From 17db76f6ba811b102935bd8796188996c89db860 Mon Sep 17 00:00:00 2001
From: Patrick McDermott <patrick.mcdermott@libiquity.com>
Date: Tue, 02 May 2023 19:14:31 -0400
Subject: gzip: Preserve gzip header

zlib doesn't copy it anywhere between deflateSetHeader() and deflate(),
so we need to make sure it doesn't get corrupted on the stack in the
meantime.
---
diff --git a/src/gzip.c b/src/gzip.c
index fbd40ef..736cbd7 100644
--- a/src/gzip.c
+++ b/src/gzip.c
@@ -38,6 +38,7 @@ struct opkg_opk_gzip {
 	opkg_opk_gzip_write_func *write_func;
 	void                     *user_data;
 	z_stream                  stream;
+	gz_header                 gz_header;
 };
 
 static struct opkg_opk_gzip *
@@ -46,7 +47,6 @@ _opkg_opk_gzip_init(enum _opkg_opk_gzip_dir dir,
 		opkg_opk_gzip_write_func *write_func, void *user_data)
 {
 	struct opkg_opk_gzip *gzip;
-	gz_header             gz_header;
 
 	gzip = malloc(sizeof(*gzip));
 	if (gzip == NULL) {
@@ -79,14 +79,14 @@ _opkg_opk_gzip_init(enum _opkg_opk_gzip_dir dir,
 			free(gzip);
 			return NULL;
 		}
-		gz_header.text    = 0;
-		gz_header.time    = 0;       /* Stored as 32-bit unsigned int */
-		gz_header.os      = 3;       /* Unix, per RFC 1952 */
-		gz_header.extra   = Z_NULL;
-		gz_header.name    = Z_NULL;
-		gz_header.comment = Z_NULL;
-		gz_header.hcrc    = 0;
-		if (deflateSetHeader(&gzip->stream, &gz_header) != Z_OK) {
+		gzip->gz_header.text    = 0;
+		gzip->gz_header.time    = 0;       /* Stored as 32-bit uint */
+		gzip->gz_header.os      = 3;       /* Unix, per RFC 1952 */
+		gzip->gz_header.extra   = Z_NULL;
+		gzip->gz_header.name    = Z_NULL;
+		gzip->gz_header.comment = Z_NULL;
+		gzip->gz_header.hcrc    = 0;
+		if (deflateSetHeader(&gzip->stream, &gzip->gz_header) != Z_OK) {
 			deflateEnd(&gzip->stream);
 			free(gzip);
 			return NULL;
--
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