File: jmemname.c

package info (click to toggle)
libjpeg7 7-2
  • links: PTS
  • area: main
  • in suites: squeeze
  • size: 3,996 kB
  • ctags: 2,846
  • sloc: ansic: 28,470; sh: 10,141; asm: 284; makefile: 128
file content (276 lines) | stat: -rw-r--r-- 8,314 bytes parent folder | download | duplicates (134)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
/*
 * jmemname.c
 *
 * Copyright (C) 1992-1997, Thomas G. Lane.
 * This file is part of the Independent JPEG Group's software.
 * For conditions of distribution and use, see the accompanying README file.
 *
 * This file provides a generic implementation of the system-dependent
 * portion of the JPEG memory manager.  This implementation assumes that
 * you must explicitly construct a name for each temp file.
 * Also, the problem of determining the amount of memory available
 * is shoved onto the user.
 */

#define JPEG_INTERNALS
#include "jinclude.h"
#include "jpeglib.h"
#include "jmemsys.h"		/* import the system-dependent declarations */

#ifndef HAVE_STDLIB_H		/* <stdlib.h> should declare malloc(),free() */
extern void * malloc JPP((size_t size));
extern void free JPP((void *ptr));
#endif

#ifndef SEEK_SET		/* pre-ANSI systems may not define this; */
#define SEEK_SET  0		/* if not, assume 0 is correct */
#endif

#ifdef DONT_USE_B_MODE		/* define mode parameters for fopen() */
#define READ_BINARY	"r"
#define RW_BINARY	"w+"
#else
#ifdef VMS			/* VMS is very nonstandard */
#define READ_BINARY	"rb", "ctx=stm"
#define RW_BINARY	"w+b", "ctx=stm"
#else				/* standard ANSI-compliant case */
#define READ_BINARY	"rb"
#define RW_BINARY	"w+b"
#endif
#endif


/*
 * Selection of a file name for a temporary file.
 * This is system-dependent!
 *
 * The code as given is suitable for most Unix systems, and it is easily
 * modified for most non-Unix systems.  Some notes:
 *  1.  The temp file is created in the directory named by TEMP_DIRECTORY.
 *      The default value is /usr/tmp, which is the conventional place for
 *      creating large temp files on Unix.  On other systems you'll probably
 *      want to change the file location.  You can do this by editing the
 *      #define, or (preferred) by defining TEMP_DIRECTORY in jconfig.h.
 *
 *  2.  If you need to change the file name as well as its location,
 *      you can override the TEMP_FILE_NAME macro.  (Note that this is
 *      actually a printf format string; it must contain %s and %d.)
 *      Few people should need to do this.
 *
 *  3.  mktemp() is used to ensure that multiple processes running
 *      simultaneously won't select the same file names.  If your system
 *      doesn't have mktemp(), define NO_MKTEMP to do it the hard way.
 *      (If you don't have <errno.h>, also define NO_ERRNO_H.)
 *
 *  4.  You probably want to define NEED_SIGNAL_CATCHER so that cjpeg.c/djpeg.c
 *      will cause the temp files to be removed if you stop the program early.
 */

#ifndef TEMP_DIRECTORY		/* can override from jconfig.h or Makefile */
#define TEMP_DIRECTORY  "/usr/tmp/" /* recommended setting for Unix */
#endif

static int next_file_num;	/* to distinguish among several temp files */

#ifdef NO_MKTEMP

#ifndef TEMP_FILE_NAME		/* can override from jconfig.h or Makefile */
#define TEMP_FILE_NAME  "%sJPG%03d.TMP"
#endif

#ifndef NO_ERRNO_H
#include <errno.h>		/* to define ENOENT */
#endif

/* ANSI C specifies that errno is a macro, but on older systems it's more
 * likely to be a plain int variable.  And not all versions of errno.h
 * bother to declare it, so we have to in order to be most portable.  Thus:
 */
#ifndef errno
extern int errno;
#endif


LOCAL(void)
select_file_name (char * fname)
{
  FILE * tfile;

  /* Keep generating file names till we find one that's not in use */
  for (;;) {
    next_file_num++;		/* advance counter */
    sprintf(fname, TEMP_FILE_NAME, TEMP_DIRECTORY, next_file_num);
    if ((tfile = fopen(fname, READ_BINARY)) == NULL) {
      /* fopen could have failed for a reason other than the file not
       * being there; for example, file there but unreadable.
       * If <errno.h> isn't available, then we cannot test the cause.
       */
#ifdef ENOENT
      if (errno != ENOENT)
	continue;
#endif
      break;
    }
    fclose(tfile);		/* oops, it's there; close tfile & try again */
  }
}

#else /* ! NO_MKTEMP */

/* Note that mktemp() requires the initial filename to end in six X's */
#ifndef TEMP_FILE_NAME		/* can override from jconfig.h or Makefile */
#define TEMP_FILE_NAME  "%sJPG%dXXXXXX"
#endif

