Introduce the 'usertemp' filesystem type

	* mount.cc (mount_info::from_fstab_line): Support mounting the current
	user's temp folder as /tmp/.  This is particularly useful a feature
	when Cygwin's own files are write-protected.

	* pathnames.xml: document the new usertemp file system type

Detailed explanation:

In the context of Windows, there is a per-user directory for temporary
files, by default specified via the environment variable %TEMP%. Let's
allow to use that directory for our /tmp/ directory.

With this patch, we introduce the special filesystem type "usertemp":
By specifying

	none /tmp usertemp binary,posix=0 0 0

in /etc/fstab, the /tmp/ directory gets auto-mounted to the directory
specified by the %TEMP% variable.

This feature comes handy in particularly in scenarios where the
administrator might want to write-protect the entire Cygwin directory
yet still needs to allow users to write into the /tmp/ directory.
This is the case in the context of Git for Windows, where the
Cygwin (MSys2) root directory lives inside C:\Program Files and hence
/tmp/ would not be writable otherwise.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

1 files changed, 2 insertions, 1 deletions

diff --git a/winsup/cygwin/include/sys/mount.h b/winsup/cygwin/include/sys/mount.h
index 458cf801f..ec927945b 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);