libudev.c revision c8e32461ccc2227da53f98ccd11bcb50d70929bd
/*
* libudev - interface to udev device information
*
* Copyright (C) 2008 Kay Sievers <kay.sievers@vrfy.org>
*
* This program 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, either version 2 of the License, or
* (at your option) any later version.
*
* 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
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <stdio.h>
#include <stdlib.h>
#include <stddef.h>
#include <stdarg.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <ctype.h>
#ifdef USE_SELINUX
#include <selinux/selinux.h>
#endif
#include "libudev.h"
#include "libudev-private.h"
struct udev {
int refcount;
void (*log_fn)(struct udev *udev,
int priority, const char *file, int line, const char *fn,
const char *format, va_list args);
void *userdata;
char *sys_path;
char *dev_path;
char *rules_path;
int log_priority;
#ifdef USE_SELINUX
int selinux_enabled;
security_context_t selinux_prev_scontext;
#endif
int run;
};
void udev_log(struct udev *udev,
int priority, const char *file, int line, const char *fn,
const char *format, ...)
{
va_list args;
if (priority > udev->log_priority)
return;
va_start(args, format);
udev->log_fn(udev, priority, file, line, fn, format, args);
va_end(args);
}
static void log_stderr(struct udev *udev,
int priority, const char *file, int line, const char *fn,
const char *format, va_list args)
{
fprintf(stderr, "libudev: %s: ", fn);
vfprintf(stderr, format, args);
}
static void selinux_init(struct udev *udev)
{
#ifdef USE_SELINUX
/*
* record the present security context, for file-creation
* restoration creation purposes.
*/
udev->selinux_enabled = (is_selinux_enabled() > 0);
info(udev, "selinux=%i\n", udev->selinux_enabled);
if (udev->selinux_enabled) {
matchpathcon_init_prefix(NULL, udev_get_dev_path(udev));
if (getfscreatecon(&udev->selinux_prev_scontext) < 0) {
err(udev, "getfscreatecon failed\n");
udev->selinux_prev_scontext = NULL;
}
}
#endif
}
void *udev_get_userdata(struct udev *udev)
{
if (udev == NULL)
return NULL;
return udev->userdata;
}
void udev_set_userdata(struct udev *udev, void *userdata)
{
if (udev == NULL)
return;
udev->userdata = userdata;
}
static void selinux_exit(struct udev *udev)
{
#ifdef USE_SELINUX
if (udev->selinux_enabled) {
freecon(udev->selinux_prev_scontext);
udev->selinux_prev_scontext = NULL;
}
#endif
}
void udev_selinux_lsetfilecon(struct udev *udev, const char *file, unsigned int mode)
{
#ifdef USE_SELINUX
if (udev->selinux_enabled) {
security_context_t scontext = NULL;
if (matchpathcon(file, mode, &scontext) < 0) {
err(udev, "matchpathcon(%s) failed\n", file);
return;
}
if (lsetfilecon(file, scontext) < 0)
err(udev, "setfilecon %s failed: %s\n", file, strerror(errno));
freecon(scontext);
}
#endif
}
void udev_selinux_setfscreatecon(struct udev *udev, const char *file, unsigned int mode)
{
#ifdef USE_SELINUX
if (udev->selinux_enabled) {
security_context_t scontext = NULL;
if (matchpathcon(file, mode, &scontext) < 0) {
err(udev, "matchpathcon(%s) failed\n", file);
return;
}
if (setfscreatecon(scontext) < 0)
err(udev, "setfscreatecon %s failed: %s\n", file, strerror(errno));
freecon(scontext);
}
#endif
}
void udev_selinux_resetfscreatecon(struct udev *udev)
{
#ifdef USE_SELINUX
if (udev->selinux_enabled) {
if (setfscreatecon(udev->selinux_prev_scontext) < 0)
err(udev, "setfscreatecon failed: %s\n", strerror(errno));
}
#endif
}
/**
* udev_new:
*
* Create udev library context.
*
* The initial refcount is 1, and needs to be decremented to
* release the ressources of the udev library context.
