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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 */ |