text: /*
   * jmemname.c
   *
   * Copyright (C) 1992-1996, Thomas G. Lane.
   * This file is part of the Independent JPEG Group's software.
   * For conditions of distribution and use, see the accompanying README file.
   *
   * This file provides a generic implementation of the system-dependent
   * portion of the JPEG memory manager.  This implementation assumes that
   * you must explicitly construct a name for each temp file.
   * Also, the problem of determining the amount of memory available
   * is shoved onto the user.
   */
  
  #define JPEG_INTERNALS
  #include "jinclude.h"
  #include "jpeglib.h"
  #include "jmemsys.h"		/* import the system-dependent declarations */
  
  #ifndef HAVE_STDLIB_H		/* <stdlib.h> should declare malloc(),free() */
  extern void * malloc JPP((size_t size));
  extern void free JPP((void *ptr));
  #endif
  
  #ifndef SEEK_SET		/* pre-ANSI systems may not define this; */
  #define SEEK_SET  0		/* if not, assume 0 is correct */
  #endif
  
  #ifdef DONT_USE_B_MODE		/* define mode parameters for fopen() */
  #define READ_BINARY	"r"
  #define RW_BINARY	"w+"
  #else
  #define READ_BINARY	"rb"
  #define RW_BINARY	"w+b"
  #endif
  
  
  /*
   * Selection of a file name for a temporary file.
   * This is system-dependent!
   *
   * The code as given is suitable for most Unix systems, and it is easily
   * modified for most non-Unix systems.  Some notes:
   *  1.  The temp file is created in the directory named by TEMP_DIRECTORY.
   *      The default value is /usr/tmp, which is the conventional place for
   *      creating large temp files on Unix.  On other systems you'll probably
   *      want to change the file location.  You can do this by editing the
   *      #define, or (preferred) by defining TEMP_DIRECTORY in jconfig.h.
   *
   *  2.  If you need to change the file name as well as its location,
   *      you can override the TEMP_FILE_NAME macro.  (Note that this is
   *      actually a printf format string; it must contain %s and %d.)
   *      Few people should need to do this.
   *
   *  3.  mktemp() is used to ensure that multiple processes running
   *      simultaneously won't select the same file names.  If your system
   *      doesn't have mktemp(), define NO_MKTEMP to do it the hard way.
   *      (If you don't have <errno.h>, also define NO_ERRNO_H.)
   *
   *  4.  You probably want to define NEED_SIGNAL_CATCHER so that cjpeg.c/djpeg.c
   *      will cause the temp files to be removed if you stop the program early.
   */
  
  #ifndef TEMP_DIRECTORY		/* can override from jconfig.h or Makefile */
  #define TEMP_DIRECTORY  "/usr/tmp/" /* recommended setting for Unix */
  #endif
  
  static int next_file_num;	/* to distinguish among several temp files */
  
  #ifdef NO_MKTEMP
  
  #ifndef TEMP_FILE_NAME		/* can override from jconfig.h or Makefile */
  #define TEMP_FILE_NAME  "%sJPG%03d.TMP"
  #endif
  
  #ifndef NO_ERRNO_H
  #include <errno.h>		/* to define ENOENT */
  #endif
  
  /* ANSI C specifies that errno is a macro, but on older systems it's more
   * likely to be a plain int variable.  And not all versions of errno.h
   * bother to declare it, so we have to in order to be most portable.  Thus:
   */
  #ifndef errno
  extern int errno;
  #endif
  
  
  LOCAL(void)
  select_file_name (char * fname)
  {
    FILE * tfile;
  
    /* Keep generating file names till we find one that's not in use */
    for (;;) {
      next_file_num++;		/* advance counter */
      sprintf(fname, TEMP_FILE_NAME, TEMP_DIRECTORY, next_file_num);
      if ((tfile = fopen(fname, READ_BINARY)) == NULL) {
        /* fopen could have failed for a reason other than the file not
         * being there; for example, file there but unreadable.
         * If <errno.h> isn't available, then we cannot test the cause.
         */
  #ifdef ENOENT
        if (errno != ENOENT)
  	continue;
  #endif
        break;
      }
      fclose(tfile);		/* oops, it's there; close tfile & try again */
    }
  }
  
  #else /* ! NO_MKTEMP */
  
  /* Note that mktemp() requires the initial filename to end in six X's */
  #ifndef TEMP_FILE_NAME		/* can override from jconfig.h or Makefile */
  #define TEMP_FILE_NAME  "%sJPG%dXXXXXX"
  #endif
  
  LOCAL(void)
  select_file_name (char * fname)
  {
    next_file_num++;		/* advance counter */
    sprintf(fname, TEMP_FILE_NAME, TEMP_DIRECTORY, next_file_num);
    mktemp(fname);		/* make sure file name is unique */
    /* mktemp replaces the trailing XXXXXX with a unique string of characters */
  }
  
