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298 lines
8.7 KiB
298 lines
8.7 KiB
/* mdev.c - Populate /dev directory and handle hotplug events
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*
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* Copyright 2005, 2008 Rob Landley <rob@landley.net>
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* Copyright 2005 Frank Sorenson <frank@tuxrocks.com>
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USE_MDEV(NEWTOY(mdev, "s", TOYFLAG_USR|TOYFLAG_BIN|TOYFLAG_UMASK))
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config MDEV
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bool "mdev"
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default n
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help
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usage: mdev [-s]
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Create devices in /dev using information from /sys.
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-s Scan all entries in /sys to populate /dev
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config MDEV_CONF
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bool "Configuration file for mdev"
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default y
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depends on MDEV
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help
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The mdev config file (/etc/mdev.conf) contains lines that look like:
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hd[a-z][0-9]* 0:3 660
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(sd[a-z]) root:disk 660 =usb_storage
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Each line must contain three whitespace separated fields. The first
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field is a regular expression matching one or more device names,
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the second and third fields are uid:gid and file permissions for
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matching devices. Fourth field is optional. It could be used to change
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device name (prefix '='), path (prefix '=' and postfix '/') or create a
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symlink (prefix '>').
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*/
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#include "toys.h"
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#include <stdbool.h>
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// mknod in /dev based on a path like "/sys/block/hda/hda1"
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static void make_device(char *path)
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{
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char *device_name = 0, *custom_name = 0, *s, *temp;
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bool create_symlink = false;
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int major = 0, minor = 0, type, len, fd, mode = 0660;
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uid_t uid = 0;
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gid_t gid = 0;
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if (path) {
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// Try to read major/minor string, returning if we can't
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temp = strrchr(path, '/');
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fd = open(path, O_RDONLY);
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*temp = 0;
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len = read(fd, toybuf, 64);
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close(fd);
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if (len<1) return;
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toybuf[len] = 0;
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// Determine device type, major and minor
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type = path[5]=='c' ? S_IFCHR : S_IFBLK;
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sscanf(toybuf, "%u:%u", &major, &minor);
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} else {
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// if (!path), do hotplug
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if (!(temp = getenv("MODALIAS"))) xrun((char *[]){"modprobe", temp, 0});
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if (!(temp = getenv("SUBSYSTEM"))) return;
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type = strcmp(temp, "block") ? S_IFCHR : S_IFBLK;
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if (!(temp = getenv("MAJOR"))) return;
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sscanf(temp, "%u", &major);
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if (!(temp = getenv("MINOR"))) return;
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sscanf(temp, "%u", &minor);
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if (!(path = getenv("DEVPATH"))) return;
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device_name = getenv("DEVNAME");
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}
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if (!device_name)
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device_name = strrchr(path, '/') + 1;
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// as in linux/drivers/base/core.c, device_get_devnode()
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while ((temp = strchr(device_name, '!'))) {
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*temp = '/';
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}
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// If we have a config file, look up permissions for this device
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if (CFG_MDEV_CONF) {
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char *conf, *pos, *end;
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bool optional_field_valid = false;
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// mmap the config file
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if (-1!=(fd = open("/etc/mdev.conf", O_RDONLY))) {
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int line = 0;
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len = fdlength(fd);
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conf = xmmap(NULL, len, PROT_READ, MAP_PRIVATE, fd, 0);
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// Loop through lines in mmaped file
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for (pos = conf; pos-conf<len;) {
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int field;
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char *end2;
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line++;
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// find end of this line
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for(end = pos; end-conf<len && *end!='\n'; end++);
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// Four fields (last is optional): regex, uid:gid, mode [, name|path ]
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// For example: (sd[a-z])1 root:disk 660 =usb_storage_p1
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for (field = 4; field; field--) {
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// Skip whitespace
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while (pos<end && isspace(*pos)) pos++;
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if (pos==end || *pos=='#') break;
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for (end2 = pos;
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end2<end && !isspace(*end2) && *end2!='#'; end2++);
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switch(field) {
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// Regex to match this device
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case 4:
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{
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char *regex = strndup(pos, end2-pos);
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regex_t match;
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regmatch_t off;
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int result;
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// Is this it?
