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/* mdev.c - Populate /dev directory and handle hotplug events
*
* Copyright 2005, 2008 Rob Landley <rob@landley.net>
* Copyright 2005 Frank Sorenson <frank@tuxrocks.com>
USE_MDEV(NEWTOY(mdev, "s", TOYFLAG_USR|TOYFLAG_BIN|TOYFLAG_UMASK))
config MDEV
bool "mdev"
default n
help
usage: mdev [-s]
Create devices in /dev using information from /sys.
-s Scan all entries in /sys to populate /dev.
config MDEV_CONF
bool "Configuration file for mdev"
default y
depends on MDEV
help
The mdev config file (/etc/mdev.conf) contains lines that look like:
hd[a-z][0-9]* 0:3 660
Each line must contain three whitespace separated fields. The first
field is a regular expression matching one or more device names, and
the second and third fields are uid:gid and file permissions for
matching devies.
*/
#include "toys.h"
// mknod in /dev based on a path like "/sys/block/hda/hda1"
static void make_device(char *path)
{
char *device_name = NULL, *s, *temp;
int major, minor, type, len, fd;
int mode = 0660;
uid_t uid = 0;
gid_t gid = 0;
if (path) {
// Try to read major/minor string
temp = strrchr(path, '/');
fd = open(path, O_RDONLY);
*temp=0;
temp = toybuf;
len = read(fd, temp, 64);
close(fd);
if (len<1) return;
temp[len] = 0;
// Determine device type, major and minor
type = path[5]=='c' ? S_IFCHR : S_IFBLK;
major = minor = 0;
sscanf(temp, "%u:%u", &major, &minor);
} else {
// if (!path), do hotplug
if (!(temp = getenv("SUBSYSTEM")))
return;
type = strcmp(temp, "block") ? S_IFCHR : S_IFBLK;
major = minor = 0;
if (!(temp = getenv("MAJOR")))
return;
sscanf(temp, "%u", &major);
if (!(temp = getenv("MINOR")))
return;
sscanf(temp, "%u", &minor);
path = getenv("DEVPATH");
device_name = getenv("DEVNAME");
if (!path)
return;
temp = toybuf;
}
if (!device_name)
device_name = strrchr(path, '/') + 1;
// If we have a config file, look up permissions for this device
if (CFG_MDEV_CONF) {
char *conf, *pos, *end;
// mmap the config file
if (-1!=(fd = open("/etc/mdev.conf", O_RDONLY))) {
len = fdlength(fd);
conf = mmap(NULL, len, PROT_READ, MAP_PRIVATE, fd, 0);
if (conf) {
int line = 0;
// Loop through lines in mmaped file
for (pos = conf; pos-conf<len;) {
int field;
char *end2;
line++;
// find end of this line
for(end = pos; end-conf<len && *end!='\n'; end++);
// Three fields: regex, uid:gid, mode
for (field = 3; field; field--) {
// Skip whitespace
while (pos<end && isspace(*pos)) pos++;
if (pos==end || *pos=='#') break;
for (end2 = pos;
end2<end && !isspace(*end2) && *end2!='#'; end2++);
switch(field) {
// Regex to match this device
case 3:
{
char *regex = strndup(pos, end2-pos);
regex_t match;
regmatch_t off;
int result;
// Is this it?
xregcomp(&match, regex, REG_EXTENDED);
result=regexec(&match, device_name, 1, &off, 0);
regfree(&match);
free(regex);
// If not this device, skip rest of line
if (result || off.rm_so
|| off.rm_eo!=strlen(device_name))
goto end_line;
break;
}
// uid:gid
case 2:
{
char *s2;
// Find :
for(s = pos; s<end2 && *s!=':'; s++);
if (s==end2) goto end_line;
// Parse UID
uid = strtoul(pos,&s2,10);
if (s!=s2) {
struct passwd *pass;
char *str = strndup(pos, s-pos);
pass = getpwnam(str);
free(str);
if (!pass) goto end_line;
uid = pass->pw_uid;
}
s++;
// parse GID
gid = strtoul(s,&s2,10);
if (end2!=s2) {
struct group *grp;
char *str = strndup(s, end2-s);
grp = getgrnam(str);
free(str);
if (!grp) goto end_line;
gid = grp->gr_gid;
}
break;
}
// mode
case 1:
{
mode = strtoul(pos, &pos, 8);
if (pos!=end2) goto end_line;
goto found_device;
}
}
pos=end2;
}
end_line:
// Did everything parse happily?
if (field && field!=3) error_exit("Bad line %d", line);
// Next line
pos = ++end;
}
found_device:
munmap(conf, len);
}
close(fd);
}
}
sprintf(temp, "/dev/%s", device_name);
if (getenv("ACTION") && !strcmp(getenv("ACTION"), "remove")) {
unlink(temp);
return;
}
if (strchr(device_name, '/'))
mkpathat(AT_FDCWD, temp, 0, 2);
if (mknod(temp, mode | type, makedev(major, minor)) && errno != EEXIST)
perror_exit("mknod %s failed", temp);
if (type == S_IFBLK) close(open(temp, O_RDONLY)); // scan for partitions
if (CFG_MDEV_CONF) mode=chown(temp, uid, gid);
}
static int callback(struct dirtree *node)
{
// Entries in /sys/class/block aren't char devices, so skip 'em. (We'll
// get block devices out of /sys/block.)
if(!strcmp(node->name, "block")) return 0;
// Does this directory have a "dev" entry in it?
// This is path based because the hotplug callbacks are
if (S_ISDIR(node->st.st_mode) || S_ISLNK(node->st.st_mode)) {
int len=4;
char *dev = dirtree_path(node, &len);
strcpy(dev+len, "/dev");
if (!access(dev, R_OK)) make_device(dev);
free(dev);
}
// Circa 2.6.25 the entries more than 2 deep are all either redundant
// (mouse#, event#) or unnamed (every usb_* entry is called "device").
return (node->parent && node->parent->parent) ? 0 : DIRTREE_RECURSE;
}
void mdev_main(void)
{
// Handle -s
if (toys.optflags) {
dirtree_read("/sys/class", callback);
dirtree_read("/sys/block", callback);
} else { // hotplug support
make_device(NULL);
}
}
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