busybox/util-linux/mdev.c

509 lines
13 KiB
C

/* vi: set sw=4 ts=4: */
/*
*
* mdev - Mini udev for busybox
*
* 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)
/* Prevent infinite loops in /sys symlinks */
#define MAX_SYSFS_DEPTH 3
/* We use additional 64+ bytes in make_device() */
#define SCRATCH_SIZE 80
#if ENABLE_FEATURE_MDEV_RENAME
/* Builds an alias path.
* This function potentionally reallocates the alias parameter.
*/
static char *build_alias(char *alias, const char *device_name)
{
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);
}
}
return alias;
}
#endif
/* 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;
int major, minor, type, len;
int mode = 0660;
#if ENABLE_FEATURE_MDEV_CONF
struct bb_uidgid_t ugid = { 0, 0 };
parser_t *parser;
char *tokens[5];
# if ENABLE_FEATURE_MDEV_EXEC
char *command = NULL;
# endif
# if ENABLE_FEATURE_MDEV_RENAME
char *alias = NULL;
char aliaslink = aliaslink; /* for compiler */
# endif
#endif
char *dev_maj_min = path + strlen(path);
/* 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.
*/
major = -1;
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';
} else if (sscanf(dev_maj_min, "%u:%u", &major, &minor) != 2) {
major = -1;
}
}
/* 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.
* But since 2.6.25 block devices are also in /sys/class/block.
* We use strstr("/block/") to forestall future surprises. */
type = S_IFCHR;
if (strstr(path, "/block/"))
type = S_IFBLK;
#if ENABLE_FEATURE_MDEV_CONF
parser = config_open2("/etc/mdev.conf", fopen_for_read);
/* If we have config file, look up user settings */
while (config_read(parser, tokens, 4, 3, "# \t", PARSE_NORMAL)) {
regmatch_t off[1 + 9*ENABLE_FEATURE_MDEV_RENAME_REGEXP];
char *val;
/* Fields: regex uid:gid mode [alias] [cmd] */
/* 1st field: @<numeric maj,min>... */
if (tokens[0][0] == '@') {
/* @major,minor[-last] */
/* (useful when name is ambiguous:
* "/sys/class/usb/lp0" and
* "/sys/class/printer/lp0") */
int cmaj, cmin0, cmin1, sc;
if (major < 0)
continue; /* no dev, no match */
sc = sscanf(tokens[0], "@%u,%u-%u", &cmaj, &cmin0, &cmin1);
if (sc < 1 || major != cmaj
|| (sc == 2 && minor != cmin0)
|| (sc == 3 && (minor < cmin0 || minor > cmin1))
) {
continue; /* no match */
}
} else { /* ... or regex to match device name */
regex_t match;
int result;
/* Is this it? */
xregcomp(&match, tokens[0], REG_EXTENDED);
result = regexec(&match, device_name, ARRAY_SIZE(off), off, 0);
regfree(&match);
//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))
) {
continue;
}
}
/* This line matches: stop parsing the file
* after parsing the rest of fields */
/* 2nd field: uid:gid - device ownership */
parse_chown_usergroup_or_die(&ugid, tokens[1]);
/* 3rd field: mode - device permissions */
mode = strtoul(tokens[2], NULL, 8);
val = tokens[3];
/* 4th field (opt): >alias */
# if ENABLE_FEATURE_MDEV_RENAME
if (!val)
break;
aliaslink = *val;
if (aliaslink == '>' || aliaslink == '=') {
char *s, *st;
# if ENABLE_FEATURE_MDEV_RENAME_REGEXP
char *p;
unsigned i, n;
# endif
char *a = val;
s = strchrnul(val, ' ');
st = strchrnul(val, '\t');
if (st < s)
s = st;
val = (s[0] && s[1]) ? s+1 : NULL;
