[pacman-dev] [PATCH v2] libalpm: download sig files with -U when missing

[morganamilo]

When downloading a package with -U, alpm only checks if the package
itself is in cache when deciding whether anything needs to be
downloaded. So if for some reason the package is in cache but the
signature file is not, there's be no attempt to download the signature
and instead just throw an error.

morganamilo at Octavia ~git/pacman % rm /var/cache/pacman/pkg/*.sig
morganamilo at Octavia ~git/pacman % sudo ./build/pacman -U https://mirrors.ims.nksc.lt/archlinux/extra/os/x86_64/xterm-363-1-x86_64.pkg.tar.zst
loading packages...
error: '/var/cache/pacman/pkg/xterm-363-1-x86_64.pkg.tar.zst': package missing required signature

So let's just make sure to check that the package and sig file is there
before downloading. Like how the -S codepath already does.

---

Also, I think the way signature downloading is a bit weird. You can't
just download a signature. You have to say you want to download the
package then the downloader will download the sig after the package
finishes downloading.

I think it would make more sense for signatures to be their own
payloads and then have a dlsigcb.

This would go towards fixing FS#67813

If totaldlcb reports 0 packages to download, then we can show the
progress bars for the sigs instead of the packages.
---
 lib/libalpm/dload.c | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/lib/libalpm/dload.c b/lib/libalpm/dload.c
index df5e8be7..66ebeae9 100644
--- a/lib/libalpm/dload.c
+++ b/lib/libalpm/dload.c
@@ -863,8 +863,27 @@ int SYMEXPORT alpm_fetch_pkgurl(alpm_handle_t *handle, const alpm_list_t *urls,
 		char *url = i->data;
 
 		/* attempt to find the file in our pkgcache */
+
 		char *filepath = filecache_find_url(handle, url);
-		if(filepath) {
+		int need_download = !filepath;
+		/* even if the package file in the cache we need to check for
+		 * accompanion *.sig file as well.
+		 * If *.sig is not cached then force download the package + its signature file.
+		 */
+		if(!need_download && (handle->siglevel & ALPM_SIG_PACKAGE)) {
+			char *sig_filename = NULL;
+			int len = strlen(filepath) + 5;
+
+			MALLOC(sig_filename, len, RET_ERR(handle, ALPM_ERR_MEMORY, -1));
+			snprintf(sig_filename, len, "%s.sig", filepath);
+
+			need_download = !_alpm_filecache_exists(handle, sig_filename);
+
+			FREE(sig_filename);
+		}
+
+
+		if(!need_download) {
 			/* the file is locally cached so add it to the output right away */
 			alpm_list_append(fetched, filepath);
 		} else {
-- 
2.30.0