1 files changed, 299 insertions, 0 deletions
diff --git a/lib/utils_io.c b/lib/utils_io.c
new file mode 100644
index 0000000..2681b8f
--- /dev/null
+++ b/lib/utils_io.c
@@ -0,0 +1,299 @@
+/*
+ * utils - miscellaneous I/O utilities for cryptsetup
+ *
+ * Copyright (C) 2004 Jana Saout <jana@saout.de>
+ * Copyright (C) 2004-2007 Clemens Fruhwirth <clemens@endorphin.org>
+ * Copyright (C) 2009-2021 Red Hat, Inc. All rights reserved.
+ * Copyright (C) 2009-2021 Milan Broz
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include <errno.h>
+#include <string.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <unistd.h>
+#include <sys/types.h>
+
+#include "utils_io.h"
+
+static ssize_t _read_buffer(int fd, void *buf, size_t length, volatile int *quit)
+{
+	size_t read_size = 0;
+	ssize_t r;
+
+	if (fd < 0 || !buf)
+		return -EINVAL;
+
+	do {
+		r = read(fd, buf, length - read_size);
+		if (r == -1 && errno != EINTR)
+			return r;
+		if (r > 0) {
+			read_size += (size_t)r;
+			buf = (uint8_t*)buf + r;
+		}
+		if (r == 0 || (quit && *quit))
+			return (ssize_t)read_size;
+	} while (read_size != length);
+
+	return (ssize_t)length;
+}
+
+ssize_t read_buffer(int fd, void *buf, size_t length)
+{
+	return _read_buffer(fd, buf, length, NULL);
+}
+
+ssize_t read_buffer_intr(int fd, void *buf, size_t length, volatile int *quit)
+{
+	return _read_buffer(fd, buf, length, quit);
+}
+
+static ssize_t _write_buffer(int fd, const void *buf, size_t length, volatile int *quit)
+{
+	size_t write_size = 0;
+	ssize_t w;
+
+	if (fd < 0 || !buf || !length)
+		return -EINVAL;
+
+	do {
+		w = write(fd, buf, length - write_size);
+		if (w < 0 && errno != EINTR)
+			return w;
+		if (w > 0) {
+			write_size += (size_t) w;
+			buf = (const uint8_t*)buf + w;
+		}
+		if (w == 0 || (quit && *quit))
+			return (ssize_t)write_size;
+	} while (write_size != length);
+
+	return (ssize_t)write_size;
+}
+
+ssize_t write_buffer(int fd, const void *buf, size_t length)
+{
+	return _write_buffer(fd, buf, length, NULL);
+}
+
+ssize_t write_buffer_intr(int fd, const void *buf, size_t length, volatile int *quit)
+{
+	return _write_buffer(fd, buf, length, quit);
+}
+
+ssize_t write_blockwise(int fd, size_t bsize, size_t alignment,
+			void *orig_buf, size_t length)
+{
+	void *hangover_buf = NULL, *buf = NULL;
+	size_t hangover, solid;
+	ssize_t r, ret = -1;
+
+	if (fd == -1 || !orig_buf || !bsize || !alignment)
+		return -1;
+
+	hangover = length % bsize;
+	solid = length - hangover;
+
+	if ((size_t)orig_buf & (alignment - 1)) {
+		if (posix_memalign(&buf, alignment, length))
+			return -1;
+		memcpy(buf, orig_buf, length);
+	} else
+		buf = orig_buf;
+
+	if (solid) {
+		r = write_buffer(fd, buf, solid);
+		if (r < 0 || r != (ssize_t)solid)
+			goto out;
+	}
+
+	if (hangover) {
+		if (posix_memalign(&hangover_buf, alignment, bsize))
+			goto out;
+		memset(hangover_buf, 0, bsize);
+
+		r = read_buffer(fd, hangover_buf, bsize);
+		if (r < 0)
+			goto out;
+
+		if (lseek(fd, -(off_t)r, SEEK_CUR) < 0)
+			goto out;
+
+		memcpy(hangover_buf, (char*)buf + solid, hangover);
+
+		r = write_buffer(fd, hangover_buf, bsize);
+		if (r < 0 || r < (ssize_t)hangover)
+			goto out;
+	}
+	ret = length;
+out:
+	free(hangover_buf);
+	if (buf != orig_buf)
+		free(buf);
+	return ret;
+}
+
+ssize_t read_blockwise(int fd, size_t bsize, size_t alignment,
+		       void *orig_buf, size_t length)
+{
+	void *hangover_buf = NULL, *buf = NULL;
