Refactor download payload reset and free

This was done to squash a memory leak in the sync database download
code. When we downloaded a database and then reused the payload struct,
we could find ourselves calling get_fullpath() for the signatures and
overwriting non-freed values we had left over from the database
download.

Refactor the payload_free function into a payload_reset function that we
can call that does NOT free the payload itself, so we can reuse payload
structs. This also allows us to move the payload to the stack in some
call paths, relieving us of the need to alloc space.

Signed-off-by: Dan McGee <dan@archlinux.org>

4 files changed, 51 insertions, 48 deletions

diff --git a/lib/libalpm/be_sync.c b/lib/libalpm/be_sync.c
index 53777d92..e9e816c0 100644
--- a/lib/libalpm/be_sync.c
+++ b/lib/libalpm/be_sync.c
@@ -201,24 +201,25 @@ int SYMEXPORT alpm_db_update(int force, alpm_db_t *db)
 
 	for(i = db->servers; i; i = i->next) {
 		const char *server = i->data;
-		struct dload_payload *payload;
+		struct dload_payload payload;
 		size_t len;
 		int sig_ret = 0;
 
-		CALLOC(payload, 1, sizeof(*payload), RET_ERR(handle, ALPM_ERR_MEMORY, -1));
+		memset(&payload, 0, sizeof(struct dload_payload));
 
 		/* set hard upper limit of 25MiB */
-		payload->max_size = 25 * 1024 * 1024;
+		payload.max_size = 25 * 1024 * 1024;
 
-		/* print server + filename into a buffer (leave space for .sig) */
-		len = strlen(server) + strlen(db->treename) + 9;
-		CALLOC(payload->fileurl, len, sizeof(char), RET_ERR(handle, ALPM_ERR_MEMORY, -1));
-		snprintf(payload->fileurl, len, "%s/%s.db", server, db->treename);
-		payload->handle = handle;
-		payload->force = force;
-		payload->unlink_on_fail = 1;
+		/* print server + filename into a buffer */
+		len = strlen(server) + strlen(db->treename) + 5;
+		MALLOC(payload.fileurl, len, RET_ERR(handle, ALPM_ERR_MEMORY, -1));
+		snprintf(payload.fileurl, len, "%s/%s.db", server, db->treename);
+		payload.handle = handle;
+		payload.force = force;
+		payload.unlink_on_fail = 1;
 
-		ret = _alpm_download(payload, syncpath, NULL);
+		ret = _alpm_download(&payload, syncpath, NULL);
+		_alpm_dload_payload_reset(&payload);
 
 		if(ret == 0 && (level & ALPM_SIG_DATABASE)) {
 			/* an existing sig file is no good at this point */
@@ -231,20 +232,23 @@ int SYMEXPORT alpm_db_update(int force, alpm_db_t *db)
 			free(sigpath);
 
 			/* if we downloaded a DB, we want the .sig from the same server */
-			snprintf(payload->fileurl, len, "%s/%s.db.sig", server, db->treename);
-			payload->handle = handle;
-			payload->force = 1;
-			payload->errors_ok = (level & ALPM_SIG_DATABASE_OPTIONAL);
+			/* print server + filename into a buffer (leave space for .sig) */
+			len = strlen(server) + strlen(db->treename) + 9;
+			MALLOC(payload.fileurl, len, RET_ERR(handle, ALPM_ERR_MEMORY, -1));
+			snprintf(payload.fileurl, len, "%s/%s.db.sig", server, db->treename);
+			payload.handle = handle;
+			payload.force = 1;
+			payload.errors_ok = (level & ALPM_SIG_DATABASE_OPTIONAL);
 
 			/* set hard upper limit of 16KiB */
-			payload->max_size = 16 * 1024;
+			payload.max_size = 16 * 1024;
 
-			sig_ret = _alpm_download(payload, syncpath, NULL);
+			sig_ret = _alpm_download(&payload, syncpath, NULL);
 			/* errors_ok suppresses error messages, but not the return code */
-			sig_ret = payload->errors_ok ? 0 : sig_ret;
+			sig_ret = payload.errors_ok ? 0 : sig_ret;
+			_alpm_dload_payload_reset(&payload);
 		}
 
-		_alpm_dload_payload_free(payload);
 		if(ret != -1 && sig_ret != -1) {
 			break;
 		}
diff --git a/lib/libalpm/dload.c b/lib/libalpm/dload.c
index dbf7a8c3..c599b7f5 100644
--- a/lib/libalpm/dload.c
+++ b/lib/libalpm/dload.c
@@ -390,7 +390,7 @@ static int curl_download_internal(struct dload_payload *payload,
 		case CURLE_OK:
 			/* get http/ftp response code */
 			curl_easy_getinfo(curl, CURLINFO_RESPONSE_CODE, &respcode);
-			if(respcode >=400) {
+			if(respcode >= 400) {
 				payload->unlink_on_fail = 1;
 				goto cleanup;
 			}
@@ -546,7 +546,7 @@ char SYMEXPORT *alpm_fetch_pkgurl(alpm_handle_t *handle, const char *url)
 	char *filepath;
 	const char *cachedir;
 	char *final_file = NULL;
-	struct dload_payload *payload;
+	struct dload_payload payload;
 	int ret;
 
 	CHECK_HANDLE(handle, return NULL);
@@ -555,15 +555,17 @@ char SYMEXPORT *alpm_fetch_pkgurl(alpm_handle_t *handle, const char *url)
 	/* find a valid cache dir to download to */
 	cachedir = _alpm_filecache_setup(handle);
 
