client/screenshooter: Client for taking screenshots

The client allows to take screenshots of all outputs, a specific output
(making use of xdg_output_manager interface) or just listing outputs.

Bug-AGL: SPEC-3580

Signed-off-by: Marius Vlad <marius.vlad@collabora.com>
Change-Id: Idd60d4892adf4c2ea493477421b6e5623e0ca1f0

7 files changed, 971 insertions, 0 deletions

diff --git a/clients/meson.build b/clients/meson.build
new file mode 100644
index 0000000..08b2c08
--- /dev/null
+++ b/clients/meson.build
@@ -0,0 +1,40 @@
+dep_wayland_client = dependency('wayland-client', version: '>= 1.17.0')
+
+clients = [
+{
+	'basename': 'agl-screenshooter',
+	'sources': [
+	  'screenshooter.c',
+	  '../shared/file-util.c',
+	  '../shared/os-compatibility.c',
+	  '../shared/xalloc.c',
+	  agl_screenshooter_client_protocol_h,
+	  agl_screenshooter_protocol_c,
+	  xdg_output_unstable_v1_client_protocol_h,
+	  xdg_output_unstable_v1_protocol_c,
+	],
+	'deps_objs' : [ dep_wayland_client ],
+	'deps': [ 'cairo' ],
+},
+]
+
+foreach t: clients
+  t_name = t.get('basename')
+  t_deps = t.get('deps_objs', [])
+
+  foreach xdep: t.get('deps', [])
+    dep = dependency(xdep, required: false)
+    if dep.found()
+      t_deps += dep
+    endif
+  endforeach
+
+  executable(
+      t_name, t.get('sources'),
+      include_directories: [ common_inc ],
+      dependencies: [ t_deps, libweston_dep ],
+      install: true,
+  )
+
+  message('Building client ' + t_name)
+endforeach
diff --git a/clients/screenshooter.c b/clients/screenshooter.c
new file mode 100644
index 0000000..faced55
--- /dev/null
+++ b/clients/screenshooter.c
@@ -0,0 +1,657 @@
+/*
+ * Copyright © 2020 Collabora, Ltd.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the
+ * next paragraph) shall be included in all copies or substantial
+ * portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#include <stdint.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <limits.h>
+#include <sys/param.h>
+#include <sys/mman.h>
+#include <getopt.h>
+#include <cairo.h>
+
+#include <wayland-client.h>
+#include "shared/helpers.h"
+#include "shared/xalloc.h"
+#include "shared/file-util.h"
+#include "shared/os-compatibility.h"
+#include "agl-screenshooter-client-protocol.h"
+#include "xdg-output-unstable-v1-client-protocol.h"
+
+struct screenshooter_data;
+
+struct screenshooter_output {
+	struct wl_output *output;
+	struct wl_buffer *buffer;
+
+	int width, height, offset_x, offset_y, scale;
+	void *data;
+	struct screenshooter_data *sh_data;
+
+	struct wl_list link;	/** screenshooter_data::output_list */
+};
+
+struct xdg_output_v1_info {
+	struct zxdg_output_v1 *xdg_output;
+	struct screenshooter_output *output;
+
+	char *name, *description;
+	struct wl_list link;	/** screenshooter_data::xdg_output_list */
+};
+
+
+struct buffer_size {
+	int width, height;
+
+	int min_x, min_y;
+	int max_x, max_y;
+};
+
+struct screenshooter_data {
+	struct wl_display *display;
+	struct wl_shm *shm;
+	struct wl_list output_list;	/** screenshooter_output::link */
+	struct wl_list xdg_output_list;	/** xdg_output_v1_info::link */
+
+	struct zxdg_output_manager_v1 *xdg_output_manager;
+	struct agl_screenshooter *screenshooter;
+	int buffer_copy_done;
+};
+
+static int opts = 0x0;
+
+#define OPT_SCREENSHOT_OUTPUT		1
+#define OPT_SHOW_ALL_OUTPUTS		2
+#define OPT_SCREENSHOT_ALL_OUTPUTS	3
+
+static void
+display_handle_geometry(void *data,
+			struct wl_output *wl_output,
+			int x,
+			int y,
+			int physical_width,
+			int physical_height,