+	size_t hangover, solid;
+	ssize_t r, ret = -1;
+
+	if (fd == -1 || !orig_buf || !bsize || !alignment)
+		return -1;
+
+	hangover = length % bsize;
+	solid = length - hangover;
+
+	if ((size_t)orig_buf & (alignment - 1)) {
+		if (posix_memalign(&buf, alignment, length))
+			return -1;
+	} else
+		buf = orig_buf;
+
+	r = read_buffer(fd, buf, solid);
+	if (r < 0 || r != (ssize_t)solid)
+		goto out;
+
+	if (hangover) {
+		if (posix_memalign(&hangover_buf, alignment, bsize))
+			goto out;
+		r = read_buffer(fd, hangover_buf, bsize);
+		if (r <  0 || r < (ssize_t)hangover)
+			goto out;
+
+		memcpy((char *)buf + solid, hangover_buf, hangover);
+	}
+	ret = length;
+out:
+	free(hangover_buf);
+	if (buf != orig_buf) {
+		if (ret != -1)
+			memcpy(orig_buf, buf, length);
+		free(buf);
+	}
+	return ret;
+}
+
+/*
+ * Combines llseek with blockwise write. write_blockwise can already deal with short writes
+ * but we also need a function to deal with short writes at the start. But this information
+ * is implicitly included in the read/write offset, which can not be set to non-aligned
+ * boundaries. Hence, we combine llseek with write.
+ */
+ssize_t write_lseek_blockwise(int fd, size_t bsize, size_t alignment,
+			      void *buf, size_t length, off_t offset)
+{
+	void *frontPadBuf = NULL;
+	size_t frontHang, innerCount = 0;
+	ssize_t r, ret = -1;
+
+	if (fd == -1 || !buf || !bsize || !alignment)
+		return -1;
+
+	if (offset < 0)
+		offset = lseek(fd, offset, SEEK_END);
+
+	if (offset < 0)
+		return -1;
+
+	frontHang = offset % bsize;
+
+	if (lseek(fd, offset - frontHang, SEEK_SET) < 0)
+		return -1;
+
+	if (frontHang && length) {
+		if (posix_memalign(&frontPadBuf, alignment, bsize))
+			return -1;
+
+		innerCount = bsize - frontHang;
+		if (innerCount > length)
+			innerCount = length;
+
+		r = read_buffer(fd, frontPadBuf, bsize);
+		if (r < 0 || r < (ssize_t)(frontHang + innerCount))
+			goto out;
+
+		memcpy((char*)frontPadBuf + frontHang, buf, innerCount);
+
+		if (lseek(fd, offset - frontHang, SEEK_SET) < 0)
+			goto out;
+
+		r = write_buffer(fd, frontPadBuf, bsize);
+		if (r < 0 || r != (ssize_t)bsize)
+			goto out;
+
+		buf = (char*)buf + innerCount;
+		length -= innerCount;
+	}
+
+	ret = length ? write_blockwise(fd, bsize, alignment, buf, length) : 0;
+	if (ret >= 0)
+		ret += innerCount;
+out:
+	free(frontPadBuf);
+	return ret;
+}
+
+ssize_t read_lseek_blockwise(int fd, size_t bsize, size_t alignment,
+			     void *buf, size_t length, off_t offset)
+{
+	void *frontPadBuf = NULL;
+	size_t frontHang, innerCount = 0;
+	ssize_t r, ret = -1;
+
+	if (fd == -1 || !buf || bsize <= 0)
+		return -1;
+
+	if (offset < 0)
+		offset = lseek(fd, offset, SEEK_END);
+
+	if (offset < 0)
+		return -1;
+
+	frontHang = offset % bsize;
+
+	if (lseek(fd, offset - frontHang, SEEK_SET) < 0)
+		return -1;
+
+	if (frontHang && length) {
+		if (posix_memalign(&frontPadBuf, alignment, bsize))
+			return -1;
+
+		innerCount = bsize - frontHang;
+		if (innerCount > length)
+			innerCount = length;
+
+		r = read_buffer(fd, frontPadBuf, bsize);
+		if (r < 0 || r < (ssize_t)(frontHang + innerCount))
+			goto out;
+
+		memcpy(buf, (char*)frontPadBuf + frontHang, innerCount);
+
+		buf = (char*)buf + innerCount;
+		length -= innerCount;
+	}
+
+	ret = read_blockwise(fd, bsize, alignment, buf, length);
+	if (ret >= 0)
+		ret += innerCount;
+out:
+	free(frontPadBuf);
+	return ret;
+}