1 | ␍␊ |
2 | /* pngwio.c - functions for data output␍␊ |
3 | *␍␊ |
4 | * Last changed in libpng 1.5.0 [January 6, 2011]␍␊ |
5 | * Copyright (c) 1998-2011 Glenn Randers-Pehrson␍␊ |
6 | * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)␍␊ |
7 | * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)␍␊ |
8 | *␍␊ |
9 | * This code is released under the libpng license.␍␊ |
10 | * For conditions of distribution and use, see the disclaimer␍␊ |
11 | * and license in png.h␍␊ |
12 | *␍␊ |
13 | * This file provides a location for all output. Users who need␍␊ |
14 | * special handling are expected to write functions that have the same␍␊ |
15 | * arguments as these and perform similar functions, but that possibly␍␊ |
16 | * use different output methods. Note that you shouldn't change these␍␊ |
17 | * functions, but rather write replacement functions and then change␍␊ |
18 | * them at run time with png_set_write_fn(...).␍␊ |
19 | */␍␊ |
20 | ␍␊ |
21 | #include "pngpriv.h"␍␊ |
22 | ␍␊ |
23 | #ifdef PNG_WRITE_SUPPORTED␍␊ |
24 | ␍␊ |
25 | /* Write the data to whatever output you are using. The default routine␍␊ |
26 | * writes to a file pointer. Note that this routine sometimes gets called␍␊ |
27 | * with very small lengths, so you should implement some kind of simple␍␊ |
28 | * buffering if you are using unbuffered writes. This should never be asked␍␊ |
29 | * to write more than 64K on a 16 bit machine.␍␊ |
30 | */␍␊ |
31 | ␍␊ |
32 | void /* PRIVATE */␍␊ |
33 | png_write_data(png_structp png_ptr, png_const_bytep data, png_size_t length)␍␊ |
34 | {␍␊ |
35 | /* NOTE: write_data_fn must not change the buffer! */␍␊ |
36 | if (png_ptr->write_data_fn != NULL )␍␊ |
37 | (*(png_ptr->write_data_fn))(png_ptr, (png_bytep)data, length);␍␊ |
38 | ␍␊ |
39 | else␍␊ |
40 | png_error(png_ptr, "Call to NULL write function");␍␊ |
41 | }␍␊ |
42 | ␍␊ |
43 | #ifdef PNG_STDIO_SUPPORTED␍␊ |
44 | /* This is the function that does the actual writing of data. If you are␍␊ |
45 | * not writing to a standard C stream, you should create a replacement␍␊ |
46 | * write_data function and use it at run time with png_set_write_fn(), rather␍␊ |
47 | * than changing the library.␍␊ |
48 | */␍␊ |
49 | #ifndef USE_FAR_KEYWORD␍␊ |
50 | void PNGCBAPI␍␊ |
51 | png_default_write_data(png_structp png_ptr, png_bytep data, png_size_t length)␍␊ |
52 | {␍␊ |
53 | png_size_t check;␍␊ |
54 | ␍␊ |
55 | if (png_ptr == NULL)␍␊ |
56 | return;␍␊ |
57 | ␍␊ |
58 | check = fwrite(data, 1, length, (png_FILE_p)(png_ptr->io_ptr));␍␊ |
59 | ␍␊ |
60 | if (check != length)␍␊ |
61 | png_error(png_ptr, "Write 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 | void PNGCBAPI␍␊ |
73 | png_default_write_data(png_structp png_ptr, png_bytep data, png_size_t length)␍␊ |
74 | {␍␊ |
75 | png_uint_32 check;␍␊ |
76 | png_byte *near_data; /* Needs to be "png_byte *" instead of "png_bytep" */␍␊ |
77 | png_FILE_p io_ptr;␍␊ |
78 | ␍␊ |
79 | if (png_ptr == NULL)␍␊ |
80 | return;␍␊ |
81 | ␍␊ |
