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-rw-r--r--lib/util/sys_rw.c295
1 files changed, 295 insertions, 0 deletions
diff --git a/lib/util/sys_rw.c b/lib/util/sys_rw.c
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+++ b/lib/util/sys_rw.c
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+/*
+ * Unix SMB/CIFS implementation.
+ * Samba system utilities
+ * Copyright (C) Andrew Tridgell 1992-1998
+ * Copyright (C) Jeremy Allison 1998-2005
+ * Copyright (C) Timur Bakeyev 2005
+ * Copyright (C) Bjoern Jacke 2006-2007
+ *
+ * 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 3 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, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "replace.h"
+#include "system/filesys.h"
+#include "lib/util/sys_rw.h"
+#include <assert.h>
+
+bool sys_valid_io_range(off_t offset, size_t length)
+{
+ uint64_t last_byte_ofs;
+
+ if (offset < 0) {
+ return false;
+ }
+
+ if (offset > INT64_MAX) {
+ return false;
+ }
+
+ if (length > UINT32_MAX) {
+ return false;
+ }
+
+ last_byte_ofs = (uint64_t)offset + (uint64_t)length;
+ if (last_byte_ofs > INT64_MAX) {
+ return false;
+ }
+
+ return true;
+}
+
+bool sys_io_ranges_overlap(size_t c1, off_t o1,
+ size_t c2, off_t o2)
+{
+ if (c1 == 0 || c2 == 0) {
+ return false;
+ }
+ if (o2 < o1) {
+ /*
+ * o1
+ * |····c1····|
+ * o2
+ * |····c2···| ?
+ */
+ return (o2 + c2 > o1);
+ } else {
+ /*
+ * o1
+ * |····c1···|
+ * o2
+ * |····c2····| ?
+ */
+ return (o1 + c1 > o2);
+ }
+}
+
+off_t sys_block_align_truncate(off_t len, off_t align)
+{
+ assert(align > 1);
+ assert(((align - 1) & align) == 0);
+ return len & (~align + 1);
+}
+
+off_t sys_block_align(off_t len, off_t align)
+{
+ assert(align > 1);
+ assert(((align - 1) & align) == 0);
+ return (len + (align - 1)) & ~(align - 1);
+}
+
+/*******************************************************************
+A read wrapper that will deal with EINTR/EWOULDBLOCK
+********************************************************************/
+
+ssize_t sys_read(int fd, void *buf, size_t count)
+{
+ ssize_t ret;
+
+ do {
+ ret = read(fd, buf, count);
+ } while (ret == -1 && (errno == EINTR || errno == EAGAIN ||
+ errno == EWOULDBLOCK));
+
+ return ret;
+}
+
+/**
+ * read wrapper, void variant:
+ * This is intended to be used as a void variant of
+ * read in situations where the caller wants to ignore
+ * the result. Hence not checking for EAGAIN|EWOULDBLOCK.
+ */
+void sys_read_v(int fd, void *buf, size_t count)
+{
+ ssize_t ret;
+
+ do {
+ ret = read(fd, buf, count);
+ } while (ret == -1 && errno == EINTR);
+}
+
+
+/*******************************************************************
+A write wrapper that will deal with EINTR/EWOULDBLOCK.
+********************************************************************/
+
+ssize_t sys_write(int fd, const void *buf, size_t count)
+{
+ ssize_t ret;
+
+ do {
+ ret = write(fd, buf, count);
+ } while (ret == -1 && (errno == EINTR || errno == EAGAIN ||
+ errno == EWOULDBLOCK));
+
+ return ret;
+}
+
+/**
+ * write wrapper to deal with EINTR and friends.
+ * void-variant that ignores the number of bytes written.
+ * This is intended to be used as a void variant of
+ * write in situations where the caller wants to ignore
+ * the result. Hence not checking for EAGAIN|EWOULDBLOCK.
+ */
+void sys_write_v(int fd, const void *buf, size_t count)
+{
+ ssize_t ret;
+
+ do {
+ ret = write(fd, buf, count);
+ } while (ret == -1 && errno == EINTR);
+}
+
+
+/*******************************************************************
+A writev wrapper that will deal with EINTR.
+********************************************************************/
+
+ssize_t sys_writev(int fd, const struct iovec *iov, int iovcnt)
+{
+ ssize_t ret;
+
+ do {
+ ret = writev(fd, iov, iovcnt);
+ } while (ret == -1 && (errno == EINTR || errno == EAGAIN ||
+ errno == EWOULDBLOCK));
+
+ return ret;
+}
+
+/*******************************************************************
+A pread wrapper that will deal with EINTR
+********************************************************************/
+
+ssize_t sys_pread(int fd, void *buf, size_t count, off_t off)
+{
+ ssize_t ret;
+
+ do {
+ ret = pread(fd, buf, count, off);
+ } while (ret == -1 && errno == EINTR);
+ return ret;
+}
+
+/*******************************************************************
+ A pread wrapper that will deal with EINTR and never return a short
+ read unless pread returns zero meaning EOF.
+********************************************************************/
+
+ssize_t sys_pread_full(int fd, void *buf, size_t count, off_t off)
+{
+ ssize_t total_read = 0;
+ uint8_t *curr_buf = (uint8_t *)buf;
+ size_t curr_count = count;
+ off_t curr_off = off;
+ bool ok;
+
+ ok = sys_valid_io_range(off, count);
+ if (!ok) {
+ errno = EINVAL;
+ return -1;
+ }
+
+ while (curr_count != 0) {
+ ssize_t ret = sys_pread(fd,
+ curr_buf,
+ curr_count,
+ curr_off);
+
+ if (ret == -1) {
+ return -1;
+ }
+ if (ret == 0) {
+ /* EOF */
+ break;
+ }
+
+ if (ret > curr_count) {
+ errno = EIO;
+ return -1;
+ }
+
+ curr_buf += ret;
+ curr_count -= ret;
+ curr_off += ret;
+
+ total_read += ret;
+ }
+
+ return total_read;
+}
+
+/*******************************************************************
+A write wrapper that will deal with EINTR
+********************************************************************/
+
+ssize_t sys_pwrite(int fd, const void *buf, size_t count, off_t off)
+{
+ ssize_t ret;
+
+ do {
+ ret = pwrite(fd, buf, count, off);
+ } while (ret == -1 && errno == EINTR);
+ return ret;
+}
+
+/*******************************************************************
+ A pwrite wrapper that will deal with EINTR and never allow a short
+ write unless the file system returns an error.
+********************************************************************/
+
+ssize_t sys_pwrite_full(int fd, const void *buf, size_t count, off_t off)
+{
+ ssize_t total_written = 0;
+ const uint8_t *curr_buf = (const uint8_t *)buf;
+ size_t curr_count = count;
+ off_t curr_off = off;
+ bool ok;
+
+ ok = sys_valid_io_range(off, count);
+ if (!ok) {
+ errno = EINVAL;
+ return -1;
+ }
+
+ while (curr_count != 0) {
+ ssize_t ret = sys_pwrite(fd,
+ curr_buf,
+ curr_count,
+ curr_off);
+
+ if (ret == -1) {
+ return -1;
+ }
+ if (ret == 0) {
+ /* Ensure we can never spin. */
+ errno = ENOSPC;
+ return -1;
+ }
+
+ if (ret > curr_count) {
+ errno = EIO;
+ return -1;
+ }
+
+ curr_buf += ret;
+ curr_count -= ret;
+ curr_off += ret;
+
+ total_written += ret;
+ }
+
+ return total_written;
+}