From ab2d7fd8bfb1eafc61953e74757e84ed407b1f21 Mon Sep 17 00:00:00 2001
From: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
Date: Sun, 15 Sep 2019 17:34:39 +0200
Subject: Add an sqfs_file_t implementation for reading from STDIN
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
---
include/sqfs/io.h | 11 +++++
lib/sqfs/Makemodule.am | 2 +-
lib/sqfs/io_stdin.c | 115 +++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 127 insertions(+), 1 deletion(-)
create mode 100644 lib/sqfs/io_stdin.c
diff --git a/include/sqfs/io.h b/include/sqfs/io.h
index 0f980d6..a544875 100644
--- a/include/sqfs/io.h
+++ b/include/sqfs/io.h
@@ -142,6 +142,17 @@ extern "C" {
*/
SQFS_API sqfs_file_t *sqfs_open_file(const char *filename, int flags);
+/**
+ * @brief Get a read-only file implementation that represents standard input
+ *
+ * This function creates a read-only file that represents STDIN. The file
+ * supports reading up to a specified number of bytes and only allows
+ * reading sequentially.
+ *
+ * @param size The alleged "size" of the file.
+ */
+SQFS_API sqfs_file_t *sqfs_get_stdin_file(uint64_t size);
+
#ifdef __cplusplus
}
#endif
diff --git a/lib/sqfs/Makemodule.am b/lib/sqfs/Makemodule.am
index 7199441..b58a28b 100644
--- a/lib/sqfs/Makemodule.am
+++ b/lib/sqfs/Makemodule.am
@@ -13,7 +13,7 @@ libsquashfs_la_SOURCES += lib/sqfs/read_super.c lib/sqfs/meta_reader.c
libsquashfs_la_SOURCES += lib/sqfs/read_inode.c lib/sqfs/write_inode.c
libsquashfs_la_SOURCES += lib/sqfs/dir_writer.c lib/sqfs/xattr_reader.c
libsquashfs_la_SOURCES += lib/sqfs/read_table.c lib/sqfs/comp/compressor.c
-libsquashfs_la_SOURCES += lib/sqfs/comp/internal.h
+libsquashfs_la_SOURCES += lib/sqfs/io_stdin.c lib/sqfs/comp/internal.h
libsquashfs_la_SOURCES += lib/sqfs/blk_proc/process_block.c
libsquashfs_la_SOURCES += lib/sqfs/blk_proc/internal.h
libsquashfs_la_CPPFLAGS = $(AM_CPPFLAGS)
diff --git a/lib/sqfs/io_stdin.c b/lib/sqfs/io_stdin.c
new file mode 100644
index 0000000..a65fa0f
--- /dev/null
+++ b/lib/sqfs/io_stdin.c
@@ -0,0 +1,115 @@
+/* SPDX-License-Identifier: LGPL-3.0-or-later */
+/*
+ * io_stdin.c
+ *
+ * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
+ */
+#define SQFS_BUILDING_DLL
+#include "config.h"
+
+#include "sqfs/io.h"
+#include "sqfs/error.h"
+
+#include <stdlib.h>
+#include <unistd.h>
+#include <errno.h>
+
+
+typedef struct {
+ sqfs_file_t base;
+
+ uint64_t offset;
+ uint64_t size;
+} sqfs_file_stdin_t;
+
+
+static void stdin_destroy(sqfs_file_t *base)
+{
+ free(base);
+}
+
+static int stdin_read_at(sqfs_file_t *base, uint64_t offset,
+ void *buffer, size_t size)
+{
+ sqfs_file_stdin_t *file = (sqfs_file_stdin_t *)base;
+ size_t temp_size = 0;
+ uint8_t *temp = NULL;
+ uint64_t 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 > (uint64_t)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_write_at(sqfs_file_t *base, uint64_t offset,
+ const void *buffer, size_t size)
+{
+ (void)base; (void)offset; (void)buffer; (void)size;
+ return SQFS_ERROR_IO;
+}
+
+static uint64_t stdin_get_size(const sqfs_file_t *base)
+{
+ return ((const sqfs_file_stdin_t *)base)->size;
+}
+
+static int stdin_truncate(sqfs_file_t *base, uint64_t size)
+{
+ (void)base; (void)size;
+ return SQFS_ERROR_IO;
+}
+
+sqfs_file_t *sqfs_get_stdin_file(uint64_t 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;
+ base->destroy = stdin_destroy;
+ base->read_at = stdin_read_at;
+ base->write_at = stdin_write_at;
+ base->get_size = stdin_get_size;
+ base->truncate = stdin_truncate;
+ return base;
+}
--
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