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FFmpeg/libavdevice/xcbgrab.c
Michael Niedermayer 78d6d13bab
avdevice/xcbgrab: Check sscanf() return 
Alot more input checking can be performed, this is only checking the obvious missing case

Fixes: CID1598562 Unchecked return value

Sponsored-by: Sovereign Tech Fund
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
2024-06-12 00:39:11 +02:00

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/*
* XCB input grabber
* Copyright (C) 2014 Luca Barbato <lu_zero@gentoo.org>
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "config.h"
#include <stdlib.h>
#include <string.h>
#include <xcb/xcb.h>
#if CONFIG_LIBXCB_XFIXES
#include <xcb/xfixes.h>
#endif
#if CONFIG_LIBXCB_SHM
#include <sys/shm.h>
#include <xcb/shm.h>
#endif
#if CONFIG_LIBXCB_SHAPE
#include <xcb/shape.h>
#endif
#include "libavutil/internal.h"
#include "libavutil/mathematics.h"
#include "libavutil/mem.h"
#include "libavutil/opt.h"
#include "libavutil/parseutils.h"
#include "libavutil/time.h"
#include "libavformat/avformat.h"
#include "libavformat/demux.h"
#include "libavformat/internal.h"
typedef struct XCBGrabContext {
const AVClass *class;
xcb_connection_t *conn;
xcb_screen_t *screen;
xcb_window_t window;
#if CONFIG_LIBXCB_SHM
AVBufferPool *shm_pool;
#endif
int64_t time_frame;
AVRational time_base;
int64_t frame_duration;
xcb_window_t window_id;
int x, y;
int width, height;
int frame_size;
int bpp;
int draw_mouse;
int follow_mouse;
int show_region;
int region_border;
int centered;
int select_region;
const char *framerate;
int has_shm;
} XCBGrabContext;
#define FOLLOW_CENTER -1
#define OFFSET(x) offsetof(XCBGrabContext, x)
#define D AV_OPT_FLAG_DECODING_PARAM
static const AVOption options[] = {
{ "window_id", "Window to capture.", OFFSET(window_id), AV_OPT_TYPE_INT, { .i64 = XCB_NONE }, 0, UINT32_MAX, D },
{ "x", "Initial x coordinate.", OFFSET(x), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, D },
{ "y", "Initial y coordinate.", OFFSET(y), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, D },
{ "grab_x", "Initial x coordinate.", OFFSET(x), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, D },
{ "grab_y", "Initial y coordinate.", OFFSET(y), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, D },
{ "video_size", "A string describing frame size, such as 640x480 or hd720.", OFFSET(width), AV_OPT_TYPE_IMAGE_SIZE, {.str = NULL }, 0, 0, D },
{ "framerate", "", OFFSET(framerate), AV_OPT_TYPE_STRING, {.str = "ntsc" }, 0, 0, D },
{ "draw_mouse", "Draw the mouse pointer.", OFFSET(draw_mouse), AV_OPT_TYPE_INT, { .i64 = 1 }, 0, 1, D },
{ "follow_mouse", "Move the grabbing region when the mouse pointer reaches within specified amount of pixels to the edge of region.",
OFFSET(follow_mouse), AV_OPT_TYPE_INT, { .i64 = 0 }, FOLLOW_CENTER, INT_MAX, D, .unit = "follow_mouse" },
{ "centered", "Keep the mouse pointer at the center of grabbing region when following.", 0, AV_OPT_TYPE_CONST, { .i64 = -1 }, INT_MIN, INT_MAX, D, .unit = "follow_mouse" },
{ "show_region", "Show the grabbing region.", OFFSET(show_region), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, 1, D },
{ "region_border", "Set the region border thickness.", OFFSET(region_border), AV_OPT_TYPE_INT, { .i64 = 3 }, 1, 128, D },
