From 06802e41107d7125f12168b32fcbb045782d4c13 Mon Sep 17 00:00:00 2001
From: John Cupitt <jcupitt@gmail.com>
Date: Mon, 9 Apr 2018 13:27:57 +0100
Subject: [PATCH] use O_TMPFILE, if available

If O_TNMPFILE is available, use it. This is a linux extension that
creates an unlinked file, so it'll be closed by the system when the last
associated fd is closed.

see https://github.com/jcupitt/libvips/pull/930
---
 ChangeLog              |  1 +
 libvips/iofuncs/vips.c | 38 ++++++++++++++++++++++++++++++++------
 2 files changed, 33 insertions(+), 6 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index c1d3066f..e81501d0 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -12,6 +12,7 @@
 - drop incompatible ICC profiles before save
 - better hasalpha rules
 - create funcs always make MULTIBAND (ie. no alpha)
+- use O_TMPFILE, if available [Alexander--]
 
 12/3/18 started 8.6.4
 - better fitting of fonts with overhanging edges, thanks Adrià 
diff --git a/libvips/iofuncs/vips.c b/libvips/iofuncs/vips.c
index 49e6614f..2a537e43 100644
--- a/libvips/iofuncs/vips.c
+++ b/libvips/iofuncs/vips.c
@@ -21,6 +21,8 @@
  * 	- use expat for xml read, printf for xml write
  * 16/8/17
  * 	- validate strs as being utf-8 before we write
+ * 9/4/18 Alexander--
+ * 	- use O_TMPFILE, if available
  */
 
 /*
@@ -55,6 +57,10 @@
 #define DEBUG
  */
 
+/* Enable linux extensions like O_TMPFILE, if available.
+ */
+#define _GNU_SOURCE
+
 #ifdef HAVE_CONFIG_H
 #include <config.h>
 #endif /*HAVE_CONFIG_H*/
@@ -69,12 +75,12 @@
 #include <assert.h>
 #include <stdlib.h>
 #include <string.h>
-#include <fcntl.h>
 #include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
 #ifdef HAVE_SYS_FILE_H
 #include <sys/file.h>
 #endif /*HAVE_SYS_FILE_H*/
-#include <sys/stat.h>
 #ifdef HAVE_UNISTD_H
 #include <unistd.h>
 #endif /*HAVE_UNISTD_H*/
@@ -181,8 +187,26 @@ vips__open_image_write( const char *filename, gboolean temp )
 
 	flags = MODE_WRITE;
 
+#ifdef O_TMPFILE
+	/* Linux-only extension creates an unlinked file. CREAT and TRUNC must
+	 * be clear. The filename arg to open() must name a directory.
+	 */
+	if( temp ) {
+		char *dirname;
+
+		flags |= O_TMPFILE;
+		flags &= ~O_CREAT;
+		flags &= ~O_TRUNC;
+
+		dirname = g_path_get_dirname( filename ); 
+		fd = vips_tracked_open( dirname, flags, 0666 );
+		g_free( dirname ); 
+	}
+	else
+		fd = vips_tracked_open( filename, flags, 0666 );
+#else /*!O_TMPFILE*/
 #ifdef _O_TEMPORARY
-	/* On Windows, setting O_TEMP gets the file automatically
+	/* On Windows, setting _O_TEMPORARY gets the file automatically
 	 * deleted on process exit, even if the processes crashes. See
 	 * vips_image_rewind() for what we do to help on *nix.
 	 */
@@ -190,10 +214,12 @@ vips__open_image_write( const char *filename, gboolean temp )
 		flags |= _O_TEMPORARY;
 #endif /*_O_TEMPORARY*/
 
-	if( (fd = vips_tracked_open( filename, flags, 0666 )) < 0 ) {
+	fd = vips_tracked_open( filename, flags, 0666 );
+#endif /*O_TMPFILE*/
+
+	if( fd < 0 ) {
 		vips_error_system( errno, "VipsImage", 
-			_( "unable to write to \"%s\"" ), 
-			filename );
+			_( "unable to write to \"%s\"" ), filename );
 		return( -1 );
 	}