1 files changed, 174 insertions, 0 deletions
diff --git a/lib/common/io_stdin.c b/lib/common/io_stdin.c
new file mode 100644
index 0000000..0e9fb17
--- /dev/null
+++ b/lib/common/io_stdin.c
@@ -0,0 +1,174 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * io_stdin.c
+ *
+ * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
+ */
+#include "common.h"
+
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <errno.h>
+
+
+typedef struct {
+	sqfs_file_t base;
+
+	const sparse_map_t *map;
+	sqfs_u64 offset;
+	sqfs_u64 size;
+} sqfs_file_stdin_t;
+
+
+static void stdin_destroy(sqfs_file_t *base)
+{
+	free(base);
+}
+
+static int stdin_read_at(sqfs_file_t *base, sqfs_u64 offset,
+			 void *buffer, size_t size)
+{
+	sqfs_file_stdin_t *file = (sqfs_file_stdin_t *)base;
+	size_t temp_size = 0;
+	sqfs_u8 *temp = NULL;
+	sqfs_u64 diff;
+	ssize_t ret;
+
+	if (offset < file->offset)
+		return SQFS_ERROR_IO;
+
+	if (offset > file->offset) {
+		temp_size = 1024;
+		temp = alloca(temp_size);
+	}
+
+	if (offset >= file->size || (offset + size) > file->size)
+		return SQFS_ERROR_OUT_OF_BOUNDS;
+
+	while (size > 0) {
+		if (offset > file->offset) {
+			diff = file->offset - offset;
+			diff = diff > (sqfs_u64)temp_size ? temp_size : diff;
+
+			ret = read(STDIN_FILENO, temp, diff);
+		} else {
+			ret = read(STDIN_FILENO, buffer, size);
+		}
+
+		if (ret < 0) {
+			if (errno == EINTR)
+				continue;
+			return SQFS_ERROR_IO;
+		}
+
+		if (ret == 0)
+			return SQFS_ERROR_OUT_OF_BOUNDS;
+
+		if (offset <= file->offset) {
+			buffer = (char *)buffer + ret;
+			size -= ret;
+			offset += ret;
+		}
+
+		file->offset += ret;
+	}
+
+	return 0;
+}
+
+static int stdin_read_condensed(sqfs_file_t *base, sqfs_u64 offset,
+				void *buffer, size_t size)
+{
+	sqfs_file_stdin_t *file = (sqfs_file_stdin_t *)base;
+	sqfs_u64 poffset = 0, src_start;
+	size_t dst_start, diff, count;
+	const sparse_map_t *it;
+	int err;
+
+	memset(buffer, 0, size);
+
+	for (it = file->map; it != NULL; it = it->next) {
+		if (it->offset + it->count <= offset) {
+			poffset += it->count;
+			continue;
+		}
+
+		if (it->offset >= offset + size) {
+			poffset += it->count;
+			continue;
+		}
+
+		count = size;
+
+		if (offset + count >= it->offset + it->count)
+			count = it->offset + it->count - offset;
+
+		if (it->offset < offset) {
+			diff = offset - it->offset;
+
+			src_start = poffset + diff;
+			dst_start = 0;
+			count -= diff;
+		} else if (it->offset > offset) {
+			diff = it->offset - offset;
+
+			src_start = poffset;
+			dst_start = diff;
+		} else {
+			src_start = poffset;
+			dst_start = 0;
+		}
+
+		err = stdin_read_at(base, src_start,
+				    (char *)buffer + dst_start, count);
+		if (err)
+			return err;
+
+		poffset += it->count;
+	}
+
+	return 0;
+}
+
+static int stdin_write_at(sqfs_file_t *base, sqfs_u64 offset,
+			  const void *buffer, size_t size)
+{
+	(void)base; (void)offset; (void)buffer; (void)size;
+	return SQFS_ERROR_IO;
+}
+
+static sqfs_u64 stdin_get_size(const sqfs_file_t *base)
+{
+	return ((const sqfs_file_stdin_t *)base)->size;
+}
+
+static int stdin_truncate(sqfs_file_t *base, sqfs_u64 size)
+{
+	(void)base; (void)size;
+	return SQFS_ERROR_IO;
+}
+
+sqfs_file_t *sqfs_get_stdin_file(const sparse_map_t *map, sqfs_u64 size)
+{
+	sqfs_file_stdin_t *file = calloc(1, sizeof(*file));
+	sqfs_file_t *base = (sqfs_file_t *)file;
+
+	if (file == NULL)
+		return NULL;
+
+	file->size = size;
+	file->map = map;
+
+	base->destroy = stdin_destroy;
+	base->write_at = stdin_write_at;
+	base->get_size = stdin_get_size;
+	base->truncate = stdin_truncate;
+
+	if (map == NULL) {
+		base->read_at = stdin_read_at;
+	} else {
+		base->read_at = stdin_read_condensed;
+	}
+	return base;
+}