Re: [PATCH v2] Introduce the 'usertemp' filesystem type

[Johannes Schindelin <Johannes.Schindelin@gmx.de>]

... and here is the interdiff vs v1 (compare also to the 'pseudo Pull
Request' at
https://github.com/dscho/msys2-runtime/compare/tempfs-cygwin-v1-rebased...tempfs-cygwin-v2):

diff --git a/winsup/cygwin/include/sys/mount.h
b/winsup/cygwin/include/sys/mount.h
index 458cf80..ec92794 100644
--- a/winsup/cygwin/include/sys/mount.h
+++ b/winsup/cygwin/include/sys/mount.h
@@ -44,7 +44,8 @@ enum
   MOUNT_DOS =		0x40000,	/* convert leading spaces and trailing
 					   dots and spaces to private use area */
   MOUNT_IHASH =		0x80000,	/* Enforce hash values for inode numbers */
-  MOUNT_BIND =		0x100000	/* Allows bind syntax in fstab file. */
+  MOUNT_BIND =		0x100000,	/* Allows bind syntax in fstab file. */
+  MOUNT_USER_TEMP =	0x200000	/* Mount the user's $TMP. */
 };
 
 int mount (const char *, const char *, unsigned __flags);
diff --git a/winsup/cygwin/mount.cc b/winsup/cygwin/mount.cc
index be5de61..fc080c9 100644
--- a/winsup/cygwin/mount.cc
+++ b/winsup/cygwin/mount.cc
@@ -1200,14 +1200,15 @@ mount_info::from_fstab_line (char *line, bool user)
     }
   else if (!strcmp (fs_type, "usertemp"))
     {
-      WCHAR tmp[MAX_PATH];
+      WCHAR tmp[PATH_MAX + 1];
 
-      if (GetEnvironmentVariableW (L"TEMP", tmp, sizeof(tmp)) && *tmp)
+      if (GetTempPathW (PATH_MAX, tmp))
 	{
-          DWORD len;
-          char mb_tmp[len = sys_wcstombs (NULL, 0, tmp)];
-          sys_wcstombs (mb_tmp, len, tmp);
+	  tmp_pathbuf tp;
+	  char *mb_tmp = tp.c_get ();
+	  sys_wcstombs (mb_tmp, PATH_MAX, tmp);
 
+	  mount_flags |= MOUNT_USER_TEMP;
 	  int res = mount_table->add_item (mb_tmp, posix_path, mount_flags);
 	  if (res && get_errno () == EMFILE)
 	    return false;
@@ -1670,6 +1671,9 @@ fillout_mntent (const char *native_path, const char *posix_path, unsigned flags)
   if (flags & (MOUNT_BIND))
     strcat (_my_tls.locals.mnt_opts, (char *) ",bind");
 
+  if (flags & (MOUNT_USER_TEMP))
+    strcat (_my_tls.locals.mnt_opts, (char *) ",usertemp");
+
   ret.mnt_opts = _my_tls.locals.mnt_opts;
 
   ret.mnt_freq = 1;