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/* Copyright (C) 2008 Intel Corporation
Author: Andi Kleen
Read/Write sysfs values
mcelog 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; version
2.
mcelog 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 find a copy of v2 of the GNU General Public License somewhere
on your Linux system; if not, write to the Free Software Foundation,
Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
#define _GNU_SOURCE 1
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <sys/fcntl.h>
#include <stdarg.h>
#include <errno.h>
#include "mcelog.h"
#include "sysfs.h"
#include "memutil.h"
char *read_field(char *base, char *name)
{
char *fn, *val;
int n, fd;
struct stat st;
char *s;
char *buf = NULL;
asprintf(&fn, "%s/%s", base, name);
fd = open(fn, O_RDONLY);
if (fstat(fd, &st) < 0)
goto bad;
buf = xalloc(st.st_size);
free(fn);
if (fd < 0)
goto bad;
n = read(fd, buf, st.st_size);
close(fd);
if (n < 0)
goto bad;
val = xalloc(n);
memcpy(val, buf, n);
free(buf);
s = strchr(val, '\n');
if (s)
*s = 0;
return val;
bad:
SYSERRprintf("Cannot read sysfs field %s/%s", base, name);
*buf = 0;
return buf;
}
unsigned read_field_num(char *base, char *name)
{
unsigned num;
char *val = read_field(base, name);
int n = sscanf(val, "%u", &num);
free(val);
if (n != 1) {
Eprintf("Cannot parse number in sysfs field %s/%s\n", base,name);
return 0;
}
return num;
}
unsigned read_field_map(char *base, char *name, struct map *map)
{
char *val = read_field(base, name);
for (; map->name; map++) {
if (!strcmp(val, map->name))
break;
}
free(val);
if (map->name)
return map->value;
Eprintf("sysfs field %s/%s has unknown string value `%s'\n", base, name, val);
return -1;
}
int sysfs_write(const char *name, const char *fmt, ...)
{
int e;
int n;
char *buf;
va_list ap;
int fd = open(name, O_WRONLY);
if (fd < 0)
return -1;
va_start(ap, fmt);
n = vasprintf(&buf, fmt, ap);
va_end(ap);
n = write(fd, buf, n);
e = errno;
close(fd);
free(buf);
errno = e;
return n;
}
int sysfs_available(const char *name, int flags)
{
return access(name, flags) == 0;
}
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