Rewrite shm buffer file allocation v2

We had duplicated code in many places, using hardcoded paths for
temporary files into more than one path. Some cases did not bother with
O_CLOEXEC, and all hardcoded paths that might not exist.

Add an OS helper function for creating a unique anonymous file with
close-on-exec semantics. The helper uses $XDG_RUNTIME_DIR as the
directory for a file.

This patch unifies the buffer file creation in both Weston and the
clients.

As simple clients are better not linking to libshared, as it would
require e.g. Cairo, they pull the OS compatibility code directly.

Android does not have mkostemp(), so a configure test is added for it,
and a fallback used if it is not available.

Changes in v2:
	remove all the alternate possible directory definitions and use
	XDG_RUNTIME_DIR only, and fail is it is not set.

Signed-off-by: Pekka Paalanen <ppaalanen@gmail.com>

clients/Makefile.am

@@ -27,11 +27,15 @@ simple_egl_SOURCES = simple-egl.c
 simple_egl_CPPFLAGS = $(SIMPLE_CLIENT_CFLAGS)
 simple_egl_LDADD = $(SIMPLE_CLIENT_LIBS) -lm
 
-simple_shm_SOURCES = simple-shm.c
+simple_shm_SOURCES = simple-shm.c 		\
+	../shared/os-compatibility.c		\
+	../shared/os-compatibility.h
 simple_shm_CPPFLAGS = $(SIMPLE_CLIENT_CFLAGS)
 simple_shm_LDADD = $(SIMPLE_CLIENT_LIBS)
 
-simple_touch_SOURCES = simple-touch.c
+simple_touch_SOURCES = simple-touch.c		\
+	../shared/os-compatibility.c		\
+	../shared/os-compatibility.h
 simple_touch_CPPFLAGS = $(SIMPLE_CLIENT_CFLAGS)
 simple_touch_LDADD = $(SIMPLE_CLIENT_LIBS)
 endif

clients/screenshot.c

@@ -33,6 +33,7 @@
 
 #include <wayland-client.h>
 #include "screenshooter-client-protocol.h"
+#include "../shared/os-compatibility.h"
 
 /* The screenshooter is a good example of a custom object exposed by
  * the compositor and serves as a test bed for implementing client
@@ -127,28 +128,22 @@ handle_global(struct wl_display *display, uint32_t id,
 static struct wl_buffer *
 create_shm_buffer(int width, int height, void **data_out)
 {
-	char filename[] = "/tmp/wayland-shm-XXXXXX";
 	struct wl_shm_pool *pool;
 	struct wl_buffer *buffer;
 	int fd, size, stride;
 	void *data;
 
-	fd = mkstemp(filename);
-	if (fd < 0) {
-		fprintf(stderr, "open %s failed: %m\n", filename);
-		return NULL;
-	}
 	stride = width * 4;
 	size = stride * height;
-	if (ftruncate(fd, size) < 0) {
-		fprintf(stderr, "ftruncate failed: %m\n");
-		close(fd);
+
+	fd = os_create_anonymous_file(size);
+	if (fd < 0) {
+		fprintf(stderr, "creating a buffer file for %d B failed: %m\n",
+			size);
 		return NULL;
 	}
 
 	data = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
-	unlink(filename);
-
 	if (data == MAP_FAILED) {
 		fprintf(stderr, "mmap failed: %m\n");
 		close(fd);

clients/simple-shm.c

@@ -31,6 +31,7 @@
 #include <signal.h>
 
 #include <wayland-client.h>
+#include "../shared/os-compatibility.h"
 
 struct display {
 	struct wl_display *display;
@@ -55,28 +56,22 @@ static struct wl_buffer *
 create_shm_buffer(struct display *display,
 		  int width, int height, uint32_t format, void **data_out)
 {
-	char filename[] = "/tmp/wayland-shm-XXXXXX";
 	struct wl_shm_pool *pool;
 	struct wl_buffer *buffer;
 	int fd, size, stride;
 	void *data;
 
-	fd = mkstemp(filename);
-	if (fd < 0) {
-		fprintf(stderr, "open %s failed: %m\n", filename);
-		return NULL;
-	}
 	stride = width * 4;
 	size = stride * height;
-	if (ftruncate(fd, size) < 0) {
-		fprintf(stderr, "ftruncate failed: %m\n");
-		close(fd);
+
+	fd = os_create_anonymous_file(size);
+	if (fd < 0) {
+		fprintf(stderr, "creating a buffer file for %d B failed: %m\n",
+			size);
 		return NULL;
 	}
 
 	data = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
-	unlink(filename);
-
 	if (data == MAP_FAILED) {
 		fprintf(stderr, "mmap failed: %m\n");
 		close(fd);

clients/simple-touch.c

@@ -32,6 +32,7 @@
 #include <GLES2/gl2.h>
 #include <wayland-client.h>
 #include <wayland-egl.h>
+#include "../shared/os-compatibility.h"
 
 struct touch {
 	struct wl_display *display;
@@ -55,26 +56,20 @@ static void
 create_shm_buffer(struct touch *touch)
 {
 	struct wl_shm_pool *pool;
-	char filename[] = "/tmp/wayland-shm-XXXXXX";
 	int fd, size, stride;
 
-	fd = mkstemp(filename);
-	if (fd < 0) {
-		fprintf(stderr, "open %s failed: %m\n", filename);
-		exit(1);
-	}
 	stride = touch->width * 4;
 	size = stride * touch->height;
-	if (ftruncate(fd, size) < 0) {
-		fprintf(stderr, "ftruncate failed: %m\n");
-		close(fd);
+
+	fd = os_create_anonymous_file(size);
+	if (fd < 0) {
+		fprintf(stderr, "creating a buffer file for %d B failed: %m\n",
+			size);
 		exit(1);
 	}
 
 	touch->data =
 		mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
-	unlink(filename);
-
 	if (touch->data == MAP_FAILED) {
 		fprintf(stderr, "mmap failed: %m\n");
 		close(fd);

clients/window.c

@@ -424,24 +424,17 @@ shm_surface_data_destroy(void *p)
 static struct wl_shm_pool *
 make_shm_pool(struct display *display, int size, void **data)
 {
-	char filename[] = "/tmp/wayland-shm-XXXXXX";
 	struct wl_shm_pool *pool;
 	int fd;
 
-	fd = mkstemp(filename);
+	fd = os_create_anonymous_file(size);
 	if (fd < 0) {
-		fprintf(stderr, "open %s failed: %m\n", filename);
-		return NULL;
-	}
-	if (ftruncate(fd, size) < 0) {
-		fprintf(stderr, "ftruncate failed: %m\n");
-		close(fd);
+		fprintf(stderr, "creating a buffer file for %d B failed: %m\n",
+			size);
 		return NULL;
 	}
 
 	*data = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
-	unlink(filename);
-
 	if (*data == MAP_FAILED) {
 		fprintf(stderr, "mmap failed: %m\n");
 		close(fd);