From ce4188fd1228c8037d1f059cf24a066941c26501 Mon Sep 17 00:00:00 2001
From: Isaac Dunham <ibid.ag@gmail.com>
Date: Sat, 1 Aug 2015 11:09:51 -0500
Subject: [PATCH] '!' replaces '/' in the sysfs paths of older drivers, so
 properly reverse that to get correct paths. While we're here, reduce the
 duplication of initialization.

While this is enough for some drivers, it won't get 'input/' stuff
in the right folder.
---
 toys/pending/mdev.c | 33 +++++++++++++++++----------------
 1 file changed, 17 insertions(+), 16 deletions(-)

diff --git a/toys/pending/mdev.c b/toys/pending/mdev.c
index 0c49633..a13a53d 100644
--- a/toys/pending/mdev.c
+++ b/toys/pending/mdev.c
@@ -35,7 +35,7 @@ config MDEV_CONF
 static void make_device(char *path)
 {
   char *device_name = NULL, *s, *temp;
-  int major, minor, type, len, fd;
+  int major = 0, minor = 0, type, len, fd;
   int mode = 0660;
   uid_t uid = 0;
   gid_t gid = 0;
@@ -46,24 +46,21 @@ static void make_device(char *path)
     temp = strrchr(path, '/');
     fd = open(path, O_RDONLY);
     *temp=0;
-    temp = toybuf;
-    len = read(fd, temp, 64);
+    len = read(fd, toybuf, 64);
     close(fd);
     if (len<1) return;
-    temp[len] = 0;
+    toybuf[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);
+    sscanf(toybuf, "%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);
@@ -74,11 +71,15 @@ static void make_device(char *path)
     device_name = getenv("DEVNAME");
     if (!path)
       return;
-    temp = toybuf;
   }
   if (!device_name)
     device_name = strrchr(path, '/') + 1;
 
+  // as in linux/drivers/base/core.c, device_get_devnode()
+  while ((temp = strchr(device_name, '!'))) {
+    *temp = '/';
+  }
+
   // If we have a config file, look up permissions for this device
 
   if (CFG_MDEV_CONF) {
@@ -185,22 +186,22 @@ found_device:
     }
   }
 
-  sprintf(temp, "/dev/%s", device_name);
+  sprintf(toybuf, "/dev/%s", device_name);
 
-  if (getenv("ACTION") && !strcmp(getenv("ACTION"), "remove")) {
-    unlink(temp);
+  if ((temp=getenv("ACTION")) && !strcmp(temp, "remove")) {
+    unlink(toybuf);
     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);
+    mkpathat(AT_FDCWD, toybuf, 0, 2);
+  if (mknod(toybuf, mode | type, makedev(major, minor)) && errno != EEXIST)
+    perror_exit("mknod %s failed", toybuf);
 
  
-  if (type == S_IFBLK) close(open(temp, O_RDONLY)); // scan for partitions
+  if (type == S_IFBLK) close(open(toybuf, O_RDONLY)); // scan for partitions
 
-  if (CFG_MDEV_CONF) mode=chown(temp, uid, gid);
+  if (CFG_MDEV_CONF) mode=chown(toybuf, uid, gid);
 }
 
 static int callback(struct dirtree *node)
-- 
2.7.4