From 278d0d3226f4bdb7c6586986ca46d0a25c976fe4 Mon Sep 17 00:00:00 2001
From: "Richard W.M. Jones" <rjones@redhat.com>
Date: Wed, 31 Mar 2021 13:40:11 +0100
Subject: [PATCH 5/5] lib/appliance-kcmdline.c: Read UUID directly from
 appliance.

Instead of using the external file utility, read the UUID directly
from the extfs filesystem.  file 5.40 broke parsing of UUIDs
(https://bugs.astron.com/view.php?id=253).

Bug: https://bugzilla.redhat.com/show_bug.cgi?id=1945122
---
 lib/appliance-kcmdline.c | 75 +++++++++++++++++++++++++---------------
 1 file changed, 48 insertions(+), 27 deletions(-)

diff --git a/lib/appliance-kcmdline.c b/lib/appliance-kcmdline.c
index 6d0deef86..8b78655eb 100644
--- a/lib/appliance-kcmdline.c
+++ b/lib/appliance-kcmdline.c
@@ -27,6 +27,9 @@
 #include <stdbool.h>
 #include <string.h>
 #include <unistd.h>
+#include <fcntl.h>
+#include <libintl.h>
+#include <sys/types.h>
 
 #include "c-ctype.h"
 #include "ignore-value.h"
@@ -56,49 +59,67 @@
 #define EARLYPRINTK "earlyprintk=pl011,0x9000000"
 #endif
 
-COMPILE_REGEXP (re_uuid, "UUID=([-0-9a-f]+)", 0)
-
-static void
-read_uuid (guestfs_h *g, void *retv, const char *line, size_t len)
-{
-  char **ret = retv;
-
-  *ret = match1 (g, line, re_uuid);
-}
-
 /**
  * Given a disk image containing an extX filesystem, return the UUID.
- * The L<file(1)> command does the hard work.
  */
 static char *
 get_root_uuid_with_file (guestfs_h *g, const char *appliance)
 {
-  CLEANUP_CMD_CLOSE struct command *cmd = guestfs_int_new_command (g);
-  char *ret = NULL;
-  int r;
+  unsigned char magic[2], uuid[16];
+  char *ret;
+  int fd;
 
-  guestfs_int_cmd_add_arg (cmd, "file");
-  guestfs_int_cmd_add_arg (cmd, "--");
-  guestfs_int_cmd_add_arg (cmd, appliance);
-  guestfs_int_cmd_set_stdout_callback (cmd, read_uuid, &ret, 0);
-  r = guestfs_int_cmd_run (cmd);
-  if (r == -1) {
-    if (ret) free (ret);
+  fd = open (appliance, O_RDONLY|O_CLOEXEC);
+  if (fd == -1) {
+    perrorf (g, _("open: %s"), appliance);
     return NULL;
   }
-  if (!WIFEXITED (r) || WEXITSTATUS (r) != 0) {
-    guestfs_int_external_command_failed (g, r, "file", NULL);
-    if (ret) free (ret);
+  if (lseek (fd, 0x438, SEEK_SET) != 0x438) {
+  magic_error:
+    error (g, _("%s: cannot read extfs magic in superblock"), appliance);
+    close (fd);
     return NULL;
   }
+  if (read (fd, magic, 2) != 2)
+    goto magic_error;
+  if (magic[0] != 0x53 || magic[1] != 0xEF) {
+    error (g, _("%s: appliance is not an extfs filesystem"), appliance);
+    close (fd);
+    return NULL;
+  }
+  if (lseek (fd, 0x468, SEEK_SET) != 0x468) {
+  super_error:
+    error (g, _("%s: cannot read UUID in superblock"), appliance);
+    close (fd);
+    return NULL;
+  }
+  if (read (fd, uuid, 16) != 16)
+    goto super_error;
+  close (fd);
 
+  /* The UUID is a binary blob, but we must return it as a printable
+   * string.  The caller frees this.
+   */
+  ret = safe_asprintf (g,
+                       "%02x%02x%02x%02x" "-"
+                       "%02x%02x" "-"
+                       "%02x%02x" "-"
+                       "%02x%02x" "-"
+                       "%02x%02x%02x%02x%02x%02x",
+                       uuid[0], uuid[1], uuid[2], uuid[3],
+                       uuid[4], uuid[5],
+                       uuid[6], uuid[7],
+                       uuid[8], uuid[9],
+                       uuid[10], uuid[11], uuid[12], uuid[13],
+                         uuid[14], uuid[15]);
   return ret;
 }
 
 /**
- * Read the first 256k bytes of the in_file with L<qemu-img(1)> command
- * and write them into the out_file. That may be useful to get UUID of
- * the QCOW2 disk image with further L<file(1)> command.
+ * Read the first 256k bytes of the in_file with L<qemu-img(1)>
+ * command and write them into the out_file. That may be useful to get
+ * UUID of the QCOW2 disk image with C<get_root_uuid_with_file>.
+ *
  * The function returns zero if successful, otherwise -1.
  */
 static int
-- 
2.29.0.rc2