4
* Copyright (C) 1992-1994, Thomas G. Lane.
5
* This file is part of the Independent JPEG Group's software.
6
* For conditions of distribution and use, see the accompanying README file.
8
* This file provides a generic implementation of the system-dependent
9
* portion of the JPEG memory manager. This implementation assumes that
10
* you must explicitly construct a name for each temp file.
11
* Also, the problem of determining the amount of memory available
12
* is shoved onto the user.
15
#define JPEG_INTERNALS
18
#include "jmemsys.h" /* import the system-dependent declarations */
20
#ifndef HAVE_STDLIB_H /* <stdlib.h> should declare malloc(),free() */
21
extern void * malloc JPP((size_t size));
22
extern void free JPP((void *ptr));
25
#ifndef SEEK_SET /* pre-ANSI systems may not define this; */
26
#define SEEK_SET 0 /* if not, assume 0 is correct */
29
#ifdef DONT_USE_B_MODE /* define mode parameters for fopen() */
30
#define READ_BINARY "r"
31
#define RW_BINARY "w+"
33
#define READ_BINARY "rb"
34
#define RW_BINARY "w+b"
39
* Selection of a file name for a temporary file.
40
* This is system-dependent!
42
* The code as given is suitable for most Unix systems, and it is easily
43
* modified for most non-Unix systems. Some notes:
44
* 1. The temp file is created in the directory named by TEMP_DIRECTORY.
45
* The default value is /usr/tmp, which is the conventional place for
46
* creating large temp files on Unix. On other systems you'll probably
47
* want to change the file location. You can do this by editing the
48
* #define, or (preferred) by defining TEMP_DIRECTORY in jconfig.h.
50
* 2. If you need to change the file name as well as its location,
51
* you can override the TEMP_FILE_NAME macro. (Note that this is
52
* actually a printf format string; it must contain %s and %d.)
53
* Few people should need to do this.
55
* 3. mktemp() is used to ensure that multiple processes running
56
* simultaneously won't select the same file names. If your system
57
* doesn't have mktemp(), define NO_MKTEMP to do it the hard way.
58
* (If you don't have <errno.h>, also define NO_ERRNO_H.)
60
* 4. You probably want to define NEED_SIGNAL_CATCHER so that cjpeg.c/djpeg.c
61
* will cause the temp files to be removed if you stop the program early.
64
#ifndef TEMP_DIRECTORY /* can override from jconfig.h or Makefile */
65
#define TEMP_DIRECTORY "/usr/tmp/" /* recommended setting for Unix */
68
static int next_file_num; /* to distinguish among several temp files */
72
#ifndef TEMP_FILE_NAME /* can override from jconfig.h or Makefile */
73
#define TEMP_FILE_NAME "%sJPG%03d.TMP"
77
#include <errno.h> /* to define ENOENT */
80
/* ANSI C specifies that errno is a macro, but on older systems it's more
81
* likely to be a plain int variable. And not all versions of errno.h
82
* bother to declare it, so we have to in order to be most portable. Thus:
90
select_file_name (char * fname)
94
/* Keep generating file names till we find one that's not in use */
96
next_file_num++; /* advance counter */
97
sprintf(fname, TEMP_FILE_NAME, TEMP_DIRECTORY, next_file_num);
98
if ((tfile = fopen(fname, READ_BINARY)) == NULL) {
99
/* fopen could have failed for a reason other than the file not
100
* being there; for example, file there but unreadable.
101
* If <errno.h> isn't available, then we cannot test the cause.
109
fclose(tfile); /* oops, it's there; close tfile & try again */
113
#else /* ! NO_MKTEMP */
115
/* Note that mktemp() requires the initial filename to end in six X's */
116
#ifndef TEMP_FILE_NAME /* can override from jconfig.h or Makefile */
117
#define TEMP_FILE_NAME "%sJPG%dXXXXXX"
121
select_file_name (char * fname)
123
next_file_num++; /* advance counter */
124
sprintf(fname, TEMP_FILE_NAME, TEMP_DIRECTORY, next_file_num);
125
mktemp(fname); /* make sure file name is unique */
126
/* mktemp replaces the trailing XXXXXX with a unique string of characters */
129
#endif /* NO_MKTEMP */
133
* Memory allocation and freeing are controlled by the regular library
134
* routines malloc() and free().