82 | /* Check if data really is near. If so, use usual code. */␍␊ |
83 | near_data = (png_byte *)CVT_PTR_NOCHECK(data);␍␊ |
84 | io_ptr = (png_FILE_p)CVT_PTR(png_ptr->io_ptr);␍␊ |
85 | ␍␊ |
86 | if ((png_bytep)near_data == data)␍␊ |
87 | {␍␊ |
88 | check = fwrite(near_data, 1, length, io_ptr);␍␊ |
89 | }␍␊ |
90 | ␍␊ |
91 | else␍␊ |
92 | {␍␊ |
93 | png_byte buf[NEAR_BUF_SIZE];␍␊ |
94 | png_size_t written, remaining, err;␍␊ |
95 | check = 0;␍␊ |
96 | remaining = length;␍␊ |
97 | ␍␊ |
98 | do␍␊ |
99 | {␍␊ |
100 | written = MIN(NEAR_BUF_SIZE, remaining);␍␊ |
101 | png_memcpy(buf, data, written); /* Copy far buffer to near buffer */␍␊ |
102 | err = fwrite(buf, 1, written, io_ptr);␍␊ |
103 | ␍␊ |
104 | if (err != written)␍␊ |
105 | break;␍␊ |
106 | ␍␊ |
107 | else␍␊ |
108 | check += err;␍␊ |
109 | ␍␊ |
110 | data += written;␍␊ |
111 | remaining -= written;␍␊ |
112 | }␍␊ |
113 | while (remaining != 0);␍␊ |
114 | }␍␊ |
115 | ␍␊ |
116 | if (check != length)␍␊ |
117 | png_error(png_ptr, "Write Error");␍␊ |
118 | }␍␊ |
119 | ␍␊ |
120 | #endif␍␊ |
121 | #endif␍␊ |
122 | ␍␊ |
123 | /* This function is called to output any data pending writing (normally␍␊ |
124 | * to disk). After png_flush is called, there should be no data pending␍␊ |
125 | * writing in any buffers.␍␊ |
126 | */␍␊ |
127 | #ifdef PNG_WRITE_FLUSH_SUPPORTED␍␊ |
128 | void /* PRIVATE */␍␊ |
129 | png_flush(png_structp png_ptr)␍␊ |
130 | {␍␊ |
131 | if (png_ptr->output_flush_fn != NULL)␍␊ |
132 | (*(png_ptr->output_flush_fn))(png_ptr);␍␊ |
133 | }␍␊ |
134 | ␍␊ |
135 | # ifdef PNG_STDIO_SUPPORTED␍␊ |
136 | void PNGCBAPI␍␊ |
137 | png_default_flush(png_structp png_ptr)␍␊ |
138 | {␍␊ |
139 | png_FILE_p io_ptr;␍␊ |
140 | ␍␊ |
141 | if (png_ptr == NULL)␍␊ |
142 | return;␍␊ |
143 | ␍␊ |
144 | io_ptr = (png_FILE_p)CVT_PTR((png_ptr->io_ptr));␍␊ |
145 | fflush(io_ptr);␍␊ |
146 | }␍␊ |
147 | # endif␍␊ |
148 | #endif␍␊ |
149 | ␍␊ |
150 | /* This function allows the application to supply new output functions for␍␊ |
151 | * libpng if standard C streams aren't being used.␍␊ |
152 | *␍␊ |
153 | * This function takes as its arguments:␍␊ |
154 | * png_ptr - pointer to a png output data structure␍␊ |
155 | * io_ptr - pointer to user supplied structure containing info about␍␊ |
156 | * the output functions. May be NULL.␍␊ |
157 | * write_data_fn - pointer to a new output function that takes as its␍␊ |
158 | * arguments a pointer to a png_struct, a pointer to␍␊ |
159 | * data to be written, and a 32-bit unsigned int that is␍␊ |
160 | * the number of bytes to be written. The new write␍␊ |
161 | * function should call png_error(png_ptr, "Error msg")␍␊ |
162 | * to exit and output any fatal error messages. May be␍␊ |
163 | * NULL, in which case libpng's default function will␍␊ |
164 | * be used.␍␊ |
165 | * flush_data_fn - pointer to a new flush function that takes as its␍␊ |
166 | * arguments a pointer to a png_struct. After a call to␍␊ |
167 | * the flush function, there should be no data in any buffers␍␊ |
