1 /*
2 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
3 *
4 * This code is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 only, as
6 * published by the Free Software Foundation. Oracle designates this
7 * particular file as subject to the "Classpath" exception as provided
8 * by Oracle in the LICENSE file that accompanied this code.
9 *
10 * This code is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
13 * version 2 for more details (a copy is included in the LICENSE file that
14 * accompanied this code).
15 *
16 * You should have received a copy of the GNU General Public License version
17 * 2 along with this work; if not, write to the Free Software Foundation,
18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
19 *
20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21 * or visit www.oracle.com if you need additional information or have any
22 * questions.
23 */
24
25 /* pngwio.c - functions for data output
26 *
27 * This file is available under and governed by the GNU General Public
28 * License version 2 only, as published by the Free Software Foundation.
29 * However, the following notice accompanied the original version of this
30 * file and, per its terms, should not be removed:
31 *
32 * Last changed in libpng 1.6.15 [November 20, 2014]
33 * Copyright (c) 1998-2002,2004,2006-2014 Glenn Randers-Pehrson
34 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
35 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
36 *
37 * This code is released under the libpng license.
38 * For conditions of distribution and use, see the disclaimer
39 * and license in png.h
40 *
41 * This file provides a location for all output. Users who need
42 * special handling are expected to write functions that have the same
43 * arguments as these and perform similar functions, but that possibly
44 * use different output methods. Note that you shouldn't change these
45 * functions, but rather write replacement functions and then change
46 * them at run time with png_set_write_fn(...).
47 */
48
49 #include "pngpriv.h"
50
51 #ifdef PNG_WRITE_SUPPORTED
52
53 /* Write the data to whatever output you are using. The default routine
54 * writes to a file pointer. Note that this routine sometimes gets called
55 * with very small lengths, so you should implement some kind of simple
56 * buffering if you are using unbuffered writes. This should never be asked
57 * to write more than 64K on a 16-bit machine.
58 */
59
60 void /* PRIVATE */
61 png_write_data(png_structrp png_ptr, png_const_bytep data, png_size_t length)
62 {
63 /* NOTE: write_data_fn must not change the buffer! */
64 if (png_ptr->write_data_fn != NULL )
65 (*(png_ptr->write_data_fn))(png_ptr, png_constcast(png_bytep,data),
66 length);
67
68 else
69 png_error(png_ptr, "Call to NULL write function");
70 }
71
72 #ifdef PNG_STDIO_SUPPORTED
73 /* This is the function that does the actual writing of data. If you are
74 * not writing to a standard C stream, you should create a replacement
75 * write_data function and use it at run time with png_set_write_fn(), rather
76 * than changing the library.
77 */
78 void PNGCBAPI
79 png_default_write_data(png_structp png_ptr, png_bytep data, png_size_t length)
80 {
81 png_size_t check;
82
83 if (png_ptr == NULL)
84 return;
85
86 check = fwrite(data, 1, length, (png_FILE_p)(png_ptr->io_ptr));
87
88 if (check != length)
89 png_error(png_ptr, "Write Error");
90 }
91 #endif
92
93 /* This function is called to output any data pending writing (normally
94 * to disk). After png_flush is called, there should be no data pending
95 * writing in any buffers.
96 */
97 #ifdef PNG_WRITE_FLUSH_SUPPORTED
98 void /* PRIVATE */
99 png_flush(png_structrp png_ptr)
100 {
101 if (png_ptr->output_flush_fn != NULL)
102 (*(png_ptr->output_flush_fn))(png_ptr);
103 }
104
105 # ifdef PNG_STDIO_SUPPORTED
106 void PNGCBAPI
107 png_default_flush(png_structp png_ptr)
108 {
109 png_FILE_p io_ptr;
110
111 if (png_ptr == NULL)
112 return;
113
114 io_ptr = png_voidcast(png_FILE_p, (png_ptr->io_ptr));
115 fflush(io_ptr);
116 }
117 # endif
118 #endif
119
120 /* This function allows the application to supply new output functions for
121 * libpng if standard C streams aren't being used.
122 *
123 * This function takes as its arguments:
124 * png_ptr - pointer to a png output data structure
125 * io_ptr - pointer to user supplied structure containing info about
126 * the output functions. May be NULL.
127 * write_data_fn - pointer to a new output function that takes as its
128 * arguments a pointer to a png_struct, a pointer to
129 * data to be written, and a 32-bit unsigned int that is
130 * the number of bytes to be written. The new write
131 * function should call png_error(png_ptr, "Error msg")
132 * to exit and output any fatal error messages. May be
133 * NULL, in which case libpng's default function will
134 * be used.
135 * flush_data_fn - pointer to a new flush function that takes as its
136 * arguments a pointer to a png_struct. After a call to
137 * the flush function, there should be no data in any buffers
138 * or pending transmission. If the output method doesn't do
139 * any buffering of output, a function prototype must still be
140 * supplied although it doesn't have to do anything. If
141 * PNG_WRITE_FLUSH_SUPPORTED is not defined at libpng compile
142 * time, output_flush_fn will be ignored, although it must be
143 * supplied for compatibility. May be NULL, in which case
144 * libpng's default function will be used, if
145 * PNG_WRITE_FLUSH_SUPPORTED is defined. This is not
146 * a good idea if io_ptr does not point to a standard
147 * *FILE structure.
148 */
149 void PNGAPI
150 png_set_write_fn(png_structrp png_ptr, png_voidp io_ptr,
151 png_rw_ptr write_data_fn, png_flush_ptr output_flush_fn)
152 {
153 if (png_ptr == NULL)
154 return;
155
156 png_ptr->io_ptr = io_ptr;
157
158 #ifdef PNG_STDIO_SUPPORTED
159 if (write_data_fn != NULL)
160 png_ptr->write_data_fn = write_data_fn;
161
162 else
163 png_ptr->write_data_fn = png_default_write_data;
164 #else
165 png_ptr->write_data_fn = write_data_fn;
166 #endif
167
168 #ifdef PNG_WRITE_FLUSH_SUPPORTED
169 # ifdef PNG_STDIO_SUPPORTED
170
171 if (output_flush_fn != NULL)
172 png_ptr->output_flush_fn = output_flush_fn;
173
174 else
175 png_ptr->output_flush_fn = png_default_flush;
176
177 # else
178 png_ptr->output_flush_fn = output_flush_fn;
179 # endif
180 #else
181 PNG_UNUSED(output_flush_fn)
182 #endif /* WRITE_FLUSH */
183
184 #ifdef PNG_READ_SUPPORTED
185 /* It is an error to read while writing a png file */
186 if (png_ptr->read_data_fn != NULL)
187 {
188 png_ptr->read_data_fn = NULL;
189
190 png_warning(png_ptr,
191 "Can't set both read_data_fn and write_data_fn in the"
192 " same structure");
193 }
194 #endif
195 }
196 #endif /* WRITE */