{ "select_region", "Select the grabbing region graphically using the pointer.", OFFSET(select_region), AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0, 1, D },
{ NULL },
};
static const AVClass xcbgrab_class = {
.class_name = "xcbgrab indev",
.item_name = av_default_item_name,
.option = options,
.version = LIBAVUTIL_VERSION_INT,
.category = AV_CLASS_CATEGORY_DEVICE_VIDEO_INPUT,
};
static int xcbgrab_reposition(AVFormatContext *s,
xcb_query_pointer_reply_t *p,
xcb_get_geometry_reply_t *geo)
{
XCBGrabContext *c = s->priv_data;
int x = c->x, y = c->y;
int w = c->width, h = c->height, f = c->follow_mouse;
int p_x, p_y;
if (!p || !geo)
return AVERROR(EIO);
p_x = p->win_x;
p_y = p->win_y;
if (f == FOLLOW_CENTER) {
x = p_x - w / 2;
y = p_y - h / 2;
} else {
int left = x + f;
int right = x + w - f;
int top = y + f;
int bottom = y + h - f;
if (p_x > right) {
x += p_x - right;
} else if (p_x < left) {
x -= left - p_x;
}
if (p_y > bottom) {
y += p_y - bottom;
} else if (p_y < top) {
y -= top - p_y;
}
}
c->x = FFMIN(FFMAX(0, x), geo->width - w);
c->y = FFMIN(FFMAX(0, y), geo->height - h);
return 0;
}
static void xcbgrab_image_reply_free(void *opaque, uint8_t *data)
{
free(opaque);
}
static int xcbgrab_frame(AVFormatContext *s, AVPacket *pkt)
{
XCBGrabContext *c = s->priv_data;
xcb_get_image_cookie_t iq;
xcb_get_image_reply_t *img;
xcb_drawable_t drawable = c->window_id;
xcb_generic_error_t *e = NULL;
uint8_t *data;
int length;
iq = xcb_get_image(c->conn, XCB_IMAGE_FORMAT_Z_PIXMAP, drawable,
c->x, c->y, c->width, c->height, ~0);
img = xcb_get_image_reply(c->conn, iq, &e);
if (e) {
av_log(s, AV_LOG_ERROR,
"Cannot get the image data "
"event_error: response_type:%u error_code:%u "
"sequence:%u resource_id:%u minor_code:%u major_code:%u.\n",
e->response_type, e->error_code,
e->sequence, e->resource_id, e->minor_code, e->major_code);
free(e);
return AVERROR(EACCES);
}
if (!img)
return AVERROR(EAGAIN);
data = xcb_get_image_data(img);
length = xcb_get_image_data_length(img);
pkt->buf = av_buffer_create(data, length, xcbgrab_image_reply_free, img, 0);
if (!pkt->buf) {
free(img);
return AVERROR(ENOMEM);
}
pkt->data = data;
pkt->size = length;
return 0;
}
static int64_t wait_frame(AVFormatContext *s, AVPacket *pkt)
{
XCBGrabContext *c = s->priv_data;
int64_t curtime, delay;
c->time_frame += c->frame_duration;
for (;;) {
curtime = av_gettime_relative();
delay = c->time_frame - curtime;
if (delay <= 0)
break;
av_usleep(delay);
}
return curtime;
}
#if CONFIG_LIBXCB_SHM
static int check_shm(xcb_connection_t *conn)
{
xcb_shm_query_version_cookie_t cookie = xcb_shm_query_version(conn);
xcb_shm_query_version_reply_t *reply;
reply = xcb_shm_query_version_reply(conn, cookie, NULL);
if (reply) {
free(reply);
return 1;
}
return 0;
}
static void free_shm_buffer(void *opaque, uint8_t *data)
{
shmdt(data);
}
static AVBufferRef *allocate_shm_buffer(void *opaque, size_t size)
{
xcb_connection_t *conn = opaque;
xcb_shm_seg_t segment;
AVBufferRef *ref;
uint8_t *data;
int id;
id = shmget(IPC_PRIVATE, size, IPC_CREAT | 0777);
if (id == -1)
return NULL;
segment = xcb_generate_id(conn);
xcb_shm_attach(conn, segment, id, 0);
data = shmat(id, NULL, 0);
shmctl(id, IPC_RMID, 0);
if ((intptr_t)data == -1 || !data)
return NULL;
