jmemname.cpp (8579B)
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 FILE * tfile; 92 93 /* Keep generating file names till we find one that's not in use */ 94 for (;; ) { 95 next_file_num++; /* advance counter */ 96 sprintf( fname, TEMP_FILE_NAME, TEMP_DIRECTORY, next_file_num ); 97 if ( ( tfile = fopen( fname, READ_BINARY ) ) == NULL ) { 98 /* fopen could have failed for a reason other than the file not 99 * being there; for example, file there but unreadable. 100 * If <errno.h> isn't available, then we cannot test the cause. 101 */ 102 #ifdef ENOENT 103 if ( errno != ENOENT ) { 104 continue; 105 } 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 next_file_num++; /* advance counter */ 123 sprintf( fname, TEMP_FILE_NAME, TEMP_DIRECTORY, next_file_num ); 124 mktemp( fname ); /* make sure file name is unique */ 125 /* mktemp replaces the trailing XXXXXX with a unique string of characters */ 126 } 127 128 #endif /* NO_MKTEMP */ 129 130 131 /* 132 * Memory allocation and freeing are controlled by the regular library 133 * routines malloc() and free(). 134 */ 135 136 GLOBAL void * 137 jpeg_get_small( j_common_ptr cinfo, size_t sizeofobject ) { 138 return (void *) malloc( sizeofobject ); 139 } 140 141 GLOBAL void 142 jpeg_free_small( j_common_ptr cinfo, void * object, size_t sizeofobject ) { 143 free( object ); 144 } 145 146 147 /* 148 * "Large" objects are treated the same as "small" ones. 149 * NB: although we include FAR keywords in the routine declarations, 150 * this file won't actually work in 80x86 small/medium model; at least, 151 * you probably won't be able to process useful-size images in only 64KB. 152 */ 153 154 GLOBAL void FAR * 155 jpeg_get_large( j_common_ptr cinfo, size_t sizeofobject ) { 156 return (void FAR *) malloc( sizeofobject ); 157 } 158 159 GLOBAL void 160 jpeg_free_large( j_common_ptr cinfo, void FAR * object, size_t sizeofobject ) { 161 free( object ); 162 } 163 164 165 /* 166 * This routine computes the total memory space available for allocation. 167 * It's impossible to do this in a portable way; our current solution is 168 * to make the user tell us (with a default value set at compile time). 169 * If you can actually get the available space, it's a good idea to subtract 170 * a slop factor of 5% or so. 171 */ 172 173 #ifndef DEFAULT_MAX_MEM /* so can override from makefile */ 174 #define DEFAULT_MAX_MEM 1000000L /* default: one megabyte */ 175 #endif 176 177 GLOBAL long 178 jpeg_mem_available( j_common_ptr cinfo, long min_bytes_needed, 179 long max_bytes_needed, long already_allocated ) { 180 return cinfo->mem->max_memory_to_use - already_allocated; 181 } 182 183 184 /* 185 * Backing store (temporary file) management. 186 * Backing store objects are only used when the value returned by 187 * jpeg_mem_available is less than the total space needed. You can dispense 188 * with these routines if you have plenty of virtual memory; see jmemnobs.c. 189 */ 190 191 192 METHODDEF void 193 read_backing_store( j_common_ptr cinfo, backing_store_ptr info, 194 void FAR * buffer_address, 195 long file_offset, long byte_count ) { 196 if ( fseek( info->temp_file, file_offset, SEEK_SET ) ) { 197 ERREXIT( cinfo, JERR_TFILE_SEEK ); 198 } 199 if ( JFREAD( info->temp_file, buffer_address, byte_count ) 200 != (size_t) byte_count ) { 201 ERREXIT( cinfo, JERR_TFILE_READ ); 202 } 203 } 204 205 206 METHODDEF void 207 write_backing_store( j_common_ptr cinfo, backing_store_ptr info, 208 void FAR * buffer_address, 209 long file_offset, long byte_count ) { 210 if ( fseek( info->temp_file, file_offset, SEEK_SET ) ) { 211 ERREXIT( cinfo, JERR_TFILE_SEEK ); 212 } 213 if ( JFWRITE( info->temp_file, buffer_address, byte_count ) 214 != (size_t) byte_count ) { 215 ERREXIT( cinfo, JERR_TFILE_WRITE ); 216 } 217 } 218 219 220 METHODDEF void 221 close_backing_store( j_common_ptr cinfo, backing_store_ptr info ) { 222 fclose( info->temp_file );/* close the file */ 223 unlink( info->temp_name );/* delete the file */ 224 /* If your system doesn't have unlink(), use remove() instead. 225 * remove() is the ANSI-standard name for this function, but if 226 * your system was ANSI you'd be using jmemansi.c, right? 227 */ 228 TRACEMSS( cinfo, 1, JTRC_TFILE_CLOSE, info->temp_name ); 229 } 230 231 232 /* 233 * Initial opening of a backing-store object. 234 */ 235 236 GLOBAL void 237 jpeg_open_backing_store( j_common_ptr cinfo, backing_store_ptr info, 238 long total_bytes_needed ) { 239 select_file_name( info->temp_name ); 240 if ( ( info->temp_file = fopen( info->temp_name, RW_BINARY ) ) == NULL ) { 241 ERREXITS( cinfo, JERR_TFILE_CREATE, info->temp_name ); 242 } 243 info->read_backing_store = read_backing_store; 244 info->write_backing_store = write_backing_store; 245 info->close_backing_store = close_backing_store; 246 TRACEMSS( cinfo, 1, JTRC_TFILE_OPEN, info->temp_name ); 247 } 248 249 250 /* 251 * These routines take care of any system-dependent initialization and 252 * cleanup required. 253 */ 254 255 GLOBAL long 256 jpeg_mem_init( j_common_ptr cinfo ) { 257 next_file_num = 0; /* initialize temp file name generator */ 258 return DEFAULT_MAX_MEM; /* default for max_memory_to_use */ 259 } 260 261 GLOBAL void 262 jpeg_mem_term( j_common_ptr cinfo ) { 263 /* no work */ 264 }