s[0] = '\0';
# if ENABLE_FEATURE_MDEV_RENAME_REGEXP
/* substitute %1..9 with off[1..9], if any */
n = 0;
s = a;
while (*s)
if (*s++ == '%')
n++;
p = alias = xzalloc(strlen(a) + n * strlen(device_name));
s = a + 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
alias = xstrdup(a + 1);
# endif
}
# endif /* ENABLE_FEATURE_MDEV_RENAME */
# if ENABLE_FEATURE_MDEV_EXEC
/* The rest (opt): command to run */
if (!val)
break;
{
const char *s = "@$*";
const char *s2 = strchr(s, *val);
if (!s2)
bb_error_msg_and_die("bad line %u", parser->lineno);
/* Correlate the position in the "@$*" 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);
}
}
# endif
/* end of field parsing */
break; /* we found matching line, stop */
} /* end of "while line is read from /etc/mdev.conf" */
config_close(parser);
#endif /* ENABLE_FEATURE_MDEV_CONF */
if (!delete && major >= 0) {
if (ENABLE_FEATURE_MDEV_RENAME)
unlink(device_name);
if (mknod(device_name, mode | type, makedev(major, minor)) && errno != EEXIST)
bb_perror_msg_and_die("mknod %s", device_name);
if (major == root_major && minor == root_minor)
symlink(device_name, "root");
#if ENABLE_FEATURE_MDEV_CONF
chown(device_name, ugid.uid, ugid.gid);
# if ENABLE_FEATURE_MDEV_RENAME
if (alias) {
alias = build_alias(alias, device_name);
/* move the device, and optionally
* make a symlink to moved device node */
if (rename(device_name, alias) == 0 && aliaslink == '>')
symlink(alias, device_name);
free(alias);
}
# endif
#endif
}
#if ENABLE_FEATURE_MDEV_EXEC
if (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);
unsetenv("MDEV");
free(s);
free(command);
}
#endif
if (delete) {
unlink(device_name);
/* At creation time, device might have been moved
* and a symlink might have been created. Undo that. */
#if ENABLE_FEATURE_MDEV_RENAME
if (alias) {
alias = build_alias(alias, device_name);
unlink(alias);
free(alias);
}
#endif
}
}
/* File callback for /sys/ traversal */
static int FAST_FUNC fileAction(const char *fileName,
struct stat *statbuf UNUSED_PARAM,
void *userData,
int depth UNUSED_PARAM)
{
size_t len = strlen(fileName) - 4; /* can't underflow */
char *scratch = userData;
/* len check is for paranoid reasons */
if (strcmp(fileName + len, "/dev") != 0 || len >= PATH_MAX)
return FALSE;
strcpy(scratch, fileName);
scratch[len] = '\0';
make_device(scratch, 0);
return TRUE;
}
/* Directory callback for /sys/ traversal */
static int FAST_FUNC dirAction(const char *fileName UNUSED_PARAM,
struct stat *statbuf UNUSED_PARAM,
void *userData UNUSED_PARAM,
int depth)
{
return (depth >= MAX_SYSFS_DEPTH ? SKIP : TRUE);
}
/* 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/$DEVPATH/loading
* - kernel loads firmware into device
*/
static void load_firmware(const char *const firmware, const char *const sysfs_path)
{
int cnt;
int firmware_fd, loading_fd, data_fd;
/* check for /lib/firmware/$FIRMWARE */
xchdir("/lib/firmware");
firmware_fd = xopen(firmware, O_RDONLY);
/* in case we goto out ... */
data_fd = -1;
/* check for /sys/$DEVPATH/loading ... give 30 seconds to appear */
xchdir(sysfs_path);
for (cnt = 0; cnt < 30; ++cnt) {
loading_fd = open("loading", O_WRONLY);
