istream, archive, db: convert db and tar function to use istream

8 files changed, 224 insertions, 156 deletions

diff --git a/src/apk.c b/src/apk.c
index ec16d28..57ac46b 100644
--- a/src/apk.c
+++ b/src/apk.c
@@ -635,14 +635,9 @@ int main(int argc, char **argv)
 		apk_blob_pull_deps(&b, &db, &db.world);
 	}
 	if (test_installed_db != NULL) {
-		struct apk_bstream *bs = apk_bstream_from_file(AT_FDCWD, test_installed_db);
-		if (!IS_ERR_OR_NULL(bs)) {
-			apk_db_index_read(&db, bs, -1);
-			apk_bstream_close(bs);
-		}
+		apk_db_index_read(&db, apk_istream_from_file(AT_FDCWD, test_installed_db), -1);
 	}
 	for (i = 0; i < test_repos->num; i++) {
-		struct apk_bstream *bs;
 		apk_blob_t spec = APK_BLOB_STR(test_repos->item[i]), name, tag;
 		int repo_tag = 0, repo = APK_REPOSITORY_FIRST_CONFIGURED + i;
 
@@ -659,14 +654,11 @@ int main(int argc, char **argv)
 			name = spec;
 		}
 
-		bs = apk_bstream_from_file(AT_FDCWD, name.ptr);
-		if (IS_ERR_OR_NULL(bs)) {
+		if (apk_db_index_read(&db, apk_istream_from_file(AT_FDCWD, name.ptr), repo) != 0) {
 			apk_error("Failed to open repository: " BLOB_FMT, BLOB_PRINTF(name));
 			goto err;
 		}
 
-		apk_db_index_read(&db, bs, repo);
-		apk_bstream_close(bs);
 		if (repo != -2) {
 			if (!(apk_flags & APK_NO_NETWORK))
 				db.available_repos |= BIT(repo);
diff --git a/src/apk_database.h b/src/apk_database.h
index 2c8bdda..30684c3 100644
--- a/src/apk_database.h
+++ b/src/apk_database.h
@@ -234,7 +234,7 @@ struct apk_package *apk_db_pkg_add(struct apk_database *db, struct apk_package *
 struct apk_package *apk_db_get_pkg(struct apk_database *db, struct apk_checksum *csum);
 struct apk_package *apk_db_get_file_owner(struct apk_database *db, apk_blob_t filename);
 
-int apk_db_index_read(struct apk_database *db, struct apk_bstream *bs, int repo);
+int apk_db_index_read(struct apk_database *db, struct apk_istream *is, int repo);
 int apk_db_index_read_file(struct apk_database *db, const char *file, int repo);
 int apk_db_index_write(struct apk_database *db, struct apk_ostream *os);
 
diff --git a/src/apk_io.h b/src/apk_io.h
index ea2eb42..db59890 100644
--- a/src/apk_io.h
+++ b/src/apk_io.h
@@ -81,6 +81,9 @@ struct apk_istream *apk_istream_from_fd(int fd);
 struct apk_istream *apk_istream_from_fd_url_if_modified(int atfd, const char *url, time_t since);
 struct apk_istream *apk_istream_from_url_gz(const char *url);
 ssize_t apk_istream_read(struct apk_istream *is, void *ptr, size_t size);
+apk_blob_t apk_istream_get(struct apk_istream *is, size_t len);
+apk_blob_t apk_istream_get_all(struct apk_istream *is);
+apk_blob_t apk_istream_get_delim(struct apk_istream *is, apk_blob_t token);
 
 #define APK_SPLICE_ALL 0xffffffff
 ssize_t apk_istream_splice(struct apk_istream *is, int fd, size_t size,
@@ -107,6 +110,14 @@ static inline void apk_istream_close(struct apk_istream *is)
 	is->ops->close(is);
 }
 