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xregcomp(&match, regex, REG_EXTENDED);
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result=regexec(&match, device_name, 1, &off, 0);
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regfree(&match);
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free(regex);
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// If not this device, skip rest of line
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if (result || off.rm_so
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|| off.rm_eo!=strlen(device_name))
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goto end_line;
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break;
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}
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// uid:gid
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case 3:
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{
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char *s2;
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// Find :
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for(s = pos; s<end2 && *s!=':'; s++);
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if (s==end2) goto end_line;
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// Parse UID
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uid = strtoul(pos,&s2,10);
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if (s!=s2) {
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struct passwd *pass;
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char *str = strndup(pos, s-pos);
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pass = getpwnam(str);
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free(str);
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if (!pass) goto end_line;
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uid = pass->pw_uid;
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}
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s++;
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// parse GID
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gid = strtoul(s,&s2,10);
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if (end2!=s2) {
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struct group *grp;
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char *str = strndup(s, end2-s);
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grp = getgrnam(str);
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free(str);
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if (!grp) goto end_line;
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gid = grp->gr_gid;
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}
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break;
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}
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// mode
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case 2:
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{
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char *beg_pos = pos;
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mode = strtoul(pos, &pos, 8);
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if (pos == beg_pos) {
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// The line is bad because mode setting could not be
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// converted to numeric value.
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goto end_line;
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}
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break;
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}
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// Try to look for name or path (optional field)
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case 1:
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{
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if(pos < end2){
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//char *name = strndup(pos, end2-pos);
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char *name = malloc(end2-pos+1);
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if(name){
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strncpy(name, pos, end2-pos+1);
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name[end2-pos] = '\0';
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switch(name[0]){
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case '>':
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create_symlink = true;
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case '=':
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custom_name = strdup(&name[1]);
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break;
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case '!':
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device_name = NULL;
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break;
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default:
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free(name);
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goto end_line;
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}
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free(name);
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optional_field_valid = true;
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}
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}
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goto found_device;
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}
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}
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pos=end2;
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}
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end_line:
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// Did everything parse happily?
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// Note: Last field is optional.
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if ((field>1 || (field==1 && !optional_field_valid)) && field!=4)
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error_exit("Bad line %d", line);
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// Next line
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pos = ++end;
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}
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found_device:
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munmap(conf, len);
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}
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close(fd);
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}
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if(device_name) {
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if(custom_name) {
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sprintf(toybuf, "/dev/%s", custom_name);
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if(custom_name[strlen(custom_name) - 1] == '/') {
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DIR *dir;
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dir = opendir(toybuf);
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if(dir) closedir(dir);
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else mkdir(toybuf, 0755);
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}
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}
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else
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sprintf(toybuf, "/dev/%s", device_name);
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if ((temp=getenv("ACTION")) && !strcmp(temp, "remove")) {
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unlink(toybuf);
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return;
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}
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if (strchr(device_name, '/')) mkpath(toybuf);
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if (mknod(toybuf, mode | type, dev_makedev(major, minor)) &&
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errno != EEXIST)
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perror_exit("mknod %s failed", toybuf);
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if(create_symlink){
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char *symlink_name = malloc(sizeof("/dev/") + strlen(device_name) + 1);
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if(symlink_name == NULL)
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perror_exit("malloc failed while creating symlink to %s", toybuf);
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sprintf(symlink_name, "/dev/%s", device_name);
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if(symlink(toybuf, symlink_name)){
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free(symlink_name);
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perror_exit("symlink creation failed for %s", toybuf);
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}
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free(symlink_name);
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}
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if (type == S_IFBLK) close(open(toybuf, O_RDONLY)); // scan for partitions
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if (CFG_MDEV_CONF) mode=chown(toybuf, uid, gid);
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}
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}
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static int callback(struct dirtree *node)
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{
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// Entries in /sys/class/block aren't char devices, so skip 'em. (We'll
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// get block devices out of /sys/block.)
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if(!strcmp(node->name, "block")) return 0;
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// Does this directory have a "dev" entry in it?
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// This is path based because the hotplug callbacks are
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if (S_ISDIR(node->st.st_mode) || S_ISLNK(node->st.st_mode)) {
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int len=4;
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char *dev = dirtree_path(node, &len);
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strcpy(dev+len, "/dev");
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if (!access(dev, R_OK)) make_device(dev);
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free(dev);
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}
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// Circa 2.6.25 the entries more than 2 deep are all either redundant
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// (mouse#, event#) or unnamed (every usb_* entry is called "device").
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if (node->parent && node->parent->parent) return 0;
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return DIRTREE_RECURSE|DIRTREE_SYMFOLLOW;
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}
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void mdev_main(void)
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{
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// Handle -s
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if (toys.optflags) {
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dirtree_read("/sys/class", callback);
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if (!access("/sys/block", R_OK)) dirtree_read("/sys/block", callback);
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} else { // hotplug support
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make_device(NULL);
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}
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}
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