+			int subpixel,
+			const char *make,
+			const char *model,
+			int transform)
+{
+	struct screenshooter_output *output;
+
+	output = wl_output_get_user_data(wl_output);
+
+	if (wl_output == output->output) {
+		output->offset_x = x;
+		output->offset_y = y;
+	}
+}
+
+static void
+display_handle_mode(void *data,
+		    struct wl_output *wl_output,
+		    uint32_t flags,
+		    int width,
+		    int height,
+		    int refresh)
+{
+	struct screenshooter_output *output;
+
+	output = wl_output_get_user_data(wl_output);
+
+	if (wl_output == output->output && (flags & WL_OUTPUT_MODE_CURRENT)) {
+		output->width = width;
+		output->height = height;
+	}
+}
+
+static void
+display_handle_done(void *data, struct wl_output *wl_output)
+{
+
+}
+
+static void
+display_handle_scale(void *data, struct wl_output *wl_output,
+		int32_t scale)
+{
+	struct screenshooter_output *output = data;
+	output->scale = scale;
+}
+
+
+static const struct wl_output_listener output_listener = {
+	display_handle_geometry,
+	display_handle_mode,
+	display_handle_done,
+	display_handle_scale,
+};
+
+static void
+handle_xdg_output_v1_logical_position(void *data, struct zxdg_output_v1 *output,
+                                      int32_t x, int32_t y)
+{
+}
+
+static void
+handle_xdg_output_v1_logical_size(void *data, struct zxdg_output_v1 *output,
+                                      int32_t width, int32_t height)
+{
+}
+
+static void
+handle_xdg_output_v1_done(void *data, struct zxdg_output_v1 *output)
+{
+	/* Don't bother waiting for this; there's no good reason a
+	 * compositor will wait more than one roundtrip before sending
+	 * these initial events. */
+}
+
+static void
+handle_xdg_output_v1_name(void *data, struct zxdg_output_v1 *output,
+                          const char *name)
+{
+	struct xdg_output_v1_info *xdg_output = data;
+	xdg_output->name = strdup(name);
+}
+
+static void
+handle_xdg_output_v1_description(void *data, struct zxdg_output_v1 *output,
+                          const char *description)
+{
+	struct xdg_output_v1_info *xdg_output = data;
+	xdg_output->description = strdup(description);
+}
+
+static const struct zxdg_output_v1_listener xdg_output_v1_listener = {
+	.logical_position = handle_xdg_output_v1_logical_position,
+	.logical_size = handle_xdg_output_v1_logical_size,
+	.done = handle_xdg_output_v1_done,
+	.name = handle_xdg_output_v1_name,
+	.description = handle_xdg_output_v1_description,
+};
+
+static void
+add_xdg_output_v1_info(struct screenshooter_data *shooter_data,
+                       struct screenshooter_output *output)
+{
+	struct xdg_output_v1_info *xdg_output = zalloc(sizeof(*xdg_output));
+
+	wl_list_insert(&shooter_data->xdg_output_list, &xdg_output->link);
+
+	xdg_output->xdg_output =
+		zxdg_output_manager_v1_get_xdg_output(shooter_data->xdg_output_manager,
+						      output->output);
+
+	zxdg_output_v1_add_listener(xdg_output->xdg_output,
+				    &xdg_output_v1_listener, xdg_output);
+	xdg_output->output = output;
+}
+
+static void
+screenshot_done(void *data, struct agl_screenshooter *screenshooter, uint32_t status)
+{
+	struct screenshooter_data *sh_data = data;
+	sh_data->buffer_copy_done = 1;
+}
+
+static const struct agl_screenshooter_listener screenshooter_listener = {
+	screenshot_done
+};
+
+static void
+handle_global(void *data, struct wl_registry *registry,
+	      uint32_t name, const char *interface, uint32_t version)
+{
+	struct screenshooter_output *output;
+	struct screenshooter_data *sh_data = data;
