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/*
* Embedded Linux library
* Copyright (C) 2017 Intel Corporation
*
* SPDX-License-Identifier: LGPL-2.1-or-later
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#define _GNU_SOURCE
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <stdlib.h>
#include <stdio.h>
#include "file.h"
#include "private.h"
#include "useful.h"
/**
* l_file_get_contents:
* @filename: File to load
* @out_len: Set to the length of the loaded file
*
* Attempts to load the contents of a file via sequential read system calls.
* This can be useful for files that are not mmapable, e.g. sysfs entries.
*
* Returns: A newly allocated memory region with the file contents
**/
LIB_EXPORT void *l_file_get_contents(const char *filename, size_t *out_len)
{
int fd;
struct stat st;
uint8_t *contents;
size_t bytes_read = 0;
ssize_t nread;
fd = open(filename, O_RDONLY);
if (fd < 0)
return NULL;
if (fstat(fd, &st) < 0) {
close(fd);
return NULL;
}
contents = l_malloc(st.st_size);
do {
nread = read(fd, contents + bytes_read, 4096);
if (nread < 0) {
if (errno == EINTR)
continue;
goto error;
}
bytes_read += nread;
} while (nread != 0);
if (out_len)
*out_len = bytes_read;
close(fd);
return contents;
error:
l_free(contents);
close(fd);
return NULL;
}
/**
* l_file_set_contents:
* @filename: Destination filename
* @contents: Pointer to the contents
* @len: Length in bytes of the contents buffer
*
* Given a content buffer, write it to a file named @filename. This function
* ensures that the contents are consistent (i.e. due to a crash right after
* opening or during write() by writing the contents to a temporary which is then
* renamed to @filename.
*
* Returns: 0 if successful, a negative errno otherwise
**/
LIB_EXPORT int l_file_set_contents(const char *filename,
const void *contents, size_t len)
{
_auto_(l_free) char *tmp_path = NULL;
ssize_t r;
int fd;
if (!filename || !contents)
return -EINVAL;
tmp_path = l_strdup_printf("%s.XXXXXX.tmp", filename);
fd = L_TFR(mkostemps(tmp_path, 4, O_CLOEXEC));
if (fd == -1)
return -errno;
r = L_TFR(write(fd, contents, len));
L_TFR(close(fd));
if (r != (ssize_t) len) {
r = -EIO;
goto error_write;
}
/*
* Now that the file contents are written, rename to the real
* file name; this way we are uniquely sure that the whole
* thing is there.
* conserve @r's value from 'write'
*/
if (rename(tmp_path, filename) == -1)
r = -errno;
error_write:
if (r < 0)
unlink(tmp_path);
return r < 0 ? r : 0;
}
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