138
jpeg_get_small (j_common_ptr cinfo, size_t sizeofobject)
140
return (void *) malloc(sizeofobject);
144
jpeg_free_small (j_common_ptr cinfo, void * object, size_t sizeofobject)
151
* "Large" objects are treated the same as "small" ones.
152
* NB: although we include FAR keywords in the routine declarations,
153
* this file won't actually work in 80x86 small/medium model; at least,
154
* you probably won't be able to process useful-size images in only 64KB.
158
jpeg_get_large (j_common_ptr cinfo, size_t sizeofobject)
160
return (void FAR *) malloc(sizeofobject);
164
jpeg_free_large (j_common_ptr cinfo, void FAR * object, size_t sizeofobject)
171
* This routine computes the total memory space available for allocation.
172
* It's impossible to do this in a portable way; our current solution is
173
* to make the user tell us (with a default value set at compile time).
174
* If you can actually get the available space, it's a good idea to subtract
175
* a slop factor of 5% or so.
178
#ifndef DEFAULT_MAX_MEM /* so can override from makefile */
179
#define DEFAULT_MAX_MEM 1000000L /* default: one megabyte */
183
jpeg_mem_available (j_common_ptr cinfo, long min_bytes_needed,
184
long max_bytes_needed, long already_allocated)
186
return cinfo->mem->max_memory_to_use - already_allocated;
191
* Backing store (temporary file) management.
192
* Backing store objects are only used when the value returned by
193
* jpeg_mem_available is less than the total space needed. You can dispense
194
* with these routines if you have plenty of virtual memory; see jmemnobs.c.
199
read_backing_store (j_common_ptr cinfo, backing_store_ptr info,
200
void FAR * buffer_address,
201
long file_offset, long byte_count)
203
if (fseek(info->temp_file, file_offset, SEEK_SET))
204
ERREXIT(cinfo, JERR_TFILE_SEEK);
205
if (JFREAD(info->temp_file, buffer_address, byte_count)
206
!= (size_t) byte_count)
207
ERREXIT(cinfo, JERR_TFILE_READ);
212
write_backing_store (j_common_ptr cinfo, backing_store_ptr info,
213
void FAR * buffer_address,
214
long file_offset, long byte_count)
216
if (fseek(info->temp_file, file_offset, SEEK_SET))
217
ERREXIT(cinfo, JERR_TFILE_SEEK);
218
if (JFWRITE(info->temp_file, buffer_address, byte_count)
219
!= (size_t) byte_count)
220
ERREXIT(cinfo, JERR_TFILE_WRITE);
225
close_backing_store (j_common_ptr cinfo, backing_store_ptr info)
227
fclose(info->temp_file); /* close the file */
228
unlink(info->temp_name); /* delete the file */
229
/* If your system doesn't have unlink(), use remove() instead.
230
* remove() is the ANSI-standard name for this function, but if
231
* your system was ANSI you'd be using jmemansi.c, right?
233
TRACEMSS(cinfo, 1, JTRC_TFILE_CLOSE, info->temp_name);
238
* Initial opening of a backing-store object.
242
jpeg_open_backing_store (j_common_ptr cinfo, backing_store_ptr info,
243
long total_bytes_needed)
245
select_file_name(info->temp_name);
246
if ((info->temp_file = fopen(info->temp_name, RW_BINARY)) == NULL)
247
ERREXITS(cinfo, JERR_TFILE_CREATE, info->temp_name);
248
info->read_backing_store = read_backing_store;
249
info->write_backing_store = write_backing_store;
250
info->close_backing_store = close_backing_store;
251
TRACEMSS(cinfo, 1, JTRC_TFILE_OPEN, info->temp_name);
256
* These routines take care of any system-dependent initialization and
261
jpeg_mem_init (j_common_ptr cinfo)
263
next_file_num = 0; /* initialize temp file name generator */
264
return DEFAULT_MAX_MEM; /* default for max_memory_to_use */
268
jpeg_mem_term (j_common_ptr cinfo)