+
+	if (strcmp(interface, "wl_output") == 0) {
+		output = zalloc(sizeof(*output));
+		if (!output)
+			return;
+
+		output->output = wl_registry_bind(registry, name,
+						  &wl_output_interface, 1);
+		output->sh_data = sh_data;
+		wl_list_insert(&sh_data->output_list, &output->link);
+		wl_output_add_listener(output->output, &output_listener, output);
+	} else if (strcmp(interface, "wl_shm") == 0) {
+		sh_data->shm = wl_registry_bind(registry, name, &wl_shm_interface, 1);
+	} else if (strcmp(interface, "agl_screenshooter") == 0) {
+		sh_data->screenshooter = wl_registry_bind(registry, name,
+							  &agl_screenshooter_interface, 1);
+
+		agl_screenshooter_add_listener(sh_data->screenshooter,
+					       &screenshooter_listener, sh_data);
+	} else if (strcmp(interface, "zxdg_output_manager_v1") == 0) {
+		sh_data->xdg_output_manager = wl_registry_bind(registry, name,
+					&zxdg_output_manager_v1_interface, version);
+	}
+}
+
+static void
+handle_global_remove(void *data, struct wl_registry *registry, uint32_t name)
+{
+	/* XXX: unimplemented */
+}
+
+static const struct wl_registry_listener registry_listener = {
+	handle_global,
+	handle_global_remove
+};
+
+static struct wl_buffer *
+screenshot_create_shm_buffer(int width, int height, void **data_out,
+			     struct wl_shm *shm)
+{
+	struct wl_shm_pool *pool;
+	struct wl_buffer *buffer;
+	int fd, size, stride;
+	void *data;
+
+	stride = width * 4;
+	size = stride * height;
+
+	fd = os_create_anonymous_file(size);
+	if (fd < 0) {
+		fprintf(stderr, "creating a buffer file for %d B failed: %s\n",
+			size, strerror(errno));
+		return NULL;
+	}
+
+	data = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
+	if (data == MAP_FAILED) {
+		fprintf(stderr, "mmap failed: %s\n", strerror(errno));
+		close(fd);
+		return NULL;
+	}
+
+	pool = wl_shm_create_pool(shm, fd, size);
+	close(fd);
+	buffer = wl_shm_pool_create_buffer(pool, 0, width, height, stride,
+					   WL_SHM_FORMAT_XRGB8888);
+	wl_shm_pool_destroy(pool);
+
+	*data_out = data;
+
+	return buffer;
+}
+
+static void
+screenshot_write_png_per_output(const struct buffer_size *buff_size,
+				struct screenshooter_output *sh_output)
+{
+	int output_stride, buffer_stride, i;
+	cairo_surface_t *surface;
+	void *data, *d, *s;
+	FILE *fp;
+	char filepath[PATH_MAX];
+
+	buffer_stride = buff_size->width * 4;
+	data = xmalloc(buffer_stride * buff_size->height);
+	if (!data)
+		return;
+
+	output_stride = sh_output->width * 4;
+	s = sh_output->data;
+	d = data + (sh_output->offset_y - buff_size->min_y) * buffer_stride +
+		   (sh_output->offset_x - buff_size->min_x) * 4;
+
+	for (i = 0; i < sh_output->height; i++) {
+		memcpy(d, s, output_stride);
+		d += buffer_stride;
+		s += output_stride;
+	}
+
+	surface = cairo_image_surface_create_for_data(data,
+						      CAIRO_FORMAT_ARGB32,
+						      buff_size->width,
+						      buff_size->height,
+						      buffer_stride);
+
+	fp = file_create_dated(getenv("XDG_PICTURES_DIR"), "agl-screenshot-",
+			       ".png", filepath, sizeof(filepath));
+	if (fp) {
+		fclose(fp);
+		cairo_surface_write_to_png(surface, filepath);
+	}
+
+	cairo_surface_destroy(surface);
+	free(data);
+}
+
+static void
+screenshot_write_png(const struct buffer_size *buff_size,
+		     struct wl_list *output_list)
+{
+	int output_stride, buffer_stride, i;
+	cairo_surface_t *surface;
+	void *data, *d, *s;
+	struct screenshooter_output *output, *next;
+	FILE *fp;
+	char filepath[PATH_MAX];
+
+	buffer_stride = buff_size->width * 4;
