klibc-bot for Rob Vandermeulen
2023-Jul-27 21:00 UTC
[klibc] [klibc:master] kinit: Support specifying root with PARTLABEL
Commit-ID: 78106790f9de2c297dbcedea7ff39ce4192ec1b2
Gitweb:
http://git.kernel.org/?p=libs/klibc/klibc.git;a=commit;h=78106790f9de2c297dbcedea7ff39ce4192ec1b2
Author: Rob Vandermeulen <rvandermeulen at google.com>
AuthorDate: Mon, 24 Jul 2023 11:41:12 +0200
Committer: Ben Hutchings <ben at decadent.org.uk>
CommitDate: Thu, 27 Jul 2023 22:57:21 +0200
[klibc] kinit: Support specifying root with PARTLABEL
Allow specifying the root device to be mounted as root=PARTLABEL=label.
The label is the GPT partition label of the intended root partition, as
presented by the kernel with the uevent entry PARTNAME.
Signed-off-by: Rob Vandermeulen <rvandermeulen at google.com>
Signed-off-by: Ben Hutchings <ben at decadent.org.uk>
---
usr/kinit/name_to_dev.c | 72 +++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 72 insertions(+)
diff --git a/usr/kinit/name_to_dev.c b/usr/kinit/name_to_dev.c
index d8c17363..c57b7cec 100644
--- a/usr/kinit/name_to_dev.c
+++ b/usr/kinit/name_to_dev.c
@@ -1,4 +1,6 @@
#include <ctype.h>
+#include <dirent.h>
+#include <errno.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <stdio.h>
@@ -73,6 +75,72 @@ fail:
return (dev_t) 0;
}
+/*
+ * Find dev_t for a block device based on the provided GPT partlabel.
+ * The partlabel to block device mapping is found by scanning all
+ * the entries in /sys/dev/block/, opening the uevent file and picking
+ * the device where the PARTNAME= entry matches partlabel.
+ */
+static dev_t partlabel_to_dev_t(const char *plabel)
+{
+ char path[BUF_SZ];
+ DIR *dir;
+ FILE *fp;
+ struct dirent *dent;
+ char *ret;
+ char line[BUF_SZ];
+ int match_label, major, minor;
+
+ dir = opendir("/sys/dev/block");
+ if (!dir) {
+ dprintf(stderr, "%s: error %i (%s) opening /sys/dev/block\n",
+ __func__, errno, strerror(errno));
+ goto fail;
+ }
+
+ while ((dent = readdir(dir)) != NULL) {
+ if (!strncmp(dent->d_name, ".", 1))
+ continue;
+ snprintf(path, sizeof(path), "/sys/dev/block/%s/uevent",
+ dent->d_name);
+
+ fp = fopen(path, "r");
+ if (fp == NULL) {
+ dprintf(stderr, "kinit %s: error %i (%s) opening %s",
+ __func__, errno, strerror(errno), path);
+ continue;
+ }
+
+ major = 0;
+ minor = 0;
+ match_label = 0;
+ while (!feof(fp)) {
+ ret = fgets(line, sizeof(line), fp);
+ if (ret == NULL)
+ continue;
+ if (!strncmp(line, "MAJOR=", 6))
+ major = atoi(line+6);
+ if (!strncmp(line, "MINOR=", 6))
+ minor = atoi(line+6);
+ if (!strncmp(line, "PARTNAME=", 9)) {
+ line[strcspn(line, "\n")] = 0;
+ if (!strncmp(line + 9, plabel, sizeof(line)-9))
+ match_label = 1;
+ }
+ if (match_label && major && minor) {
+ fclose(fp);
+ closedir(dir);
+ return makedev(major, minor);
+ }
+ }
+ fclose(fp);
+ }
+ closedir(dir);
+
+fail:
+ return (dev_t) 0;
+}
+
/*
* Convert a name into device number. We accept the following variants:
*
@@ -85,6 +153,7 @@ fail:
* 6) /dev/<disk_name>p<decimal> - same as the above, that form is
* used when disk name of partitioned disk ends on a digit.
* 7) an actual block device node in the initramfs filesystem
+ * 8) PARTLABEL=<name> with name being the GPT partition label.
*
* If name doesn't have fall into the categories above, we return 0.
* Driverfs is used to check if something is a disk name - it has
@@ -110,6 +179,9 @@ static inline dev_t name_to_dev_t_real(const char *name)
if (strchr(name, ','))
return Root_MULTI;
+ if (!strncmp(name, "PARTLABEL=", 10))
+ return partlabel_to_dev_t(name + 10);
+
if (name[0] == '/') {
devname = name;
} else {