src/png/pngwio.c


/* pngwio.c - functions for data output
 *
 * Last changed in libpng 1.2.37 [June 4, 2009]
 * Copyright (c) 1998-2009 Glenn Randers-Pehrson
 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
 *
 * This code is released under the libpng license.
 * For conditions of distribution and use, see the disclaimer
 * and license in png.h
 *
 * This file provides a location for all output.  Users who need
 * special handling are expected to write functions that have the same
 * arguments as these and perform similar functions, but that possibly
 * use different output methods.  Note that you shouldn't change these
 * functions, but rather write replacement functions and then change
 * them at run time with png_set_write_fn(...).
 */

#define PNG_INTERNAL
#include "png.h"
#ifdef PNG_WRITE_SUPPORTED

/* Write the data to whatever output you are using.  The default routine
 * writes to a file pointer.  Note that this routine sometimes gets called
 * with very small lengths, so you should implement some kind of simple
 * buffering if you are using unbuffered writes.  This should never be asked
 * to write more than 64K on a 16 bit machine.
 */

void /* PRIVATE */
png_write_data(png_structp png_ptr, png_bytep data, png_size_t length)
{
   if (png_ptr->write_data_fn != NULL )
      (*(png_ptr->write_data_fn))(png_ptr, data, length);
   else
      png_error(png_ptr, "Call to NULL write function");
}

#if !defined(PNG_NO_STDIO)
/* This is the function that does the actual writing of data.  If you are
 * not writing to a standard C stream, you should create a replacement
 * write_data function and use it at run time with png_set_write_fn(), rather
 * than changing the library.
 */
#ifndef USE_FAR_KEYWORD
void PNGAPI
png_default_write_data(png_structp png_ptr, png_bytep data, png_size_t length)
{
   png_uint_32 check;

   if (png_ptr == NULL)
      return;
#if defined(_WIN32_WCE)
   if ( !WriteFile((HANDLE)(png_ptr->io_ptr), data, length, &check, NULL) )
      check = 0;
#else
   check = fwrite(data, 1, length, (png_FILE_p)(png_ptr->io_ptr));
#endif
   if (check != length)
      png_error(png_ptr, "Write Error");
}
#else
/* This is the model-independent version. Since the standard I/O library
 * can't handle far buffers in the medium and small models, we have to copy
 * the data.
 */

#define NEAR_BUF_SIZE 1024
#define MIN(a,b) (a <= b ? a : b)

void PNGAPI
png_default_write_data(png_structp png_ptr, png_bytep data, png_size_t length)
{
   png_uint_32 check;
   png_byte *near_data;  /* Needs to be "png_byte *" instead of "png_bytep" */
   png_FILE_p io_ptr;

   if (png_ptr == NULL)
      return;
   /* Check if data really is near. If so, use usual code. */
   near_data = (png_byte *)CVT_PTR_NOCHECK(data);
   io_ptr = (png_FILE_p)CVT_PTR(png_ptr->io_ptr);
   if ((png_bytep)near_data == data)
   {
#if defined(_WIN32_WCE)
      if ( !WriteFile(io_ptr, near_data, length, &check, NULL) )
         check = 0;
#else
      check = fwrite(near_data, 1, length, io_ptr);
#endif
   }
   else
   {
      png_byte buf[NEAR_BUF_SIZE];
      png_size_t written, remaining, err;
      check = 0;
      remaining = length;
      do
      {
         written = MIN(NEAR_BUF_SIZE, remaining);
         png_memcpy(buf, data, written); /* Copy far buffer to near buffer */
#if defined(_WIN32_WCE)
         if ( !WriteFile(io_ptr, buf, written, &err, NULL) )
            err = 0;
#else
         err = fwrite(buf, 1, written, io_ptr);
#endif
         if (err != written)
            break;

         else
            check += err;

         data += written;
         remaining -= written;
      }
      while (remaining != 0);
   }
   if (check != length)
      png_error(png_ptr, "Write Error");
}

#endif
#endif

/* This function is called to output any data pending writing (normally
 * to disk).  After png_flush is called, there should be no data pending
 * writing in any buffers.
 */
#if defined(PNG_WRITE_FLUSH_SUPPORTED)
void /* PRIVATE */
png_flush(png_structp png_ptr)
{
   if (png_ptr->output_flush_fn != NULL)
      (*(png_ptr->output_flush_fn))(png_ptr);
}