+
+	data = xmalloc(buffer_stride * buff_size->height);
+	if (!data)
+		return;
+
+	wl_list_for_each_safe(output, next, output_list, link) {
+		output_stride = output->width * 4;
+		s = output->data;
+		d = data + (output->offset_y - buff_size->min_y) * buffer_stride +
+			   (output->offset_x - buff_size->min_x) * 4;
+
+		for (i = 0; i < output->height; i++) {
+			memcpy(d, s, output_stride);
+			d += buffer_stride;
+			s += output_stride;
+		}
+
+		free(output);
+	}
+
+	surface = cairo_image_surface_create_for_data(data,
+						      CAIRO_FORMAT_ARGB32,
+						      buff_size->width,
+						      buff_size->height,
+						      buffer_stride);
+
+	fp = file_create_dated(getenv("XDG_PICTURES_DIR"), "agl-screenshot-",
+			       ".png", filepath, sizeof(filepath));
+	if (fp) {
+		fclose(fp);
+		cairo_surface_write_to_png(surface, filepath);
+	}
+
+	cairo_surface_destroy(surface);
+	free(data);
+}
+
+static int
+screenshot_set_buffer_size_per_output(struct buffer_size *buff_size,
+				      struct screenshooter_output *output)
+{
+	buff_size->min_x = buff_size->min_y = INT_MAX;
+	buff_size->max_x = buff_size->max_y = INT_MIN;
+
+	buff_size->min_x = MIN(buff_size->min_x, output->offset_x);
+	buff_size->min_y = MIN(buff_size->min_y, output->offset_y);
+	buff_size->max_x =
+		MAX(buff_size->max_x, output->offset_x + output->width);
+	buff_size->max_y =
+		MAX(buff_size->max_y, output->offset_y + output->height);
+
+	if (buff_size->max_x <= buff_size->min_x ||
+	    buff_size->max_y <= buff_size->min_y)
+		return -1;
+
+	buff_size->width = buff_size->max_x - buff_size->min_x;
+	buff_size->height = buff_size->max_y - buff_size->min_y;
+
+	return 0;
+}
+
+static void
+screenshot_compute_output_offset(int *pos, struct screenshooter_output *sh_output)
+{
+	sh_output->offset_x = *pos;
+	*pos += sh_output->width;
+}
+
+static int
+screenshot_set_buffer_size(struct buffer_size *buff_size, struct wl_list *output_list)
+{
+	struct screenshooter_output *output;
+	int pos = 0;
+
+	wl_list_for_each_reverse(output, output_list, link)
+		screenshot_compute_output_offset(&pos, output);
+
+	wl_list_for_each(output, output_list, link)
+		if (screenshot_set_buffer_size_per_output(buff_size, output))
+			return -1;
+
+	return 0;
+}
+
+static struct screenshooter_output *
+agl_shooter_search_for_output(const char *output_name,
+			      struct screenshooter_data *sh_data)
+{
+	struct screenshooter_output *found_output = NULL;
+	struct xdg_output_v1_info *output;
+
+	if (!output_name)
+		return found_output;
+
+	wl_list_for_each(output, &sh_data->xdg_output_list, link) {
+		if (output->name && strcmp(output->name, output_name) == 0) {
+			found_output = output->output;
+			break;
+		}
+	}
+
+	return found_output;
+}
+
+static void
+agl_shooter_display_all_outputs(struct screenshooter_data *sh_data)
+{
+	struct xdg_output_v1_info *xdg_output;
+	wl_list_for_each(xdg_output, &sh_data->xdg_output_list, link) {
+		fprintf(stdout, "Output '%s', desc: '%s'\n", xdg_output->name,
+				xdg_output->description);
+	}
+}
+
+
+static void
+agl_shooter_screenshot_all_outputs(struct screenshooter_data *sh_data)
+{
+	struct screenshooter_output *output;
+	struct buffer_size buff_size = {};
+
+	if (screenshot_set_buffer_size(&buff_size, &sh_data->output_list))
+		return;
+
+	wl_list_for_each(output, &sh_data->output_list, link) {
+		output->buffer =
+			screenshot_create_shm_buffer(output->width,
+						     output->height,
+						     &output->data,
+						     sh_data->shm);
+
