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/*
* pnglite.c - pnglite library
* For conditions of distribution and use, see copyright notice in pnglite.h
*/
/*
* Note: this source is updated to enable build for FreeBSD boot loader.
*/
#ifdef _STANDALONE
#include <sys/cdefs.h>
#include <stand.h>
#else
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#endif
#include <zlib.h>
#include "pnglite.h"
#ifndef abs
#define abs(x) ((x) < 0? -(x):(x))
#endif
#define PNG_32b(b, s) ((uint32_t)(b) << (s))
#define PNG_U32(b1, b2, b3, b4) \
(PNG_32b(b1, 24) | PNG_32b(b2, 16) | PNG_32b(b3, 8) | PNG_32b(b4, 0))
#define png_IDAT PNG_U32(73, 68, 65, 84)
#define png_IEND PNG_U32(73, 69, 78, 68)
static ssize_t
file_read(png_t *png, void *out, size_t size, size_t numel)
{
ssize_t result;
off_t offset = (off_t)(size * numel);
if (offset < 0)
return (PNG_FILE_ERROR);
if (!out) {
result = lseek(png->fd, offset, SEEK_CUR);
} else {
result = read(png->fd, out, size * numel);
}
return (result);
}
static int
file_read_ul(png_t *png, unsigned *out)
{
uint8_t buf[4];
if (file_read(png, buf, 1, 4) != 4)
return (PNG_FILE_ERROR);
*out = (buf[0]<<24) | (buf[1]<<16) | (buf[2]<<8) | buf[3];
return (PNG_NO_ERROR);
}
static unsigned
get_ul(uint8_t *buf)
{
unsigned result;
uint8_t foo[4];
memcpy(foo, buf, 4);
result = (foo[0]<<24) | (foo[1]<<16) | (foo[2]<<8) | foo[3];
return (result);
}
static int
png_get_bpp(png_t *png)
{
int bpp;
switch (png->color_type) {
case PNG_GREYSCALE:
bpp = 1; break;
case PNG_TRUECOLOR:
bpp = 3; break;
case PNG_INDEXED:
bpp = 1; break;
case PNG_GREYSCALE_ALPHA:
bpp = 2; break;
case PNG_TRUECOLOR_ALPHA:
bpp = 4; break;
default:
return (PNG_FILE_ERROR);
}
bpp *= png->depth / 8;
return (bpp);
}
static int
png_read_ihdr(png_t *png)
{
unsigned length = 0;
unsigned orig_crc;
unsigned calc_crc;
uint8_t ihdr[13+4]; /* length should be 13, make room for type (IHDR) */
if (file_read_ul(png, &length) != PNG_NO_ERROR)
return (PNG_FILE_ERROR);
if (length != 13)
return (PNG_CRC_ERROR);
if (file_read(png, ihdr, 1, 13+4) != 13+4)
return (PNG_EOF_ERROR);
if (file_read_ul(png, &orig_crc) != PNG_NO_ERROR)
return (PNG_FILE_ERROR);
calc_crc = crc32(0L, Z_NULL, 0);
calc_crc = crc32(calc_crc, ihdr, 13+4);
if (orig_crc != calc_crc) {
return (PNG_CRC_ERROR);
}
png->width = get_ul(ihdr+4);
png->height = get_ul(ihdr+8);
png->depth = ihdr[12];
png->color_type = ihdr[13];
png->compression_method = ihdr[14];
png->filter_method = ihdr[15];
png->interlace_method = ihdr[16];
if (png->color_type == PNG_INDEXED)
return (PNG_NOT_SUPPORTED);
if (png->depth != 8 && png->depth != 16)
return (PNG_NOT_SUPPORTED);
if (png->interlace_method)
return (PNG_NOT_SUPPORTED);
return (PNG_NO_ERROR);
}
void
png_print_info(png_t *png)
{
printf("PNG INFO:\n");
printf("\twidth:\t\t%d\n", png->width);
printf("\theight:\t\t%d\n", png->height);
printf("\tdepth:\t\t%d\n", png->depth);
printf("\tcolor:\t\t");
switch (png->color_type) {
case PNG_GREYSCALE:
printf("greyscale\n"); break;
case PNG_TRUECOLOR:
printf("truecolor\n"); break;
case PNG_INDEXED:
printf("palette\n"); break;
case PNG_GREYSCALE_ALPHA:
printf("greyscale with alpha\n"); break;
case PNG_TRUECOLOR_ALPHA:
printf("truecolor with alpha\n"); break;
default:
printf("unknown, this is not good\n"); break;
}
printf("\tcompression:\t%s\n",
png->compression_method?
