jmemname.c (8136B)
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 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 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 * 138 jpeg_get_small (j_common_ptr cinfo, size_t sizeofobject) 139 { 140 return (void *) malloc(sizeofobject); 141 } 142 143 GLOBAL void 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 * 158 jpeg_get_large (j_common_ptr cinfo, size_t sizeofobject) 159 { 160 return (void FAR *) malloc(sizeofobject); 161 } 162 163 GLOBAL void 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 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 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 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 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 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 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 268 jpeg_mem_term (j_common_ptr cinfo) 269 { 270 /* no work */ 271 }