+		agl_screenshooter_take_shot(sh_data->screenshooter,
+					    output->output,
+					    output->buffer);
+
+		sh_data->buffer_copy_done = 0;
+		while (!sh_data->buffer_copy_done)
+			wl_display_roundtrip(sh_data->display);
+	}
+
+	screenshot_write_png(&buff_size, &sh_data->output_list);
+}
+
+static void
+agl_shooter_screenshot_output(struct screenshooter_output *sh_output)
+{
+	int pos = 0;
+	struct buffer_size buff_size = {};
+	struct screenshooter_data *sh_data = sh_output->sh_data;
+
+	screenshot_compute_output_offset(&pos, sh_output);
+	screenshot_set_buffer_size_per_output(&buff_size, sh_output);
+
+	sh_output->buffer =
+		screenshot_create_shm_buffer(sh_output->width,
+					     sh_output->height,
+					     &sh_output->data, sh_data->shm);
+
+	agl_screenshooter_take_shot(sh_data->screenshooter,
+				    sh_output->output,
+				    sh_output->buffer);
+
+	sh_data->buffer_copy_done = 0;
+	while (!sh_data->buffer_copy_done)
+		wl_display_roundtrip(sh_data->display);
+
+	screenshot_write_png_per_output(&buff_size, sh_output);
+}
+
+static void
+agl_shooter_destroy_xdg_output_manager(struct screenshooter_data *sh_data)
+{
+	struct xdg_output_v1_info *xdg_output;
+
+	wl_list_for_each(xdg_output, &sh_data->xdg_output_list, link) {
+		free(xdg_output->name);
+		free(xdg_output->description);
+		zxdg_output_v1_destroy(xdg_output->xdg_output);
+	}
+
+	zxdg_output_manager_v1_destroy(sh_data->xdg_output_manager);
+}
+
+static void
+print_usage_and_exit(void)
+{
+	fprintf(stderr, "./agl-screenshooter [-o OUTPUT_NAME] [-l] [-a]\n");
+
+	fprintf(stderr, "\t-o OUTPUT_NAME -- take a screenshot of the output "
+				"specified by OUTPUT_NAME\n");
+	fprintf(stderr, "\t-a  -- take a screenshot of all the outputs found\n");
+	fprintf(stderr, "\t-l  -- list all the outputs found\n");
+	exit(EXIT_FAILURE);
+}
+
+int main(int argc, char *argv[])
+{
+	struct wl_display *display;
+	struct wl_registry *registry;
+
+	struct screenshooter_data sh_data = {};
+	struct screenshooter_output *sh_output = NULL;
+	int c, option_index;
+
+	char *output_name = NULL;
+
+	static struct option long_options[] = {
+		{"output", 	required_argument, 0,  'o' },
+		{"list", 	required_argument, 0,  'l' },
+		{"all", 	required_argument, 0,  'a' },
+		{"help",	no_argument      , 0,  'h' },
+		{0, 0, 0, 0}
+	};
+
+	while ((c = getopt_long(argc, argv, "o:lah",
+				long_options, &option_index)) != -1) {
+		switch (c) {
+		case 'o':
+			output_name = optarg;
+			opts |= (1 << OPT_SCREENSHOT_OUTPUT);
+			break;
+		case 'l':
+			opts |= (1 << OPT_SHOW_ALL_OUTPUTS);
+			break;
+		case 'a':
+			opts |= (1 << OPT_SCREENSHOT_ALL_OUTPUTS);
+			break;
+		default:
+			print_usage_and_exit();
+		}
+	}
+
+	display = wl_display_connect(NULL);
+	if (display == NULL) {
+		fprintf(stderr, "failed to create display: %s\n",
+			strerror(errno));
+		return EXIT_FAILURE;
+	}
+
+	wl_list_init(&sh_data.output_list);
+	wl_list_init(&sh_data.xdg_output_list);
+	sh_data.display = display;
+
+	registry = wl_display_get_registry(display);
+	wl_registry_add_listener(registry, &registry_listener, &sh_data);
+
+	wl_display_dispatch(display);
+	wl_display_roundtrip(display);
+
+
+	if (sh_data.screenshooter == NULL) {
+		fprintf(stderr, "Compositor doesn't support screenshooter\n");
+		return EXIT_FAILURE;
+	}
+
+	wl_list_for_each(sh_output, &sh_data.output_list, link)
+		add_xdg_output_v1_info(&sh_data, sh_output);
+
+	/* do another round-trip for xdg_output */
+	wl_display_roundtrip(sh_data.display);
+
+	if (opts & (1 << OPT_SHOW_ALL_OUTPUTS)) {