168 | * or pending transmission. If the output method doesn't do␍␊ |
169 | * any buffering of output, a function prototype must still be␍␊ |
170 | * supplied although it doesn't have to do anything. If␍␊ |
171 | * PNG_WRITE_FLUSH_SUPPORTED is not defined at libpng compile␍␊ |
172 | * time, output_flush_fn will be ignored, although it must be␍␊ |
173 | * supplied for compatibility. May be NULL, in which case␍␊ |
174 | * libpng's default function will be used, if␍␊ |
175 | * PNG_WRITE_FLUSH_SUPPORTED is defined. This is not␍␊ |
176 | * a good idea if io_ptr does not point to a standard␍␊ |
177 | * *FILE structure.␍␊ |
178 | */␍␊ |
179 | void PNGAPI␍␊ |
180 | png_set_write_fn(png_structp png_ptr, png_voidp io_ptr,␍␊ |
181 | png_rw_ptr write_data_fn, png_flush_ptr output_flush_fn)␍␊ |
182 | {␍␊ |
183 | if (png_ptr == NULL)␍␊ |
184 | return;␍␊ |
185 | ␍␊ |
186 | png_ptr->io_ptr = io_ptr;␍␊ |
187 | ␍␊ |
188 | #ifdef PNG_STDIO_SUPPORTED␍␊ |
189 | if (write_data_fn != NULL)␍␊ |
190 | png_ptr->write_data_fn = write_data_fn;␍␊ |
191 | ␍␊ |
192 | else␍␊ |
193 | png_ptr->write_data_fn = png_default_write_data;␍␊ |
194 | #else␍␊ |
195 | png_ptr->write_data_fn = write_data_fn;␍␊ |
196 | #endif␍␊ |
197 | ␍␊ |
198 | #ifdef PNG_WRITE_FLUSH_SUPPORTED␍␊ |
199 | # ifdef PNG_STDIO_SUPPORTED␍␊ |
200 | ␍␊ |
201 | if (output_flush_fn != NULL)␍␊ |
202 | png_ptr->output_flush_fn = output_flush_fn;␍␊ |
203 | ␍␊ |
204 | else␍␊ |
205 | png_ptr->output_flush_fn = png_default_flush;␍␊ |
206 | ␍␊ |
207 | # else␍␊ |
208 | png_ptr->output_flush_fn = output_flush_fn;␍␊ |
209 | # endif␍␊ |
210 | #endif /* PNG_WRITE_FLUSH_SUPPORTED */␍␊ |
211 | ␍␊ |
212 | /* It is an error to read while writing a png file */␍␊ |
213 | if (png_ptr->read_data_fn != NULL)␍␊ |
214 | {␍␊ |
215 | png_ptr->read_data_fn = NULL;␍␊ |
216 | ␍␊ |
217 | png_warning(png_ptr,␍␊ |
218 | "Can't set both read_data_fn and write_data_fn in the"␍␊ |
219 | " same structure");␍␊ |
220 | }␍␊ |
221 | }␍␊ |
222 | ␍␊ |
223 | #ifdef USE_FAR_KEYWORD␍␊ |
224 | # ifdef _MSC_VER␍␊ |
225 | void *png_far_to_near(png_structp png_ptr, png_voidp ptr, int check)␍␊ |
226 | {␍␊ |
227 | void *near_ptr;␍␊ |
228 | void FAR *far_ptr;␍␊ |
229 | FP_OFF(near_ptr) = FP_OFF(ptr);␍␊ |
230 | far_ptr = (void FAR *)near_ptr;␍␊ |
231 | ␍␊ |
232 | if (check != 0)␍␊ |
233 | if (FP_SEG(ptr) != FP_SEG(far_ptr))␍␊ |
234 | png_error(png_ptr, "segment lost in conversion");␍␊ |
235 | ␍␊ |
236 | return(near_ptr);␍␊ |
237 | }␍␊ |
238 | # else␍␊ |
239 | void *png_far_to_near(png_structp png_ptr, png_voidp ptr, int check)␍␊ |
240 | {␍␊ |
241 | void *near_ptr;␍␊ |
242 | void FAR *far_ptr;␍␊ |
243 | near_ptr = (void FAR *)ptr;␍␊ |
244 | far_ptr = (void FAR *)near_ptr;␍␊ |
245 | ␍␊ |
246 | if (check != 0)␍␊ |
247 | if (far_ptr != ptr)␍␊ |
248 | png_error(png_ptr, "segment lost in conversion");␍␊ |
249 | ␍␊ |
250 | return(near_ptr);␍␊ |
251 | }␍␊ |
252 | # endif␍␊ |
253 | #endif␍␊ |
254 | #endif /* PNG_WRITE_SUPPORTED */␍␊ |
255 | |