Add stream I/O abstraction library

Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>

1 files changed, 124 insertions, 0 deletions

diff --git a/lib/fstream/unix/istream.c b/lib/fstream/unix/istream.c
new file mode 100644
index 0000000..5898141
--- /dev/null
+++ b/lib/fstream/unix/istream.c
@@ -0,0 +1,124 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * istream.c
+ *
+ * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
+ */
+#include "../internal.h"
+
+typedef struct {
+	istream_t base;
+	char *path;
+	int fd;
+	bool eof;
+
+	sqfs_u8 buffer[BUFSZ];
+} file_istream_t;
+
+static int file_precache(istream_t *strm)
+{
+	file_istream_t *file = (file_istream_t *)strm;
+	ssize_t ret;
+	size_t diff;
+
+	while (strm->buffer_used < sizeof(file->buffer)) {
+		diff = sizeof(file->buffer) - strm->buffer_used;
+
+		ret = read(file->fd, strm->buffer + strm->buffer_used, diff);
+
+		if (ret == 0) {
+			file->eof = true;
+			break;
+		}
+
+		if (ret < 0) {
+			if (errno == EINTR)
+				continue;
+
+			perror(file->path);
+			return -1;
+		}
+
+		strm->buffer_used += ret;
+	}
+
+	return 0;
+}
+
+static const char *file_get_filename(istream_t *strm)
+{
+	file_istream_t *file = (file_istream_t *)strm;
+
+	return file->path;
+}
+
+static void file_destroy(sqfs_object_t *obj)
+{
+	file_istream_t *file = (file_istream_t *)obj;
+
+	if (file->fd != STDIN_FILENO)
+		close(file->fd);
+
+	free(file->path);
+	free(file);
+}
+
+istream_t *istream_open_file(const char *path)
+{
+	file_istream_t *file = calloc(1, sizeof(*file));
+	sqfs_object_t *obj = (sqfs_object_t *)file;
+	istream_t *strm = (istream_t *)file;
+
+	if (file == NULL) {
+		perror(path);
+		return NULL;
+	}
+
+	file->path = strdup(path);
+	if (file->path == NULL) {
+		perror(path);
+		goto fail_free;
+	}
+
+	file->fd = open(path, O_RDONLY);
+	if (file->fd < 0) {
+		perror(path);
+		goto fail_path;
+	}
+
+	strm->buffer = file->buffer;
+	strm->precache = file_precache;
+	strm->get_filename = file_get_filename;
+	obj->destroy = file_destroy;
+	return strm;
+fail_path:
+	free(file->path);
+fail_free:
+	free(file);
+	return NULL;
+}
+
+istream_t *istream_open_stdin(void)
+{
+	file_istream_t *file = calloc(1, sizeof(*file));
+	sqfs_object_t *obj = (sqfs_object_t *)file;
+	istream_t *strm = (istream_t *)file;
+
+	if (file == NULL)
+		goto fail;
+
+	file->path = strdup("stdin");
+	if (file->path == NULL)
+		goto fail;
+
+	file->fd = STDIN_FILENO;
+	strm->buffer = file->buffer;
+	strm->precache = file_precache;
+	strm->get_filename = file_get_filename;
+	obj->destroy = file_destroy;
+	return strm;
+fail:
+	perror("creating file wrapper for stdin");
+	free(file);
+	return NULL;
+}