+struct apk_segment_istream {
+	struct apk_istream is;
+	struct apk_istream *pis;
+	size_t bytes_left;
+	time_t mtime;
+};
+void apk_istream_segment(struct apk_segment_istream *sis, struct apk_istream *is, size_t len, time_t mtime);
+
 #define APK_BSTREAM_SINGLE_READ			0x0001
 #define APK_BSTREAM_EOF				0x0002
 
diff --git a/src/archive.c b/src/archive.c
index 1d956f3..eabd3bf 100644
--- a/src/archive.c
+++ b/src/archive.c
@@ -73,55 +73,6 @@ static void put_octal(char *s, size_t l, size_t value)
 		*(ptr--) = '0';
 }
 
-struct apk_tar_entry_istream {
-	struct apk_istream is;
-	struct apk_istream *tar_is;
-	size_t bytes_left;
-	time_t mtime;
-};
-
-static void tar_entry_get_meta(struct apk_istream *is, struct apk_file_meta *meta)
-{
-	struct apk_tar_entry_istream *teis = container_of(is, struct apk_tar_entry_istream, is);
-	*meta = (struct apk_file_meta) {
-		.atime = teis->mtime,
-		.mtime = teis->mtime,
-	};
-}
-
-static ssize_t tar_entry_read(struct apk_istream *is, void *ptr, size_t size)
-{
-	struct apk_tar_entry_istream *teis = container_of(is, struct apk_tar_entry_istream, is);
-	ssize_t r;
-
-	if (size > teis->bytes_left)
-		size = teis->bytes_left;
-	if (size == 0)
-		return 0;
-
-	r = apk_istream_read(teis->tar_is, ptr, size);
-	if (r <= 0) {
-		/* If inner stream returned zero (end-of-stream), we
-		 * are getting short read, because tar header indicated
-		 * more was to be expected. */
-		if (r == 0) return -ECONNABORTED;
-		return r;
-	}
-
-	teis->bytes_left -= r;
-	return r;
-}
-
-static void tar_entry_close(struct apk_istream *is)
-{
-}
-
-static const struct apk_istream_ops tar_istream_ops = {
-	.get_meta = tar_entry_get_meta,
-	.read = tar_entry_read,
-	.close = tar_entry_close,
-};
-
 static int blob_realloc(apk_blob_t *b, size_t newsize)
 {
 	char *tmp;
@@ -180,12 +131,8 @@ int apk_tar_parse(struct apk_istream *is, apk_archive_entry_parser parser,
 		  void *ctx, struct apk_id_cache *idc)
 {
 	struct apk_file_info entry;
-	struct apk_tar_entry_istream teis = {
-		.is.ops = &tar_istream_ops,
-		.tar_is = is,
-	};
+	struct apk_segment_istream segment;
 	struct tar_header buf;
-	unsigned long offset = 0;
 	int end = 0, r;
 	size_t toskip, paxlen = 0;
 	apk_blob_t pax = APK_BLOB_NULL, longname = APK_BLOB_NULL;
@@ -194,7 +141,6 @@ int apk_tar_parse(struct apk_istream *is, apk_archive_entry_parser parser,
 	memset(&entry, 0, sizeof(entry));
 	entry.name = buf.name;
 	while ((r = apk_istream_read(is, &buf, 512)) == 512) {
-		offset += 512;
 		if (buf.name[0] == '\0') {
 			if (end) break;
 			end++;
@@ -222,7 +168,6 @@ int apk_tar_parse(struct apk_istream *is, apk_archive_entry_parser parser,
 		}
 		buf.mode[0] = 0; /* to nul terminate 100-byte buf.name */
 		buf.magic[0] = 0; /* to nul terminate 100-byte buf.linkname */
-		teis.mtime = entry.mtime;
 		apk_xattr_array_resize(&entry.xattrs, 0);
 
 		if (entry.size >= SSIZE_MAX-512) goto err;
@@ -232,6 +177,7 @@ int apk_tar_parse(struct apk_istream *is, apk_archive_entry_parser parser,
 			apk_fileinfo_hash_xattr(&entry);
 		}
 
