libfstools: ubi: rework reading volumes

UBI volume IDs don't have to be contiguous, this may happen if there
were few and the not last one was removed. In such case we may have
e.g. ubi0_0, ubi0_2.
It means we can't simply read value from "volumes_count" and iterate
from 0 to the count - 1.

This patch rewrites ubi_part_match to read whole directory and look
for ubi%d_%d entries in it.

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>

1 files changed, 19 insertions, 7 deletions

diff --git a/libfstools/ubi.c b/libfstools/ubi.c
index ac9eb1b..0f6e37a 100644
--- a/libfstools/ubi.c
+++ b/libfstools/ubi.c
@@ -165,22 +165,34 @@ static int ubi_volume_match(struct volume *v, char *name, int ubi_num, int volid
 
 static int ubi_part_match(struct volume *v, char *name, unsigned int ubi_num)
 {
-	unsigned int i, volumes_count;
+	DIR *ubi_dir;
+	struct dirent *ubi_dirent;
+	unsigned int volid;
 	char devdir[BUFLEN];
+	int ret = -1;
 
 	snprintf(devdir, sizeof(devdir), "%s/ubi%u",
 		ubi_dir_name, ubi_num);
 
-	if (read_uint_from_file(devdir, "volumes_count", &volumes_count))
-		return -1;
+	ubi_dir = opendir(devdir);
+	if (!ubi_dir)
+		return ret;
 
-	for (i=0;i<volumes_count;i++) {
-		if (!ubi_volume_match(v, name, ubi_num, i)) {
-			return 0;
+	while ((ubi_dirent = readdir(ubi_dir)) != NULL) {
+		if (strncmp(ubi_dirent->d_name, "ubi", 3))
+			continue;
+
+		if (sscanf(ubi_dirent->d_name, "ubi%*u_%u", &volid) != 1)
+			continue;
+
+		if (!ubi_volume_match(v, name, ubi_num, volid)) {
+			ret = 0;
+			break;
 		}
 	}
+	closedir(ubi_dir);
 
-	return -1;
+	return ret;
 }
 
 static int ubi_volume_find(struct volume *v, char *name)