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 */
/* We use additional 64+ bytes in make_device() */
#define SCRATCH_SIZE 80
static char *next_field(char *s)
{
char *end = skip_non_whitespace(s);
s = skip_whitespace(end);
*end = '\0';
if (*s == '\0')
s = NULL;
return s;
}
/* mknod in /dev based on a path like "/sys/block/hda/hda1" */
/* NB: "mdev -s" may call us many times, do not leak memory/fds! */
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 *dev_maj_min = path + strlen(path);
char *command = NULL;
char *alias = NULL;
/* Force the configuration file settings exactly. */
umask(0);
/* 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) {
strcpy(dev_maj_min, "/dev");
len = open_read_close(path, dev_maj_min + 1, 64);
*dev_maj_min++ = '\0';
if (len < 1) {
if (!ENABLE_FEATURE_MDEV_EXEC)
return;
/* no "dev" file, so just try to run script */
*dev_maj_min = '\0';
}
}
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/* Determine device name, type, major and minor */
device_name = bb_basename(path);
/* http://kernel.org/doc/pending/hotplug.txt says that only
* "/sys/block/..." is for block devices. "/sys/bus" etc is not!
* Since kernel 2.6.25 block devices are also in /sys/class/block. */
/* TODO: would it be acceptable to just use strstr(path, "/block/")? */
if (strncmp(&path[5], "class/block/"+6, 6) != 0
&& strncmp(&path[5], "class/block/", 12) != 0)
type = S_IFCHR;
else
type = S_IFBLK;
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if (ENABLE_FEATURE_MDEV_CONF) {
FILE *fp;
char *line, *val, *next;
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unsigned lineno = 0;
/* If we have config file, look up user settings */
fp = fopen_or_warn("/etc/mdev.conf", "r");
if (!fp)
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goto end_parse;
while ((line = xmalloc_fgetline(fp)) != NULL) {
regmatch_t off[1+9*ENABLE_FEATURE_MDEV_RENAME_REGEXP];
++lineno;
trim(line);
if (!line[0])
goto next_line;
/* Fields: regex uid:gid mode [alias] [cmd] */
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/* 1st field: regex to match this device */
next = next_field(line);
{
regex_t match;
int result;
/* Is this it? */
xregcomp(&match, line, REG_EXTENDED);
result = regexec(&match, device_name, ARRAY_SIZE(off), off, 0);
regfree(&match);
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//bb_error_msg("matches:");
//for (int i = 0; i < ARRAY_SIZE(off); i++) {
// if (off[i].rm_so < 0) continue;
// bb_error_msg("match %d: '%.*s'\n", i,
// (int)(off[i].rm_eo - off[i].rm_so),
// device_name + off[i].rm_so);
//}
/* If not this device, skip rest of line */
/* (regexec returns whole pattern as "range" 0) */
if (result || off[0].rm_so
|| ((int)off[0].rm_eo != (int)strlen(device_name))
) {
goto next_line;
}
}
/* This line matches: stop parsing the file
* after parsing the rest of fields */
/* 2nd field: uid:gid - device ownership */
if (!next) /* field must exist */
bb_error_msg_and_die("bad line %u", lineno);
val = next;
next = next_field(val);
{
struct passwd *pass;
struct group *grp;
char *str_uid = val;
char *str_gid = strchrnul(val, ':');
if (*str_gid)
*str_gid++ = '\0';
/* Parse UID */
pass = getpwnam(str_uid);
if (pass)
uid = pass->pw_uid;
else
uid = strtoul(str_uid, NULL, 10);
/* Parse GID */
grp = getgrnam(str_gid);
if (grp)
gid = grp->gr_gid;
else
gid = strtoul(str_gid, NULL, 10);
}
/* 3rd field: mode - device permissions */
if (!next) /* field must exist */
bb_error_msg_and_die("bad line %u", lineno);
val = next;
next = next_field(val);
mode = strtoul(val, NULL, 8);
/* 4th field (opt): >alias */
#if ENABLE_FEATURE_MDEV_RENAME
if (!next)
break;
if (*next == '>') {
#if ENABLE_FEATURE_MDEV_RENAME_REGEXP
char *s, *p;
unsigned i, n;
val = next;
next = next_field(val);
/* substitute %1..9 with off[1..9], if any */
n = 0;
s = val;
while (*s && *s++ == '%')
n++;
p = alias = xzalloc(strlen(val) + n * strlen(device_name));
s = val + 1;
while (*s) {
*p = *s;
if ('%' == *s) {
i = (s[1] - '0');
if (i <= 9 && off[i].rm_so >= 0) {
n = off[i].rm_eo - off[i].rm_so;