if (loading_fd != -1)
goto loading;
sleep(1);
}
goto out;
loading:
/* tell kernel we're loading by `echo 1 > /sys/$DEVPATH/loading` */
if (full_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)
full_write(loading_fd, "0", 1);
else
full_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 UNUSED_PARAM, char **argv)
{
RESERVE_CONFIG_BUFFER(temp, PATH_MAX + SCRATCH_SIZE);
/* We can be called as hotplug helper */
/* Kernel cannot provide suitable stdio fds for us, do it ourself */
#if 1
bb_sanitize_stdio();
#else
/* Debug code */
/* Replace LOGFILE by other file or device name if you need */
#define LOGFILE "/dev/console"
/* Just making sure fd 0 is not closed,
* we don't really intend to read from it */
xmove_fd(xopen("/", O_RDONLY), STDIN_FILENO);
xmove_fd(xopen(LOGFILE, O_WRONLY|O_APPEND), STDOUT_FILENO);
xmove_fd(xopen(LOGFILE, O_WRONLY|O_APPEND), STDERR_FILENO);
#endif
xchdir("/dev");
if (argv[1] && strcmp(argv[1], "-s") == 0) {
/* Scan:
* mdev -s
*/
struct stat st;
xstat("/", &st);
root_major = major(st.st_dev);
root_minor = minor(st.st_dev);
/* ACTION_FOLLOWLINKS is needed since in newer kernels
* /sys/block/loop* (for example) are symlinks to dirs,
* not real directories.
* (kernel's CONFIG_SYSFS_DEPRECATED makes them real dirs,
* but we can't enforce that on users)
*/
if (access("/sys/class/block", F_OK) != 0) {
/* Scan obsolete /sys/block only if /sys/class/block
* doesn't exist. Otherwise we'll have dupes.
* Also, do not complain if it doesn't exist.
* Some people configure kernel to have no blockdevs.
*/
recursive_action("/sys/block",
ACTION_RECURSE | ACTION_FOLLOWLINKS | ACTION_QUIET,
fileAction, dirAction, temp, 0);
}
recursive_action("/sys/class",
ACTION_RECURSE | ACTION_FOLLOWLINKS,
fileAction, dirAction, temp, 0);
} else {
char *fw;
char *seq;
char *action;
char *env_path;
/* Hotplug:
* env ACTION=... DEVPATH=... [SEQNUM=...] mdev
* ACTION can be "add" or "remove"
* DEVPATH is like "/block/sda" or "/class/input/mice"
*/
action = getenv("ACTION");
env_path = getenv("DEVPATH");
if (!action || !env_path)
bb_show_usage();
fw = getenv("FIRMWARE");
/* If it exists, does /dev/mdev.seq match $SEQNUM?
* If it does not match, earlier mdev is running
* in parallel, and we need to wait */
seq = getenv("SEQNUM");
if (seq) {
int timeout = 2000 / 32; /* 2000 msec */
do {
int seqlen;
char seqbuf[sizeof(int)*3 + 2];
seqlen = open_read_close("mdev.seq", seqbuf, sizeof(seqbuf-1));
if (seqlen < 0) {
seq = NULL;
break;
}
seqbuf[seqlen] = '\0';
if (seqbuf[0] == '\n' /* seed file? */
|| strcmp(seq, seqbuf) == 0 /* correct idx? */
) {
break;
}
usleep(32*1000);
} while (--timeout);
}
snprintf(temp, PATH_MAX, "/sys%s", env_path);
if (strcmp(action, "remove") == 0) {
/* Ignoring "remove firmware". It was reported
* to happen and to cause erroneous deletion
* of device nodes. */
if (!fw)
make_device(temp, 1);
}
else if (strcmp(action, "add") == 0) {
make_device(temp, 0);
if (ENABLE_FEATURE_MDEV_LOAD_FIRMWARE) {
if (fw)
load_firmware(fw, temp);
}
}
if (seq) {
xopen_xwrite_close("mdev.seq", utoa(xatou(seq) + 1));
}
}
if (ENABLE_FEATURE_CLEAN_UP)
RELEASE_CONFIG_BUFFER(temp);
return EXIT_SUCCESS;
}