util-sysfs.c

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/* Copyright (C) 2011-2022 Open Information Security Foundation
 *
 * You can copy, redistribute or modify this Program under the terms of
 * the GNU General Public License version 2 as published by the Free
 * Software Foundation.
 *
 * 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
 * version 2 along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA.
 */
 
/**
 * \file
 *
 * \author Richard McConnell <richard_mcconnell@rapid7.com>
 *
 * Sysfs utility file
 */
 
#include "util-sysfs.h"
 
TmEcode SysFsWriteValue(const char *path, int64_t value)
{
#if defined(__linux__)
#define SYSFS_MAX_FILENAME_LEN (SYSFS_MAX_FILENAME_SIZE + 5)
    char fname[SYSFS_MAX_FILENAME_LEN] = "/sys/";
    char sentence[64];
 
    if (!path || strlen(path) > SYSFS_MAX_FILENAME_SIZE) {
        SCLogWarning("File path too long, max allowed: %d", SYSFS_MAX_FILENAME_SIZE);
        SCReturnInt(TM_ECODE_FAILED);
    }
 
    strlcat(fname, path, sizeof(fname));
 
    /* File must be present and process have correct capabilities to open */
    int fd = open(fname, O_WRONLY);
    if (fd < 0) {
        SCLogError("Could not open file: %s", fname);
        SCReturnInt(TM_ECODE_FAILED);
    }
 
    snprintf(sentence, sizeof(sentence), "%" PRIu64, value);
    ssize_t len = strlen(sentence);
 
    if (write(fd, sentence, len) != len) {
        SCLogError("Could not write to file: %s", fname);
        close(fd);
        SCReturnInt(TM_ECODE_FAILED);
    }
    close(fd);
#endif /* __LINUX__ */
 
    SCReturnInt(TM_ECODE_OK);
}