[96425] | 1 |
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| 2 | /* pngwio.c - functions for data output
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| 3 | *
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| 4 | * Copyright (c) 2018 Cosmin Truta
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| 5 | * Copyright (c) 1998-2002,2004,2006-2014,2016,2018 Glenn Randers-Pehrson
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| 6 | * Copyright (c) 1996-1997 Andreas Dilger
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| 7 | * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
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| 8 | *
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| 9 | * This code is released under the libpng license.
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| 10 | * For conditions of distribution and use, see the disclaimer
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| 11 | * and license in png.h
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| 12 | *
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| 13 | * This file provides a location for all output. Users who need
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| 14 | * special handling are expected to write functions that have the same
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| 15 | * arguments as these and perform similar functions, but that possibly
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| 16 | * use different output methods. Note that you shouldn't change these
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| 17 | * functions, but rather write replacement functions and then change
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| 18 | * them at run time with png_set_write_fn(...).
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| 19 | */
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| 20 |
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| 21 | #include "pngpriv.h"
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| 22 |
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| 23 | #ifdef PNG_WRITE_SUPPORTED
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| 24 |
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| 25 | /* Write the data to whatever output you are using. The default routine
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| 26 | * writes to a file pointer. Note that this routine sometimes gets called
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| 27 | * with very small lengths, so you should implement some kind of simple
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| 28 | * buffering if you are using unbuffered writes. This should never be asked
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| 29 | * to write more than 64K on a 16-bit machine.
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| 30 | */
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| 31 |
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| 32 | void /* PRIVATE */
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| 33 | png_write_data(png_structrp png_ptr, png_const_bytep data, size_t length)
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| 34 | {
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| 35 | /* NOTE: write_data_fn must not change the buffer! */
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| 36 | if (png_ptr->write_data_fn != NULL )
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| 37 | (*(png_ptr->write_data_fn))(png_ptr, png_constcast(png_bytep,data),
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| 38 | length);
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| 39 |
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| 40 | else
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| 41 | png_error(png_ptr, "Call to NULL write function");
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| 42 | }
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| 43 |
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| 44 | #ifdef PNG_STDIO_SUPPORTED
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| 45 | /* This is the function that does the actual writing of data. If you are
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| 46 | * not writing to a standard C stream, you should create a replacement
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| 47 | * write_data function and use it at run time with png_set_write_fn(), rather
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| 48 | * than changing the library.
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| 49 | */
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| 50 | void PNGCBAPI
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| 51 | png_default_write_data(png_structp png_ptr, png_bytep data, size_t length)
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| 52 | {
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| 53 | size_t check;
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| 54 |
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| 55 | if (png_ptr == NULL)
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| 56 | return;
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| 57 |
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| 58 | check = fwrite(data, 1, length, (png_FILE_p)(png_ptr->io_ptr));
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| 59 |
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| 60 | if (check != length)
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| 61 | png_error(png_ptr, "Write Error");
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| 62 | }
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| 63 | #endif
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| 64 |
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| 65 | /* This function is called to output any data pending writing (normally
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| 66 | * to disk). After png_flush is called, there should be no data pending
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| 67 | * writing in any buffers.
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| 68 | */
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| 69 | #ifdef PNG_WRITE_FLUSH_SUPPORTED
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| 70 | void /* PRIVATE */
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| 71 | png_flush(png_structrp png_ptr)
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| 72 | {
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| 73 | if (png_ptr->output_flush_fn != NULL)
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| 74 | (*(png_ptr->output_flush_fn))(png_ptr);
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| 75 | }
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| 76 |
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| 77 | # ifdef PNG_STDIO_SUPPORTED
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| 78 | void PNGCBAPI
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| 79 | png_default_flush(png_structp png_ptr)
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| 80 | {
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| 81 | png_FILE_p io_ptr;
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| 82 |
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| 83 | if (png_ptr == NULL)
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| 84 | return;
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| 85 |
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| 86 | io_ptr = png_voidcast(png_FILE_p, (png_ptr->io_ptr));
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| 87 | fflush(io_ptr);
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| 88 | }
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| 89 | # endif
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| 90 | #endif
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| 91 |
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| 92 | /* This function allows the application to supply new output functions for
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| 93 | * libpng if standard C streams aren't being used.