  #endif /* NO_MKTEMP */
  
  
  /*
   * Memory allocation and freeing are controlled by the regular library
   * routines malloc() and free().
   */
  
  GLOBAL(void *)
  jpeg_get_small (j_common_ptr cinfo, size_t sizeofobject)
  {
    return (void *) malloc(sizeofobject);
  }
  
  GLOBAL(void)
  jpeg_free_small (j_common_ptr cinfo, void * object, size_t sizeofobject)
  {
    free(object);
  }
  
  
  /*
   * "Large" objects are treated the same as "small" ones.
   * NB: although we include FAR keywords in the routine declarations,
   * this file won't actually work in 80x86 small/medium model; at least,
   * you probably won't be able to process useful-size images in only 64KB.
   */
  
  GLOBAL(void FAR *)
  jpeg_get_large (j_common_ptr cinfo, size_t sizeofobject)
  {
    return (void FAR *) malloc(sizeofobject);
  }
  
  GLOBAL(void)
  jpeg_free_large (j_common_ptr cinfo, void FAR * object, size_t sizeofobject)
  {
    free(object);
  }
  
  
  /*
   * This routine computes the total memory space available for allocation.
   * It's impossible to do this in a portable way; our current solution is
   * to make the user tell us (with a default value set at compile time).
   * If you can actually get the available space, it's a good idea to subtract
   * a slop factor of 5% or so.
   */
  
  #ifndef DEFAULT_MAX_MEM		/* so can override from makefile */
  #define DEFAULT_MAX_MEM		1000000L /* default: one megabyte */
  #endif
  
  GLOBAL(long)
  jpeg_mem_available (j_common_ptr cinfo, long min_bytes_needed,
  		    long max_bytes_needed, long already_allocated)
  {
    return cinfo->mem->max_memory_to_use - already_allocated;
  }
  
  
  /*
   * Backing store (temporary file) management.
   * Backing store objects are only used when the value returned by
   * jpeg_mem_available is less than the total space needed.  You can dispense
   * with these routines if you have plenty of virtual memory; see jmemnobs.c.
   */
  
  
  METHODDEF(void)
  read_backing_store (j_common_ptr cinfo, backing_store_ptr info,
  		    void FAR * buffer_address,
  		    long file_offset, long byte_count)
  {
    if (fseek(info->temp_file, file_offset, SEEK_SET))
      ERREXIT(cinfo, JERR_TFILE_SEEK);
    if (JFREAD(info->temp_file, buffer_address, byte_count)
        != (size_t) byte_count)
      ERREXIT(cinfo, JERR_TFILE_READ);
  }
  
  
  METHODDEF(void)
  write_backing_store (j_common_ptr cinfo, backing_store_ptr info,
  		     void FAR * buffer_address,
  		     long file_offset, long byte_count)
  {
    if (fseek(info->temp_file, file_offset, SEEK_SET))
      ERREXIT(cinfo, JERR_TFILE_SEEK);
    if (JFWRITE(info->temp_file, buffer_address, byte_count)
        != (size_t) byte_count)
      ERREXIT(cinfo, JERR_TFILE_WRITE);
  }
  
  
  METHODDEF(void)
  close_backing_store (j_common_ptr cinfo, backing_store_ptr info)
  {
    fclose(info->temp_file);	/* close the file */
    unlink(info->temp_name);	/* delete the file */
  /* If your system doesn't have unlink(), use remove() instead.
   * remove() is the ANSI-standard name for this function, but if
   * your system was ANSI you'd be using jmemansi.c, right?
   */
    TRACEMSS(cinfo, 1, JTRC_TFILE_CLOSE, info->temp_name);
  }
  
  
  /*
   * Initial opening of a backing-store object.
   */
  
  GLOBAL(void)
  jpeg_open_backing_store (j_common_ptr cinfo, backing_store_ptr info,
  			 long total_bytes_needed)
  {
    select_file_name(info->temp_name);
    if ((info->temp_file = fopen(info->temp_name, RW_BINARY)) == NULL)
      ERREXITS(cinfo, JERR_TFILE_CREATE, info->temp_name);
    info->read_backing_store = read_backing_store;
    info->write_backing_store = write_backing_store;
    info->close_backing_store = close_backing_store;
    TRACEMSS(cinfo, 1, JTRC_TFILE_OPEN, info->temp_name);
  }
  
  
  /*
   * These routines take care of any system-dependent initialization and
   * cleanup required.
   */
  
  GLOBAL(long)
  jpeg_mem_init (j_common_ptr cinfo)
  {
    next_file_num = 0;		/* initialize temp file name generator */
    return DEFAULT_MAX_MEM;	/* default for max_memory_to_use */
  }
  
  GLOBAL(void)
  jpeg_mem_term (j_common_ptr cinfo)
  {
    /* no work */
  }
  