File pass-the-correct-stat-to-backup-files.patch of Package patch.34931

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File pass-the-correct-stat-to-backup-files.patch of Package patch.34931

From: Takashi Iwai <tiwai@suse.de>
Date: Wed, 6 Apr 2022 10:48:35 +0200
Subject: Pass the correct stat to backup files
Patch-mainline: Yes
Git-commit: c835ecc67b7e37c0d0b7dd7e032209fdaa285808
References: boo#1198106 savananh#62364

The last case to call output_file() in the main loop is
    output_file (outname, NULL, &tmpoutst, NULL, NULL,
                 file_type | 0, backup);
and this essentially means to create a backup file (where to=NULL)
only if backup=true, and does nothing else.

And, in the current code, the passed file stat (&tmpoutst) is a file
stat of the temporary file that has been processed, not the original
file (outname) to be backed up.  When the backup is performed
immediately, this is no big problem.  However, output_file() may
schedule the deferred handling, and the given file may be backed up at
a later point.  The problem is that create_backup() tries to avoid the
backup of the same file twice, and it checks the given stat i-node
number in the hash list.  Since it's a stat of a temporary file, the
same i-node number may be reused once a temp file is deleted and
another is created.  This results in a false-positive detection of the
already existing file, eventually missing a backup file.

This patch attempts to address the issue:
- Modify the condition for better understanding, clearly indicating
  that the code there is for creating a backup file
- Pass the stat of the original file instead of a temporary file

BugLink: https://bugzilla.opensuse.org/show_bug.cgi?id=1198106
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jean Delvare <jdelvare@suse.de>
---
 src/patch.c |   13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

--- a/src/patch.c
+++ b/src/patch.c
@@ -601,9 +601,16 @@ main (int argc, char **argv)
 			output_file (NULL, NULL, NULL, inname, &instat,
 				     mode, backup);
 		    }
-		  else
-		    output_file (outname, NULL, &tmpoutst, NULL, NULL,
-				 file_type | 0, backup);
+		  else if (backup)
+		    {
+		      struct stat outstat;
+
+		      if (stat_file (outname, &outstat) != 0)
+			say ("Cannot stat file %s, skipping backup\n", outname);
+		      else
+			output_file (outname, NULL, &outstat, NULL, NULL,
+				     file_type | 0, true);
+		    }
 		}
 	    }
       }

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File pass-the-correct-stat-to-backup-files.patch of Package patch.34931

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