Imported from libpng-0.90.tar
diff --git a/png.c b/png.c
index d582f42..eb69411 100644
--- a/png.c
+++ b/png.c
@@ -1,10 +1,10 @@
/* png.c - location for general purpose png functions
- libpng 1.0 beta 3 - version 0.89
+ libpng 1.0 beta 4 - version 0.90
For conditions of distribution and use, see copyright notice in png.h
Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
- May 25, 1996
+ January 10, 1997
*/
#define PNG_INTERNAL
@@ -13,7 +13,7 @@
/* version information for c files. This better match the version
string defined in png.h */
-char png_libpng_ver[] = "0.89";
+char png_libpng_ver[] = "0.90";
/* place to hold the signiture string for a png file. */
png_byte FARDATA png_sig[8] = {137, 80, 78, 71, 13, 10, 26, 10};
@@ -70,15 +70,52 @@
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)
+{
+ if (num_bytes > 8)
+ png_error(png_ptr, "Too many bytes for PNG signature.");
+
+ png_ptr->sig_bytes = 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, int start, int num_to_check)
+{
+ if (num_to_check > 8)
+ num_to_check = 8;
+ else if (num_to_check < 1)
+ return 0;
+
+ if (start > 7 || start < 0)
+ return 0;
+
+ if (start + num_to_check > 8)
+ num_to_check = 8 - start;
+
+ return (png_memcmp(sig, &png_sig[start], (unsigned int)num_to_check));
+}
+
+/* (Obsolete) function to check signature bytes. It does not allow one
+ to check a partial signature. This function will be removed in the
+ future - use png_sig_cmp(). */
int
png_check_sig(png_bytep sig, int num)
{
- if (num > 8)
- num = 8;
- if (num < 1)
- return 0;
-
- return (!png_memcmp(sig, png_sig, num));
+ return !png_sig_cmp(sig, 0, num);
}
/* Function to allocate memory for zlib. */
@@ -88,7 +125,7 @@
png_voidp ptr;
png_uint_32 num_bytes;
- ptr = png_large_malloc((png_structp)png_ptr,
+ ptr = png_malloc((png_structp)png_ptr,
(png_uint_32)items * (png_uint_32)size);
num_bytes = (png_uint_32)items * (png_uint_32)size;
if (num_bytes > (png_uint_32)0x7fff)
@@ -108,26 +145,27 @@
void
png_zfree(voidpf png_ptr, voidpf ptr)
{
- png_large_free((png_structp)png_ptr, (png_voidp)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 */
+/* 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)
{
/* set crc to all 1's */
+#ifdef PNG_USE_OWN_CRC
png_ptr->crc = 0xffffffffL;
+#else
+ png_ptr->crc = crc32(0, Z_NULL, 0);
+#endif
}
-/* Note: the crc code below was copied from the sample code in the
- PNG spec, with appropriate modifications made to ensure the
- variables are large enough */
-
-/* table of crc's of all 8-bit messages. If you wish to png_malloc this
- table, turn this into a pointer, and png_malloc it in make_crc_table().
+#ifdef PNG_USE_OWN_CRC
+/* Table of CRC's of all 8-bit messages. If you wish to png_malloc this
+ table, turn this into a pointer, and png_malloc() it in make_crc_table().
You may then want to hook it into png_struct and free it with the
- destroy functions. */
+ destroy functions. Another alternative is to pre-fill the table. */
static png_uint_32 crc_table[256];
/* Flag: has the table been computed? Initially false. */
@@ -150,9 +188,9 @@
crc_table_computed = 1;
}
-/* update a running crc with the bytes buf[0..len-1]--the crc should be
+/* Update a running CRC with the bytes buf[0..len-1]--the crc should be
initialized to all 1's, and the transmitted value is the 1's complement
- of the final running crc. */
+ of the final running CRC. */
static png_uint_32
update_crc(png_uint_32 crc, png_bytep buf, png_uint_32 len)
{
@@ -176,8 +214,9 @@
return c;
}
+#endif /* PNG_USE_OWN_CRC */
-/* calculate the crc over a section of data. Note that while we
+/* Calculate the crc over a section of data. Note that while we
are passing in a 32 bit value for length, on 16 bit machines, you
would need to use huge pointers to access all that data. If you
need this, put huge here and above. */
@@ -185,9 +224,18 @@
png_calculate_crc(png_structp png_ptr, png_bytep ptr,
png_uint_32 length)
{
+#ifdef PNG_USE_OWN_CRC
png_ptr->crc = update_crc(png_ptr->crc, ptr, length);
+#else
+ png_ptr->crc = crc32(png_ptr->crc, ptr, length);
+#endif
}
+/* 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)
{
@@ -195,23 +243,65 @@
if ((info_ptr = (png_infop)png_create_struct(PNG_STRUCT_INFO)) != NULL)
{
- png_memset(info_ptr, 0, sizeof(png_info));
- png_ptr->do_free |= PNG_FREE_INFO;
+ 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_info_init(png_infop info)
+png_destroy_info_struct(png_structp png_ptr, png_infopp info_ptr_ptr)
+{
+ png_infop info_ptr = NULL;
+
+ if (info_ptr_ptr)
+ info_ptr = *info_ptr_ptr;
+
+ if (info_ptr)
+ {
+ png_info_destroy(png_ptr, info_ptr);
+
+ png_destroy_struct((png_voidp)info_ptr);
+ *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)
{
/* set everything to 0 */
- png_memset(info, 0, sizeof (png_info));
+ 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. */
+void
+png_info_destroy(png_structp png_ptr, png_infop info_ptr)
+{
+#if defined(PNG_READ_tEXt_SUPPORTED) || defined(PNG_READ_zTXt_SUPPORTED)
+ 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
+
+ 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 and png_read_destroy are called. */
+ pointer before png_write_destroy() or png_read_destroy() are called. */
png_voidp
png_get_io_ptr(png_structp png_ptr)
{