#if !defined(PNG_NO_STDIO)
void PNGAPI
png_default_flush(png_structp png_ptr)
{
#if !defined(_WIN32_WCE)
   png_FILE_p io_ptr;
#endif
   if (png_ptr == NULL)
      return;
#if !defined(_WIN32_WCE)
   io_ptr = (png_FILE_p)CVT_PTR((png_ptr->io_ptr));
   fflush(io_ptr);
#endif
}
#endif
#endif

/* This function allows the application to supply new output functions for
 * libpng if standard C streams aren't being used.
 *
 * This function takes as its arguments:
 * png_ptr       - pointer to a png output data structure
 * io_ptr        - pointer to user supplied structure containing info about
 *                 the output functions.  May be NULL.
 * write_data_fn - pointer to a new output function that takes as its
 *                 arguments a pointer to a png_struct, a pointer to
 *                 data to be written, and a 32-bit unsigned int that is
 *                 the number of bytes to be written.  The new write
 *                 function should call png_error(png_ptr, "Error msg")
 *                 to exit and output any fatal error messages.  May be
 *                 NULL, in which case libpng's default function will
 *                 be used.
 * flush_data_fn - pointer to a new flush function that takes as its
 *                 arguments a pointer to a png_struct.  After a call to
 *                 the flush function, there should be no data in any buffers
 *                 or pending transmission.  If the output method doesn't do
 *                 any buffering of ouput, a function prototype must still be
 *                 supplied although it doesn't have to do anything.  If
 *                 PNG_WRITE_FLUSH_SUPPORTED is not defined at libpng compile
 *                 time, output_flush_fn will be ignored, although it must be
 *                 supplied for compatibility.  May be NULL, in which case
 *                 libpng's default function will be used, if
 *                 PNG_WRITE_FLUSH_SUPPORTED is defined.  This is not
 *                 a good idea if io_ptr does not point to a standard
 *                 *FILE structure.
 */
void PNGAPI
png_set_write_fn(png_structp png_ptr, png_voidp io_ptr,
   png_rw_ptr write_data_fn, png_flush_ptr output_flush_fn)
{
   if (png_ptr == NULL)
      return;

   png_ptr->io_ptr = io_ptr;

#if !defined(PNG_NO_STDIO)
   if (write_data_fn != NULL)
      png_ptr->write_data_fn = write_data_fn;

   else
      png_ptr->write_data_fn = png_default_write_data;
#else
   png_ptr->write_data_fn = write_data_fn;
#endif

#if defined(PNG_WRITE_FLUSH_SUPPORTED)
#if !defined(PNG_NO_STDIO)
   if (output_flush_fn != NULL)
      png_ptr->output_flush_fn = output_flush_fn;

   else
      png_ptr->output_flush_fn = png_default_flush;
#else
   png_ptr->output_flush_fn = output_flush_fn;
#endif
#endif /* PNG_WRITE_FLUSH_SUPPORTED */

   /* It is an error to read while writing a png file */
   if (png_ptr->read_data_fn != NULL)
   {
      png_ptr->read_data_fn = NULL;
      png_warning(png_ptr,
         "Attempted to set both read_data_fn and write_data_fn in");
      png_warning(png_ptr,
         "the same structure.  Resetting read_data_fn to NULL.");
   }
}

#if defined(USE_FAR_KEYWORD)
#if defined(_MSC_VER)
void *png_far_to_near(png_structp png_ptr, png_voidp ptr, int check)
{
   void *near_ptr;
   void FAR *far_ptr;
   FP_OFF(near_ptr) = FP_OFF(ptr);
   far_ptr = (void FAR *)near_ptr;

   if (check != 0)
      if (FP_SEG(ptr) != FP_SEG(far_ptr))
         png_error(png_ptr, "segment lost in conversion");

   return(near_ptr);
}
#  else
void *png_far_to_near(png_structp png_ptr, png_voidp ptr, int check)
{
   void *near_ptr;
   void FAR *far_ptr;
   near_ptr = (void FAR *)ptr;
   far_ptr = (void FAR *)near_ptr;