"unknown, this is not good":"inflate/deflate");
printf("\tfilter:\t\t%s\n",
png->filter_method? "unknown, this is not good":"adaptive");
printf("\tinterlace:\t%s\n",
png->interlace_method? "interlace":"no interlace");
}
int
png_open(png_t *png, const char *filename)
{
char header[8];
int result;
png->image = NULL;
png->fd = open(filename, O_RDONLY);
if (png->fd == -1)
return (PNG_FILE_ERROR);
if (file_read(png, header, 1, 8) != 8) {
result = PNG_EOF_ERROR;
goto done;
}
if (memcmp(header, "\x89\x50\x4E\x47\x0D\x0A\x1A\x0A", 8) != 0) {
result = PNG_HEADER_ERROR;
goto done;
}
result = png_read_ihdr(png);
if (result == PNG_NO_ERROR) {
result = png_get_bpp(png);
if (result > 0) {
png->bpp = (uint8_t)result;
result = PNG_NO_ERROR;
}
}
done:
if (result == PNG_NO_ERROR) {
uint64_t size = png->width * png->height * png->bpp;
if (size < UINT_MAX)
png->image = malloc(size);
if (png->image == NULL)
result = PNG_MEMORY_ERROR;
}
if (result == PNG_NO_ERROR)
result = png_get_data(png, png->image);
if (result != PNG_NO_ERROR) {
free(png->image);
(void) close(png->fd);
png->fd = -1;
return (result);
}
return (result);
}
int
png_close(png_t *png)
{
(void) close(png->fd);
png->fd = -1;
free(png->image);
png->image = NULL;
return (PNG_NO_ERROR);
}
static int
png_init_inflate(png_t *png)
{
z_stream *stream;
png->zs = calloc(1, sizeof (z_stream));
stream = png->zs;
if (!stream)
return (PNG_MEMORY_ERROR);
if (inflateInit(stream) != Z_OK) {
free(png->zs);
png->zs = NULL;
return (PNG_ZLIB_ERROR);
}
stream->next_out = png->png_data;
stream->avail_out = png->png_datalen;
return (PNG_NO_ERROR);
}
static int
png_end_inflate(png_t *png)
{
z_stream *stream = png->zs;
int rc = PNG_NO_ERROR;
if (!stream)
return (PNG_MEMORY_ERROR);
if (inflateEnd(stream) != Z_OK) {
printf("ZLIB says: %s\n", stream->msg);
rc = PNG_ZLIB_ERROR;
}
free(png->zs);
png->zs = NULL;
return (rc);
}
static int
png_inflate(png_t *png, uint8_t *data, int len)
{
int result;
z_stream *stream = png->zs;
if (!stream)
return (PNG_MEMORY_ERROR);
stream->next_in = data;
stream->avail_in = len;
result = inflate(stream, Z_SYNC_FLUSH);
if (result != Z_STREAM_END && result != Z_OK) {
printf("%s\n", stream->msg);
return (PNG_ZLIB_ERROR);
}
if (stream->avail_in != 0)
return (PNG_ZLIB_ERROR);
return (PNG_NO_ERROR);
}
static int
png_read_idat(png_t *png, unsigned length)
{
unsigned orig_crc;
unsigned calc_crc;
ssize_t len = length;
if (!png->readbuf || png->readbuflen < length) {
png->readbuf = realloc(png->readbuf, length);
png->readbuflen = length;
}
if (!png->readbuf)
return (PNG_MEMORY_ERROR);
if (file_read(png, png->readbuf, 1, length) != len)
return (PNG_FILE_ERROR);
calc_crc = crc32(0L, Z_NULL, 0);
calc_crc = crc32(calc_crc, (uint8_t *)"IDAT", 4);
calc_crc = crc32(calc_crc, (uint8_t *)png->readbuf, length);
if (file_read_ul(png, &orig_crc) != PNG_NO_ERROR)
return (PNG_FILE_ERROR);
if (orig_crc != calc_crc)
return (PNG_CRC_ERROR);
return (png_inflate(png, png->readbuf, length));
}
static int
png_process_chunk(png_t *png)
{
int result = PNG_NO_ERROR;
unsigned type;
unsigned length;
if (file_read_ul(png, &length) != PNG_NO_ERROR)
return (PNG_FILE_ERROR);
if (file_read_ul(png, &type) != PNG_NO_ERROR)
return (PNG_FILE_ERROR);
/*
* if we found an idat, all other idats should be followed with no
* other chunks in between
*/
if (type == png_IDAT) {
if (!png->png_data) { /* first IDAT */
png->png_datalen = png->width * png->height *
png->bpp + png->height;
png->png_data = malloc(png->png_datalen);
}
if (!png->png_data)
return (PNG_MEMORY_ERROR);
if (!png->zs) {
result = png_init_inflate(png);
if (result != PNG_NO_ERROR)
return (result);
}
return (png_read_idat(png, length));
} else if (type == png_IEND)
return (PNG_DONE);
else
(void) file_read(png, 0, 1, length + 4); /* unknown chunk */
return (result);
}
static void
png_filter_sub(unsigned stride, uint8_t *in, uint8_t *out, unsigned len)
{
unsigned i;
uint8_t a = 0;
for (i = 0; i < len; i++) {
if (i >= stride)
a = out[i - stride];
out[i] = in[i] + a;
}
}
static void