*
* Returns: a new udev library context
**/
struct udev *udev_new(void)
{
struct udev *udev;
const char *env;
char *config_file;
FILE *f;
udev = malloc(sizeof(struct udev));
if (udev == NULL)
return NULL;
memset(udev, 0x00, (sizeof(struct udev)));
udev->refcount = 1;
udev->log_fn = log_stderr;
udev->log_priority = LOG_ERR;
udev->run = 1;
udev->dev_path = strdup(UDEV_PREFIX "/dev");
udev->sys_path = strdup("/sys");
config_file = strdup(SYSCONFDIR "/udev/udev.conf");
if (udev->dev_path == NULL ||
udev->sys_path == NULL ||
config_file == NULL)
goto err;
/* settings by environment and config file */
env = getenv("SYSFS_PATH");
if (env != NULL) {
free(udev->sys_path);
udev->sys_path = strdup(env);
util_remove_trailing_chars(udev->sys_path, '/');
}
env = getenv("UDEV_RUN");
if (env != NULL && strcmp(env, "0") == 0)
udev->run = 0;
env = getenv("UDEV_CONFIG_FILE");
if (env != NULL) {
free(config_file);
config_file = strdup(env);
util_remove_trailing_chars(config_file, '/');
}
if (config_file == NULL)
goto err;
f = fopen(config_file, "r");
if (f != NULL) {
char line[UTIL_LINE_SIZE];
int line_nr = 0;
while (fgets(line, sizeof(line), f)) {
size_t len;
char *key;
char *val;
line_nr++;
/* find key */
key = line;
while (isspace(key[0]))
key++;
/* comment or empty line */
if (key[0] == '#' || key[0] == '\0')
continue;
/* split key/value */
val = strchr(key, '=');
if (val == NULL) {
err(udev, "missing <key>=<value> in '%s'[%i], skip line\n", config_file, line_nr);
continue;
}
val[0] = '\0';
val++;
/* find value */
while (isspace(val[0]))
val++;
/* terminate key */
len = strlen(key);
if (len == 0)
continue;
while (isspace(key[len-1]))
len--;
key[len] = '\0';
/* terminate value */
len = strlen(val);
if (len == 0)
continue;
while (isspace(val[len-1]))
len--;
val[len] = '\0';
if (len == 0)
continue;
/* unquote */
if (val[0] == '"' || val[0] == '\'') {
if (val[len-1] != val[0]) {
err(udev, "inconsistent quoting in '%s'[%i], skip line\n", config_file, line_nr);
continue;
}
val[len-1] = '\0';
val++;
}
if (strcasecmp(key, "udev_log") == 0) {
udev->log_priority = util_log_priority(val);
continue;
}
if (strcasecmp(key, "udev_root") == 0) {
free(udev->dev_path);
udev->dev_path = strdup(val);
util_remove_trailing_chars(udev->dev_path, '/');
continue;
}
if (strcasecmp(key, "udev_rules") == 0) {
free(udev->rules_path);
udev->rules_path = strdup(val);
util_remove_trailing_chars(udev->rules_path, '/');
continue;
}
}
fclose(f);
}
env = getenv("UDEV_ROOT");
if (env != NULL) {
free(udev->dev_path);
udev->dev_path = strdup(env);
util_remove_trailing_chars(udev->dev_path, '/');
}
env = getenv("UDEV_LOG");
if (env != NULL)
udev->log_priority = util_log_priority(env);
if (udev->dev_path == NULL || udev->sys_path == NULL)
goto err;
selinux_init(udev);
info(udev, "context %p created\n", udev);
info(udev, "log_priority=%d\n", udev->log_priority);
info(udev, "config_file='%s'\n", config_file);
info(udev, "dev_path='%s'\n", udev->dev_path);
info(udev, "sys_path='%s'\n", udev->sys_path);
if (udev->rules_path != NULL)
info(udev, "rules_path='%s'\n", udev->rules_path);
free(config_file);
return udev;
err:
free(config_file);
err(udev, "context creation failed\n");
udev_unref(udev);
return NULL;
}
/**
* udev_ref:
* @udev: udev library context
*
* Take a reference of the udev library context.
*
* Returns: the passed udev library context
**/
struct udev *udev_ref(struct udev *udev)
{
if (udev == NULL)
return NULL;
udev->refcount++;
return udev;
}
/**
* udev_unref:
* @udev: udev library context
*
* Drop a reference of the udev library context. If the refcount
* reaches zero, the ressources of the context will be released.
*
**/
void udev_unref(struct udev *udev)
{
if (udev == NULL)
return;
udev->refcount--;
if (udev->refcount > 0)
return;
selinux_exit(udev);
free(udev->dev_path);
free(udev->sys_path);
free(udev->rules_path);
info(udev, "context %p released\n", udev);
free(udev);
}
/**
* udev_set_log_fn:
* @udev: udev library context
* @log_fn: function to be called for logging messages
*
* The built-in logging, which writes to stderr if the
* LIBUDEV_DEBUG environment variable is set, can be
* overridden by a custom function, to plug log messages
* into the users logging functionality.
*
**/
void udev_set_log_fn(struct udev *udev,
void (*log_fn)(struct udev *udev,
int priority, const char *file, int line, const char *fn,
const char *format, va_list args))
{
udev->log_fn = log_fn;
info(udev, "custom logging function %p registered\n", udev);
}
int udev_get_log_priority(struct udev *udev)
{
return udev->log_priority;
}
void udev_set_log_priority(struct udev *udev, int priority)
{
udev->log_priority = priority;
}
const char *udev_get_rules_path(struct udev *udev)
{
return udev->rules_path;
}
int udev_get_run(struct udev *udev)
{
return udev->run;
}
/**
* udev_get_sys_path:
* @udev: udev library context
*
* Retrieve the sysfs mount point. The default is "/sys". For
* testing purposes, it can be overridden with the environment
* variable SYSFS_PATH.
*
* Returns: the sys mount point
**/
const char *udev_get_sys_path(struct udev *udev)
{
if (udev == NULL)
return NULL;
return udev->sys_path;
}
/**
* udev_get_dev_path:
* @udev: udev library context
*
* Retrieve the device directory path. The default value is "/dev",
* the actual value may be overridden in the udev configuration
* file.
*
* Returns: the device directory path
**/
const char *udev_get_dev_path(struct udev *udev)
{
if (udev == NULL)
return NULL;
return udev->dev_path;
}