ref = av_buffer_create(data, size, free_shm_buffer, (void *)(ptrdiff_t)segment, 0);
if (!ref)
shmdt(data);
return ref;
}
static int xcbgrab_frame_shm(AVFormatContext *s, AVPacket *pkt)
{
XCBGrabContext *c = s->priv_data;
xcb_shm_get_image_cookie_t iq;
xcb_shm_get_image_reply_t *img;
xcb_drawable_t drawable = c->window_id;
xcb_generic_error_t *e = NULL;
AVBufferRef *buf;
xcb_shm_seg_t segment;
buf = av_buffer_pool_get(c->shm_pool);
if (!buf) {
av_log(s, AV_LOG_ERROR, "Could not get shared memory buffer.\n");
return AVERROR(ENOMEM);
}
segment = (xcb_shm_seg_t)(uintptr_t)av_buffer_pool_buffer_get_opaque(buf);
iq = xcb_shm_get_image(c->conn, drawable,
c->x, c->y, c->width, c->height, ~0,
XCB_IMAGE_FORMAT_Z_PIXMAP, segment, 0);
img = xcb_shm_get_image_reply(c->conn, iq, &e);
xcb_flush(c->conn);
if (e) {
av_log(s, AV_LOG_ERROR,
"Cannot get the image data "
"event_error: response_type:%u error_code:%u "
"sequence:%u resource_id:%u minor_code:%u major_code:%u.\n",
e->response_type, e->error_code,
e->sequence, e->resource_id, e->minor_code, e->major_code);
free(e);
av_buffer_unref(&buf);
return AVERROR(EACCES);
}
free(img);
pkt->buf = buf;
pkt->data = buf->data;
pkt->size = c->frame_size;
return 0;
}
#endif /* CONFIG_LIBXCB_SHM */
#if CONFIG_LIBXCB_XFIXES
static int check_xfixes(xcb_connection_t *conn)
{
xcb_xfixes_query_version_cookie_t cookie;
xcb_xfixes_query_version_reply_t *reply;
cookie = xcb_xfixes_query_version(conn, XCB_XFIXES_MAJOR_VERSION,
XCB_XFIXES_MINOR_VERSION);
reply = xcb_xfixes_query_version_reply(conn, cookie, NULL);
if (reply) {
free(reply);
return 1;
}
return 0;
}
#define BLEND(target, source, alpha) \
(target) + ((source) * (255 - (alpha)) + 255 / 2) / 255
static void xcbgrab_draw_mouse(AVFormatContext *s, AVPacket *pkt,
xcb_query_pointer_reply_t *p,
xcb_get_geometry_reply_t *geo,
int win_x, int win_y)
{
XCBGrabContext *gr = s->priv_data;
uint32_t *cursor;
uint8_t *image = pkt->data;
int stride = gr->bpp / 8;
xcb_xfixes_get_cursor_image_cookie_t cc;
xcb_xfixes_get_cursor_image_reply_t *ci;
int cx, cy, x, y, w, h, c_off, i_off;
cc = xcb_xfixes_get_cursor_image(gr->conn);
ci = xcb_xfixes_get_cursor_image_reply(gr->conn, cc, NULL);
if (!ci)
return;
cursor = xcb_xfixes_get_cursor_image_cursor_image(ci);
if (!cursor)
return;
cx = ci->x - ci->xhot;
cy = ci->y - ci->yhot;
x = FFMAX(cx, win_x + gr->x);
y = FFMAX(cy, win_y + gr->y);
w = FFMIN(cx + ci->width, win_x + gr->x + gr->width) - x;
h = FFMIN(cy + ci->height, win_y + gr->y + gr->height) - y;
c_off = x - cx;
i_off = x - gr->x - win_x;
cursor += (y - cy) * ci->width;
image += (y - gr->y - win_y) * gr->width * stride;
for (y = 0; y < h; y++) {
cursor += c_off;
image += i_off * stride;
for (x = 0; x < w; x++, cursor++, image += stride) {
int r, g, b, a;
r = *cursor & 0xff;
g = (*cursor >> 8) & 0xff;
b = (*cursor >> 16) & 0xff;
a = (*cursor >> 24) & 0xff;
if (!a)
continue;
if (a == 255) {
image[0] = r;
image[1] = g;
image[2] = b;
} else {
image[0] = BLEND(r, image[0], a);
image[1] = BLEND(g, image[1], a);
image[2] = BLEND(b, image[2], a);
}
}
cursor += ci->width - w - c_off;
image += (gr->width - w - i_off) * stride;
}
free(ci);
}
#endif /* CONFIG_LIBXCB_XFIXES */
static void xcbgrab_update_region(AVFormatContext *s, int win_x, int win_y)
{
