1 /*
2 * jmemname.c
3 *
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.
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 #define READ_BINARY "rb"
34 #define RW_BINARY "w+b"
35 #endif
36
37
38 /*
39 * Selection of a file name for a temporary file.
40 * This is system-dependent!
41 *
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.
49 *
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.
54 *
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.)
59 *
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.
62 */
63
64 #ifndef TEMP_DIRECTORY /* can override from jconfig.h or Makefile */
65 #define TEMP_DIRECTORY "/usr/tmp/" /* recommended setting for Unix */
66 #endif
67
68 static int next_file_num; /* to distinguish among several temp files */
69
70 #ifdef NO_MKTEMP
71
72 #ifndef TEMP_FILE_NAME /* can override from jconfig.h or Makefile */
73 #define TEMP_FILE_NAME "%sJPG%03d.TMP"
74 #endif
75
76 #ifndef NO_ERRNO_H
77 #include <errno.h> /* to define ENOENT */
78 #endif
79
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:
83 */
84 #ifndef errno
85 extern int errno;
86 #endif
87
88
89 LOCAL void
select_file_name(char * fname)90 select_file_name (char * fname)
91 {
92 FILE * tfile;
93
94 /* Keep generating file names till we find one that's not in use */
95 for (;;) {
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.
102 */
103 #ifdef ENOENT
104 if (errno != ENOENT)
105 continue;
106 #endif
107 break;
108 }
109 fclose(tfile); /* oops, it's there; close tfile & try again */
110 }
111 }
112
113 #else /* ! NO_MKTEMP */
114
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"
118 #endif
119
120 LOCAL void
select_file_name(char * fname)121 select_file_name (char * fname)
122 {
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 */
127 }
128
129 #endif /* NO_MKTEMP */
130
131
132 /*
133 * Memory allocation and freeing are controlled by the regular library
134 * routines malloc() and free().
135 */
136
137 GLOBAL void *
jpeg_get_small(j_common_ptr cinfo,size_t sizeofobject)138 jpeg_get_small (j_common_ptr cinfo, size_t sizeofobject)
139 {
140 return (void *) malloc(sizeofobject);
141 }
142
143 GLOBAL void
jpeg_free_small(j_common_ptr cinfo,void * object,size_t sizeofobject)144 jpeg_free_small (j_common_ptr cinfo, void * object, size_t sizeofobject)
145 {
146 free(object);
147 }
148
149
150 /*
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.
155 */
156
157 GLOBAL void FAR *
jpeg_get_large(j_common_ptr cinfo,size_t sizeofobject)158 jpeg_get_large (j_common_ptr cinfo, size_t sizeofobject)
159 {
160 return (void FAR *) malloc(sizeofobject);
161 }
162
163 GLOBAL void
jpeg_free_large(j_common_ptr cinfo,void FAR * object,size_t sizeofobject)164 jpeg_free_large (j_common_ptr cinfo, void FAR * object, size_t sizeofobject)
165 {
166 free(object);
167 }
168
169
170 /*
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.
176 */
177
178 #ifndef DEFAULT_MAX_MEM /* so can override from makefile */
179 #define DEFAULT_MAX_MEM 1000000L /* default: one megabyte */
180 #endif
181
182 GLOBAL long
jpeg_mem_available(j_common_ptr cinfo,long min_bytes_needed,long max_bytes_needed,long already_allocated)183 jpeg_mem_available (j_common_ptr cinfo, long min_bytes_needed,
184 long max_bytes_needed, long already_allocated)
185 {
186 return cinfo->mem->max_memory_to_use - already_allocated;
187 }
188
189
190 /*
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.
195 */
196
197
198 METHODDEF void
read_backing_store(j_common_ptr cinfo,backing_store_ptr info,void FAR * buffer_address,long file_offset,long byte_count)199 read_backing_store (j_common_ptr cinfo, backing_store_ptr info,
200 void FAR * buffer_address,
201 long file_offset, long byte_count)
202 {
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);
208 }
209
210
211 METHODDEF void
write_backing_store(j_common_ptr cinfo,backing_store_ptr info,void FAR * buffer_address,long file_offset,long byte_count)212 write_backing_store (j_common_ptr cinfo, backing_store_ptr info,
213 void FAR * buffer_address,
214 long file_offset, long byte_count)
215 {
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);
221 }
222
223
224 METHODDEF void
close_backing_store(j_common_ptr cinfo,backing_store_ptr info)225 close_backing_store (j_common_ptr cinfo, backing_store_ptr info)
226 {
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?
232 */
233 TRACEMSS(cinfo, 1, JTRC_TFILE_CLOSE, info->temp_name);
234 }
235
236
237 /*
238 * Initial opening of a backing-store object.
239 */
240
241 GLOBAL void
jpeg_open_backing_store(j_common_ptr cinfo,backing_store_ptr info,long total_bytes_needed)242 jpeg_open_backing_store (j_common_ptr cinfo, backing_store_ptr info,
243 long total_bytes_needed)
244 {
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);
252 }
253
254
255 /*
256 * These routines take care of any system-dependent initialization and
257 * cleanup required.
258 */
259
260 GLOBAL long
jpeg_mem_init(j_common_ptr cinfo)261 jpeg_mem_init (j_common_ptr cinfo)
262 {
263 next_file_num = 0; /* initialize temp file name generator */
264 return DEFAULT_MAX_MEM; /* default for max_memory_to_use */
265 }
266
267 GLOBAL void
jpeg_mem_term(j_common_ptr cinfo)268 jpeg_mem_term (j_common_ptr cinfo)
269 {
270 /* no work */
271 }
272