/* png.c - location for general purpose libpng functions
*
* libpng version 1.0.5 - October 15, 1999
* Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
* Copyright (c) 1996, 1997 Andreas Dilger
* Copyright (c) 1998, 1999 Glenn Randers-Pehrson
*
*/
#define PNG_INTERNAL
#define PNG_NO_EXTERN
#include "png.h"
PNG_GET_HEADER
/* Version information for C files. This had better match the version
* string defined in png.h.
*/
char png_libpng_ver
[12] = "1.0.5";
/* Place to hold the signature string for a PNG file. */
png_byte FARDATA png_sig
[8] = {137, 80, 78, 71, 13, 10, 26, 10};
/* Constant strings for known chunk types. If you need to add a chunk,
* add a string holding the name here. If you want to make the code
* portable to EBCDIC machines, use ASCII numbers, not characters.
*/
png_byte FARDATA png_IHDR
[5] = { 73, 72, 68, 82, '\0'};
png_byte FARDATA png_IDAT
[5] = { 73, 68, 65, 84, '\0'};
png_byte FARDATA png_IEND
[5] = { 73, 69, 78, 68, '\0'};
png_byte FARDATA png_PLTE
[5] = { 80, 76, 84, 69, '\0'};
png_byte FARDATA png_bKGD
[5] = { 98, 75, 71, 68, '\0'};
png_byte FARDATA png_cHRM
[5] = { 99, 72, 82, 77, '\0'};
png_byte FARDATA png_gAMA
[5] = {103, 65, 77, 65, '\0'};
png_byte FARDATA png_hIST
[5] = {104, 73, 83, 84, '\0'};
png_byte FARDATA png_oFFs
[5] = {111, 70, 70, 115, '\0'};
png_byte FARDATA png_pCAL
[5] = {112, 67, 65, 76, '\0'};
png_byte FARDATA png_pHYs
[5] = {112, 72, 89, 115, '\0'};
png_byte FARDATA png_sBIT
[5] = {115, 66, 73, 84, '\0'};
png_byte FARDATA png_sRGB
[5] = {115, 82, 71, 66, '\0'};
png_byte FARDATA png_tEXt
[5] = {116, 69, 88, 116, '\0'};
png_byte FARDATA png_tIME
[5] = {116, 73, 77, 69, '\0'};
png_byte FARDATA png_tRNS
[5] = {116, 82, 78, 83, '\0'};
png_byte FARDATA png_zTXt
[5] = {122, 84, 88, 116, '\0'};
/* arrays to facilitate easy interlacing - use pass (0 - 6) as index */
/* start of interlace block */
int FARDATA png_pass_start
[] = {0, 4, 0, 2, 0, 1, 0};
/* offset to next interlace block */
int FARDATA png_pass_inc
[] = {8, 8, 4, 4, 2, 2, 1};
/* start of interlace block in the y direction */
int FARDATA png_pass_ystart
[] = {0, 0, 4, 0, 2, 0, 1};
/* offset to next interlace block in the y direction */
int FARDATA png_pass_yinc
[] = {8, 8, 8, 4, 4, 2, 2};
/* Width of interlace block. This is not currently used - if you need
* it, uncomment it here and in png.h
int FARDATA png_pass_width[] = {8, 4, 4, 2, 2, 1, 1};
*/
/* Height of interlace block. This is not currently used - if you need
* it, uncomment it here and in png.h
int FARDATA png_pass_height[] = {8, 8, 4, 4, 2, 2, 1};
*/
/* Mask to determine which pixels are valid in a pass */
int FARDATA png_pass_mask
[] = {0x80, 0x08, 0x88, 0x22, 0xaa, 0x55, 0xff};
/* Mask to determine which pixels to overwrite while displaying */
int FARDATA png_pass_dsp_mask
[] = {0xff, 0x0f, 0xff, 0x33, 0xff, 0x55, 0xff};
/* Tells libpng that we have already handled the first "num_bytes" bytes
* of the PNG file signature. If the PNG data is embedded into another
* stream we can set num_bytes = 8 so that libpng will not attempt to read
* or write any of the magic bytes before it starts on the IHDR.
*/
void
png_set_sig_bytes
(png_structp png_ptr
, int num_bytes
)
{
png_debug
(1, "in png_set_sig_bytes\n");
if (num_bytes
> 8)
png_error
(png_ptr
, "Too many bytes for PNG signature.");
png_ptr
->sig_bytes
= (png_byte
)(num_bytes
< 0 ? 0 : num_bytes
);
}
/* Checks whether the supplied bytes match the PNG signature. We allow
* checking less than the full 8-byte signature so that those apps that
* already read the first few bytes of a file to determine the file type
* can simply check the remaining bytes for extra assurance. Returns
* an integer less than, equal to, or greater than zero if sig is found,
* respectively, to be less than, to match, or be greater than the correct
* PNG signature (this is the same behaviour as strcmp, memcmp, etc).