XCBGrabContext *c = s->priv_data;
const uint32_t args[] = { win_x + c->x - c->region_border,
win_y + c->y - c->region_border };
xcb_configure_window(c->conn,
c->window,
XCB_CONFIG_WINDOW_X | XCB_CONFIG_WINDOW_Y,
args);
}
static int xcbgrab_read_packet(AVFormatContext *s, AVPacket *pkt)
{
XCBGrabContext *c = s->priv_data;
xcb_query_pointer_cookie_t pc;
xcb_get_geometry_cookie_t gc;
xcb_translate_coordinates_cookie_t tc;
xcb_query_pointer_reply_t *p = NULL;
xcb_get_geometry_reply_t *geo = NULL;
xcb_translate_coordinates_reply_t *translate = NULL;
int ret = 0;
int64_t pts;
int win_x = 0, win_y = 0;
wait_frame(s, pkt);
pts = av_gettime();
if (c->follow_mouse || c->draw_mouse) {
pc = xcb_query_pointer(c->conn, c->window_id);
gc = xcb_get_geometry(c->conn, c->window_id);
p = xcb_query_pointer_reply(c->conn, pc, NULL);
if (!p) {
av_log(s, AV_LOG_ERROR, "Failed to query xcb pointer\n");
return AVERROR_EXTERNAL;
}
geo = xcb_get_geometry_reply(c->conn, gc, NULL);
if (!geo) {
av_log(s, AV_LOG_ERROR, "Failed to get xcb geometry\n");
free(p);
return AVERROR_EXTERNAL;
}
}
if (c->window_id != c->screen->root) {
tc = xcb_translate_coordinates(c->conn, c->window_id, c->screen->root, 0, 0);
translate = xcb_translate_coordinates_reply(c->conn, tc, NULL);
if (!translate) {
free(p);
free(geo);
av_log(s, AV_LOG_ERROR, "Failed to translate xcb geometry\n");
return AVERROR_EXTERNAL;
}
win_x = translate->dst_x;
win_y = translate->dst_y;
free(translate);
}
if (c->follow_mouse && p->same_screen)
xcbgrab_reposition(s, p, geo);
if (c->show_region)
xcbgrab_update_region(s, win_x, win_y);
#if CONFIG_LIBXCB_SHM
if (c->has_shm && xcbgrab_frame_shm(s, pkt) < 0) {
av_log(s, AV_LOG_WARNING, "Continuing without shared memory.\n");
c->has_shm = 0;
}
#endif
if (!c->has_shm)
ret = xcbgrab_frame(s, pkt);
pkt->dts = pkt->pts = pts;
pkt->duration = c->frame_duration;
#if CONFIG_LIBXCB_XFIXES
if (ret >= 0 && c->draw_mouse && p->same_screen)
xcbgrab_draw_mouse(s, pkt, p, geo, win_x, win_y);
#endif
free(p);
free(geo);
return ret;
}
static av_cold int xcbgrab_read_close(AVFormatContext *s)
{
XCBGrabContext *ctx = s->priv_data;
#if CONFIG_LIBXCB_SHM
av_buffer_pool_uninit(&ctx->shm_pool);
#endif
xcb_disconnect(ctx->conn);
return 0;
}
static xcb_screen_t *get_screen(const xcb_setup_t *setup, int screen_num)
{
xcb_screen_iterator_t it = xcb_setup_roots_iterator(setup);
xcb_screen_t *screen = NULL;
for (; it.rem > 0; xcb_screen_next (&it)) {
if (!screen_num) {
screen = it.data;
break;
}
screen_num--;
}
return screen;
}
static int pixfmt_from_pixmap_format(AVFormatContext *s, int depth,
int *pix_fmt, int *bpp)
{
XCBGrabContext *c = s->priv_data;
const xcb_setup_t *setup = xcb_get_setup(c->conn);
const xcb_format_t *fmt = xcb_setup_pixmap_formats(setup);
int length = xcb_setup_pixmap_formats_length(setup);
*pix_fmt = 0;
while (length--) {
if (fmt->depth == depth) {
switch (depth) {
case 32:
if (fmt->bits_per_pixel == 32)
*pix_fmt = setup->image_byte_order == XCB_IMAGE_ORDER_LSB_FIRST ?
AV_PIX_FMT_BGR0 : AV_PIX_FMT_0RGB;
break;
case 24:
if (fmt->bits_per_pixel == 32)
*pix_fmt = setup->image_byte_order == XCB_IMAGE_ORDER_LSB_FIRST ?
AV_PIX_FMT_BGR0 : AV_PIX_FMT_0RGB;
else if (fmt->bits_per_pixel == 24)
*pix_fmt = setup->image_byte_order == XCB_IMAGE_ORDER_LSB_FIRST ?
