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| Rev | Author | Line No. | Line |
|---|---|---|---|
| 4349 | Serge | 1 | |
| 2 | * |
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| 3 | * Last changed in libpng 1.6.0 [February 14, 2013] |
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| 4 | * Copyright (c) 1998-2013 Glenn Randers-Pehrson |
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| 5 | * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger) |
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| 6 | * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.) |
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| 7 | * |
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| 8 | * This code is released under the libpng license. |
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| 9 | * For conditions of distribution and use, see the disclaimer |
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| 10 | * and license in png.h |
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| 11 | * |
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| 12 | * This file provides a location for all input. Users who need |
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| 13 | * special handling are expected to write a function that has the same |
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| 14 | * arguments as this and performs a similar function, but that possibly |
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| 15 | * has a different input method. Note that you shouldn't change this |
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| 16 | * function, but rather write a replacement function and then make |
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| 17 | * libpng use it at run time with png_set_read_fn(...). |
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| 18 | */ |
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| 19 | |||
| 20 | |||
| 21 | |||
| 22 | |||
| 23 | |||
| 24 | |||
| 25 | * reads from a file pointer. Note that this routine sometimes gets called |
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| 26 | * with very small lengths, so you should implement some kind of simple |
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| 27 | * buffering if you are using unbuffered reads. This should never be asked |
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| 28 | * to read more then 64K on a 16 bit machine. |
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| 29 | */ |
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| 30 | void /* PRIVATE */ |
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| 31 | png_read_data(png_structrp png_ptr, png_bytep data, png_size_t length) |
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| 32 | { |
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| 33 | png_debug1(4, "reading %d bytes", (int)length); |
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| 34 | |||
| 35 | |||
| 36 | (*(png_ptr->read_data_fn))(png_ptr, data, length); |
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| 37 | |||
| 38 | |||
| 39 | png_error(png_ptr, "Call to NULL read function"); |
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| 40 | } |
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| 41 | |||
| 42 | |||
| 43 | /* This is the function that does the actual reading of data. If you are |
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| 44 | * not reading from a standard C stream, you should create a replacement |
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| 45 | * read_data function and use it at run time with png_set_read_fn(), rather |
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| 46 | * than changing the library. |
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| 47 | */ |
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| 48 | void PNGCBAPI |
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| 49 | png_default_read_data(png_structp png_ptr, png_bytep data, png_size_t length) |
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| 50 | { |
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| 51 | png_size_t check; |
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| 52 | |||
| 53 | |||
| 54 | return; |
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| 55 | |||
| 56 | |||
| 57 | * instead of an int, which is what fread() actually returns. |
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| 58 | */ |
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| 59 | check = fread(data, 1, length, png_voidcast(png_FILE_p, png_ptr->io_ptr)); |
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| 60 | |||
| 61 | |||
| 62 | png_error(png_ptr, "Read Error"); |
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| 63 | } |
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| 64 | #endif |
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| 65 | |||
| 66 | |||
| 67 | * for libpng if standard C streams aren't being used. |
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| 68 | * |
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| 69 | * This function takes as its arguments: |
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| 70 | * |
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| 71 | * png_ptr - pointer to a png input data structure |
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| 72 | * |
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| 73 | * io_ptr - pointer to user supplied structure containing info about |
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| 74 | * the input functions. May be NULL. |
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| 75 | * |
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| 76 | * read_data_fn - pointer to a new input function that takes as its |
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| 77 | * arguments a pointer to a png_struct, a pointer to |
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| 78 | * a location where input data can be stored, and a 32-bit |
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| 79 | * unsigned int that is the number of bytes to be read. |
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| 80 | * To exit and output any fatal error messages the new write |
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| 81 | * function should call png_error(png_ptr, "Error msg"). |
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| 82 | * May be NULL, in which case libpng's default function will |
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| 83 | * be used. |
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| 84 | */ |
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| 85 | void PNGAPI |
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| 86 | png_set_read_fn(png_structrp png_ptr, png_voidp io_ptr, |
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| 87 | png_rw_ptr read_data_fn) |
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| 88 | { |
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| 89 | if (png_ptr == NULL) |
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| 90 | return; |
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| 91 | |||
| 92 | |||
| 93 | |||
| 94 | |||
| 95 | if (read_data_fn != NULL) |
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| 96 | png_ptr->read_data_fn = read_data_fn; |
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| 97 | |||
| 98 | |||
| 99 | png_ptr->read_data_fn = png_default_read_data; |
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| 100 | #else |
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| 101 | png_ptr->read_data_fn = read_data_fn; |
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| 102 | #endif |
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| 103 | |||
| 104 | |||
| 105 | if (png_ptr->write_data_fn != NULL) |
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| 106 | { |
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| 107 | png_ptr->write_data_fn = NULL; |
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| 108 | png_warning(png_ptr, |
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| 109 | "Can't set both read_data_fn and write_data_fn in the" |
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| 110 | " same structure"); |
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| 111 | } |
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| 112 | |||
| 113 | |||
| 114 | png_ptr->output_flush_fn = NULL; |
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| 115 | #endif |
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| 116 | } |
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| 117 | #endif /* PNG_READ_SUPPORTED */ |
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| 118 |