*/
int
png_sig_cmp
(png_bytep sig
, png_size_t start
, png_size_t num_to_check
)
{
if (num_to_check
> 8)
num_to_check
= 8;
else if (num_to_check
< 1)
return (0);
if (start
> 7)
return (0);
if (start
+ num_to_check
> 8)
num_to_check
= 8 - start
;
return ((int)(png_memcmp
(&sig
[start
], &png_sig
[start
], num_to_check
)));
}
/* (Obsolete) function to check signature bytes. It does not allow one
* to check a partial signature. This function might be removed in the
* future - use png_sig_cmp(). Returns true (nonzero) if the file is a PNG.
*/
int
png_check_sig
(png_bytep sig
, int num
)
{
return ((int)!png_sig_cmp
(sig
, (png_size_t
)0, (png_size_t
)num
));
}
/* Function to allocate memory for zlib. */
voidpf
png_zalloc
(voidpf png_ptr
, uInt items
, uInt size
)
{
png_uint_32 num_bytes
= (png_uint_32
)items
* size
;
png_voidp ptr
= (png_voidp
)png_malloc
((png_structp
)png_ptr
, num_bytes
);
if (num_bytes
> (png_uint_32
)0x8000L
)
{
png_memset
(ptr
, 0, (png_size_t
)0x8000L
);
png_memset
((png_bytep
)ptr
+ (png_size_t
)0x8000L
, 0,
(png_size_t
)(num_bytes
- (png_uint_32
)0x8000L
));
}
else
{
png_memset
(ptr
, 0, (png_size_t
)num_bytes
);
}
return ((voidpf
)ptr
);
}
/* function to free memory for zlib */
void
png_zfree
(voidpf png_ptr
, voidpf ptr
)
{
png_free
((png_structp
)png_ptr
, (png_voidp
)ptr
);
}
/* Reset the CRC variable to 32 bits of 1's. Care must be taken
* in case CRC is > 32 bits to leave the top bits 0.
*/
void
png_reset_crc
(png_structp png_ptr
)
{
png_ptr
->crc
= crc32
(0, Z_NULL
, 0);
}
/* Calculate the CRC over a section of data. We can only pass as
* much data to this routine as the largest single buffer size. We
* also check that this data will actually be used before going to the
* trouble of calculating it.
*/
void
png_calculate_crc
(png_structp png_ptr
, png_bytep ptr
, png_size_t length
)
{
int need_crc
= 1;
if (png_ptr
->chunk_name
[0] & 0x20) /* ancillary */
{
if ((png_ptr
->flags
& PNG_FLAG_CRC_ANCILLARY_MASK
) ==
(PNG_FLAG_CRC_ANCILLARY_USE
| PNG_FLAG_CRC_ANCILLARY_NOWARN
))
need_crc
= 0;
}
else /* critical */
{
if (png_ptr
->flags
& PNG_FLAG_CRC_CRITICAL_IGNORE
)
need_crc
= 0;
}
if (need_crc
)
png_ptr
->crc
= crc32
(png_ptr
->crc
, ptr
, (uInt
)length
);
}
/* Allocate the memory for an info_struct for the application. We don't
* really need the png_ptr, but it could potentially be useful in the
* future. This should be used in favour of malloc(sizeof(png_info))
* and png_info_init() so that applications that want to use a shared
* libpng don't have to be recompiled if png_info changes size.
*/
png_infop
png_create_info_struct
(png_structp png_ptr
)
{
png_infop info_ptr
;
png_debug
(1, "in png_create_info_struct\n");
if(png_ptr
== NULL
) return (NULL
);
#ifdef PNG_USER_MEM_SUPPORTED
if ((info_ptr
= (png_infop
)png_create_struct_2
(PNG_STRUCT_INFO
,
png_ptr
->malloc_fn
)) != NULL
)
#else
if ((info_ptr
= (png_infop
)png_create_struct
(PNG_STRUCT_INFO
)) != NULL
)
#endif
{
png_info_init
(info_ptr
);
}
return (info_ptr
);
}
/* This function frees the memory associated with a single info struct.
* Normally, one would use either png_destroy_read_struct() or
* png_destroy_write_struct() to free an info struct, but this may be
* useful for some applications.
*/
void
png_destroy_info_struct
(png_structp png_ptr
, png_infopp info_ptr_ptr
)
{
png_infop info_ptr
= NULL
;
png_debug
(1, "in png_destroy_info_struct\n");
if (info_ptr_ptr
!= NULL
)
info_ptr
= *info_ptr_ptr
;
if (info_ptr
!= NULL
)
{
png_info_destroy
(png_ptr
, info_ptr
);
#ifdef PNG_USER_MEM_SUPPORTED
png_destroy_struct_2
((png_voidp
)info_ptr
, png_ptr
->free_fn
);
#else
png_destroy_struct
((png_voidp
)info_ptr
);
#endif
*info_ptr_ptr
= (png_infop
)NULL
;
}
}
/* Initialize the info structure. This is now an internal function (0.89)
* and applications using it are urged to use png_create_info_struct()
* instead.