AV_PIX_FMT_BGR24 : AV_PIX_FMT_RGB24;
break;
case 16:
if (fmt->bits_per_pixel == 16)
*pix_fmt = setup->image_byte_order == XCB_IMAGE_ORDER_LSB_FIRST ?
AV_PIX_FMT_RGB565LE : AV_PIX_FMT_RGB565BE;
break;
case 15:
if (fmt->bits_per_pixel == 16)
*pix_fmt = setup->image_byte_order == XCB_IMAGE_ORDER_LSB_FIRST ?
AV_PIX_FMT_RGB555LE : AV_PIX_FMT_RGB555BE;
break;
case 8:
if (fmt->bits_per_pixel == 8)
*pix_fmt = AV_PIX_FMT_RGB8;
break;
}
}
if (*pix_fmt) {
*bpp = fmt->bits_per_pixel;
return 0;
}
fmt++;
}
avpriv_report_missing_feature(s, "Mapping this pixmap format");
return AVERROR_PATCHWELCOME;
}
static int create_stream(AVFormatContext *s)
{
XCBGrabContext *c = s->priv_data;
AVStream *st = avformat_new_stream(s, NULL);
xcb_get_geometry_cookie_t gc;
xcb_get_geometry_reply_t *geo;
int64_t frame_size_bits;
int ret;
if (!st)
return AVERROR(ENOMEM);
ret = av_parse_video_rate(&st->avg_frame_rate, c->framerate);
if (ret < 0)
return ret;
avpriv_set_pts_info(st, 64, 1, 1000000);
gc = xcb_get_geometry(c->conn, c->window_id);
geo = xcb_get_geometry_reply(c->conn, gc, NULL);
if (!geo) {
av_log(s, AV_LOG_ERROR, "Can't find window '0x%x', aborting.\n", c->window_id);
return AVERROR_EXTERNAL;
}
if (!c->width || !c->height) {
c->width = geo->width;
c->height = geo->height;
}
if (c->x + c->width > geo->width ||
c->y + c->height > geo->height) {
av_log(s, AV_LOG_ERROR,
"Capture area %dx%d at position %d.%d "
"outside the screen size %dx%d\n",
c->width, c->height,
c->x, c->y,
geo->width, geo->height);
free(geo);
return AVERROR(EINVAL);
}
c->time_base = (AVRational){ st->avg_frame_rate.den,
st->avg_frame_rate.num };
c->frame_duration = av_rescale_q(1, c->time_base, AV_TIME_BASE_Q);
c->time_frame = av_gettime_relative();
ret = pixfmt_from_pixmap_format(s, geo->depth, &st->codecpar->format, &c->bpp);
free(geo);
if (ret < 0)
return ret;
frame_size_bits = (int64_t)c->width * c->height * c->bpp;
if (frame_size_bits / 8 + AV_INPUT_BUFFER_PADDING_SIZE > INT_MAX) {
av_log(s, AV_LOG_ERROR, "Captured area is too large\n");
return AVERROR_PATCHWELCOME;
}
c->frame_size = frame_size_bits / 8;
#if CONFIG_LIBXCB_SHM
c->shm_pool = av_buffer_pool_init2(c->frame_size + AV_INPUT_BUFFER_PADDING_SIZE,
c->conn, allocate_shm_buffer, NULL);
if (!c->shm_pool)
return AVERROR(ENOMEM);
#endif
st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
st->codecpar->codec_id = AV_CODEC_ID_RAWVIDEO;
st->codecpar->width = c->width;
st->codecpar->height = c->height;
st->codecpar->bit_rate = av_rescale(frame_size_bits, st->avg_frame_rate.num, st->avg_frame_rate.den);
return ret;
}
static void draw_rectangle(AVFormatContext *s)
{
XCBGrabContext *c = s->priv_data;
xcb_gcontext_t gc = xcb_generate_id(c->conn);
uint32_t mask = XCB_GC_FOREGROUND |
XCB_GC_BACKGROUND |
XCB_GC_LINE_WIDTH |
XCB_GC_LINE_STYLE |
XCB_GC_FILL_STYLE;
uint32_t values[] = { c->screen->black_pixel,
c->screen->white_pixel,
c->region_border,
XCB_LINE_STYLE_DOUBLE_DASH,
XCB_FILL_STYLE_SOLID };
xcb_rectangle_t r = { 1, 1,
c->width + c->region_border * 2 - 3,
c->height + c->region_border * 2 - 3 };
xcb_create_gc(c->conn, gc, c->window, mask, values);
