pngrio.c
Go to the documentation of this file.
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 */
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
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
74 {
75  int check;
76  png_byte *n_data;
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
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 */
png_byte FAR * png_bytep
Definition: pngconf.h:1197
#define MIN(a, b)
Returns the min value between a and b.
Definition: IceTypes.h:146
png_bytep png_bytep png_size_t length
Definition: png.h:1541
#define CVT_PTR_NOCHECK(ptr)
Definition: pngconf.h:1441
#define PNGAPI
Definition: pngconf.h:1386
png_struct FAR * png_structp
Definition: png.h:1108
void PNGAPI png_error(png_structp png_ptr, png_const_charp error_message)
Definition: pngerror.c:36
unsigned char png_byte
Definition: pngconf.h:1120
#define png_memcpy
Definition: pngconf.h:1465
void PNGAPI png_warning(png_structp png_ptr, png_const_charp warning_message)
Definition: pngerror.c:102
#define png_debug1(l, m, p1)
Definition: png.h:2559
png_bytep buf
Definition: png.h:2729
void PNGAPI png_set_read_fn(png_structp png_ptr, png_voidp io_ptr, png_rw_ptr read_data_fn)
Definition: pngrio.c:137
png_voidp io_ptr
Definition: png.h:1974
void png_read_data(png_structp png_ptr, png_bytep data, png_size_t length)
Definition: pngrio.c:28
png_voidp png_rw_ptr read_data_fn
Definition: png.h:1978
void FAR * png_voidp
Definition: pngconf.h:1196
size_t png_size_t
Definition: pngconf.h:1128
JSAMPIMAGE data
Definition: jpeglib.h:945
void PNGAPI png_default_read_data(png_structp png_ptr, png_bytep data, png_size_t length)
Definition: pngrio.c:44
unsigned long png_uint_32
Definition: pngconf.h:1116
FILE * png_FILE_p
Definition: pngconf.h:1210
#define CVT_PTR(ptr)
Definition: pngconf.h:1440


openhrp3
Author(s): AIST, General Robotix Inc., Nakamura Lab of Dept. of Mechano Informatics at University of Tokyo
autogenerated on Sat Apr 13 2019 02:14:24