prober_raid); i++) {
+		if (prober_raid[i].prober(id, off, size) == 0) {
+			info("signature '%s' detected\n", id->type);
 			goto found;
+		}
+	}
 	return -1;
 
 found:
@@ -380,6 +396,18 @@ found:
 	return 0;
 }
 
+static void volume_id_reset_result(struct volume_id *id)
+{
+	id->label_raw_len = 0;
+	id->label[0] = '\0';
+	id->uuid_raw_len = 0;
+	id->uuid[0] = '\0';
+	id->usage_id = VOLUME_ID_UNUSED;
+	id->usage = NULL;
+	id->type = NULL;
+	id->type_version[0] = '\0';
+}
+
 /**
  * volume_id_probe_filesystem:
  * @id: Probing context.
@@ -402,11 +430,66 @@ int volume_id_probe_filesystem(struct volume_id *id, uint64_t off, uint64_t size
 
 	info("probing at offset 0x%" PRIx64 ", size 0x%" PRIx64 "\n", off, size);
 
-	for (i = 0; i < ARRAY_SIZE(prober_filesystem); i++)
-		if (prober_filesystem[i].prober(id, off, size) == 0)
+	/*
+	 * We probe for all known filesystems to find conflicting signatures. If
+	 * we find multiple matching signatures and one of the detected filesystem
+	 * types claims that it can not co-exist with any other filesystem type,
+	 * we do not return a probing result.
+	 *
+	 * We can not afford to mount a volume with the wrong filesystem code and
+	 * possibly corrupt it. Linux sytems have the problem of dozens of possible
+	 * filesystem types, and volumes with left-over signatures from former
+	 * filesystem types. Invalid signatures need to be removed from the volume
+	 * to make the filesystem detection successful.
+	 *
+	 * We do not want to read that many bytes from probed floppies, skip volumes
+	 * smaller than a usual floppy disk.
+	 */
+	if (size > 1440 * 1024) {
+		int found = 0;
+		int force_unique_result = 0;
+		int first_match = -1;
+
+		volume_id_reset_result(id);
+		for (i = 0; i < ARRAY_SIZE(prober_filesystem); i++) {
+			int match;
+
+			match = (prober_filesystem[i].prober(id, off, size) == 0);
+			if (match) {
+				info("signature '%s' %i detected\n", id->type, i);
+				if (id->force_unique_result)
+					force_unique_result = 1;
+				if (found > 0 && force_unique_result) {
+					info("conflicting signatures found, skip results\n");
+					return -1;
+				}
+				found++;
+				if (first_match < 0)
+					first_match = i;
+			}
+		}
+		if (found < 1)
+			return -1;
+		if (found == 1)
 			goto found;
-	return -1;
+		if (found > 1) {
+			volume_id_reset_result(id);
+			info("re-read first match metadata %i\n", first_match);
+			if (prober_filesystem[first_match].prober(id, off, size) == 0)
+				goto found;
+			return -1;
+		}
+	}
 
+	/* return the first match */
+	volume_id_reset_result(id);
+	for (i = 0; i < ARRAY_SIZE(prober_filesystem); i++) {
+		if (prober_filesystem[i].prober(id, off, size) == 0) {
+			info("signature '%s' detected\n", id->type);
+			goto found;
+		}
+	}
+	return -1;
 found:
 	/* If recognized, we free the allocated buffers */
 	volume_id_free_buffer(id);