strncpy(p, device_name + off[i].rm_so, n);
p += n - 1;
s++;
}
}
p++;
s++;
}
#else
val = next;
next = next_field(val);
alias = xstrdup(val + 1);
#endif
}
#endif /* ENABLE_FEATURE_MDEV_RENAME */
/* The rest (opt): command to run */
if (!next)
break;
val = next;
if (ENABLE_FEATURE_MDEV_EXEC) {
const char *s = "@$*";
const char *s2 = strchr(s, *val);
if (!s2)
bb_error_msg_and_die("bad line %u", lineno);
/* Correlate the position in the "@$*" with the delete
* step so that we get the proper behavior:
* @cmd: run on create
* $cmd: run on delete
* *cmd: run on both
*/
if ((s2 - s + 1) /*1/2/3*/ & /*1/2*/ (1 + delete)) {
command = xstrdup(val + 1);
}
}
/* end of field parsing */
break; /* we found matching line, stop */
next_line:
free(line);
} /* end of "while line is read from /etc/mdev.conf" */
free(line); /* in case we used "break" to get here */
fclose(fp);
}
end_parse:
if (!delete && sscanf(dev_maj_min, "%u:%u", &major, &minor) == 2) {
if (ENABLE_FEATURE_MDEV_RENAME)
unlink(device_name);
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 (ENABLE_FEATURE_MDEV_RENAME && alias) {
char *dest;
/* ">bar/": rename to bar/device_name */
/* ">bar[/]baz": rename to bar[/]baz */
dest = strrchr(alias, '/');
if (dest) { /* ">bar/[baz]" ? */
*dest = '\0'; /* mkdir bar */
bb_make_directory(alias, 0755, FILEUTILS_RECUR);
*dest = '/';
if (dest[1] == '\0') { /* ">bar/" => ">bar/device_name" */
dest = alias;
alias = concat_path_file(alias, device_name);
free(dest);
}
}
/* recreate device_name as a symlink to moved device node */
if (rename(device_name, alias) == 0) {
symlink(alias, device_name);
}
free(alias);
}
}
}
if (ENABLE_FEATURE_MDEV_EXEC && command) {
/* setenv will leak memory, use putenv/unsetenv/free */
char *s = xasprintf("MDEV=%s", device_name);
putenv(s);
if (system(command) == -1)
bb_perror_msg_and_die("can't run '%s'", command);
s[4] = '\0';
unsetenv(s);
free(s);
free(command);
}
if (delete)
unlink(device_name);
}
/* File callback for /sys/ traversal */
static int fileAction(const char *fileName,
struct stat *statbuf ATTRIBUTE_UNUSED,
void *userData,
int depth ATTRIBUTE_UNUSED)
{
size_t len = strlen(fileName) - 4; /* can't underflow */
char *scratch = userData;
/* len check is for paranoid reasons */
if (strcmp(fileName + len, "/dev") || len >= PATH_MAX)
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 ATTRIBUTE_UNUSED,
struct stat *statbuf ATTRIBUTE_UNUSED,
void *userData ATTRIBUTE_UNUSED,
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/$DEVPATH/loading
* - kernel loads firmware into device
*/
static void load_firmware(const char *const firmware, const char *const sysfs_path)
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{
int cnt;
int firmware_fd, loading_fd, data_fd;
/* check for /lib/firmware/$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/$DEVPATH/loading ... give 30 seconds to appear */
xchdir(sysfs_path);
for (cnt = 0; cnt < 30; ++cnt) {
loading_fd = open("loading", O_WRONLY);
if (loading_fd != -1)
goto loading;
sleep(1);
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}
goto out;
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loading:
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/* tell kernel we're loading by `echo 1 > /sys/$DEVPATH/loading` */
if (full_write(loading_fd, "1", 1) != 1)
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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)
full_write(loading_fd, "0", 1);
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else
full_write(loading_fd, "-1", 2);
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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 + SCRATCH_SIZE);
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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snprintf(temp, PATH_MAX, "/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) {
char *fw = getenv("FIRMWARE");
if (fw)
load_firmware(fw, temp);
}
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}
}
if (ENABLE_FEATURE_CLEAN_UP)
RELEASE_CONFIG_BUFFER(temp);
return 0;
}