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annotate libs/libpng/pngrio.c @ 2:334d17aed7de

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author John Tsiombikas <nuclear@member.fsf.org>
date Sun, 02 Feb 2014 18:36:38 +0200
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nuclear@0 1
nuclear@0 2 /* pngrio.c - functions for data input
nuclear@0 3 *
nuclear@0 4 * Last changed in libpng 1.2.30 [August 15, 2008]
nuclear@0 5 * For conditions of distribution and use, see copyright notice in png.h
nuclear@0 6 * Copyright (c) 1998-2008 Glenn Randers-Pehrson
nuclear@0 7 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
nuclear@0 8 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
nuclear@0 9 *
nuclear@0 10 * This file provides a location for all input. Users who need
nuclear@0 11 * special handling are expected to write a function that has the same
nuclear@0 12 * arguments as this and performs a similar function, but that possibly
nuclear@0 13 * has a different input method. Note that you shouldn't change this
nuclear@0 14 * function, but rather write a replacement function and then make
nuclear@0 15 * libpng use it at run time with png_set_read_fn(...).
nuclear@0 16 */
nuclear@0 17
nuclear@0 18 #define PNG_INTERNAL
nuclear@0 19 #include "png.h"
nuclear@0 20 #if defined(PNG_READ_SUPPORTED)
nuclear@0 21
nuclear@0 22 /* Read the data from whatever input you are using. The default routine
nuclear@0 23 reads from a file pointer. Note that this routine sometimes gets called
nuclear@0 24 with very small lengths, so you should implement some kind of simple
nuclear@0 25 buffering if you are using unbuffered reads. This should never be asked
nuclear@0 26 to read more then 64K on a 16 bit machine. */
nuclear@0 27 void /* PRIVATE */
nuclear@0 28 png_read_data(png_structp png_ptr, png_bytep data, png_size_t length)
nuclear@0 29 {
nuclear@0 30 png_debug1(4, "reading %d bytes\n", (int)length);
nuclear@0 31 if (png_ptr->read_data_fn != NULL)
nuclear@0 32 (*(png_ptr->read_data_fn))(png_ptr, data, length);
nuclear@0 33 else
nuclear@0 34 png_error(png_ptr, "Call to NULL read function");
nuclear@0 35 }
nuclear@0 36
nuclear@0 37 #if !defined(PNG_NO_STDIO)
nuclear@0 38 /* This is the function that does the actual reading of data. If you are
nuclear@0 39 not reading from a standard C stream, you should create a replacement
nuclear@0 40 read_data function and use it at run time with png_set_read_fn(), rather
nuclear@0 41 than changing the library. */
nuclear@0 42 #ifndef USE_FAR_KEYWORD
nuclear@0 43 void PNGAPI
nuclear@0 44 png_default_read_data(png_structp png_ptr, png_bytep data, png_size_t length)
nuclear@0 45 {
nuclear@0 46 png_size_t check;
nuclear@0 47
nuclear@0 48 if (png_ptr == NULL) return;
nuclear@0 49 /* fread() returns 0 on error, so it is OK to store this in a png_size_t
nuclear@0 50 * instead of an int, which is what fread() actually returns.
nuclear@0 51 */
nuclear@0 52 #if defined(_WIN32_WCE)
nuclear@0 53 if ( !ReadFile((HANDLE)(png_ptr->io_ptr), data, length, &check, NULL) )
nuclear@0 54 check = 0;
nuclear@0 55 #else
nuclear@0 56 check = (png_size_t)fread(data, (png_size_t)1, length,
nuclear@0 57 (png_FILE_p)png_ptr->io_ptr);
nuclear@0 58 #endif
nuclear@0 59
nuclear@0 60 if (check != length)
nuclear@0 61 png_error(png_ptr, "Read Error");
nuclear@0 62 }
nuclear@0 63 #else
nuclear@0 64 /* this is the model-independent version. Since the standard I/O library
nuclear@0 65 can't handle far buffers in the medium and small models, we have to copy
nuclear@0 66 the data.
