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// SPDX-License-Identifier: GPL-2.0
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "file_utils.h"
int read_file(const char *path, char *buf, size_t buflen)
{
int fd, err;
ssize_t numread;
fd = open(path, O_RDONLY);
if (fd == -1)
return -errno;
numread = read(fd, buf, buflen - 1);
if (numread < 1) {
err = numread ? errno : ENODATA;
close(fd);
return -err;
}
buf[numread] = '\0';
close(fd);
return 0;
}
int write_file(const char *path, const char *buf, size_t buflen)
{
int fd, saved_errno;
ssize_t numwritten;
if (buflen < 2)
return -EINVAL;
fd = open(path, O_WRONLY);
if (fd == -1)
return -errno;
numwritten = write(fd, buf, buflen - 1);
saved_errno = errno;
close(fd);
if (numwritten < 0)
return -saved_errno;
if (numwritten != (ssize_t)(buflen - 1))
return -EIO;
return 0;
}
int read_num(const char *path, unsigned long *num)
{
unsigned long val;
int ret;
char buf[21];
char *end;
if (!num)
return -EINVAL;
ret = read_file(path, buf, sizeof(buf));
if (ret)
return ret;
/* Reject signs and leading whitespace that are accepted by strtoul() */
if (buf[0] < '0' || buf[0] > '9')
return -EINVAL;
errno = 0;
val = strtoul(buf, &end, 10);
if (errno)
return -errno;
/* Only allow a newline after the number */
if (*end == '\n')
end++;
if (*end != '\0')
return -EINVAL;
*num = val;
return 0;
}
int write_num(const char *path, unsigned long num)
{
char buf[21];
sprintf(buf, "%lu", num);
return write_file(path, buf, strlen(buf) + 1);
}
int write_num_ignore_einval(const char *path, unsigned long num)
{
int ret;
ret = write_num(path, num);
return ret == -EINVAL ? 0 : ret;
}
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