   if (check != 0)
      if (far_ptr != ptr)
         png_error(png_ptr, "segment lost in conversion");

   return(near_ptr);
}
#   endif
#   endif
#endif /* PNG_WRITE_SUPPORTED */
1
2	/* pngwio.c - functions for data output
3	*
4	* Last changed in libpng 1.2.37 [June 4, 2009]
5	* Copyright (c) 1998-2009 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	#define PNG_INTERNAL
22	#include "png.h"
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_bytep data, png_size_t length)
34	{
35	if (png_ptr->write_data_fn != NULL )
36	(*(png_ptr->write_data_fn))(png_ptr, data, length);
37	else
38	png_error(png_ptr, "Call to NULL write function");
39	}
40
41	#if !defined(PNG_NO_STDIO)
42	/* This is the function that does the actual writing of data. If you are
43	* not writing to a standard C stream, you should create a replacement
44	* write_data function and use it at run time with png_set_write_fn(), rather
45	* than changing the library.
46	*/
47	#ifndef USE_FAR_KEYWORD
48	void PNGAPI
49	png_default_write_data(png_structp png_ptr, png_bytep data, png_size_t length)
50	{
51	png_uint_32 check;
52
53	if (png_ptr == NULL)
54	return;
55	#if defined(_WIN32_WCE)
56	if ( !WriteFile((HANDLE)(png_ptr->io_ptr), data, length, &check, NULL) )
57	check = 0;
58	#else
59	check = fwrite(data, 1, length, (png_FILE_p)(png_ptr->io_ptr));
60	#endif
61	if (check != length)
62	png_error(png_ptr, "Write Error");
63	}
64	#else
65	/* This is the model-independent version. Since the standard I/O library
66	* can't handle far buffers in the medium and small models, we have to copy
67	* the data.
68	*/
69
70	#define NEAR_BUF_SIZE 1024
71	#define MIN(a,b) (a <= b ? a : b)
72
73	void PNGAPI
74	png_default_write_data(png_structp png_ptr, png_bytep data, png_size_t length)
75	{
76	png_uint_32 check;
77	png_byte near_data; / Needs to be "png_byte " instead of "png_bytep" /
78	png_FILE_p io_ptr;
79
80	if (png_ptr == NULL)
81	return;
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	if ((png_bytep)near_data == data)
86	{
87	#if defined(_WIN32_WCE)
88	if ( !WriteFile(io_ptr, near_data, length, &check, NULL) )
89	check = 0;
90	#else
91	check = fwrite(near_data, 1, length, io_ptr);
92	#endif
93	}
94	else
95	{
96	png_byte buf[NEAR_BUF_SIZE];
97	png_size_t written, remaining, err;
98	check = 0;
99	remaining = length;
100	do
101	{
102	written = MIN(NEAR_BUF_SIZE, remaining);
103	png_memcpy(buf, data, written); /* Copy far buffer to near buffer */
104	#if defined(_WIN32_WCE)
105	if ( !WriteFile(io_ptr, buf, written, &err, NULL) )
106	err = 0;
107	#else
108	err = fwrite(buf, 1, written, io_ptr);
109	#endif
110	if (err != written)
111	break;
112
113	else
114	check += err;
115
116	data += written;
117	remaining -= written;
118	}
119	while (remaining != 0);
120	}
121	if (check != length)
122	png_error(png_ptr, "Write Error");
123	}
124
125	#endif
126	#endif
127
128	/* This function is called to output any data pending writing (normally
129	* to disk). After png_flush is called, there should be no data pending
130	* writing in any buffers.
131	*/
132	#if defined(PNG_WRITE_FLUSH_SUPPORTED)
133	void /* PRIVATE */
134	png_flush(png_structp png_ptr)
135	{
136	if (png_ptr->output_flush_fn != NULL)
137	(*(png_ptr->output_flush_fn))(png_ptr);
138	}
139
140	#if !defined(PNG_NO_STDIO)
141	void PNGAPI
142	png_default_flush(png_structp png_ptr)
143	{
144	#if !defined(_WIN32_WCE)
145	png_FILE_p io_ptr;
146	#endif
147	if (png_ptr == NULL)
148	return;
149	#if !defined(_WIN32_WCE)
150	io_ptr = (png_FILE_p)CVT_PTR((png_ptr->io_ptr));
