Use /var/tmp for the cached appliance (for FHS compliance).

The FHS advises large files not to be stored in the root
filesystem[1], and that /var/tmp is persistent across reboots[2]
(whereas /tmp is possibly not[3]).

Therefore we should store the large cached supermin appliance in
/var/tmp instead of /tmp.  /tmp is still used for all other temporary
files and directories.

In either case you can override this by setting $TMPDIR.

[1] http://www.pathname.com/fhs/pub/fhs-2.3.html#THEROOTFILESYSTEM
[2] http://www.pathname.com/fhs/pub/fhs-2.3.html#VARTMPTEMPORARYFILESPRESERVEDBETWEE
[3] http://www.pathname.com/fhs/pub/fhs-2.3.html#TMPTEMPORARYFILES

1 files changed, 18 insertions, 0 deletions

diff --git a/src/launch.c b/src/launch.c
index e009aae1..a7a86b97 100644
--- a/src/launch.c
+++ b/src/launch.c
@@ -770,6 +770,7 @@ guestfs__launch (guestfs_h *g)
 
 /* Return the location of the tmpdir (eg. "/tmp") and allow users
  * to override it at runtime using $TMPDIR.
+ * http://www.pathname.com/fhs/pub/fhs-2.3.html#TMPTEMPORARYFILES
  */
 const char *
 guestfs_tmpdir (void)
@@ -788,6 +789,23 @@ guestfs_tmpdir (void)
   return tmpdir;
 }
 
+/* Return the location of the persistent tmpdir (eg. "/var/tmp") and
+ * allow users to override it at runtime using $TMPDIR.
+ * http://www.pathname.com/fhs/pub/fhs-2.3.html#VARTMPTEMPORARYFILESPRESERVEDBETWEE
+ */
+const char *
+guestfs___persistent_tmpdir (void)
+{
+  const char *tmpdir;
+
+  tmpdir = "/var/tmp";
+
+  const char *t = getenv ("TMPDIR");
+  if (t) tmpdir = t;
+
+  return tmpdir;
+}
+
 /* Compute Y - X and return the result in milliseconds.
  * Approximately the same as this code:
  * http://www.mpp.mpg.de/~huber/util/timevaldiff.c