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// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
// vim: ts=8 sw=2 smarttab
/*
* Ceph - scalable distributed file system
*
* Copyright (C) 2011 New Dream Network
*
* This is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License version 2.1, as published by the Free Software
* Foundation. See file COPYING.
*
*/
#include "common/safe_io.h"
#include "include/compat.h"
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
ssize_t safe_read(int fd, void *buf, size_t count)
{
size_t cnt = 0;
while (cnt < count) {
ssize_t r = read(fd, buf, count - cnt);
if (r <= 0) {
if (r == 0) {
// EOF
return cnt;
}
if (errno == EINTR)
continue;
return -errno;
}
cnt += r;
buf = (char *)buf + r;
}
return cnt;
}
ssize_t safe_read_exact(int fd, void *buf, size_t count)
{
ssize_t ret = safe_read(fd, buf, count);
if (ret < 0)
return ret;
if ((size_t)ret != count)
return -EDOM;
return 0;
}
ssize_t safe_write(int fd, const void *buf, size_t count)
{
while (count > 0) {
ssize_t r = write(fd, buf, count);
if (r < 0) {
if (errno == EINTR)
continue;
return -errno;
}
count -= r;
buf = (char *)buf + r;
}
return 0;
}
ssize_t safe_pread(int fd, void *buf, size_t count, off_t offset)
{
size_t cnt = 0;
char *b = (char*)buf;
while (cnt < count) {
ssize_t r = pread(fd, b + cnt, count - cnt, offset + cnt);
if (r <= 0) {
if (r == 0) {
// EOF
return cnt;
}
if (errno == EINTR)
continue;
return -errno;
}
cnt += r;
}
return cnt;
}
ssize_t safe_pread_exact(int fd, void *buf, size_t count, off_t offset)
{
ssize_t ret = safe_pread(fd, buf, count, offset);
if (ret < 0)
return ret;
if ((size_t)ret != count)
return -EDOM;
return 0;
}
ssize_t safe_pwrite(int fd, const void *buf, size_t count, off_t offset)
{
while (count > 0) {
ssize_t r = pwrite(fd, buf, count, offset);
if (r < 0) {
if (errno == EINTR)
continue;
return -errno;
}
count -= r;
buf = (char *)buf + r;
offset += r;
}
return 0;
}
#ifdef CEPH_HAVE_SPLICE
ssize_t safe_splice(int fd_in, off_t *off_in, int fd_out, off_t *off_out,
size_t len, unsigned int flags)
{
size_t cnt = 0;
while (cnt < len) {
ssize_t r = splice(fd_in, off_in, fd_out, off_out, len - cnt, flags);
if (r <= 0) {
if (r == 0) {
// EOF
return cnt;
}
if (errno == EINTR)
continue;
if (errno == EAGAIN)
break;
return -errno;
}
cnt += r;
}
return cnt;
}
ssize_t safe_splice_exact(int fd_in, off_t *off_in, int fd_out,
off_t *off_out, size_t len, unsigned int flags)
{
ssize_t ret = safe_splice(fd_in, off_in, fd_out, off_out, len, flags);
if (ret < 0)
return ret;
if ((size_t)ret != len)
return -EDOM;
return 0;
}
#endif
int safe_write_file(const char *base, const char *file,
const char *val, size_t vallen,
unsigned mode)
{
int ret;
char fn[PATH_MAX];
char tmp[PATH_MAX];
int fd;
// does the file already have correct content?
char oldval[80];
ret = safe_read_file(base, file, oldval, sizeof(oldval));
if (ret == (int)vallen && memcmp(oldval, val, vallen) == 0)
return 0; // yes.
snprintf(fn, sizeof(fn), "%s/%s", base, file);
snprintf(tmp, sizeof(tmp), "%s/%s.tmp", base, file);
fd = open(tmp, O_WRONLY|O_CREAT|O_TRUNC, mode);
if (fd < 0) {
ret = errno;
return -ret;
}
ret = safe_write(fd, val, vallen);
if (ret) {
VOID_TEMP_FAILURE_RETRY(close(fd));
return ret;
}
ret = fsync(fd);
if (ret < 0) ret = -errno;
VOID_TEMP_FAILURE_RETRY(close(fd));
if (ret < 0) {
unlink(tmp);
return ret;
}
ret = rename(tmp, fn);
if (ret < 0) {
ret = -errno;
unlink(tmp);
return ret;
}
fd = open(base, O_RDONLY);
if (fd < 0) {
ret = -errno;
return ret;
}
ret = fsync(fd);
if (ret < 0) ret = -errno;
VOID_TEMP_FAILURE_RETRY(close(fd));
return ret;
}
int safe_read_file(const char *base, const char *file,
char *val, size_t vallen)
{
char fn[PATH_MAX];
int fd, len;
snprintf(fn, sizeof(fn), "%s/%s", base, file);
fd = open(fn, O_RDONLY);
if (fd < 0) {
return -errno;
}
len = safe_read(fd, val, vallen);
if (len < 0) {
VOID_TEMP_FAILURE_RETRY(close(fd));
return len;
}
// close sometimes returns errors, but only after write()
VOID_TEMP_FAILURE_RETRY(close(fd));
return len;
}
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