Add stream I/O abstraction library

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

1 files changed, 152 insertions, 0 deletions

diff --git a/lib/fstream/unix/ostream.c b/lib/fstream/unix/ostream.c
new file mode 100644
index 0000000..dac675f
--- /dev/null
+++ b/lib/fstream/unix/ostream.c
@@ -0,0 +1,152 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * ostream.c
+ *
+ * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
+ */
+#include "../internal.h"
+
+typedef struct {
+	ostream_t base;
+	char *path;
+	int fd;
+} file_ostream_t;
+
+static int file_append(ostream_t *strm, const void *data, size_t size)
+{
+	file_ostream_t *file = (file_ostream_t *)strm;
+	ssize_t ret;
+
+	while (size > 0) {
+		ret = write(file->fd, data, size);
+
+		if (ret == 0) {
+			fprintf(stderr, "%s: truncated data write.\n",
+				file->path);
+			return -1;
+		}
+
+		if (ret < 0) {
+			if (errno == EINTR)
+				continue;
+
+			perror(file->path);
+			return -1;
+		}
+
+		size -= ret;
+		data = (const char *)data + ret;
+	}
+
+	return 0;
+}
+
+static int file_append_sparse(ostream_t *strm, size_t size)
+{
+	file_ostream_t *file = (file_ostream_t *)strm;
+
+	if (lseek(file->fd, size, SEEK_CUR) == (off_t)-1) {
+		perror(file->path);
+		return -1;
+	}
+
+	return 0;
+}
+
+static int file_flush(ostream_t *strm)
+{
+	file_ostream_t *file = (file_ostream_t *)strm;
+
+	if (fsync(file->fd) != 0) {
+		perror(file->path);
+		return -1;
+	}
+
+	return 0;
+}
+
+static void file_destroy(sqfs_object_t *obj)
+{
+	file_ostream_t *file = (file_ostream_t *)obj;
+
+	if (file->fd != STDOUT_FILENO)
+		close(file->fd);
+
+	free(file->path);
+	free(file);
+}
+
+static const char *file_get_filename(ostream_t *strm)
+{
+	file_ostream_t *file = (file_ostream_t *)strm;
+
+	return file->path;
+}
+
+ostream_t *ostream_open_file(const char *path, int flags)
+{
+	file_ostream_t *file = calloc(1, sizeof(*file));
+	sqfs_object_t *obj = (sqfs_object_t *)file;
+	ostream_t *strm = (ostream_t *)file;
+
+	if (file == NULL) {
+		perror(path);
+		return NULL;
+	}
+
+	file->path = strdup(path);
+	if (file->path == NULL) {
+		perror(path);
+		goto fail_free;
+	}
+
+	if (flags & OSTREAM_OPEN_OVERWRITE) {
+		file->fd = open(path, O_WRONLY | O_CREAT | O_TRUNC, 0644);
+	} else {
+		file->fd = open(path, O_WRONLY | O_CREAT | O_EXCL, 0644);
+	}
+
+	if (file->fd < 0) {
+		perror(path);
+		goto fail_path;
+	}
+
+	if (flags & OSTREAM_OPEN_SPARSE)
+		strm->append_sparse = file_append_sparse;
+
+	strm->append = file_append;
+	strm->flush = file_flush;
+	strm->get_filename = file_get_filename;
+	obj->destroy = file_destroy;
+	return strm;
+fail_path:
+	free(file->path);
+fail_free:
+	free(file);
+	return NULL;
+}
+
+ostream_t *ostream_open_stdout(void)
+{
+	file_ostream_t *file = calloc(1, sizeof(*file));
+	sqfs_object_t *obj = (sqfs_object_t *)file;
+	ostream_t *strm = (ostream_t *)file;
+
+	if (file == NULL)
+		goto fail;
+
+	file->path = strdup("stdout");
+	if (file->path == NULL)
+		goto fail;
+
+	file->fd = STDOUT_FILENO;
+	strm->append = file_append;
+	strm->flush = file_flush;
+	strm->get_filename = file_get_filename;
+	obj->destroy = file_destroy;
+	return strm;
+fail:
+	perror("creating file wrapper for stdout");
+	free(file);
+	return NULL;
+}