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#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <fcntl.h>
#include <errno.h>
#include <linux/fb.h>
#include <zlib.h>
#include <libpng/png.h>
#include "private/android_filesystem_config.h"
#define LOG_TAG "screenshot"
#include <utils/Log.h>
void take_screenshot(FILE *fb_in, FILE *fb_out) {
int fb;
char imgbuf[0x10000];
struct fb_var_screeninfo vinfo;
png_structp png;
png_infop info;
unsigned int r,c,rowlen;
unsigned int bytespp,offset;
fb = fileno(fb_in);
if(fb < 0) {
LOGE("failed to open framebuffer\n");
return;
}
fb_in = fdopen(fb, "r");
if(ioctl(fb, FBIOGET_VSCREENINFO, &vinfo) < 0) {
LOGE("failed to get framebuffer info\n");
return;
}
fcntl(fb, F_SETFD, FD_CLOEXEC);
png = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
if (png == NULL) {
LOGE("failed png_create_write_struct\n");
fclose(fb_in);
return;
}
png_init_io(png, fb_out);
info = png_create_info_struct(png);
if (info == NULL) {
LOGE("failed png_create_info_struct\n");
png_destroy_write_struct(&png, NULL);
fclose(fb_in);
return;
}
if (setjmp(png_jmpbuf(png))) {
LOGE("failed png setjmp\n");
png_destroy_write_struct(&png, NULL);
fclose(fb_in);
return;
}
bytespp = vinfo.bits_per_pixel / 8;
png_set_IHDR(png, info,
vinfo.xres, vinfo.yres, vinfo.bits_per_pixel / 4,
PNG_COLOR_TYPE_RGB_ALPHA, PNG_INTERLACE_NONE,
PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
png_write_info(png, info);
rowlen=vinfo.xres * bytespp;
if (rowlen > sizeof(imgbuf)) {
LOGE("crazy rowlen: %d\n", rowlen);
png_destroy_write_struct(&png, NULL);
fclose(fb_in);
return;
}
offset = vinfo.xoffset * bytespp + vinfo.xres * vinfo.yoffset * bytespp;
fseek(fb_in, offset, SEEK_SET);
for(r=0; r<vinfo.yres; r++) {
int len = fread(imgbuf, 1, rowlen, fb_in);
if (len <= 0) break;
png_write_row(png, (png_bytep)imgbuf);
}
png_write_end(png, info);
fclose(fb_in);
png_destroy_write_struct(&png, NULL);
}
int main(int argc, char**argv) {
FILE *png = NULL;
FILE *fb_in = NULL;
if (argc < 2) {
fprintf(stderr, "usage: screenshot filename.png\n");
exit(1);
}
fb_in = fopen("/dev/graphics/fb0", "r");
if (!fb_in) {
fprintf(stderr, "error: could not read framebuffer\n");
exit(1);
}
/* switch to non-root user and group */
gid_t groups[] = { AID_LOG, AID_SDCARD_RW };
setgroups(sizeof(groups)/sizeof(groups[0]), groups);
setuid(AID_SHELL);
png = fopen(argv[1], "w");
if (!png) {
fprintf(stderr, "error: writing file %s: %s\n", argv[1], strerror(errno));
exit(1);
}
take_screenshot(fb_in, png);
exit(0);
}
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