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() */ 21extern void * malloc JPP((size_t size)); 22extern 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 73static 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 90extern int errno; 91#endif 92 93 94LOCAL(void) 95select_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 125LOCAL(void) 126select_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 142GLOBAL(void *) 143jpeg_get_small (j_common_ptr cinfo, size_t sizeofobject) 144{ 145 return (void *) malloc(sizeofobject); 146} 147 148GLOBAL(void) 149jpeg_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 162GLOBAL(void FAR *) 163jpeg_get_large (j_common_ptr cinfo, size_t sizeofobject) 164{ 165 return (void FAR *) malloc(sizeofobject); 166} 167 168GLOBAL(void) 169jpeg_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 187GLOBAL(long) 188jpeg_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 203METHODDEF(void) 204read_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 216METHODDEF(void) 217write_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 229METHODDEF(void) 230close_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 246GLOBAL(void) 247jpeg_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 265GLOBAL(long) 266jpeg_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 272GLOBAL(void) 273jpeg_mem_term (j_common_ptr cinfo) 274{ 275 /* no work */ 276} 277