/**
* scrotty — Screenshot program for Linux's TTY
*
* Copyright © 2014, 2015 Mattias Andrée (maandree@member.fsf.org)
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "common.h"
#include "png.h"
#include "kern.h"
/*
* Rationale:
*
* Users want their files in PNG (most often), not PNM.
* Calling an external program for conversion poses
* potential security risks, and is significantly slower.
*/
/**
* Create an PNG file.
*
* @param fbfd The file descriptor connected to framebuffer device.
* @param width The width of the image.
* @param height The height of the image.
* @param imgfd The file descriptor connected to conversion process's stdin.
* @param data Additional data for `convert_fb_to_pnm`
* and `convert_fb_to_png`.
* @return Zero on success, -1 on error.
*/
int
save_png (int fbfd, long width, long height, int imgfd, void *restrict data)
{
char buf[8 << 10];
FILE *file = NULL;
ssize_t got, off;
size_t adjustment;
png_byte *restrict pixbuf = NULL;
png_struct *pngbuf = NULL;
png_info *pnginfo = NULL;
long width3, state = 0;
int rc, saved_errno;
/* Get a FILE * for the output, libpng wants a FILE *, not a file descriptor. */
file = fdopen (imgfd, "w");
if (file == NULL)
goto fail;
/* Allocte structures for the PNG. */
width3 = width * 3;
pixbuf = malloc ((size_t)width3 * sizeof (png_byte));
if (pixbuf == NULL)
goto fail;
pngbuf = png_create_write_struct (png_get_libpng_ver (NULL), NULL, NULL, NULL);
if (pngbuf == NULL)
goto fail;
pnginfo = png_create_info_struct (pngbuf);
if (pnginfo == NULL)
goto fail;
/* Initialise PNG write, and write head. */
if (setjmp (png_jmpbuf(pngbuf))) /* Failing libpng calls jump here. */
goto fail;
png_init_io (pngbuf, file);
png_set_IHDR (pngbuf, pnginfo, (png_uint_32)width, (png_uint_32)height,
8 /* bit depth */, PNG_COLOR_TYPE_RGB, PNG_INTERLACE_NONE,
PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
png_write_info (pngbuf, pnginfo);
/* TODO (maybe) The image shall be packed. That is, if 24 bits per pixel is
* unnecessary, less shall be used. 6 bits is often sufficient. */
/* Convert raw framebuffer data into a PNG image (body). */
for (off = 0;;)
{
/* Read data from the framebuffer, we may have up to 3 bytes buffered. */
got = read (fbfd, buf + off, sizeof (buf) - (size_t)off * sizeof (char));
if (got < 0)
goto fail;
if (got == 0)
break;
got += off;
/* Convert read pixels. */
if (convert_fb_to_png (pngbuf, pixbuf, buf, (size_t)got,
width3, &adjustment, &state, data) < 0)
goto fail;
/* If we read a whole number of pixels, reset the buffer, otherwise,
move the unconverted bytes to the beginning of the buffer. */
if (adjustment)
{
off -= (ssize_t)adjustment;
memcpy (buf, buf + off, (size_t)(got - off) * sizeof (char));
off = got - off;
}
else
off = 0;
}
/* Done! */
png_write_end (pngbuf, pnginfo);
rc = 0;
goto cleanup;
fail:
saved_errno = errno;
rc = -1;
goto cleanup;
cleanup:
png_destroy_write_struct (&pngbuf, (pnginfo ? &pnginfo : NULL));
if (file != NULL)
{
fflush (file);
fclose (file);
}
free (pixbuf);
errno = saved_errno;
return rc;
}