+		toskip = (entry.size + 511) & -512;
 		switch (buf.typeflag) {
 		case 'L': /* GNU long name extension */
 			if ((r = blob_realloc(&longname, entry.size+1)) != 0 ||
@@ -239,8 +185,7 @@ int apk_tar_parse(struct apk_istream *is, apk_archive_entry_parser parser,
 				goto err;
 			entry.name = longname.ptr;
 			entry.name[entry.size] = 0;
-			offset += entry.size;
-			entry.size = 0;
+			toskip -= entry.size;
 			break;
 		case 'K': /* GNU long link target extension - ignored */
 			break;
@@ -272,11 +217,10 @@ int apk_tar_parse(struct apk_istream *is, apk_archive_entry_parser parser,
 			break;
 		case 'x': /* file specific pax header */
 			paxlen = entry.size;
-			entry.size = 0;
 			if ((r = blob_realloc(&pax, (paxlen + 511) & -512)) != 0 ||
 			    (r = apk_istream_read(is, pax.ptr, paxlen)) != paxlen)
 				goto err;
-			offset += paxlen;
+			toskip -= entry.size;
 			break;
 		default:
 			break;
@@ -288,26 +232,19 @@ int apk_tar_parse(struct apk_istream *is, apk_archive_entry_parser parser,
 			goto err;
 		}
 
-		teis.bytes_left = entry.size;
 		if (entry.mode & S_IFMT) {
-			r = parser(ctx, &entry, &teis.is);
+			apk_istream_segment(&segment, is, entry.size, entry.mtime);
+			r = parser(ctx, &entry, &segment.is);
 			if (r != 0) goto err;
+			apk_istream_close(&segment.is);
 
 			entry.name = buf.name;
+			toskip -= entry.size;
 			paxlen = 0;
 		}
 
-		offset += entry.size - teis.bytes_left;
-		toskip = teis.bytes_left;
-		if ((offset + toskip) & 511)
-			toskip += 512 - ((offset + toskip) & 511);
-		offset += toskip;
-		if (toskip != 0) {
-			if ((r = apk_istream_read(is, NULL, toskip)) != toskip) {
-				r = -EIO;
-				goto err;
-			}
-		}
+		if (toskip && (r = apk_istream_read(is, NULL, toskip)) != toskip)
+			goto err;
 	}
 
 	/* Read remaining end-of-archive records, to ensure we read all of
diff --git a/src/blob.c b/src/blob.c
index c6c5029..68a596e 100644
--- a/src/blob.c
+++ b/src/blob.c
@@ -174,13 +174,11 @@ int apk_blob_split(apk_blob_t blob, apk_blob_t split, apk_blob_t *l, apk_blob_t
 {
 	char *pos = blob.ptr, *end = blob.ptr + blob.len - split.len + 1;
 
-	if (end < pos)
-		return 0;
+	if (!pos || end < pos) return 0;
 
 	while (1) {
 		pos = memchr(pos, split.ptr[0], end - pos);
-		if (pos == NULL)
-			return 0;
+		if (!pos) return 0;
 
 		if (split.len > 1 && memcmp(pos, split.ptr, split.len) != 0) {
 			pos++;
diff --git a/src/database.c b/src/database.c
index 6fe637f..5b94d5c 100644
--- a/src/database.c
+++ b/src/database.c
@@ -715,27 +715,26 @@ static struct apk_db_dir_instance *find_diri(struct apk_installed_package *ipkg,
 	return NULL;
 }
 
-int apk_db_read_overlay(struct apk_database *db, struct apk_bstream *bs)
+int apk_db_read_overlay(struct apk_database *db, struct apk_istream *is)
 {
 	struct apk_db_dir_instance *diri = NULL;
 	struct hlist_node **diri_node = NULL, **file_diri_node = NULL;
 	struct apk_package *pkg;
 	struct apk_installed_package *ipkg;
 	apk_blob_t token = APK_BLOB_STR("\n"), line, bdir, bfile;
+	int r = -1;
 
