nano

commit 8d31ad8a705ea2b94bafb61c75cc47d88b63a103
parent 3480518a5ce1232e005ff4907599193c1ff8394f
Author: Benno Schulenberg <bensberg@telfort.nl>
Date:   Thu, 28 May 2020 14:15:40 +0200

files: ignore errors when calling chmod() on a backup file

First, it is very unlikely that chmod() would fail as the user just
created the file herself.  Second, even if chmod() would fail, this
is not a problem, because we have created the file with read+write
permissions for the owner only, so the file cannot accidentally be
left accessible to unintended others.

But most of all, such a failure should not stop nano from trying to
write the backup file.  Only when the actual *writing* fails, should
we bother the user with a prompt.

Diffstat:
M
src/files.c
 | 
17
+++++------------

1 file changed, 5 insertions(+), 12 deletions(-)
diff --git a/src/files.c b/src/files.c
@@ -1666,7 +1666,7 @@ bool write_file(const char *name, FILE *thefile, bool tmp,
 			backup_cflags = O_WRONLY | O_CREAT | O_EXCL;
 
 		/* Create the backup file (or truncate the existing one). */
-		backup_fd = open(backupname, backup_cflags, RW_FOR_ALL);
+		backup_fd = open(backupname, backup_cflags, S_IRUSR|S_IWUSR);
 
 		if (backup_fd >= 0)
 			backup_file = fdopen(backup_fd, "wb");
@@ -1683,17 +1683,10 @@ bool write_file(const char *name, FILE *thefile, bool tmp,
 		IGNORE_CALL_RESULT(fchown(backup_fd, openfile->current_stat->st_uid,
 											openfile->current_stat->st_gid));
 
-		/* Set the backup's mode bits. */
-		if (fchmod(backup_fd, openfile->current_stat->st_mode) == -1 &&
-						!ISSET(INSECURE_BACKUP)) {
-			fclose(backup_file);
-			if (prompt_failed_backupwrite(backupname))
-				goto skip_backup;
-			statusline(HUSH, _("Error writing backup file %s: %s"),
-								backupname, strerror(errno));
-			free(backupname);
-			goto cleanup_and_exit;
-		}
+		/* Set the backup's permissions to those of the original file.
+		 * It is not a security issue if this fails, as we have created
+		 * the file with just read and write permission for the owner. */
+		IGNORE_CALL_RESULT(fchmod(backup_fd, openfile->current_stat->st_mode));
 
 		/* Copy the existing file to the backup. */
 		verdict = copy_file(original, backup_file, FALSE);