1 /*
2 * jmemname.c
3 *
4 * Copyright (C) 1992-1997, 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.
7 *
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.
13 */
14
15 #define JPEG_INTERNALS
16 #include "jinclude.h"
17 #include "jpeglib.h"
18 #include "jmemsys.h" /* import the system-dependent declarations */
19
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));
23 #endif
24
25 #ifndef SEEK_SET /* pre-ANSI systems may not define this; */
26 #define SEEK_SET 0 /* if not, assume 0 is correct */
27 #endif
28
29 #ifdef DONT_USE_B_MODE /* define mode parameters for fopen() */
30 #define READ_BINARY "r"
31 #define RW_BINARY "w+"
32 #else
33 #ifdef VMS /* VMS is very nonstandard */
34 #define READ_BINARY "rb", "ctx=stm"
35 #define RW_BINARY "w+b", "ctx=stm"
36 #else /* standard ANSI-compliant case */
37 #define READ_BINARY "rb"
38 #define RW_BINARY "w+b"
39 #endif
40 #endif
41
42
43 /*
44 * Selection of a file name for a temporary file.
45 * This is system-dependent!
46 *
47 * The code as given is suitable for most Unix systems, and it is easily
48 * modified for most non-Unix systems. Some notes:
49 * 1. The temp file is created in the directory named by TEMP_DIRECTORY.
50 * The default value is /usr/tmp, which is the conventional place for
51 * creating large temp files on Unix. On other systems you'll probably
52 * want to change the file location. You can do this by editing the
53 * #define, or (preferred) by defining TEMP_DIRECTORY in jconfig.h.
54 *
55 * 2. If you need to change the file name as well as its location,
56 * you can override the TEMP_FILE_NAME macro. (Note that this is
57 * actually a printf format string; it must contain %s and %d.)
58 * Few people should need to do this.
59 *
60 * 3. mktemp() is used to ensure that multiple processes running
61 * simultaneously won't select the same file names. If your system
62 * doesn't have mktemp(), define NO_MKTEMP to do it the hard way.
63 * (If you don't have <errno.h>, also define NO_ERRNO_H.)
64 *
65 * 4. You probably want to define NEED_SIGNAL_CATCHER so that cjpeg.c/djpeg.c
66 * will cause the temp files to be removed if you stop the program early.
67 */
68
69 #ifndef TEMP_DIRECTORY /* can override from jconfig.h or Makefile */
70 #define TEMP_DIRECTORY "/usr/tmp/" /* recommended setting for Unix */
71 #endif
72
73 static int next_file_num; /* to distinguish among several temp files */
74
75 #ifdef NO_MKTEMP
76
77 #ifndef TEMP_FILE_NAME /* can override from jconfig.h or Makefile */
78 #define TEMP_FILE_NAME "%sJPG%03d.TMP"
79 #endif
80
81 #ifndef NO_ERRNO_H
82 #include <errno.h> /* to define ENOENT */
83 #endif
84
85 /* ANSI C specifies that errno is a macro, but on older systems it's more
86 * likely to be a plain int variable. And not all versions of errno.h
87 * bother to declare it, so we have to in order to be most portable. Thus:
88 */
89 #ifndef errno
90 extern int errno;
91 #endif
92
93
94 LOCAL(void)
select_file_name(char * fname)95 select_file_name (char * fname)
96 {
97 FILE * tfile;
98
99 /* Keep generating file names till we find one that's not in use */
100 for (;;) {
101 next_file_num++; /* advance counter */
102 sprintf(fname, TEMP_FILE_NAME, TEMP_DIRECTORY, next_file_num);
103 if ((tfile = fopen(fname, READ_BINARY)) == NULL) {
104 /* fopen could have failed for a reason other than the file not
105 * being there; for example, file there but unreadable.
106 * If <errno.h> isn't available, then we cannot test the cause.
107 */
108 #ifdef ENOENT
109 if (errno != ENOENT)
110 continue;
111 #endif
112 break;
113 }
114 fclose(tfile); /* oops, it's there; close tfile & try again */
115 }
116 }
117
118 #else /* ! NO_MKTEMP */
119
120 /* Note that mktemp() requires the initial filename to end in six X's */
121 #ifndef TEMP_FILE_NAME /* can override from jconfig.h or Makefile */
122 #define TEMP_FILE_NAME "%sJPG%dXXXXXX"
123 #endif
124
125 LOCAL(void)
select_file_name(char * fname)126 select_file_name (char * fname)
127 {
128 next_file_num++; /* advance counter */
129 sprintf(fname, TEMP_FILE_NAME, TEMP_DIRECTORY, next_file_num);
130 mktemp(fname); /* make sure file name is unique */
131 /* mktemp replaces the trailing XXXXXX with a unique string of characters */
132 }
133
134 #endif /* NO_MKTEMP */
135
136
137 /*
138 * Memory allocation and freeing are controlled by the regular library
139 * routines malloc() and free().
140 */
141
142 GLOBAL(void *)
jpeg_get_small(j_common_ptr cinfo,size_t sizeofobject)143 jpeg_get_small (j_common_ptr cinfo, size_t sizeofobject)
144 {
145 return (void *) malloc(sizeofobject);
146 }
147
148 GLOBAL(void)
jpeg_free_small(j_common_ptr cinfo,void * object,size_t sizeofobject)149 jpeg_free_small (j_common_ptr cinfo, void * object, size_t sizeofobject)
150 {
151 free(object);
152 }
153
154
155 /*
156 * "Large" objects are treated the same as "small" ones.