-	if (IS_ERR_OR_NULL(bs)) return -1;
+	if (IS_ERR_OR_NULL(is)) return -1;
 
 	pkg = apk_pkg_new();
-	if (pkg == NULL)
-		return -1;
+	if (pkg == NULL) goto err;
 
 	ipkg = apk_pkg_install(db, pkg);
-	if (ipkg == NULL)
-		return -1;
+	if (ipkg == NULL) goto err;
 
 	diri_node = hlist_tail_ptr(&ipkg->owned_dirs);
 
-	while (!APK_BLOB_IS_NULL(line = apk_bstream_read(bs, token))) {
+	while (!APK_BLOB_IS_NULL(line = apk_istream_get_delim(is, token))) {
 		if (!apk_blob_rsplit(line, '/', &bdir, &bfile))
 			break;
 
@@ -752,11 +751,13 @@ int apk_db_read_overlay(struct apk_database *db, struct apk_bstream *bs)
 			(void) apk_db_file_get(db, diri, bfile, &file_diri_node);
 		}
 	}
-
-	return 0;
+	r = 0;
+err:
+	apk_istream_close(is);
+	return r;
 }
 
-int apk_db_index_read(struct apk_database *db, struct apk_bstream *bs, int repo)
+int apk_db_index_read(struct apk_database *db, struct apk_istream *is, int repo)
 {
 	struct apk_package *pkg = NULL;
 	struct apk_installed_package *ipkg = NULL;
@@ -772,7 +773,9 @@ int apk_db_index_read(struct apk_database *db, struct apk_bstream *bs, int repo)
 	gid_t gid;
 	int field, r, lineno = 0;
 
-	while (!APK_BLOB_IS_NULL(l = apk_bstream_read(bs, token))) {
+	if (IS_ERR_OR_NULL(is)) return PTR_ERR(is);
+
+	while (!APK_BLOB_IS_NULL(l = apk_istream_get_delim(is, token))) {
 		lineno++;
 
 		if (l.len < 2 || l.ptr[1] != ':') {
@@ -893,13 +896,16 @@ int apk_db_index_read(struct apk_database *db, struct apk_bstream *bs, int repo)
 		}
 		if (APK_BLOB_IS_NULL(l)) goto bad_entry;
 	}
+	apk_istream_close(is);
 	return 0;
 old_apk_tools:
 	/* Installed db should not have unsupported fields */
 	apk_error("This apk-tools is too old to handle installed packages");
-	return -1;
+	goto err;
 bad_entry:
 	apk_error("FDB format error (line %d, entry '%c')", lineno, field);
+err:
+	apk_istream_close(is);
 	return -1;
 }
 
@@ -1114,14 +1120,16 @@ static void apk_db_triggers_write(struct apk_database *db, struct apk_ostream *o
 	}
 }
 
-static void apk_db_triggers_read(struct apk_database *db, struct apk_bstream *bs)
+static void apk_db_triggers_read(struct apk_database *db, struct apk_istream *is)
 {
 	struct apk_checksum csum;
 	struct apk_package *pkg;
 	struct apk_installed_package *ipkg;
 	apk_blob_t l;
 
-	while (!APK_BLOB_IS_NULL(l = apk_bstream_read(bs, APK_BLOB_STR("\n")))) {
+	if (IS_ERR_OR_NULL(is)) return;
+
+	while (!APK_BLOB_IS_NULL(l = apk_istream_get_delim(is, APK_BLOB_STR("\n")))) {
 		apk_blob_pull_csum(&l, &csum);
 		apk_blob_pull_char(&l, ' ');
 
