[pacman-dev] [PATCH] libalpm: fix 404 pages ending up inside package downloads

[morganamilo]

Previously successfull but non 200 responses would still be written to
disk before trying the next server. This would lead to the next download
resuming with the html response in the file.

Signed-off-by: morganamilo <morganamilo at archlinux.org>
---
 lib/libalpm/dload.c | 23 ++++++++++++++++++-----
 1 file changed, 18 insertions(+), 5 deletions(-)

diff --git a/lib/libalpm/dload.c b/lib/libalpm/dload.c
index 2d8b4d6d..f6a4f012 100644
--- a/lib/libalpm/dload.c
+++ b/lib/libalpm/dload.c
@@ -403,6 +403,17 @@ static FILE *create_tempfile(struct dload_payload *payload, const char *localpat
 	return fp;
 }
 
+/* truncates tempfile without deleting it */
+static int clear_tempfile(struct dload_payload *payload) {
+	fflush(payload->localf);
+	if(ftruncate(fileno(payload->localf), 0)) {
+		return -1;
+	}
+	fseek(payload->localf, 0, SEEK_SET);
+	return 0;
+}
+
+
 /* Return 0 if retry was successful, -1 otherwise */
 static int curl_retry_next_server(CURLM *curlm, CURL *curl, struct dload_payload *payload)
 {
@@ -428,11 +439,9 @@ static int curl_retry_next_server(CURLM *curlm, CURL *curl, struct dload_payload
 	MALLOC(payload->fileurl, len, RET_ERR(handle, ALPM_ERR_MEMORY, -1));
 	snprintf(payload->fileurl, len, "%s/%s", server, payload->filepath);
 
-
-	fflush(payload->localf);
-
 	if(payload->allow_resume && stat(payload->tempfile_name, &st) == 0) {
 		/* a previous partial download exists, resume from end of file. */
+		fflush(payload->localf);
 		payload->tempfile_openmode = "ab";
 		curl_easy_setopt(curl, CURLOPT_RESUME_FROM_LARGE, (curl_off_t)st.st_size);
 		_alpm_log(handle, ALPM_LOG_DEBUG,
@@ -441,10 +450,9 @@ static int curl_retry_next_server(CURLM *curlm, CURL *curl, struct dload_payload
 		payload->initial_size = st.st_size;
 	} else {
 		/* we keep the file for a new retry but remove its data if any */
-		if(ftruncate(fileno(payload->localf), 0)) {
+		if(clear_tempfile(payload)) {
 			RET_ERR(handle, ALPM_ERR_SYSTEM, -1);
 		}
-		fseek(payload->localf, 0, SEEK_SET);
 	}
 
 	if(handle->dlcb && !payload->signature) {
@@ -500,6 +508,11 @@ static int curl_check_finished_download(CURLM *curlm, CURLMsg *msg,
 			_alpm_log(handle, ALPM_LOG_DEBUG, "%s: response code %ld\n",
 					payload->remote_name, payload->respcode);
 			if(payload->respcode >= 400) {
+				/* make sure 404 pages and similar don't end up in the file */
+				if(clear_tempfile(payload)) {
+					RET_ERR(handle, ALPM_ERR_SYSTEM, -1);
+				}
+
 				if(!payload->errors_ok) {
 					handle->pm_errno = ALPM_ERR_RETRIEVE;
 					/* non-translated message is same as libcurl */
-- 
2.31.1