xcb_poly_rectangle(c->conn, c->window, gc, 1, &r);
}
static void setup_window(AVFormatContext *s)
{
XCBGrabContext *c = s->priv_data;
uint32_t mask = XCB_CW_OVERRIDE_REDIRECT | XCB_CW_EVENT_MASK;
uint32_t values[] = { 1,
XCB_EVENT_MASK_EXPOSURE |
XCB_EVENT_MASK_STRUCTURE_NOTIFY };
av_unused xcb_rectangle_t rect = { 0, 0, c->width, c->height };
c->window = xcb_generate_id(c->conn);
xcb_create_window(c->conn, XCB_COPY_FROM_PARENT,
c->window,
c->screen->root,
c->x - c->region_border,
c->y - c->region_border,
c->width + c->region_border * 2,
c->height + c->region_border * 2,
0,
XCB_WINDOW_CLASS_INPUT_OUTPUT,
XCB_COPY_FROM_PARENT,
mask, values);
#if CONFIG_LIBXCB_SHAPE
xcb_shape_rectangles(c->conn, XCB_SHAPE_SO_SUBTRACT,
XCB_SHAPE_SK_BOUNDING, XCB_CLIP_ORDERING_UNSORTED,
c->window,
c->region_border, c->region_border,
1, &rect);
#endif
xcb_map_window(c->conn, c->window);
draw_rectangle(s);
}
#define CROSSHAIR_CURSOR 34
static xcb_rectangle_t rectangle_from_corners(xcb_point_t *corner_a,
xcb_point_t *corner_b)
{
xcb_rectangle_t rectangle;
rectangle.x = FFMIN(corner_a->x, corner_b->x);
rectangle.y = FFMIN(corner_a->y, corner_b->y);
rectangle.width = FFABS(corner_a->x - corner_b->x);
rectangle.height = FFABS(corner_a->y - corner_b->y);
return rectangle;
}
static int select_region(AVFormatContext *s)
{
XCBGrabContext *c = s->priv_data;
xcb_connection_t *conn = c->conn;
xcb_screen_t *screen = c->screen;
int ret = 0, done = 0, was_pressed = 0;
xcb_cursor_t cursor;
xcb_font_t cursor_font;
xcb_point_t press_position;
xcb_generic_event_t *event;
xcb_rectangle_t rectangle = { 0 };
xcb_grab_pointer_reply_t *reply;
xcb_grab_pointer_cookie_t cookie;
xcb_window_t root_window = screen->root;
xcb_gcontext_t gc = xcb_generate_id(conn);
uint32_t mask = XCB_GC_FUNCTION | XCB_GC_SUBWINDOW_MODE;
uint32_t values[] = { XCB_GX_INVERT, XCB_SUBWINDOW_MODE_INCLUDE_INFERIORS };
xcb_create_gc(conn, gc, root_window, mask, values);
cursor_font = xcb_generate_id(conn);
xcb_open_font(conn, cursor_font, strlen("cursor"), "cursor");
cursor = xcb_generate_id(conn);
xcb_create_glyph_cursor(conn, cursor, cursor_font, cursor_font,
CROSSHAIR_CURSOR, CROSSHAIR_CURSOR + 1, 0, 0, 0,
0xFFFF, 0xFFFF, 0xFFFF);
cookie = xcb_grab_pointer(conn, 0, root_window,
XCB_EVENT_MASK_BUTTON_PRESS |
XCB_EVENT_MASK_BUTTON_RELEASE |
XCB_EVENT_MASK_BUTTON_MOTION,
XCB_GRAB_MODE_ASYNC, XCB_GRAB_MODE_ASYNC,
root_window, cursor, XCB_CURRENT_TIME);
reply = xcb_grab_pointer_reply(conn, cookie, NULL);
if (!reply || reply->status != XCB_GRAB_STATUS_SUCCESS) {
av_log(s, AV_LOG_ERROR,
"Failed to select region. Could not grab pointer.\n");
ret = AVERROR(EIO);
free(reply);
goto fail;
}
free(reply);
xcb_grab_server(conn);
while (!done && (event = xcb_wait_for_event(conn))) {
switch (event->response_type & ~0x80) {
case XCB_BUTTON_PRESS: {
xcb_button_press_event_t *press = (xcb_button_press_event_t *)event;
press_position = (xcb_point_t){ press->event_x, press->event_y };
rectangle.x = press_position.x;
rectangle.y = press_position.y;
xcb_poly_rectangle(conn, root_window, gc, 1, &rectangle);
was_pressed = 1;