@@ -1136,12 +1144,12 @@ static void apk_db_triggers_read(struct apk_database *db, struct apk_bstream *bs
 			list_add_tail(&ipkg->trigger_pkgs_list,
 				      &db->installed.triggers);
 	}
+	apk_istream_close(is);
 }
 
 static int apk_db_read_state(struct apk_database *db, int flags)
 {
 	struct apk_istream *is;
-	struct apk_bstream *bs;
 	apk_blob_t blob, world;
 	int r;
 
@@ -1153,26 +1161,16 @@ static int apk_db_read_state(struct apk_database *db, int flags)
 	 */
 	if (!(flags & APK_OPENF_NO_WORLD)) {
 		blob = world = apk_blob_from_file(db->root_fd, apk_world_file);
-		if (APK_BLOB_IS_NULL(blob))
-			return -ENOENT;
+		if (APK_BLOB_IS_NULL(blob)) return -ENOENT;
 		blob = apk_blob_trim(blob);
 		apk_blob_pull_deps(&blob, db, &db->world);
 		free(world.ptr);
 	}
 
 	if (!(flags & APK_OPENF_NO_INSTALLED)) {
-		bs = apk_bstream_from_file(db->root_fd, apk_installed_file);
-		if (!IS_ERR_OR_NULL(bs)) {
-			r = apk_db_index_read(db, bs, -1);
-			apk_bstream_close(bs);
-			if (r != 0) return -1;
-		}
-
-		bs = apk_bstream_from_file(db->root_fd, apk_triggers_file);
-		if (!IS_ERR_OR_NULL(bs)) {
-			apk_db_triggers_read(db, bs);
-			apk_bstream_close(bs);
-		}
+		r = apk_db_index_read(db, apk_istream_from_file(db->root_fd, apk_installed_file), -1);
+		if (r != 0) return -1;
+		apk_db_triggers_read(db, apk_istream_from_file(db->root_fd, apk_triggers_file));
 	}
 
 	if (!(flags & APK_OPENF_NO_SCRIPTS)) {
@@ -1514,7 +1512,6 @@ int apk_db_open(struct apk_database *db, struct apk_db_options *dbopts)
 {
 	const char *msg = NULL;
 	struct apk_repository_list *repo = NULL;
-	struct apk_bstream *bs;
 	struct statfs stfs;
 	apk_blob_t blob;
 	int r, fd, write_arch = FALSE;
@@ -1662,8 +1659,7 @@ int apk_db_open(struct apk_database *db, struct apk_db_options *dbopts)
 
 	if (apk_flags & APK_OVERLAY_FROM_STDIN) {
 		apk_flags &= ~APK_OVERLAY_FROM_STDIN;
-		apk_db_read_overlay(db, apk_bstream_from_istream(
-				apk_istream_from_fd(STDIN_FILENO)));
+		apk_db_read_overlay(db, apk_istream_from_fd(STDIN_FILENO));
 	}
 
 	r = apk_db_read_state(db, dbopts->open_flags);
@@ -1682,11 +1678,7 @@ int apk_db_open(struct apk_database *db, struct apk_db_options *dbopts)
 
 	if (!(dbopts->open_flags & APK_OPENF_NO_INSTALLED_REPO)) {
 		if (apk_db_cache_active(db)) {
-			bs = apk_bstream_from_file(db->cache_fd, "installed");
-			if (!IS_ERR_OR_NULL(bs)) {
-				apk_db_index_read(db, bs, -2);
-				apk_bstream_close(bs);
-			}
+			apk_db_index_read(db, apk_istream_from_file(db->cache_fd, "installed"), -2);
 		}
 	}
 
@@ -2165,7 +2157,6 @@ static int load_apkindex(void *sctx, const struct apk_file_info *fi,
 			 struct apk_istream *is)
 {
 	struct apkindex_ctx *ctx = (struct apkindex_ctx *) sctx;
-	struct apk_bstream *bs;
 	struct apk_repository *repo;
 	int r;
 
