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

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