LOCAL(void)
select_file_name (char * fname)
{
  next_file_num++;		/* advance counter */
  sprintf(fname, TEMP_FILE_NAME, TEMP_DIRECTORY, next_file_num);
  mktemp(fname);		/* make sure file name is unique */
  /* mktemp replaces the trailing XXXXXX with a unique string of characters */
}

#endif /* NO_MKTEMP */


/*
 * Memory allocation and freeing are controlled by the regular library
 * routines malloc() and free().
 */

GLOBAL(void *)
jpeg_get_small (j_common_ptr cinfo, size_t sizeofobject)
{
  return (void *) malloc(sizeofobject);
}

GLOBAL(void)
jpeg_free_small (j_common_ptr cinfo, void * object, size_t sizeofobject)
{
  free(object);
}


/*
 * "Large" objects are treated the same as "small" ones.
 * NB: although we include FAR keywords in the routine declarations,
 * this file won't actually work in 80x86 small/medium model; at least,
 * you probably won't be able to process useful-size images in only 64KB.
 */

GLOBAL(void FAR *)
jpeg_get_large (j_common_ptr cinfo, size_t sizeofobject)
{
  return (void FAR *) malloc(sizeofobject);
}

GLOBAL(void)
jpeg_free_large (j_common_ptr cinfo, void FAR * object, size_t sizeofobject)
{
  free(object);
}


/*
 * This routine computes the total memory space available for allocation.
 * It's impossible to do this in a portable way; our current solution is
 * to make the user tell us (with a default value set at compile time).
 * If you can actually get the available space, it's a good idea to subtract
 * a slop factor of 5% or so.
 */

#ifndef DEFAULT_MAX_MEM		/* so can override from makefile */
#define DEFAULT_MAX_MEM		1000000L /* default: one megabyte */
#endif

GLOBAL(long)
jpeg_mem_available (j_common_ptr cinfo, long min_bytes_needed,
		    long max_bytes_needed, long already_allocated)
{
  return cinfo->mem->max_memory_to_use - already_allocated;
}


/*
 * Backing store (temporary file) management.
 * Backing store objects are only used when the value returned by
 * jpeg_mem_available is less than the total space needed.  You can dispense
 * with these routines if you have plenty of virtual memory; see jmemnobs.c.
 */


METHODDEF(void)
read_backing_store (j_common_ptr cinfo, backing_store_ptr info,
		    void FAR * buffer_address,
		    long file_offset, long byte_count)
{
  if (fseek(info->temp_file, file_offset, SEEK_SET))
    ERREXIT(cinfo, JERR_TFILE_SEEK);
  if (JFREAD(info->temp_file, buffer_address, byte_count)
      != (size_t) byte_count)
    ERREXIT(cinfo, JERR_TFILE_READ);
}


METHODDEF(void)
write_backing_store (j_common_ptr cinfo, backing_store_ptr info,
		     void FAR * buffer_address,
		     long file_offset, long byte_count)
{
  if (fseek(info->temp_file, file_offset, SEEK_SET))
    ERREXIT(cinfo, JERR_TFILE_SEEK);
  if (JFWRITE(info->temp_file, buffer_address, byte_count)
      != (size_t) byte_count)
    ERREXIT(cinfo, JERR_TFILE_WRITE);
}


METHODDEF(void)
close_backing_store (j_common_ptr cinfo, backing_store_ptr info)
{
  fclose(info->temp_file);	/* close the file */
  unlink(info->temp_name);	/* delete the file */
/* If your system doesn't have unlink(), use remove() instead.
 * remove() is the ANSI-standard name for this function, but if
 * your system was ANSI you'd be using jmemansi.c, right?
 */
  TRACEMSS(cinfo, 1, JTRC_TFILE_CLOSE, info->temp_name);
}


/*
 * Initial opening of a backing-store object.
 */

GLOBAL(void)
jpeg_open_backing_store (j_common_ptr cinfo, backing_store_ptr info,
			 long total_bytes_needed)
{
  select_file_name(info->temp_name);
  if ((info->temp_file = fopen(info->temp_name, RW_BINARY)) == NULL)
    ERREXITS(cinfo, JERR_TFILE_CREATE, info->temp_name);
  info->read_backing_store = read_backing_store;
  info->write_backing_store = write_backing_store;
  info->close_backing_store = close_backing_store;
  TRACEMSS(cinfo, 1, JTRC_TFILE_OPEN, info->temp_name);
}


/*
 * These routines take care of any system-dependent initialization and
 * cleanup required.
 */

GLOBAL(long)
jpeg_mem_init (j_common_ptr cinfo)
{
  next_file_num = 0;		/* initialize temp file name generator */
  return DEFAULT_MAX_MEM;	/* default for max_memory_to_use */
}

GLOBAL(void)
jpeg_mem_term (j_common_ptr cinfo)
{
  /* no work */
}