busybox/util-linux/mdev.c

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/* vi: set sw=4 ts=4: */
/*
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*
* mdev - Mini udev for busybox
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*
* Copyright 2005 Rob Landley <rob@landley.net>
* Copyright 2005 Frank Sorenson <frank@tuxrocks.com>
*
* Licensed under GPL version 2, see file LICENSE in this tarball for details.
*/
#include "libbb.h"
#include "xregex.h"
struct globals {
int root_major, root_minor;
};
#define G (*(struct globals*)&bb_common_bufsiz1)
#define root_major (G.root_major)
#define root_minor (G.root_minor)
#define MAX_SYSFS_DEPTH 3 /* prevent infinite loops in /sys symlinks */
/* mknod in /dev based on a path like "/sys/block/hda/hda1" */
static void make_device(char *path, int delete)
{
const char *device_name;
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int major, minor, type, len;
int mode = 0660;
uid_t uid = 0;
gid_t gid = 0;
char *temp = path + strlen(path);
char *command = NULL;
/* Try to read major/minor string. Note that the kernel puts \n after
* the data, so we don't need to worry about null terminating the string
* because sscanf() will stop at the first nondigit, which \n is. We
* also depend on path having writeable space after it.
*/
if (!delete) {
strcat(path, "/dev");
len = open_read_close(path, temp + 1, 64);
*temp++ = 0;
if (len < 1)
return;
}
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/* Determine device name, type, major and minor */
device_name = bb_basename(path);
type = (path[5] == 'c' ? S_IFCHR : S_IFBLK);
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if (ENABLE_FEATURE_MDEV_CONF) {
FILE *fp;
char *line, *vline;
size_t lineno = 0;
/* If we have a config file, look up the user settings */
fp = fopen_or_warn("/etc/mdev.conf", "r");
if (!fp)
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goto end_parse;
while ((vline = line = xmalloc_getline(fp)) != NULL) {
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int field;
/* A pristine copy for command execution. */
char *orig_line;
if (ENABLE_FEATURE_MDEV_EXEC)
orig_line = xstrdup(line);
++lineno;
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/* Three fields: regex, uid:gid, mode */
for (field = 0; field < (3 + ENABLE_FEATURE_MDEV_EXEC); ++field) {
/* Find a non-empty field */
char *val;
do {
val = strtok(vline, " \t");
vline = NULL;
} while (val && !*val);
if (!val)
break;
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if (field == 0) {
/* Regex to match this device */
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regex_t match;
regmatch_t off;
int result;
/* Is this it? */
xregcomp(&match, val, REG_EXTENDED);
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result = regexec(&match, device_name, 1, &off, 0);
regfree(&match);
/* If not this device, skip rest of line */
if (result || off.rm_so || off.rm_eo != strlen(device_name))
goto next_line;
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} else if (field == 1) {
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/* uid:gid device ownership */
struct passwd *pass;
struct group *grp;
char *str_uid = val;
char *str_gid = strchr(val, ':');
if (str_gid)
*str_gid = '\0', ++str_gid;
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/* Parse UID */
pass = getpwnam(str_uid);
if (pass)
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uid = pass->pw_uid;
else
uid = strtoul(str_uid, NULL, 10);
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/* parse GID */
grp = getgrnam(str_gid);
if (grp)
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gid = grp->gr_gid;
else
gid = strtoul(str_gid, NULL, 10);
} else if (field == 2) {
/* Mode device permissions */
mode = strtoul(val, NULL, 8);
} else if (ENABLE_FEATURE_MDEV_EXEC && field == 3) {
/* Optional command to run */
const char *s = "@$*";
const char *s2 = strchr(s, *val);
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if (!s2) {
/* Force error */
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field = 1;
break;
}
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/* Correlate the position in the "@$*" with the delete
* step so that we get the proper behavior.
