[PATCH] libblkid: match uppercase UUIDs

* [PATCH] libblkid: match uppercase UUIDs
@ 2021-06-14 20:40 Alyssa Ross
  2021-06-14 21:04 ` Alyssa Ross
  0 siblings, 1 reply; 4+ messages in thread
From: Alyssa Ross @ 2021-06-14 20:40 UTC (permalink / raw)
  To: util-linux; +Cc: Alyssa Ross

In a script, I wanted to look up the device node for the booted EFI
partition.  systemd-boot exposes this in an EFI variable but it's
uppercase, so when I tried to do this, it didn't work:

    findfs "(< /sys/firmware/efi/vars/LoaderDevicePartUUID-4a67b082-0a4c-41cf-b6c7-440)"

This was very confusing to me, and I lost some time trying to figure
out what was wrong before I realised that case of UUIDs was
significant to findfs.

Here, I've made comparisons of UUID and PARTUUID case-insensitive in
libblkid, which fixes the command above.

Signed-off-by: Alyssa Ross <hi@alyssa.is>
---
 libblkid/src/evaluate.c | 12 ++++++++++++
 libblkid/src/tag.c      | 22 +++++++++++++++++++---
 2 files changed, 31 insertions(+), 3 deletions(-)

diff --git a/libblkid/src/evaluate.c b/libblkid/src/evaluate.c
index 710eac956..ceaa63cc7 100644
--- a/libblkid/src/evaluate.c
+++ b/libblkid/src/evaluate.c
@@ -135,6 +135,15 @@ int blkid_send_uevent(const char *devname, const char *action)
 	return rc;
 }
 
+static void ascii_downcase(char *s)
+{
+	while (*s) {
+		if ('A' <= *s && *s <= 'Z')
+			*s += 'a' - 'A';
+		s++;
+	}
+}
+
 static char *evaluate_by_udev(const char *token, const char *value, int uevent)
 {
 	char dev[PATH_MAX];
@@ -163,6 +172,9 @@ static char *evaluate_by_udev(const char *token, const char *value, int uevent)
 	if (blkid_encode_string(value, &dev[len], sizeof(dev) - len) != 0)
 		return NULL;
 
+	if (!strcmp(token, "UUID") || !strcmp(token, "PARTUUID"))
+		ascii_downcase(dev);
+
 	DBG(EVALUATE, ul_debug("expected udev link: %s", dev));
 
 	if (stat(dev, &st))
diff --git a/libblkid/src/tag.c b/libblkid/src/tag.c
index 390a64864..ca81c6921 100644
--- a/libblkid/src/tag.c
+++ b/libblkid/src/tag.c
@@ -10,10 +10,13 @@
  * %End-Header%
  */
 
-#include <unistd.h>
+#include <locale.h>
+#include <stdbool.h>
+#include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
-#include <stdio.h>
+#include <strings.h>
+#include <unistd.h>
 
 #include "blkidP.h"
 
@@ -101,6 +104,19 @@ static blkid_tag blkid_find_head_cache(blkid_cache cache, const char *type)
 	return head;
 }
 
+static bool tag_value_matches(const char *type, const char *expected,
+			      const char *actual)
+{
+	if (!strcmp(type, "UUID") || !strcmp(type, "PARTUUID")) {
+		locale_t posix = newlocale(0, "POSIX", 0);
+		bool r = !strcasecmp_l(expected, actual, posix);
+		freelocale(posix);
+		return r;
+	}
+
+	return !strcmp(expected, actual);
+}
+
 /*
  * Set a tag on an existing device.
  *
@@ -345,7 +361,7 @@ try_again:
 			blkid_tag tmp = list_entry(p, struct blkid_struct_tag,
 						   bit_names);
 
-			if (!strcmp(tmp->bit_val, value) &&
+			if (tag_value_matches(type, tmp->bit_val, value) &&
 			    (tmp->bit_dev->bid_pri > pri) &&
 			    !access(tmp->bit_dev->bid_name, F_OK)) {
 				dev = tmp->bit_dev;
-- 
2.31.1


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