jpeg/jmemname.c

   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 }