*/
void
png_info_init
(png_infop info_ptr
)
{
png_debug
(1, "in png_info_init\n");
/* set everything to 0 */
png_memset
(info_ptr
, 0, sizeof (png_info
));
}
/* This is an internal routine to free any memory that the info struct is
* pointing to before re-using it or freeing the struct itself. Recall
* that png_free() checks for NULL pointers for us.
*/
void
png_info_destroy
(png_structp png_ptr
, png_infop info_ptr
)
{
#if defined(PNG_READ_tEXt_SUPPORTED) || defined(PNG_READ_zTXt_SUPPORTED)
png_debug
(1, "in png_info_destroy\n");
if (info_ptr
->text
!= NULL
)
{
int i
;
for (i
= 0; i
< info_ptr
->num_text
; i
++)
{
png_free
(png_ptr
, info_ptr
->text
[i
].
key);
}
png_free
(png_ptr
, info_ptr
->text
);
}
#endif
#if defined(PNG_READ_pCAL_SUPPORTED)
png_free
(png_ptr
, info_ptr
->pcal_purpose
);
png_free
(png_ptr
, info_ptr
->pcal_units
);
if (info_ptr
->pcal_params
!= NULL
)
{
int i
;
for (i
= 0; i
< (int)info_ptr
->pcal_nparams
; i
++)
{
png_free
(png_ptr
, info_ptr
->pcal_params
[i
]);
}
png_free
(png_ptr
, info_ptr
->pcal_params
);
}
#endif
png_info_init
(info_ptr
);
}
/* This function returns a pointer to the io_ptr associated with the user
* functions. The application should free any memory associated with this
* pointer before png_write_destroy() or png_read_destroy() are called.
*/
png_voidp
png_get_io_ptr
(png_structp png_ptr
)
{
return (png_ptr
->io_ptr
);
}
#if !defined(PNG_NO_STDIO)
/* Initialize the default input/output functions for the PNG file. If you
* use your own read or write routines, you can call either png_set_read_fn()
* or png_set_write_fn() instead of png_init_io().
*/
void
png_init_io
(png_structp png_ptr
, FILE
*fp
)
{
png_debug
(1, "in png_init_io\n");
png_ptr
->io_ptr
= (png_voidp
)fp
;
}
#endif
#if defined(PNG_TIME_RFC1123_SUPPORTED)
/* Convert the supplied time into an RFC 1123 string suitable for use in
* a "Creation Time" or other text-based time string.
*/
png_charp
png_convert_to_rfc1123
(png_structp png_ptr
, png_timep ptime
)
{
static PNG_CONST
char short_months
[12][4] =
{"Jan", "Feb", "Mar", "Apr", "May", "Jun",
"Jul", "Aug", "Sep", "Oct", "Nov", "Dec"};
if (png_ptr
->time_buffer
== NULL
)
{
png_ptr
->time_buffer
= (png_charp
)png_malloc
(png_ptr
, (png_uint_32
)(29*
sizeof(char)));
}
#ifdef USE_FAR_KEYWORD
{
char near_time_buf
[29];
sprintf(near_time_buf
, "%d %s %d %02d:%02d:%02d +0000",
ptime
->day
% 32, short_months
[(ptime
->month
- 1) % 12],
ptime
->year
, ptime
->hour
% 24, ptime
->minute
% 60,
ptime
->second
% 61);
png_memcpy
(png_ptr
->time_buffer
, near_time_buf
,
29*sizeof(char));
}
#else
sprintf(png_ptr
->time_buffer
, "%d %s %d %02d:%02d:%02d +0000",
ptime
->day
% 32, short_months
[(ptime
->month
- 1) % 12],
ptime
->year
, ptime
->hour
% 24, ptime
->minute
% 60,
ptime
->second
% 61);
#endif
return ((png_charp
)png_ptr
->time_buffer
);
}
#endif /* PNG_TIME_RFC1123_SUPPORTED */
png_charp
png_get_copyright
(png_structp png_ptr
)
{
if (png_ptr
!= NULL
|| png_ptr
== NULL
) /* silence compiler warning */
return ("\n libpng version 1.0.5 - October 15, 1999\n\
Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.\n\
Copyright (c) 1996, 1997 Andreas Dilger\n\
Copyright (c) 1998, 1999 Glenn Randers-Pehrson\n");
return ("");
}
/* Generate a compiler error if there is an old png.h in the search path. */
void
png_check_version
(version_1_0_5 png_h_is_not_version_1_0_5
)
{
if(png_h_is_not_version_1_0_5
== NULL
)
return;
}