cache: report errors when unlinkingfor-alpine/cache-errors

Before:

$ abuild-apk del mutt
(1/3) Purging mutt (1.12.1-r0)
(2/3) Purging gdbm (1.18.1-r0)
(3/3) Purging libidn (1.35-r0)
OK: 3752 MiB in 805 packages
$ apk cache sync --purge || echo nope, sorry
$ ls /home/apk-cache/*gdbm*
/home/apk-cache/gdbm-1.18.1-r0.b0b17e93.apk

After:

$ apk cache sync --purge || echo nope, sorry
ERROR: Unable to delete gdbm-1.18.1-r0.b0b17e93.apk: Permission denied
nope, sorry

3 files changed, 19 insertions, 12 deletions

diff --git a/src/apk_database.h b/src/apk_database.h
index 3488031..81d04b0 100644
--- a/src/apk_database.h
+++ b/src/apk_database.h
@@ -254,7 +254,7 @@ int apk_cache_download(struct apk_database *db, struct apk_repository *repo,
 		       struct apk_package *pkg, int verify, int autoupdate,
 		       apk_progress_cb cb, void *cb_ctx);
 
-typedef void (*apk_cache_item_cb)(struct apk_database *db,
+typedef int (*apk_cache_item_cb)(struct apk_database *db,
 				  int dirfd, const char *name,
 				  struct apk_package *pkg);
 int apk_db_cache_foreach_item(struct apk_database *db, apk_cache_item_cb cb);
diff --git a/src/app_cache.c b/src/app_cache.c
index f4dd951..75d27c2 100644
--- a/src/app_cache.c
+++ b/src/app_cache.c
@@ -13,6 +13,7 @@
 #include <dirent.h>
 #include <unistd.h>
 #include <limits.h>
+#include <string.h>
 
 #include "apk_defines.h"
 #include "apk_applet.h"
@@ -108,35 +109,42 @@ static int cache_download(struct cache_ctx *cctx, struct apk_database *db)
 	return ret;
 }
 
-static void cache_clean_item(struct apk_database *db, int dirfd, const char *name, struct apk_package *pkg)
+static int cache_clean_item(struct apk_database *db, int dirfd, const char *name, struct apk_package *pkg)
 {
 	char tmp[PATH_MAX];
 	apk_blob_t b;
 	int i;
 
-	if (strcmp(name, "installed") == 0) return;
+	if (strcmp(name, "installed") == 0) return 0;
 
 	if (pkg) {
 		if ((apk_flags & APK_PURGE) && pkg->ipkg == NULL) goto delete;
 		if (pkg->repos & db->local_repos & ~BIT(APK_REPOSITORY_CACHED)) goto delete;
 		if (pkg->ipkg == NULL && !(pkg->repos & ~BIT(APK_REPOSITORY_CACHED))) goto delete;
-		return;
+		return 0;
 	}
 
 	b = APK_BLOB_STR(name);
 	for (i = 0; i < db->num_repos; i++) {
 		/* Check if this is a valid index */
 		apk_repo_format_cache_index(APK_BLOB_BUF(tmp), &db->repos[i]);
-		if (apk_blob_compare(b, APK_BLOB_STR(tmp)) == 0) return;
+		if (apk_blob_compare(b, APK_BLOB_STR(tmp)) == 0) return 0;
 	}
 
 delete:
 	if (apk_verbosity >= 2)
 		apk_message("deleting %s", name);
 	if (!(apk_flags & APK_SIMULATE)) {
-		if (unlinkat(dirfd, name, 0) < 0 && errno == EISDIR)
-			unlinkat(dirfd, name, AT_REMOVEDIR);
+		if (unlinkat(dirfd, name, 0) < 0) {
+			if (errno != EISDIR ||
+			    (errno == EISDIR && unlinkat(dirfd, name, AT_REMOVEDIR) < 0)) {
+				apk_error("Unable to delete %s: %s", name, strerror(errno));
+				return -errno;
+			}
+		}
 	}
+
+	return 0;
 }
 
 static int cache_clean(struct apk_database *db)
diff --git a/src/database.c b/src/database.c
index bbf072e..80f9d1b 100644
--- a/src/database.c
+++ b/src/database.c
@@ -1393,12 +1393,13 @@ static char *find_mountpoint(int atfd, const char *rel_path)
 	return ret;
 }
 
-static void mark_in_cache(struct apk_database *db, int dirfd, const char *name, struct apk_package *pkg)
+static int mark_in_cache(struct apk_database *db, int dirfd, const char *name, struct apk_package *pkg)
 {
 	if (pkg == NULL)
-		return;
+		return 0;
 
 	pkg->repos |= BIT(APK_REPOSITORY_CACHED);
+	return 0;
 }
 
 static int add_repos_from_file(void *ctx, int dirfd, const char *file)
@@ -2048,9 +2049,7 @@ static int foreach_cache_file(void *pctx, int dirfd, const char *name)
 		}
 	}
 no_pkg:
-	ctx->cb(db, dirfd, name, pkg);
-
-	return 0;
+	return ctx->cb(db, dirfd, name, pkg);
 }
 
 int apk_db_cache_foreach_item(struct apk_database *db, apk_cache_item_cb cb)