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)