[pacman-dev] [PATCH] Handle bad .part files when encountered

[Allan McRae]

We can end up with .part files downloaded that are unable to be used by pacman
in two ways:  1) a well timed ctrl+c right at the rename of the download file
can leave a complete download with a .part extension, or 2) for some reason
(bad mirror) a .part file can be larger than the file to be downloaded. In
both cases, pacman fails with a very cryptic error message.

When these files are encountered by libalpm, they are now either renamed to
remove the if .part suffix if the download is complete, or deleted if the
download file is too large.

Fixes FS#35789 and FS#39257.

Signed-off-by: Allan McRae <allan at archlinux.org>
---
 lib/libalpm/sync.c | 22 +++++++++++++++++++++-
 1 file changed, 21 insertions(+), 1 deletion(-)

diff --git a/lib/libalpm/sync.c b/lib/libalpm/sync.c
index 00b68d0..95e34f8 100644
--- a/lib/libalpm/sync.c
+++ b/lib/libalpm/sync.c
@@ -337,7 +337,27 @@ static int compute_download_size(alpm_pkg_t *newpkg)
 			/* subtract the size of the .part file */
 			_alpm_log(handle, ALPM_LOG_DEBUG, "using (package - .part) size\n");
 			size = newpkg->size - st.st_size;
-			size = size < 0 ? 0 : size;
+			if(size < 0) {
+				/* we have a bad .part file - delete it */
+				_alpm_log(handle, ALPM_LOG_DEBUG, "deleting invalid .part file\n");
+				unlink(fpath);
+				size = newpkg->size;
+				goto finish;
+			} else if (size == 0) {
+				/* the .part file is complete, but needs renamed */
+				char *newpath;
+				size_t fpathlen = strlen(fpath);
+
+				_alpm_log(handle, ALPM_LOG_DEBUG, "renaming complete .part file\n");
+
+				CALLOC(newpath, fpathlen + 1, sizeof(char), return -1);
+				strcpy(newpath, fpath);
+				newpath[fpathlen - 5] = '\0';
+				rename(fpath, newpath);
+				FREE(newpath);
+
+				goto finish;
+			}
 		}
 
 		/* tell the caller that we have a partial */
-- 
2.7.4