157 * NB: although we include FAR keywords in the routine declarations,
158 * this file won't actually work in 80x86 small/medium model; at least,
159 * you probably won't be able to process useful-size images in only 64KB.
160 */
161
162 GLOBAL(void FAR *)
jpeg_get_large(j_common_ptr cinfo,size_t sizeofobject)163 jpeg_get_large (j_common_ptr cinfo, size_t sizeofobject)
164 {
165 return (void FAR *) malloc(sizeofobject);
166 }
167
168 GLOBAL(void)
jpeg_free_large(j_common_ptr cinfo,void FAR * object,size_t sizeofobject)169 jpeg_free_large (j_common_ptr cinfo, void FAR * object, size_t sizeofobject)
170 {
171 free(object);
172 }
173
174
175 /*
176 * This routine computes the total memory space available for allocation.
177 * It's impossible to do this in a portable way; our current solution is
178 * to make the user tell us (with a default value set at compile time).
179 * If you can actually get the available space, it's a good idea to subtract
180 * a slop factor of 5% or so.
181 */
182
183 #ifndef DEFAULT_MAX_MEM /* so can override from makefile */
184 #define DEFAULT_MAX_MEM 1000000L /* default: one megabyte */
185 #endif
186
187 GLOBAL(long)
jpeg_mem_available(j_common_ptr cinfo,long min_bytes_needed,long max_bytes_needed,long already_allocated)188 jpeg_mem_available (j_common_ptr cinfo, long min_bytes_needed,
189 long max_bytes_needed, long already_allocated)
190 {
191 return cinfo->mem->max_memory_to_use - already_allocated;
192 }
193
194
195 /*
196 * Backing store (temporary file) management.
197 * Backing store objects are only used when the value returned by
198 * jpeg_mem_available is less than the total space needed. You can dispense
199 * with these routines if you have plenty of virtual memory; see jmemnobs.c.
200 */
201
202
203 METHODDEF(void)
read_backing_store(j_common_ptr cinfo,backing_store_ptr info,void FAR * buffer_address,long file_offset,long byte_count)204 read_backing_store (j_common_ptr cinfo, backing_store_ptr info,
205 void FAR * buffer_address,
206 long file_offset, long byte_count)
207 {
208 if (fseek(info->temp_file, file_offset, SEEK_SET))
209 ERREXIT(cinfo, JERR_TFILE_SEEK);
210 if (JFREAD(info->temp_file, buffer_address, byte_count)
211 != (size_t) byte_count)
212 ERREXIT(cinfo, JERR_TFILE_READ);
213 }
214
215
216 METHODDEF(void)
write_backing_store(j_common_ptr cinfo,backing_store_ptr info,void FAR * buffer_address,long file_offset,long byte_count)217 write_backing_store (j_common_ptr cinfo, backing_store_ptr info,
218 void FAR * buffer_address,
219 long file_offset, long byte_count)
220 {
221 if (fseek(info->temp_file, file_offset, SEEK_SET))
222 ERREXIT(cinfo, JERR_TFILE_SEEK);
223 if (JFWRITE(info->temp_file, buffer_address, byte_count)
224 != (size_t) byte_count)
225 ERREXIT(cinfo, JERR_TFILE_WRITE);
226 }
227
228
229 METHODDEF(void)
close_backing_store(j_common_ptr cinfo,backing_store_ptr info)230 close_backing_store (j_common_ptr cinfo, backing_store_ptr info)
231 {
232 fclose(info->temp_file); /* close the file */
233 unlink(info->temp_name); /* delete the file */
234 /* If your system doesn't have unlink(), use remove() instead.
235 * remove() is the ANSI-standard name for this function, but if
236 * your system was ANSI you'd be using jmemansi.c, right?
237 */
238 TRACEMSS(cinfo, 1, JTRC_TFILE_CLOSE, info->temp_name);
239 }
240
241
242 /*
243 * Initial opening of a backing-store object.
244 */
245
246 GLOBAL(void)
jpeg_open_backing_store(j_common_ptr cinfo,backing_store_ptr info,long total_bytes_needed)247 jpeg_open_backing_store (j_common_ptr cinfo, backing_store_ptr info,
248 long total_bytes_needed)
249 {
250 select_file_name(info->temp_name);
251 if ((info->temp_file = fopen(info->temp_name, RW_BINARY)) == NULL)
252 ERREXITS(cinfo, JERR_TFILE_CREATE, info->temp_name);
253 info->read_backing_store = read_backing_store;
254 info->write_backing_store = write_backing_store;
255 info->close_backing_store = close_backing_store;
256 TRACEMSS(cinfo, 1, JTRC_TFILE_OPEN, info->temp_name);
257 }
258
259
260 /*
261 * These routines take care of any system-dependent initialization and
262 * cleanup required.
263 */
264
265 GLOBAL(long)
jpeg_mem_init(j_common_ptr cinfo)266 jpeg_mem_init (j_common_ptr cinfo)
267 {
268 next_file_num = 0; /* initialize temp file name generator */
269 return DEFAULT_MAX_MEM; /* default for max_memory_to_use */
270 }
271
272 GLOBAL(void)
jpeg_mem_term(j_common_ptr cinfo)273 jpeg_mem_term (j_common_ptr cinfo)
274 {
275 /* no work */
276 }
277