151	fflush(io_ptr);
152	#endif
153	}
154	#endif
155	#endif
156
157	/* This function allows the application to supply new output functions for
158	* libpng if standard C streams aren't being used.
159	*
160	* This function takes as its arguments:
161	* png_ptr - pointer to a png output data structure
162	* io_ptr - pointer to user supplied structure containing info about
163	* the output functions. May be NULL.
164	* write_data_fn - pointer to a new output function that takes as its
165	* arguments a pointer to a png_struct, a pointer to
166	* data to be written, and a 32-bit unsigned int that is
167	* the number of bytes to be written. The new write
168	* function should call png_error(png_ptr, "Error msg")
169	* to exit and output any fatal error messages. May be
170	* NULL, in which case libpng's default function will
171	* be used.
172	* flush_data_fn - pointer to a new flush function that takes as its
173	* arguments a pointer to a png_struct. After a call to
174	* the flush function, there should be no data in any buffers
175	* or pending transmission. If the output method doesn't do
176	* any buffering of ouput, a function prototype must still be
177	* supplied although it doesn't have to do anything. If
178	* PNG_WRITE_FLUSH_SUPPORTED is not defined at libpng compile
179	* time, output_flush_fn will be ignored, although it must be
180	* supplied for compatibility. May be NULL, in which case
181	* libpng's default function will be used, if
182	* PNG_WRITE_FLUSH_SUPPORTED is defined. This is not
183	* a good idea if io_ptr does not point to a standard
184	* *FILE structure.
185	*/
186	void PNGAPI
187	png_set_write_fn(png_structp png_ptr, png_voidp io_ptr,
188	png_rw_ptr write_data_fn, png_flush_ptr output_flush_fn)
189	{
190	if (png_ptr == NULL)
191	return;
192
193	png_ptr->io_ptr = io_ptr;
194
195	#if !defined(PNG_NO_STDIO)
196	if (write_data_fn != NULL)
197	png_ptr->write_data_fn = write_data_fn;
198
199	else
200	png_ptr->write_data_fn = png_default_write_data;
201	#else
202	png_ptr->write_data_fn = write_data_fn;
203	#endif
204
205	#if defined(PNG_WRITE_FLUSH_SUPPORTED)
206	#if !defined(PNG_NO_STDIO)
207	if (output_flush_fn != NULL)
208	png_ptr->output_flush_fn = output_flush_fn;
209
210	else
211	png_ptr->output_flush_fn = png_default_flush;
212	#else
213	png_ptr->output_flush_fn = output_flush_fn;
214	#endif
215	#endif /* PNG_WRITE_FLUSH_SUPPORTED */
216
217	/* It is an error to read while writing a png file */
218	if (png_ptr->read_data_fn != NULL)
219	{
220	png_ptr->read_data_fn = NULL;
221	png_warning(png_ptr,
222	"Attempted to set both read_data_fn and write_data_fn in");
223	png_warning(png_ptr,
224	"the same structure. Resetting read_data_fn to NULL.");
225	}
226	}
227
228	#if defined(USE_FAR_KEYWORD)
229	#if defined(_MSC_VER)
230	void *png_far_to_near(png_structp png_ptr, png_voidp ptr, int check)
231	{
232	void *near_ptr;
233	void FAR *far_ptr;
234	FP_OFF(near_ptr) = FP_OFF(ptr);
235	far_ptr = (void FAR *)near_ptr;
236
237	if (check != 0)
238	if (FP_SEG(ptr) != FP_SEG(far_ptr))
239	png_error(png_ptr, "segment lost in conversion");
240
241	return(near_ptr);
242	}
243	# else
244	void *png_far_to_near(png_structp png_ptr, png_voidp ptr, int check)
245	{
246	void *near_ptr;
247	void FAR *far_ptr;
248	near_ptr = (void FAR *)ptr;
249	far_ptr = (void FAR *)near_ptr;
250
251	if (check != 0)
252	if (far_ptr != ptr)
253	png_error(png_ptr, "segment lost in conversion");
254
255	return(near_ptr);
256	}
257	# endif
258	# endif
259	#endif /* PNG_WRITE_SUPPORTED */