From 2c1f783f5f4ad28d89f2e83d7253bae7bba98440 Mon Sep 17 00:00:00 2001
From: David Bremner <david@tethera.net>
Date: Sun, 12 Apr 2020 20:00:31 -0300
Subject: [PATCH] don't pass NULL as second parameter to gzerror

Although (as of 1.2.11) zlib checks this parameter before writing to
it, the docs don't promise to keep doing so, so be safe.
---
 notmuch-dump.c    | 6 +++---
 notmuch-restore.c | 2 +-
 util/zlib-extra.c | 2 +-
 util/zlib-extra.h | 5 +++++
 4 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/notmuch-dump.c b/notmuch-dump.c
index 65e02639..af346ba2 100644
--- a/notmuch-dump.c
+++ b/notmuch-dump.c
@@ -21,7 +21,7 @@
 #include "notmuch-client.h"
 #include "hex-escape.h"
 #include "string-util.h"
-#include <zlib.h>
+#include "zlib-extra.h"
 
 static int
 database_dump_config (notmuch_database_t *notmuch, gzFile output)
@@ -316,7 +316,7 @@ notmuch_database_dump (notmuch_database_t *notmuch,
 
     ret = gzflush (output, Z_FINISH);
     if (ret) {
-	fprintf (stderr, "Error flushing output: %s\n", gzerror (output, NULL));
+	fprintf (stderr, "Error flushing output: %s\n", gzerror_str (output));
 	goto DONE;
     }
 
@@ -332,7 +332,7 @@ notmuch_database_dump (notmuch_database_t *notmuch,
     ret = gzclose_w (output);
     if (ret) {
 	fprintf (stderr, "Error closing %s: %s\n", name_for_error,
-		 gzerror (output, NULL));
+		 gzerror_str (output));
 	ret = EXIT_FAILURE;
 	output = NULL;
 	goto DONE;
diff --git a/notmuch-restore.c b/notmuch-restore.c
index 4b509d95..9a8b7fb5 100644
--- a/notmuch-restore.c
+++ b/notmuch-restore.c
@@ -450,7 +450,7 @@ notmuch_restore_command (notmuch_config_t *config, int argc, char *argv[])
 
     if (input && gzclose_r (input)) {
 	fprintf (stderr, "Error closing %s: %s\n",
-		 name_for_error, gzerror (input, NULL));
+		 name_for_error, gzerror_str (input));
 	ret = EXIT_FAILURE;
     }
 
diff --git a/util/zlib-extra.c b/util/zlib-extra.c
index f691cccf..623f6d62 100644
--- a/util/zlib-extra.c
+++ b/util/zlib-extra.c
@@ -80,7 +80,7 @@ const char *
 gz_error_string (util_status_t status, gzFile file)
 {
     if (status == UTIL_GZERROR)
-	return gzerror (file, NULL);
+	return gzerror_str (file);
     else
 	return util_error_string (status);
 }
diff --git a/util/zlib-extra.h b/util/zlib-extra.h
index 209fa998..296dc914 100644
--- a/util/zlib-extra.h
+++ b/util/zlib-extra.h
@@ -27,6 +27,11 @@ gz_getline (void *ctx, char **lineptr, ssize_t *bytes_read, gzFile stream);
 const char *
 gz_error_string (util_status_t status, gzFile stream);
 
+/* Call gzerror with a dummy errno argument, the docs don't promise to
+ * support the NULL case */
+inline const char *
+gzerror_str(gzFile file) { int dummy; return gzerror (file, &dummy); }
+
 #ifdef __cplusplus
 }
 #endif