+		agl_shooter_display_all_outputs(&sh_data);
+		agl_shooter_destroy_xdg_output_manager(&sh_data);
+		return EXIT_SUCCESS;
+	}
+
+	if (opts & (1 << OPT_SCREENSHOT_ALL_OUTPUTS)) {
+		agl_shooter_screenshot_all_outputs(&sh_data);
+		agl_shooter_destroy_xdg_output_manager(&sh_data);
+		return EXIT_SUCCESS;
+	}
+
+	sh_output = NULL;
+	if (output_name)
+		sh_output = agl_shooter_search_for_output(output_name, &sh_data);
+
+	if (!sh_output && (opts & (1 << OPT_SCREENSHOT_OUTPUT))) {
+		fprintf(stderr, "Could not find an output matching '%s'\n",
+				output_name);
+		agl_shooter_destroy_xdg_output_manager(&sh_data);
+		return EXIT_FAILURE;
+	}
+
+	/* if we're still here just pick the first one available
+	 * and use that. Still useful in case we are run without
+	 * any args whatsoever */
+	if (!sh_output)
+		sh_output = container_of(sh_data.output_list.next,
+					 struct screenshooter_output, link);
+
+	/* take a screenshot only of that specific output */
+	agl_shooter_screenshot_output(sh_output);
+	agl_shooter_destroy_xdg_output_manager(&sh_data);
+
+	return 0;
+}
diff --git a/meson.build b/meson.build
index 4299d58..6809579 100644
--- a/meson.build
+++ b/meson.build
@@ -73,6 +73,7 @@ protocols = [
   { 'name': 'agl-shell-desktop', 'source': 'internal' },
   { 'name': 'agl-screenshooter', 'source': 'internal' },
   { 'name': 'xdg-shell', 'source': 'wp-stable' },
+  { 'name': 'xdg-output', 'source': 'unstable', 'version': 'v1' },
 ]
 
 foreach proto: protocols
@@ -225,3 +226,6 @@ install_data(
         [ agl_shell_xml, agl_shell_desktop_xml ],
         install_dir: join_paths(dir_data, dir_data_agl_compositor)
 )
+
+common_inc = [ include_directories('src'), include_directories('.') ]
+subdir('clients')
diff --git a/shared/file-util.c b/shared/file-util.c
new file mode 100644
index 0000000..4170771
--- /dev/null
+++ b/shared/file-util.c
@@ -0,0 +1,126 @@
+/*
+ * Copyright © 2015 Collabora, Ltd.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the
+ * next paragraph) shall be included in all copies or substantial
+ * portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#include <stdio.h>
+#include <errno.h>
+#include <time.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <stdlib.h>
+
+#include "file-util.h"
+
+static int
+current_time_str(char *str, size_t len, const char *fmt)
+{
+	time_t t;
+	struct tm *t_local;
+	int ret;
+
+	t = time(NULL);
+	t_local = localtime(&t);
+	if (!t_local) {
+		errno = ETIME;
+		return -1;
+	}
+
+	ret = strftime(str, len, fmt, t_local);
+	if (ret == 0) {
+		errno = ETIME;
+		return -1;
+	}
+
+	return ret;
+}
+
+static int
+create_file_excl(const char *fname)
+{
+	return open(fname, O_RDWR | O_CLOEXEC | O_CREAT | O_EXCL, 00666);
+}
+
+/** Create a unique file with date and time in the name
+ *
+ * \param path File path
+ * \param prefix File name prefix.
+ * \param suffix File name suffix.
+ * \param[out] name_out Buffer for the resulting file name.
+ * \param name_len Number of bytes usable in name_out.
+ * \return stdio FILE pointer, or NULL on failure.
+ *
+ * Create and open a new file with the name concatenated from
+ * path/prefix, date and time, and suffix. If a file with this name
+ * already exists, an counter number is added to the end of the
+ * date and time sub-string. The counter is increased until a free file
+ * name is found.
+ *
+ * Once creating the file succeeds, the name of the file is in name_out.
+ * On failure, the contents of name_out are undefined and errno is set.