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| 94 | *
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| 95 | * This function takes as its arguments:
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| 96 | * png_ptr - pointer to a png output data structure
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| 97 | * io_ptr - pointer to user supplied structure containing info about
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| 98 | * the output functions. May be NULL.
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| 99 | * write_data_fn - pointer to a new output function that takes as its
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| 100 | * arguments a pointer to a png_struct, a pointer to
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| 101 | * data to be written, and a 32-bit unsigned int that is
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| 102 | * the number of bytes to be written. The new write
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| 103 | * function should call png_error(png_ptr, "Error msg")
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| 104 | * to exit and output any fatal error messages. May be
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| 105 | * NULL, in which case libpng's default function will
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| 106 | * be used.
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| 107 | * flush_data_fn - pointer to a new flush function that takes as its
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| 108 | * arguments a pointer to a png_struct. After a call to
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| 109 | * the flush function, there should be no data in any buffers
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| 110 | * or pending transmission. If the output method doesn't do
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| 111 | * any buffering of output, a function prototype must still be
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| 112 | * supplied although it doesn't have to do anything. If
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| 113 | * PNG_WRITE_FLUSH_SUPPORTED is not defined at libpng compile
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| 114 | * time, output_flush_fn will be ignored, although it must be
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| 115 | * supplied for compatibility. May be NULL, in which case
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| 116 | * libpng's default function will be used, if
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| 117 | * PNG_WRITE_FLUSH_SUPPORTED is defined. This is not
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| 118 | * a good idea if io_ptr does not point to a standard
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| 119 | * *FILE structure.
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| 120 | */
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| 121 | void PNGAPI
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| 122 | png_set_write_fn(png_structrp png_ptr, png_voidp io_ptr,
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| 123 | png_rw_ptr write_data_fn, png_flush_ptr output_flush_fn)
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| 124 | {
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| 125 | if (png_ptr == NULL)
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| 126 | return;
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| 127 |
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| 128 | png_ptr->io_ptr = io_ptr;
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| 129 |
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| 130 | #ifdef PNG_STDIO_SUPPORTED
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| 131 | if (write_data_fn != NULL)
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| 132 | png_ptr->write_data_fn = write_data_fn;
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| 133 |
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| 134 | else
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| 135 | png_ptr->write_data_fn = png_default_write_data;
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| 136 | #else
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| 137 | png_ptr->write_data_fn = write_data_fn;
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| 138 | #endif
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| 139 |
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| 140 | #ifdef PNG_WRITE_FLUSH_SUPPORTED
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| 141 | # ifdef PNG_STDIO_SUPPORTED
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| 142 |
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| 143 | if (output_flush_fn != NULL)
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| 144 | png_ptr->output_flush_fn = output_flush_fn;
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| 145 |
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| 146 | else
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| 147 | png_ptr->output_flush_fn = png_default_flush;
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| 148 |
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| 149 | # else
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| 150 | png_ptr->output_flush_fn = output_flush_fn;
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| 151 | # endif
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| 152 | #else
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| 153 | PNG_UNUSED(output_flush_fn)
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| 154 | #endif /* WRITE_FLUSH */
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| 155 |
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| 156 | #ifdef PNG_READ_SUPPORTED
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| 157 | /* It is an error to read while writing a png file */
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| 158 | if (png_ptr->read_data_fn != NULL)
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| 159 | {
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| 160 | png_ptr->read_data_fn = NULL;
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| 161 |
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| 162 | png_warning(png_ptr,
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| 163 | "Can't set both read_data_fn and write_data_fn in the"
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| 164 | " same structure");
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| 165 | }
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| 166 | #endif
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| 167 | }
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| 168 | #endif /* WRITE */
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