@@ -2179,11 +2170,7 @@ static int load_apkindex(void *sctx, const struct apk_file_info *fi,
 		repo->description = apk_blob_from_istream(is, fi->size);
 	} else if (strcmp(fi->name, "APKINDEX") == 0) {
 		ctx->found = 1;
-		bs = apk_bstream_from_istream(is);
-		if (!IS_ERR_OR_NULL(bs)) {
-			apk_db_index_read(ctx->db, bs, ctx->repo);
-			apk_bstream_close(bs);
-		}
+		apk_db_index_read(ctx->db, is, ctx->repo);
 	}
 
 	return 0;
@@ -2212,11 +2199,7 @@ static int load_index(struct apk_database *db, struct apk_bstream *bs,
 		if (r >= 0 && ctx.found == 0)
 			r = -ENOMSG;
 	} else {
-		bs = apk_bstream_from_istream(apk_bstream_gunzip(bs));
-		if (!IS_ERR_OR_NULL(bs)) {
-			apk_db_index_read(db, bs, repo);
-			apk_bstream_close(bs);
-		}
+		apk_db_index_read(db, apk_bstream_gunzip(bs), repo);
 	}
 	return r;
 }
@@ -2440,9 +2423,9 @@ static int apk_db_install_archive_entry(void *_ctx,
 	if (ae->name[0] == '.') {
 		/* APK 2.0 format */
 		if (strcmp(ae->name, ".PKGINFO") == 0) {
-			apk_blob_t blob = apk_blob_from_istream(is, ae->size);
-			apk_blob_for_each_segment(blob, "\n", read_info_line, ctx);
-			free(blob.ptr);
+			apk_blob_t l, token = APK_BLOB_STR("\n");
+			while (!APK_BLOB_IS_NULL(l = apk_istream_get_delim(is, token)))
+				read_info_line(ctx, l);
 			return 0;
 		}
 		type = apk_script_type(&ae->name[1]);
diff --git a/src/io.c b/src/io.c
index d7c3bb9..3de415a 100644
--- a/src/io.c
+++ b/src/io.c
@@ -35,7 +35,7 @@
 #define HAVE_FGETGRENT_R
 #endif
 
-size_t apk_io_bufsize = 2*1024;
+size_t apk_io_bufsize = 8*1024;
 
 static void apk_file_meta_from_fd(int fd, struct apk_file_meta *meta)
 {
@@ -96,6 +96,157 @@ ssize_t apk_istream_read(struct apk_istream *is, void *ptr, size_t size)
 	return size - left;
 }
 