-	CALLOC(payload, 1, sizeof(*payload), RET_ERR(handle, ALPM_ERR_MEMORY, NULL));
-	payload->handle = handle;
-	STRDUP(payload->fileurl, url, RET_ERR(handle, ALPM_ERR_MEMORY, NULL));
-	payload->allow_resume = 1;
+	memset(&payload, 0, sizeof(struct dload_payload));
+	payload.handle = handle;
+	STRDUP(payload.fileurl, url, RET_ERR(handle, ALPM_ERR_MEMORY, NULL));
+	payload.allow_resume = 1;
 
 	/* download the file */
-	ret = _alpm_download(payload, cachedir, &final_file);
+	ret = _alpm_download(&payload, cachedir, &final_file);
+	_alpm_dload_payload_reset(&payload);
 	if(ret == -1) {
 		_alpm_log(handle, ALPM_LOG_WARNING, _("failed to download %s\n"), url);
+		free(final_file);
 		return NULL;
 	}
 	_alpm_log(handle, ALPM_LOG_DEBUG, "successfully downloaded %s\n", url);
@@ -572,37 +574,37 @@ char SYMEXPORT *alpm_fetch_pkgurl(alpm_handle_t *handle, const char *url)
 	if(ret == 0 && (handle->siglevel & ALPM_SIG_PACKAGE)) {
 		char *sig_final_file = NULL;
 		size_t len;
-		struct dload_payload *sig_payload;
 
-		CALLOC(sig_payload, 1, sizeof(*sig_payload), RET_ERR(handle, ALPM_ERR_MEMORY, NULL));
 		len = strlen(url) + 5;
-		CALLOC(sig_payload->fileurl, len, sizeof(char), RET_ERR(handle, ALPM_ERR_MEMORY, NULL));
-		snprintf(sig_payload->fileurl, len, "%s.sig", url);
-		sig_payload->handle = handle;
-		sig_payload->force = 1;
-		sig_payload->errors_ok = (handle->siglevel & ALPM_SIG_PACKAGE_OPTIONAL);
-
-		ret = _alpm_download(sig_payload, cachedir, &sig_final_file);
-		if(ret == -1 && !sig_payload->errors_ok) {
-			_alpm_log(handle, ALPM_LOG_WARNING, _("failed to download %s\n"), sig_payload->fileurl);
+		MALLOC(payload.fileurl, len, RET_ERR(handle, ALPM_ERR_MEMORY, NULL));
+		snprintf(payload.fileurl, len, "%s.sig", url);
+		payload.handle = handle;
+		payload.force = 1;
+		payload.errors_ok = (handle->siglevel & ALPM_SIG_PACKAGE_OPTIONAL);
+
+		ret = _alpm_download(&payload, cachedir, &sig_final_file);
+		if(ret == -1 && !payload.errors_ok) {
+			_alpm_log(handle, ALPM_LOG_WARNING,
+					_("failed to download %s\n"), payload.fileurl);
 			/* Warn now, but don't return NULL. We will fail later during package
 			 * load time. */
 		} else if(ret == 0) {
-			_alpm_log(handle, ALPM_LOG_DEBUG, "successfully downloaded %s\n", sig_payload->fileurl);
+			_alpm_log(handle, ALPM_LOG_DEBUG,
+					"successfully downloaded %s\n", payload.fileurl);
 		}
 		FREE(sig_final_file);
-		_alpm_dload_payload_free(sig_payload);
+		_alpm_dload_payload_reset(&payload);
 	}
 
 	/* we should be able to find the file the second time around */
 	filepath = _alpm_filecache_find(handle, final_file);
-	FREE(final_file);
-	_alpm_dload_payload_free(payload);
+	free(final_file);
 
 	return filepath;
 }
 
-void _alpm_dload_payload_free(struct dload_payload *payload) {
+void _alpm_dload_payload_reset(struct dload_payload *payload)
+{
 	ASSERT(payload, return);
 
 	FREE(payload->remote_name);
@@ -610,8 +612,6 @@ void _alpm_dload_payload_free(struct dload_payload *payload) {
 	FREE(payload->destfile_name);
 	FREE(payload->content_disp_name);
 	FREE(payload->fileurl);
-	FREE(payload);
-
 }
 
 /* vim: set ts=2 sw=2 noet: */
diff --git a/lib/libalpm/dload.h b/lib/libalpm/dload.h
index c2fd6095..9be29bc8 100644
--- a/lib/libalpm/dload.h
+++ b/lib/libalpm/dload.h
@@ -42,7 +42,7 @@ struct dload_payload {
 	CURLcode curlerr;       /* last error produced by curl */
 };
 
-void _alpm_dload_payload_free(struct dload_payload *payload);
+void _alpm_dload_payload_reset(struct dload_payload *payload);
 
 int _alpm_download(struct dload_payload *payload, const char *localpath,
 		char **final_file);
diff --git a/lib/libalpm/sync.c b/lib/libalpm/sync.c
index 8c50ec88..08d634d6 100644
--- a/lib/libalpm/sync.c
+++ b/lib/libalpm/sync.c
@@ -891,9 +891,8 @@ static int download_files(alpm_handle_t *handle, alpm_list_t **deltas)
 				}
 			}
 
-			alpm_list_free_inner(files, (alpm_list_fn_free)_alpm_dload_payload_free);
-			alpm_list_free(files);
-			files = NULL;
+			alpm_list_free_inner(files, (alpm_list_fn_free)_alpm_dload_payload_reset);
+			FREELIST(files);
 		}
 	}