nuclear@0 67 */
nuclear@0 68
nuclear@0 69 #define NEAR_BUF_SIZE 1024
nuclear@0 70 #define MIN(a,b) (a <= b ? a : b)
nuclear@0 71
nuclear@0 72 static void PNGAPI
nuclear@0 73 png_default_read_data(png_structp png_ptr, png_bytep data, png_size_t length)
nuclear@0 74 {
nuclear@0 75 int check;
nuclear@0 76 png_byte *n_data;
nuclear@0 77 png_FILE_p io_ptr;
nuclear@0 78
nuclear@0 79 if (png_ptr == NULL) return;
nuclear@0 80 /* Check if data really is near. If so, use usual code. */
nuclear@0 81 n_data = (png_byte *)CVT_PTR_NOCHECK(data);
nuclear@0 82 io_ptr = (png_FILE_p)CVT_PTR(png_ptr->io_ptr);
nuclear@0 83 if ((png_bytep)n_data == data)
nuclear@0 84 {
nuclear@0 85 #if defined(_WIN32_WCE)
nuclear@0 86 if ( !ReadFile((HANDLE)(png_ptr->io_ptr), data, length, &check, NULL) )
nuclear@0 87 check = 0;
nuclear@0 88 #else
nuclear@0 89 check = fread(n_data, 1, length, io_ptr);
nuclear@0 90 #endif
nuclear@0 91 }
nuclear@0 92 else
nuclear@0 93 {
nuclear@0 94 png_byte buf[NEAR_BUF_SIZE];
nuclear@0 95 png_size_t read, remaining, err;
nuclear@0 96 check = 0;
nuclear@0 97 remaining = length;
nuclear@0 98 do
nuclear@0 99 {
nuclear@0 100 read = MIN(NEAR_BUF_SIZE, remaining);
nuclear@0 101 #if defined(_WIN32_WCE)
nuclear@0 102 if ( !ReadFile((HANDLE)(io_ptr), buf, read, &err, NULL) )
nuclear@0 103 err = 0;
nuclear@0 104 #else
nuclear@0 105 err = fread(buf, (png_size_t)1, read, io_ptr);
nuclear@0 106 #endif
nuclear@0 107 png_memcpy(data, buf, read); /* copy far buffer to near buffer */
nuclear@0 108 if (err != read)
nuclear@0 109 break;
nuclear@0 110 else
nuclear@0 111 check += err;
nuclear@0 112 data += read;
nuclear@0 113 remaining -= read;
nuclear@0 114 }
nuclear@0 115 while (remaining != 0);
nuclear@0 116 }
nuclear@0 117 if ((png_uint_32)check != (png_uint_32)length)
nuclear@0 118 png_error(png_ptr, "read Error");
nuclear@0 119 }
nuclear@0 120 #endif
nuclear@0 121 #endif
nuclear@0 122
nuclear@0 123 /* This function allows the application to supply a new input function
nuclear@0 124 for libpng if standard C streams aren't being used.
nuclear@0 125
nuclear@0 126 This function takes as its arguments:
nuclear@0 127 png_ptr - pointer to a png input data structure
nuclear@0 128 io_ptr - pointer to user supplied structure containing info about
nuclear@0 129 the input functions. May be NULL.
nuclear@0 130 read_data_fn - pointer to a new input function that takes as its
nuclear@0 131 arguments a pointer to a png_struct, a pointer to
nuclear@0 132 a location where input data can be stored, and a 32-bit
nuclear@0 133 unsigned int that is the number of bytes to be read.
nuclear@0 134 To exit and output any fatal error messages the new write
nuclear@0 135 function should call png_error(png_ptr, "Error msg"). */
nuclear@0 136 void PNGAPI
nuclear@0 137 png_set_read_fn(png_structp png_ptr, png_voidp io_ptr,
nuclear@0 138 png_rw_ptr read_data_fn)
nuclear@0 139 {
nuclear@0 140 if (png_ptr == NULL) return;
nuclear@0 141 png_ptr->io_ptr = io_ptr;
nuclear@0 142
nuclear@0 143 #if !defined(PNG_NO_STDIO)
nuclear@0 144 if (read_data_fn != NULL)
nuclear@0 145 png_ptr->read_data_fn = read_data_fn;
nuclear@0 146 else
nuclear@0 147 png_ptr->read_data_fn = png_default_read_data;
nuclear@0 148 #else
nuclear@0 149 png_ptr->read_data_fn = read_data_fn;
nuclear@0 150 #endif
nuclear@0 151
nuclear@0 152 /* It is an error to write to a read device */
nuclear@0 153 if (png_ptr->write_data_fn != NULL)
nuclear@0 154 {
nuclear@0 155 png_ptr->write_data_fn = NULL;
nuclear@0 156 png_warning(png_ptr,
nuclear@0 157 "It's an error to set both read_data_fn and write_data_fn in the ");
nuclear@0 158 png_warning(png_ptr,
nuclear@0 159 "same structure. Resetting write_data_fn to NULL.");
nuclear@0 160 }
nuclear@0 161
nuclear@0 162 #if defined(PNG_WRITE_FLUSH_SUPPORTED)
nuclear@0 163 png_ptr->output_flush_fn = NULL;
nuclear@0 164 #endif
nuclear@0 165 }
nuclear@0 166 #endif /* PNG_READ_SUPPORTED */