+static int __apk_istream_fill(struct apk_istream *is)
+{
+	ssize_t sz;
+
+	if (is->err) return is->err;
+
+	if (is->ptr != is->buf) {
+		sz = is->end - is->ptr;
+		memmove(is->buf, is->ptr, sz);
+		is->ptr = is->buf;
+		is->end = is->buf + sz;
+	}
+
+	sz = is->ops->read(is, is->end, is->buf + is->buf_size - is->end);
+	if (sz <= 0) {
+		is->err = sz ?: 1;
+		return is->err;
+	}
+	is->end += sz;
+	return 0;
+}
+
+apk_blob_t apk_istream_get(struct apk_istream *is, size_t len)
+{
+	apk_blob_t ret = APK_BLOB_NULL;
+
+	do {
+		if (is->end - is->ptr >= len) {
+			ret = APK_BLOB_PTR_LEN((char*)is->ptr, len);
+			break;
+		}
+		if (is->err>0 || is->end-is->ptr == is->buf_size) {
+			ret = APK_BLOB_PTR_LEN((char*)is->ptr, is->end - is->ptr);
+			break;
+		}
+	} while (!__apk_istream_fill(is));
+
+	if (!APK_BLOB_IS_NULL(ret)) {
+		is->ptr = (uint8_t*)ret.ptr + ret.len;
+		return ret;
+	}
+
+	return (struct apk_blob) { .len = is->err < 0 ? is->err : 0 };
+}
+
+apk_blob_t apk_istream_get_all(struct apk_istream *is)
+{
+	if (is->ptr == is->end)
+		__apk_istream_fill(is);
+
+	if (is->ptr != is->end) {
+		apk_blob_t ret = APK_BLOB_PTR_LEN((char*)is->ptr, is->end - is->ptr);
+		is->ptr = is->end = 0;
+		return ret;
+	}
+
+	return (struct apk_blob) { .len = is->err < 0 ? is->err : 0 };
+}
+
+apk_blob_t apk_istream_get_delim(struct apk_istream *is, apk_blob_t token)
+{
+	apk_blob_t ret = APK_BLOB_NULL, left = APK_BLOB_NULL;
+
+	do {
+		if (apk_blob_split(APK_BLOB_PTR_LEN((char*)is->ptr, is->end - is->ptr), token, &ret, &left))
+			break;
+		if (is->end - is->ptr == is->buf_size) {
+			is->err = -ENOBUFS;
+			break;
+		}
+	} while (!__apk_istream_fill(is));
+
+	/* Last segment before end-of-file. Return also zero length non-null
+	 * blob if eof comes immediately after the delimiter. */
+	if (is->ptr && is->err > 0)
+		ret = APK_BLOB_PTR_LEN((char*)is->ptr, is->end - is->ptr);
+
+	if (!APK_BLOB_IS_NULL(ret)) {
+		is->ptr = (uint8_t*)left.ptr;
+		is->end = (uint8_t*)left.ptr + left.len;
+		return ret;
+	}
+	return (struct apk_blob) { .len = is->err < 0 ? is->err : 0 };
+}
+
+static void segment_get_meta(struct apk_istream *is, struct apk_file_meta *meta)
+{
+	struct apk_segment_istream *sis = container_of(is, struct apk_segment_istream, is);
+	*meta = (struct apk_file_meta) {
+		.atime = sis->mtime,
+		.mtime = sis->mtime,
+	};
+}
+
+static ssize_t segment_read(struct apk_istream *is, void *ptr, size_t size)
+{
+	struct apk_segment_istream *sis = container_of(is, struct apk_segment_istream, is);
+	ssize_t r;
+
+	if (size > sis->bytes_left) size = sis->bytes_left;
+	if (size == 0) return 0;
+
+	r = sis->pis->ops->read(sis->pis, ptr, size);
+	if (r <= 0) {
+		/* If inner stream returned zero (end-of-stream), we
+		 * are getting short read, because tar header indicated
+		 * more was to be expected. */
+		if (r == 0) r = -ECONNABORTED;
+	} else {
+		sis->bytes_left -= r;
+	}
+	return r;
+}
+
+static void segment_close(struct apk_istream *is)
+{
+	struct apk_segment_istream *sis = container_of(is, struct apk_segment_istream, is);
+
+	if (sis->bytes_left) {
+		apk_istream_read(sis->pis, NULL, sis->bytes_left);
+		sis->bytes_left = 0;
+	}
+}
+
+static const struct apk_istream_ops segment_istream_ops = {
+	.get_meta = segment_get_meta,
+	.read = segment_read,
+	.close = segment_close,
+};
+
+void apk_istream_segment(struct apk_segment_istream *sis, struct apk_istream *is, size_t len, time_t mtime)
+{
+	*sis = (struct apk_segment_istream) {
+		.is.ops = &segment_istream_ops,
+		.is.buf = is->buf,
+		.is.buf_size = is->buf_size,
+		.is.ptr = is->ptr,
+		.is.end = is->end,
+		.pis = is,
+		.bytes_left = len,
+		.mtime = mtime,
+	};
+	if (sis->is.end - sis->is.ptr > len) {
+		sis->is.end = sis->is.ptr + len;
+		is->ptr += len;
+	} else {
+		is->ptr = is->end = 0;
+	}
+	sis->bytes_left -= sis->is.end - sis->is.ptr;
+}
+
 struct apk_fd_istream {
 	struct apk_istream is;
 	int fd;
@@ -630,7 +781,6 @@ int apk_fileinfo_get(int atfd, const char *filename, unsigned int flags,
 		     struct apk_file_info *fi)
 {
 	struct stat64 st;
-	struct apk_bstream *bs;
 	unsigned int checksum = flags & 0xff;
 	unsigned int xattr_checksum = (flags >> 8) & 0xff;
 	int atflags = 0;
@@ -701,23 +851,23 @@ int apk_fileinfo_get(int atfd, const char *filename, unsigned int flags,
 			   apk_checksum_evp(checksum), NULL);
 		fi->csum.type = checksum;
 	} else {
-		bs = apk_bstream_from_file(atfd, filename);
-		if (!IS_ERR_OR_NULL(bs)) {
+		struct apk_istream *is = apk_istream_from_file(atfd, filename);
+		if (!IS_ERR_OR_NULL(is)) {
 			EVP_MD_CTX *mdctx;
 			apk_blob_t blob;
 