png_filter_up(unsigned stride __unused, uint8_t *in, uint8_t *out,
uint8_t *prev_line, unsigned len)
{
unsigned i;
if (prev_line) {
for (i = 0; i < len; i++)
out[i] = in[i] + prev_line[i];
} else
memcpy(out, in, len);
}
static void
png_filter_average(unsigned stride, uint8_t *in, uint8_t *out,
uint8_t *prev_line, unsigned len)
{
unsigned int i;
uint8_t a = 0;
uint8_t b = 0;
unsigned int sum = 0;
for (i = 0; i < len; i++) {
if (prev_line)
b = prev_line[i];
if (i >= stride)
a = out[i - stride];
sum = a;
sum += b;
out[i] = in[i] + sum/2;
}
}
static uint8_t
png_paeth(uint8_t a, uint8_t b, uint8_t c)
{
int p = (int)a + b - c;
int pa = abs(p - a);
int pb = abs(p - b);
int pc = abs(p - c);
int pr;
if (pa <= pb && pa <= pc)
pr = a;
else if (pb <= pc)
pr = b;
else
pr = c;
return (pr);
}
static void
png_filter_paeth(unsigned stride, uint8_t *in, uint8_t *out, uint8_t *prev_line,
unsigned len)
{
unsigned i;
uint8_t a;
uint8_t b;
uint8_t c;
for (i = 0; i < len; i++) {
if (prev_line && i >= stride) {
a = out[i - stride];
b = prev_line[i];
c = prev_line[i - stride];
} else {
if (prev_line)
b = prev_line[i];
else
b = 0;
if (i >= stride)
a = out[i - stride];
else
a = 0;
c = 0;
}
out[i] = in[i] + png_paeth(a, b, c);
}
}
static int
png_unfilter(png_t *png, uint8_t *data)
{
unsigned i;
unsigned pos = 0;
unsigned outpos = 0;
uint8_t *filtered = png->png_data;
unsigned stride = png->bpp;
while (pos < png->png_datalen) {
uint8_t filter = filtered[pos];
pos++;
if (png->depth == 16) {
for (i = 0; i < png->width * stride; i += 2) {
*(short *)(filtered+pos+i) =
(filtered[pos+i] << 8) | filtered[pos+i+1];
}
}
switch (filter) {
case 0: /* none */
memcpy(data+outpos, filtered+pos, png->width * stride);
break;
case 1: /* sub */
png_filter_sub(stride, filtered+pos, data+outpos,
png->width * stride);
break;
case 2: /* up */
if (outpos) {
png_filter_up(stride, filtered+pos, data+outpos,
data + outpos - (png->width*stride),
png->width*stride);
} else {
png_filter_up(stride, filtered+pos, data+outpos,
0, png->width*stride);
}
break;
case 3: /* average */
if (outpos) {
png_filter_average(stride, filtered+pos,
data+outpos,
data + outpos - (png->width*stride),
png->width*stride);
} else {
png_filter_average(stride, filtered+pos,
data+outpos, 0, png->width*stride);
}
break;
case 4: /* paeth */
if (outpos) {
png_filter_paeth(stride, filtered+pos,
data+outpos,
data + outpos - (png->width*stride),
png->width*stride);
} else {
png_filter_paeth(stride, filtered+pos,
data+outpos, 0, png->width*stride);
}
break;
default:
return (PNG_UNKNOWN_FILTER);
}
outpos += png->width * stride;
pos += png->width * stride;
}
return (PNG_NO_ERROR);
}
int
png_get_data(png_t *png, uint8_t *data)
{
int result = PNG_NO_ERROR;
png->zs = NULL;
png->png_datalen = 0;
png->png_data = NULL;
png->readbuf = NULL;
png->readbuflen = 0;
while (result == PNG_NO_ERROR)
result = png_process_chunk(png);
if (png->readbuf) {
free(png->readbuf);
png->readbuflen = 0;
}
if (png->zs)
(void) png_end_inflate(png);
if (result != PNG_DONE) {
free(png->png_data);
return (result);
}
result = png_unfilter(png, data);
free(png->png_data);
return (result);
}
char *
png_error_string(int error)
{
switch (error) {
case PNG_NO_ERROR:
return ("No error");
case PNG_FILE_ERROR:
return ("Unknown file error.");
case PNG_HEADER_ERROR:
return ("No PNG header found. Are you sure this is a PNG?");
case PNG_IO_ERROR:
return ("Failure while reading file.");
case PNG_EOF_ERROR:
return ("Reached end of file.");
case PNG_CRC_ERROR:
return ("CRC or chunk length error.");
case PNG_MEMORY_ERROR:
return ("Could not allocate memory.");
case PNG_ZLIB_ERROR:
return ("zlib reported an error.");
case PNG_UNKNOWN_FILTER:
return ("Unknown filter method used in scanline.");
case PNG_DONE:
return ("PNG done");
case PNG_NOT_SUPPORTED:
return ("The PNG is unsupported by pnglite, too bad for you!");
case PNG_WRONG_ARGUMENTS:
return ("Wrong combination of arguments passed to png_open. "
"You must use either a read_function or supply a file "
"pointer to use.");
default:
return ("Unknown error.");
};
}