io,url,db: support for if-modified-since

1 files changed, 20 insertions, 18 deletions

diff --git a/src/database.c b/src/database.c
index ef9f73c..3962a8e 100644
--- a/src/database.c
+++ b/src/database.c
@@ -605,6 +605,7 @@ int apk_cache_download(struct apk_database *db, struct apk_repository *repo,
 		       struct apk_package *pkg, int verify,
 		       apk_progress_cb cb, void *cb_ctx)
 {
+	struct stat st;
 	struct apk_istream *is;
 	struct apk_bstream *bs;
 	struct apk_sign_ctx sctx;
@@ -618,40 +619,42 @@ int apk_cache_download(struct apk_database *db, struct apk_repository *repo,
 		r = apk_pkg_format_cache_pkg(b, pkg);
 	else
 		r = apk_repo_format_cache_index(b, repo);
-	if (r < 0)
-		return r;
+	if (r < 0) return r;
 
 	r = apk_repo_format_real_url(db, repo, pkg, url, sizeof(url));
-	if (r < 0)
-		return r;
+	if (r < 0) return r;
 
-	apk_message("fetch %s", url);
+	if (fstatat(db->cache_fd, cacheitem, &st, 0) != 0) st.st_mtime = 0;
 
-	if (apk_flags & APK_SIMULATE)
-		return 0;
+	apk_message("fetch %s", url);
 
-	if (cb)
-		cb(cb_ctx, 0);
+	if (apk_flags & APK_SIMULATE) return 0;
+	if (cb) cb(cb_ctx, 0);
 
 	if (verify != APK_SIGN_NONE) {
 		apk_sign_ctx_init(&sctx, APK_SIGN_VERIFY, NULL, db->keys_fd);
-		bs = apk_bstream_from_url(url);
+		bs = apk_bstream_from_url_if_modified(url, st.st_mtime);
 		bs = apk_bstream_tee(bs, db->cache_fd, tmpcacheitem, cb, cb_ctx);
 		is = apk_bstream_gunzip_mpart(bs, apk_sign_ctx_mpart_cb, &sctx);
-		if (is) r = apk_tar_parse(is, apk_sign_ctx_verify_tar, &sctx, FALSE, &db->id_cache);
-		else r = -errno;
+		if (!IS_ERR_OR_NULL(is))
+			r = apk_tar_parse(is, apk_sign_ctx_verify_tar, &sctx, FALSE, &db->id_cache);
+		else
+			r = PTR_ERR(is) ?: -EIO;
 		apk_sign_ctx_free(&sctx);
 	} else {
-		is = apk_istream_from_url(url);
-		fd = openat(db->cache_fd, tmpcacheitem, O_RDWR | O_CREAT | O_TRUNC | O_CLOEXEC, 0644);
+		is = apk_istream_from_url_if_modified(url, st.st_mtime);
+		if (!IS_ERR_OR_NULL(is)) {
+			fd = openat(db->cache_fd, tmpcacheitem, O_RDWR | O_CREAT | O_TRUNC | O_CLOEXEC, 0644);
+			if (fd < 0) r = -errno;
+		} else fd = -1, r = PTR_ERR(is) ?: -EIO;
+
 		if (fd >= 0) {
 			r = apk_istream_splice(is, fd, APK_SPLICE_ALL, cb, cb_ctx);
 			close(fd);
-		} else {
-			r = -errno;
 		}
 	}
-	if (is) is->close(is);
+	if (!IS_ERR_OR_NULL(is)) is->close(is);
+	if (r == -EALREADY) return 0;
 	if (r < 0) {
 		unlinkat(db->cache_fd, tmpcacheitem, 0);
 		return r;
@@ -659,7 +662,6 @@ int apk_cache_download(struct apk_database *db, struct apk_repository *repo,
 
 	if (renameat(db->cache_fd, tmpcacheitem, db->cache_fd, cacheitem) < 0)
 		return -errno;
-
 	return 0;
 }