 			mdctx = EVP_MD_CTX_new();
 			if (mdctx) {
 				EVP_DigestInit_ex(mdctx, apk_checksum_evp(checksum), NULL);
-				if (bs->flags & APK_BSTREAM_SINGLE_READ)
+				if (is->flags & APK_ISTREAM_SINGLE_READ)
 					EVP_MD_CTX_set_flags(mdctx, EVP_MD_CTX_FLAG_ONESHOT);
-				while (!APK_BLOB_IS_NULL(blob = apk_bstream_read(bs, APK_BLOB_NULL)))
+				while (!APK_BLOB_IS_NULL(blob = apk_istream_get_all(is)))
 					EVP_DigestUpdate(mdctx, (void*) blob.ptr, blob.len);
 				fi->csum.type = EVP_MD_CTX_size(mdctx);
 				EVP_DigestFinal_ex(mdctx, fi->csum.data, NULL);
 				EVP_MD_CTX_free(mdctx);
 			}
-			apk_bstream_close(bs);
+			apk_istream_close(is);
 		}
 	}
 
diff --git a/src/package.c b/src/package.c
index 7981b49..12f2245 100644
--- a/src/package.c
+++ b/src/package.c
@@ -637,11 +637,9 @@ int apk_sign_ctx_verify_tar(void *sctx, const struct apk_file_info *fi,
 		return r;
 
 	if (strcmp(fi->name, ".PKGINFO") == 0) {
-		apk_blob_t blob = apk_blob_from_istream(is, fi->size);
-		apk_blob_for_each_segment(
-			blob, "\n",
-			apk_sign_ctx_parse_pkginfo_line, ctx);
-		free(blob.ptr);
+		apk_blob_t l, token = APK_BLOB_STR("\n");
+		while (!APK_BLOB_IS_NULL(l = apk_istream_get_delim(is, token)))
+			apk_sign_ctx_parse_pkginfo_line(ctx, l);
 	}
 
 	return 0;
@@ -883,15 +881,14 @@ static int read_info_entry(void *ctx, const struct apk_file_info *ae,
 
 	/* Meta info and scripts */
 	r = apk_sign_ctx_process_file(ri->sctx, ae, is);
-	if (r <= 0)
-		return r;
+	if (r <= 0) return r;
 
 	if (ae->name[0] == '.') {
 		/* APK 2.0 format */
 		if (strcmp(ae->name, ".PKGINFO") == 0) {
-			apk_blob_t blob = apk_blob_from_istream(is, ae->size);
-			apk_blob_for_each_segment(blob, "\n", read_info_line, ctx);
-			free(blob.ptr);
+			apk_blob_t l, token = APK_BLOB_STR("\n");
+			while (!APK_BLOB_IS_NULL(l = apk_istream_get_delim(is, token)))
+				read_info_line(ctx, l);
 		} else if (strcmp(ae->name, ".INSTALL") == 0) {
 			apk_warning("Package '%s-%s' contains deprecated .INSTALL",
 				    pkg->name->name, pkg->version);