*/
if ((s2 - s + 1) & (1 << delete))
command = xstrdup(orig_line + (val + 1 - line));
}
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}
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/* Did everything parse happily? */
if (field <= 2)
bb_error_msg_and_die("bad line %i", lineno);
next_line:
free(line);
if (ENABLE_FEATURE_MDEV_EXEC)
free(orig_line);
}
if (ENABLE_FEATURE_CLEAN_UP)
fclose(fp);
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end_parse: /* nothing */ ;
}
umask(0);
if (!delete) {
if (sscanf(temp, "%d:%d", &major, &minor) != 2)
return;
if (mknod(device_name, mode | type, makedev(major, minor)) && errno != EEXIST)
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bb_perror_msg_and_die("mknod %s", device_name);
if (major == root_major && minor == root_minor)
symlink(device_name, "root");
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if (ENABLE_FEATURE_MDEV_CONF)
chown(device_name, uid, gid);
}
if (command) {
/* setenv will leak memory, so use putenv */
char *s = xasprintf("MDEV=%s", device_name);
putenv(s);
if (system(command) == -1)
bb_perror_msg_and_die("cannot run %s", command);
s[4] = '\0';
unsetenv(s);
free(s);
free(command);
}
if (delete)
remove_file(device_name, FILEUTILS_FORCE);
}
/* File callback for /sys/ traversal */
static int fileAction(const char *fileName, struct stat *statbuf,
void *userData, int depth)
{
size_t len = strlen(fileName) - 4;
char *scratch = userData;
if (strcmp(fileName + len, "/dev"))
return FALSE;
strcpy(scratch, fileName);
scratch[len] = 0;
make_device(scratch, 0);
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return TRUE;
}
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/* Directory callback for /sys/ traversal */
static int dirAction(const char *fileName, struct stat *statbuf,
void *userData, int depth)
{
return (depth >= MAX_SYSFS_DEPTH ? SKIP : TRUE);
}
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/* For the full gory details, see linux/Documentation/firmware_class/README
*
* Firmware loading works like this:
* - kernel sets FIRMWARE env var
* - userspace checks /lib/firmware/$FIRMWARE
* - userspace waits for /sys/$DEVPATH/loading to appear
* - userspace writes "1" to /sys/$DEVPATH/loading
* - userspace copies /lib/firmware/$FIRMWARE into /sys/$DEVPATH/data
* - userspace writes "0" (worked) or "-1" (failed) to /sys/$DEVPATH/loading
* - kernel loads firmware into device
*/
static void load_firmware(const char *const firmware, const char *const sysfs_path)
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{
int cnt;
int firmware_fd, loading_fd, data_fd;
/* check for $FIRMWARE from kernel */
/* XXX: dont bother: open(NULL) works same as open("no-such-file")
* if (!firmware)
* return;
*/
/* check for /lib/firmware/$FIRMWARE */
xchdir("/lib/firmware");
firmware_fd = xopen(firmware, O_RDONLY);
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/* in case we goto out ... */
data_fd = -1;
/* check for /sys/$DEVPATH/loading ... give 30 seconds to appear */
xchdir(sysfs_path);
for (cnt = 0; cnt < 30; ++cnt) {
loading_fd = open("loading", O_WRONLY);
if (loading_fd == -1)
sleep(1);
else
break;
}
if (loading_fd == -1)
goto out;
/* tell kernel we're loading by `echo 1 > /sys/$DEVPATH/loading` */
if (write(loading_fd, "1", 1) != 1)
goto out;
/* load firmware by `cat /lib/firmware/$FIRMWARE > /sys/$DEVPATH/data */
data_fd = open("data", O_WRONLY);
if (data_fd == -1)
goto out;
cnt = bb_copyfd_eof(firmware_fd, data_fd);
/* tell kernel result by `echo [0|-1] > /sys/$DEVPATH/loading` */
if (cnt > 0)
write(loading_fd, "0", 1);
else
write(loading_fd, "-1", 2);
out:
if (ENABLE_FEATURE_CLEAN_UP) {
close(firmware_fd);
close(loading_fd);
close(data_fd);
}
}
int mdev_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int mdev_main(int argc, char **argv)
{
char *action;
char *env_path;
RESERVE_CONFIG_BUFFER(temp,PATH_MAX);
xchdir("/dev");
if (argc == 2 && !strcmp(argv[1],"-s")) {
/* Scan:
* mdev -s
*/
struct stat st;
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xstat("/", &st);
root_major = major(st.st_dev);
root_minor = minor(st.st_dev);
recursive_action("/sys/block",
ACTION_RECURSE | ACTION_FOLLOWLINKS,
fileAction, dirAction, temp, 0);
recursive_action("/sys/class",
ACTION_RECURSE | ACTION_FOLLOWLINKS,
fileAction, dirAction, temp, 0);
} else {
/* Hotplug:
* env ACTION=... DEVPATH=... mdev
* ACTION can be "add" or "remove"
* DEVPATH is like "/block/sda" or "/class/input/mice"
*/
action = getenv("ACTION");
env_path = getenv("DEVPATH");
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if (!action || !env_path)
bb_show_usage();
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sprintf(temp, "/sys%s", env_path);
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if (!strcmp(action, "remove"))
make_device(temp, 1);
else if (!strcmp(action, "add")) {
make_device(temp, 0);
if (ENABLE_FEATURE_MDEV_LOAD_FIRMWARE)
load_firmware(getenv("FIRMWARE"), temp);
}
}
if (ENABLE_FEATURE_CLEAN_UP)
RELEASE_CONFIG_BUFFER(temp);
return 0;
}