+ */
+FILE *
+file_create_dated(const char *path, const char *prefix, const char *suffix,
+		  char *name_out, size_t name_len)
+{
+	char timestr[128];
+	int ret;
+	int fd;
+	int cnt = 0;
+	int with_path;
+
+	with_path = path && path[0];
+
+	if (current_time_str(timestr, sizeof(timestr), "%F_%H-%M-%S") < 0)
+		return NULL;
+
+	ret = snprintf(name_out, name_len, "%s%s%s%s%s",
+		       with_path ? path : "", with_path ? "/" : "",
+		       prefix, timestr, suffix);
+	if (ret < 0 || (size_t)ret >= name_len) {
+		errno = ENOBUFS;
+		return NULL;
+	}
+
+	fd = create_file_excl(name_out);
+
+	while (fd == -1 && errno == EEXIST) {
+		cnt++;
+
+		ret = snprintf(name_out, name_len, "%s%s%s%s-%d%s",
+			       with_path ? path : "", with_path ? "/" : "",
+			       prefix, timestr, cnt, suffix);
+		if (ret < 0 || (size_t)ret >= name_len) {
+			errno = ENOBUFS;
+			return NULL;
+		}
+
+		fd = create_file_excl(name_out);
+	}
+
+	if (fd == -1)
+		return NULL;
+
+	return fdopen(fd, "w");
+}
diff --git a/shared/file-util.h b/shared/file-util.h
new file mode 100644
index 0000000..e272dde
--- /dev/null
+++ b/shared/file-util.h
@@ -0,0 +1,43 @@
+/*
+ * Copyright © 2015 Collabora, Ltd.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the
+ * next paragraph) shall be included in all copies or substantial
+ * portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#ifndef WESTON_FILE_UTIL_H
+#define WESTON_FILE_UTIL_H
+
+#ifdef  __cplusplus
+extern "C" {
+#endif
+
+#include <stdio.h>
+
+FILE *
+file_create_dated(const char *path, const char *prefix, const char *suffix,
+		  char *name_out, size_t name_len);
+
+#ifdef  __cplusplus
+}
+#endif
+
+#endif /* WESTON_FILE_UTIL_H */
diff --git a/shared/xalloc.c b/shared/xalloc.c
new file mode 100644
index 0000000..1cc5c12
--- /dev/null
+++ b/shared/xalloc.c
@@ -0,0 +1,50 @@
+/*
+ * Copyright © 2008 Kristian Høgsberg
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the
+ * next paragraph) shall be included in all copies or substantial
+ * portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#include "config.h"
+
+#include <errno.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "xalloc.h"
+
+void *
+fail_on_null(void *p, size_t size, char *file, int32_t line)
+{
+	if (p == NULL) {
+		fprintf(stderr, "[%s] ", program_invocation_short_name);
+		if (file)
+			fprintf(stderr, "%s:%d: ", file, line);
+		fprintf(stderr, "out of memory");
+		if (size)
+			fprintf(stderr, " (%zd)", size);
+		fprintf(stderr, "\n");
+		exit(EXIT_FAILURE);
+	}
+
+	return p;
+}
diff --git a/shared/xalloc.h b/shared/xalloc.h
new file mode 100644
index 0000000..cd39dd8
--- /dev/null
+++ b/shared/xalloc.h
@@ -0,0 +1,51 @@
+/*
+ * Copyright © 2008 Kristian Høgsberg
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the
+ * next paragraph) shall be included in all copies or substantial
+ * portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#ifndef WESTON_XALLOC_H
+#define WESTON_XALLOC_H
+
+#ifdef  __cplusplus
+extern "C" {
+#endif
+
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <libweston/zalloc.h>
+
+void *
+fail_on_null(void *p, size_t size, char *file, int32_t line);
+
+#define xmalloc(s) (fail_on_null(malloc(s), (s), __FILE__, __LINE__))
+#define xzalloc(s) (fail_on_null(zalloc(s), (s), __FILE__, __LINE__))
+#define xstrdup(s) (fail_on_null(strdup(s), 0, __FILE__, __LINE__))
+#define xrealloc(p, s) (fail_on_null(realloc(p, s), (s), __FILE__, __LINE__))
+
+#ifdef  __cplusplus
+}
+#endif
+
+#endif /* WESTON_XALLOC_H */