From: Daniel Golle <daniel@makrotopia.org>
Date: Mon, 1 Nov 2021 12:39:11 +0000 (+0000)
Subject: libfstools: use uevent instead of relying on custom kernel patch
X-Git-Url: http://git.openwrt.org/openwrt/docs.git?p=project%2Ffstools.git;a=commitdiff_plain;h=d3907445b7aa9cbde70d501bd68a5e38db90c6b2

libfstools: use uevent instead of relying on custom kernel patch

Detect partition name based on 'uevent' instead of relying in custom
kernel patch exposing 'name' in sysfs directly.
This will allow to drop the custom patch again.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>
---

diff --git a/libfstools/partname.c b/libfstools/partname.c
index 5d4fde5..773df8c 100644
--- a/libfstools/partname.c
+++ b/libfstools/partname.c
@@ -61,11 +61,14 @@ static int partname_volume_init(struct volume *v)
 	return block_volume_format(v, 0, p->parent_dev.devpathstr);
 }
 
-/* from procd/utils.c -> should go to libubox */
-static char* get_cmdline_val(const char* name, char* out, int len)
+/* adapted from procd/utils.c -> should go to libubox */
+static char* get_var_from_file(const char* filename, const char* name, char* out, int len)
 {
 	char line[1024], *c, *sptr;
-	int fd = open("/proc/cmdline", O_RDONLY);
+	int fd = open(filename, O_RDONLY);
+	if (fd == -1)
+		return NULL;
+
 	ssize_t r = read(fd, line, sizeof(line) - 1);
 	close(fd);
 
@@ -112,7 +115,7 @@ static char *rootdevname(char *devpath) {
 static struct volume *partname_volume_find(char *name)
 {
 	struct partname_volume *p;
-	char volnamegstr[BUFLEN];
+	char ueventgstr[BUFLEN];
 	char namebuf[BUFLEN];
 	char rootparam[BUFLEN];
 	char *rootdev = NULL, *devname, *tmp;
@@ -120,23 +123,23 @@ static struct volume *partname_volume_find(char *name)
 	bool found = false;
 	glob_t gl;
 
-	if (get_cmdline_val("fstools_ignore_partname", rootparam, sizeof(rootparam))) {
+	if (get_var_from_file("/proc/cmdline", "fstools_ignore_partname", rootparam, sizeof(rootparam))) {
 		if (!strcmp("1", rootparam))
 			return NULL;
 	}
 
-	if (get_cmdline_val("root", rootparam, sizeof(rootparam))) {
+	if (get_var_from_file("/proc/cmdline", "root", rootparam, sizeof(rootparam))) {
 		rootdev = rootdevname(rootparam);
 		/* find partition on same device as rootfs */
-		snprintf(volnamegstr, sizeof(volnamegstr), "%s/%s/*/name", block_dir_name, rootdev);
+		snprintf(ueventgstr, sizeof(ueventgstr), "%s/%s/*/uevent", block_dir_name, rootdev);
 	} else {
 		/* no 'root=' kernel cmdline parameter, find on any block device */
-		snprintf(volnamegstr, sizeof(volnamegstr), "%s/*/name", block_dir_name);
+		snprintf(ueventgstr, sizeof(ueventgstr), "%s/*/uevent", block_dir_name);
 	}
 
-	if (!glob(volnamegstr, GLOB_NOESCAPE, NULL, &gl))
+	if (!glob(ueventgstr, GLOB_NOESCAPE, NULL, &gl))
 		for (j = 0; j < gl.gl_pathc; j++) {
-			if (!read_string_from_file("", gl.gl_pathv[j], namebuf, sizeof(namebuf)))
+			if (!get_var_from_file(gl.gl_pathv[j], "PARTNAME", namebuf, sizeof(namebuf)))
 				continue;
 			if (!strncmp(namebuf, name, sizeof(namebuf))) {
 				found = 1;