cmd: ubi: Add 'ubi list' command for printing list of all UBI volumes

To allow easily iterate over all UBI volumes, add a new command which
either print all user UBI volumes on output or set them into env variable.

As UBI volumes can have arbitrary name/label, in most cases it is useful to
iterate them by their numbers. This can be achieved by -numeric flag.

This functionality is similar to already existing 'part list' command which
prints partitions on formatted block device.

Signed-off-by: Pali Rohár <pali@kernel.org>

cmd/ubi.c

@@ -27,6 +27,7 @@
 #include <ubi_uboot.h>
 #include <linux/errno.h>
 #include <jffs2/load_kernel.h>
+#include <linux/log2.h>
 
 #undef ubi_msg
 #define ubi_msg(fmt, ...) printf("UBI: " fmt "\n", ##__VA_ARGS__)
@@ -84,6 +85,70 @@ static int ubi_info(int layout)
 	return 0;
 }
 
+static int ubi_list(const char *var, int numeric)
+{
+	size_t namelen, len, size;
+	char *str, *str2;
+	int i;
+
+	if (!var) {
+		for (i = 0; i < (ubi->vtbl_slots + 1); i++) {
+			if (!ubi->volumes[i])
+				continue;
+			if (ubi->volumes[i]->vol_id >= UBI_INTERNAL_VOL_START)
+				continue;
+			printf("%d: %s\n",
+			       ubi->volumes[i]->vol_id,
+			       ubi->volumes[i]->name);
+		}
+		return 0;
+	}
+
+	len = 0;
+	size = 16;
+	str = malloc(size);
+	if (!str)
+		return 1;
+
+	for (i = 0; i < (ubi->vtbl_slots + 1); i++) {
+		if (!ubi->volumes[i])
+			continue;
+		if (ubi->volumes[i]->vol_id >= UBI_INTERNAL_VOL_START)
+			continue;
+
+		if (numeric)
+			namelen = 10; /* strlen(stringify(INT_MAX)) */
+		else
+			namelen = strlen(ubi->volumes[i]->name);
+
+		if (len + namelen + 1 > size) {
+			size = roundup_pow_of_two(len + namelen + 1) * 2;
+			str2 = realloc(str, size);
+			if (!str2) {
+				free(str);
+				return 1;
+			}
+			str = str2;
+		}
+
+		if (len)
+			str[len++] = ' ';
+
+		if (numeric) {
+			len += sprintf(str + len, "%d", ubi->volumes[i]->vol_id) + 1;
+		} else {
+			memcpy(str + len, ubi->volumes[i]->name, namelen);
+			len += namelen;
+			str[len] = 0;
+		}
+	}
+
+	env_set(var, str);
+	free(str);
+
+	return 0;
+}
+
 static int ubi_check_volumename(const struct ubi_volume *vol, char *name)
 {
 	return strcmp(vol->name, name);
@@ -586,6 +651,21 @@ static int do_ubi(struct cmd_tbl *cmdtp, int flag, int argc, char *const argv[])
 		return ubi_info(layout);
 	}
 
+	if (strcmp(argv[1], "list") == 0) {
+		int numeric = 0;
+		if (argc >= 2 && argv[2][0] == '-') {
+			if (strcmp(argv[2], "-numeric") == 0)
+				numeric = 1;
+			else
+				return CMD_RET_USAGE;
+		}
+		if (!numeric && argc != 2 && argc != 3)
+			return CMD_RET_USAGE;
+		if (numeric && argc != 3 && argc != 4)
+			return CMD_RET_USAGE;
+		return ubi_list(argv[numeric ? 3 : 2], numeric);
+	}
+
 	if (strcmp(argv[1], "check") == 0) {
 		if (argc > 2)
 			return ubi_check(argv[2]);
@@ -725,6 +805,11 @@ U_BOOT_CMD(
 		" header offset)\n"
 	"ubi info [l[ayout]]"
 		" - Display volume and ubi layout information\n"
+	"ubi list [flags]"
+		" - print the list of volumes\n"
+	"ubi list [flags] <varname>"
+		" - set environment variable to the list of volumes"
+		" (flags can be -numeric)\n"
 	"ubi check volumename"
 		" - check if volumename exists\n"
 	"ubi create[vol] volume [size] [type] [id] [--skipcheck]\n"