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) 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) 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 *) 143 jpeg_get_small (j_common_ptr cinfo, size_t sizeofobject) 144 { 145 return (void *) malloc(sizeofobject); 146 } 147 148 GLOBAL(void) 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 *) 163 jpeg_get_large (j_common_ptr cinfo, size_t sizeofobject) 164 { 165 return (void FAR *) malloc(sizeofobject); 166 } 167 168 GLOBAL(void) 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) 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) 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) 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) 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) 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) 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) 273 jpeg_mem_term (j_common_ptr cinfo) 274 { 275 /* no work */ 276 } 277
