From c7c88f880ad11a4afe2fab9bfb4f9d505f25b492 Mon Sep 17 00:00:00 2001
From: morganamilo <morganamilo@archlinux.org>
Date: Mon, 27 Sep 2021 18:30:17 +0100
Subject: [PATCH] libalpm: check filecache_find return and log errors

Some user had erros while updating their system.

:: Proceed with installation? [Y/n]
:: Retrieving packages...
checking keyring...
checking package integrity...
error: failed to commit transaction (invalid or corrupted package)
Errors occurred, no packages were upgraded.

The issue was filecache_find returning null and alpm passing that null
path to check validity. How this happened I have no idea. It may be
something to do with the user's cachedir being a network drive.

Also warn when the file exists but it is not a regular file or can not
be opened.
---
 lib/libalpm/sync.c | 13 +++++++++++++
 lib/libalpm/util.c | 15 +++++++++++----
 2 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/lib/libalpm/sync.c b/lib/libalpm/sync.c
index 36ad6242..8deb9b3a 100644
--- a/lib/libalpm/sync.c
+++ b/lib/libalpm/sync.c
@@ -991,6 +991,13 @@ static int check_validity(alpm_handle_t *handle,
 
 		current_bytes += v.pkg->size;
 		v.path = _alpm_filecache_find(handle, v.pkg->filename);
+
+		if(!v.path) {
+			_alpm_log(handle, ALPM_LOG_ERROR,
+					_("%s: could not find package in cache\n"), v.pkg->name);
+			RET_ERR(handle, ALPM_ERR_PKG_NOT_FOUND, -1);
+		}
+
 		v.siglevel = alpm_db_get_siglevel(alpm_pkg_get_db(v.pkg));
 
 		if(_alpm_pkg_validate_internal(handle, v.path, v.pkg,
@@ -1082,6 +1089,12 @@ static int load_packages(alpm_handle_t *handle, alpm_list_t **data,
 		current_bytes += spkg->size;
 		filepath = _alpm_filecache_find(handle, spkg->filename);
 
+		if(!filepath) {
+			_alpm_log(handle, ALPM_LOG_ERROR,
+					_("%s: could not find package in cache\n"), spkg->name);
+			RET_ERR(handle, ALPM_ERR_PKG_NOT_FOUND, -1);
+		}
+
 		/* load the package file and replace pkgcache entry with it in the target list */
 		/* TODO: alpm_pkg_get_db() will not work on this target anymore */
 		_alpm_log(handle, ALPM_LOG_DEBUG,
diff --git a/lib/libalpm/util.c b/lib/libalpm/util.c
index 299d287e..f73556a8 100644
--- a/lib/libalpm/util.c
+++ b/lib/libalpm/util.c
@@ -831,10 +831,17 @@ char *_alpm_filecache_find(alpm_handle_t *handle, const char *filename)
 	for(i = handle->cachedirs; i; i = i->next) {
 		snprintf(path, PATH_MAX, "%s%s", (char *)i->data,
 				filename);
-		if(stat(path, &buf) == 0 && S_ISREG(buf.st_mode)) {
-			retpath = strdup(path);
-			_alpm_log(handle, ALPM_LOG_DEBUG, "found cached pkg: %s\n", retpath);
-			return retpath;
+		if(stat(path, &buf) == 0) {
+			if(S_ISREG(buf.st_mode)) {
+				retpath = strdup(path);
+				_alpm_log(handle, ALPM_LOG_DEBUG, "found cached pkg: %s\n", retpath);
+				return retpath;
+			} else {
+				_alpm_log(handle, ALPM_LOG_WARNING,
+						"cached pkg '%s' is not a regular file: mode=%i\n", path, buf.st_mode);
+			}
+		} else if(errno != ENOENT) {
+			_alpm_log(handle, ALPM_LOG_WARNING, "could not open '%s'\n: %s", path, strerror(errno));
 		}
 	}
 	/* package wasn't found in any cachedir */