Preserve original permissions when rewriting config files on commit

Patch provided by Patrick Grimm <patrick@lunatiki.de>

Signed-off-by: Jo-Philipp Wich <jow@openwrt.org>

delta.c

@@ -240,7 +240,7 @@ static int uci_load_delta_file(struct uci_context *ctx, struct uci_package *p, c
 	int changes = 0;
 
 	UCI_TRAP_SAVE(ctx, done);
-	stream = uci_open_stream(ctx, filename, SEEK_SET, flush, false);
+	stream = uci_open_stream(ctx, filename, NULL, SEEK_SET, flush, false);
 	if (p)
 		changes = uci_parse_delta(ctx, stream, p);
 	UCI_TRAP_RESTORE(ctx);
@@ -305,7 +305,7 @@ static void uci_filter_delta(struct uci_context *ctx, const char *name, const ch
 		UCI_THROW(ctx, UCI_ERR_MEM);
 
 	UCI_TRAP_SAVE(ctx, done);
-	f = uci_open_stream(ctx, filename, SEEK_SET, true, false);
+	f = uci_open_stream(ctx, filename, NULL, SEEK_SET, true, false);
 	pctx->file = f;
 	while (!feof(f)) {
 		struct uci_element *e;
@@ -435,7 +435,7 @@ int uci_save(struct uci_context *ctx, struct uci_package *p)
 
 	ctx->err = 0;
 	UCI_TRAP_SAVE(ctx, done);
-	f = uci_open_stream(ctx, filename, SEEK_END, true, true);
+	f = uci_open_stream(ctx, filename, NULL, SEEK_END, true, true);
 	UCI_TRAP_RESTORE(ctx);
 
 	uci_foreach_element_safe(&p->delta, tmp, e) {

file.c

@@ -714,7 +714,7 @@ static void uci_file_commit(struct uci_context *ctx, struct uci_package **packag
 		UCI_THROW(ctx, UCI_ERR_IO);
 
 	/* open the config file for writing now, so that it is locked */
-	f1 = uci_open_stream(ctx, p->path, SEEK_SET, true, true);
+	f1 = uci_open_stream(ctx, p->path, NULL, SEEK_SET, true, true);
 
 	/* flush unsaved changes and reload from delta file */
 	UCI_TRAP_SAVE(ctx, done);
@@ -747,7 +747,7 @@ static void uci_file_commit(struct uci_context *ctx, struct uci_package **packag
 			goto done;
 	}
 
-	f2 = uci_open_stream(ctx, filename, SEEK_SET, true, true);
+	f2 = uci_open_stream(ctx, filename, p->path, SEEK_SET, true, true);
 	uci_export(ctx, f2, p, false);
 
 	fflush(f2);
@@ -864,7 +864,7 @@ static struct uci_package *uci_file_load(struct uci_context *ctx, const char *na
 	}
 
 	UCI_TRAP_SAVE(ctx, done);
-	file = uci_open_stream(ctx, filename, SEEK_SET, false, false);
+	file = uci_open_stream(ctx, filename, NULL, SEEK_SET, false, false);
 	ctx->err = 0;
 	UCI_INTERNAL(uci_import, ctx, file, name, &package, true);
 	UCI_TRAP_RESTORE(ctx);

uci_internal.h

@@ -46,7 +46,7 @@ __private void uci_add_delta(struct uci_context *ctx, struct uci_list *list, int
 __private void uci_free_delta(struct uci_delta *h);
 __private struct uci_package *uci_alloc_package(struct uci_context *ctx, const char *name);
 
-__private FILE *uci_open_stream(struct uci_context *ctx, const char *filename, int pos, bool write, bool create);
+__private FILE *uci_open_stream(struct uci_context *ctx, const char *filename, const char *origfilename, int pos, bool write, bool create);
 __private void uci_close_stream(FILE *stream);
 __private void uci_getln(struct uci_context *ctx, int offset);
 

util.c

@@ -178,7 +178,7 @@ __private void uci_parse_error(struct uci_context *ctx, char *pos, char *reason)
  * note: when opening for write and seeking to the beginning of
  * the stream, truncate the file
  */
-__private FILE *uci_open_stream(struct uci_context *ctx, const char *filename, int pos, bool write, bool create)
+__private FILE *uci_open_stream(struct uci_context *ctx, const char *filename, const char *origfilename, int pos, bool write, bool create)
 {
 	struct stat statbuf;
 	FILE *file = NULL;
@@ -190,7 +190,11 @@ __private FILE *uci_open_stream(struct uci_context *ctx, const char *filename, i
 
 	if (create) {
 		flags |= O_CREAT;
-		name = basename((char *) filename);
+		if (origfilename) {
+			name = basename((char *) origfilename);
+		} else {
+			name = basename((char *) filename);
+		}
 		if ((asprintf(&filename2, "%s/%s", ctx->confdir, name) < 0) || !filename2) {
 			UCI_THROW(ctx, UCI_ERR_MEM);
 		} else {