break;
}
case XCB_MOTION_NOTIFY: {
if (was_pressed) {
xcb_motion_notify_event_t *motion =
(xcb_motion_notify_event_t *)event;
xcb_point_t cursor_position = { motion->event_x, motion->event_y };
xcb_poly_rectangle(conn, root_window, gc, 1, &rectangle);
rectangle = rectangle_from_corners(&press_position, &cursor_position);
xcb_poly_rectangle(conn, root_window, gc, 1, &rectangle);
}
break;
}
case XCB_BUTTON_RELEASE: {
xcb_poly_rectangle(conn, root_window, gc, 1, &rectangle);
done = 1;
break;
}
default:
break;
}
xcb_flush(conn);
free(event);
}
c->width = rectangle.width;
c->height = rectangle.height;
if (c->width && c->height) {
c->x = rectangle.x;
c->y = rectangle.y;
} else {
c->x = 0;
c->y = 0;
}
xcb_ungrab_server(conn);
xcb_ungrab_pointer(conn, XCB_CURRENT_TIME);
xcb_flush(conn);
fail:
xcb_free_cursor(conn, cursor);
xcb_close_font(conn, cursor_font);
xcb_free_gc(conn, gc);
return ret;
}
static av_cold int xcbgrab_read_header(AVFormatContext *s)
{
XCBGrabContext *c = s->priv_data;
int screen_num, ret;
const xcb_setup_t *setup;
char *display_name = av_strdup(s->url);
if (!display_name)
return AVERROR(ENOMEM);
if (!sscanf(s->url, "%[^+]+%d,%d", display_name, &c->x, &c->y)) {
*display_name = 0;
if(sscanf(s->url, "+%d,%d", &c->x, &c->y) != 2) {
if (*s->url)
av_log(s, AV_LOG_WARNING, "Ambigous URL: %s\n", s->url);
}
}
c->conn = xcb_connect(display_name[0] ? display_name : NULL, &screen_num);
av_freep(&display_name);
if ((ret = xcb_connection_has_error(c->conn))) {
av_log(s, AV_LOG_ERROR, "Cannot open display %s, error %d.\n",
s->url[0] ? s->url : "default", ret);
return AVERROR(EIO);
}
setup = xcb_get_setup(c->conn);
c->screen = get_screen(setup, screen_num);
if (!c->screen) {
av_log(s, AV_LOG_ERROR, "The screen %d does not exist.\n",
screen_num);
xcbgrab_read_close(s);
return AVERROR(EIO);
}
if (c->window_id == XCB_NONE)
c->window_id = c->screen->root;
else {
if (c->select_region) {
av_log(s, AV_LOG_WARNING, "select_region ignored with window_id.\n");
c->select_region = 0;
}
if (c->follow_mouse) {
av_log(s, AV_LOG_WARNING, "follow_mouse ignored with window_id.\n");
c->follow_mouse = 0;
}
}
if (c->select_region) {
ret = select_region(s);
if (ret < 0) {
xcbgrab_read_close(s);
return ret;
}
}
ret = create_stream(s);
if (ret < 0) {
xcbgrab_read_close(s);
return ret;
}
#if CONFIG_LIBXCB_SHM
c->has_shm = check_shm(c->conn);
#endif
#if CONFIG_LIBXCB_XFIXES
if (c->draw_mouse) {
if (!(c->draw_mouse = check_xfixes(c->conn))) {
av_log(s, AV_LOG_WARNING,
"XFixes not available, cannot draw the mouse.\n");
}
if (c->bpp < 24) {
avpriv_report_missing_feature(s, "%d bits per pixel screen",
c->bpp);
c->draw_mouse = 0;
}
}
#endif
if (c->show_region)
setup_window(s);
return 0;
}
const FFInputFormat ff_xcbgrab_demuxer = {
.p.name = "x11grab",
.p.long_name = NULL_IF_CONFIG_SMALL("X11 screen capture, using XCB"),
.p.flags = AVFMT_NOFILE,
.p.priv_class = &xcbgrab_class,
.priv_data_size = sizeof(XCBGrabContext),
.read_header = xcbgrab_read_header,
.read_packet = xcbgrab_read_packet,
.read_close = xcbgrab_read_close,
};
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