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/*
* jmemname.c (jmemsys.c)
*
* Copyright (C) 1992, 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.
*/
#include "jinclude.h"
#include "jmemsys.h"
#ifdef INCLUDES_ARE_ANSI
#include <stdlib.h> /* to declare malloc(), free() */
#else
extern void * malloc PP((size_t size));
extern void free PP((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
static external_methods_ptr methods; /* saved for access to error_exit */
static long total_used; /* total memory requested so far */
/*
* 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 by defining TEMP_DIRECTORY in CFLAGS in the Makefile.
* For example, you might say
* CFLAGS= ... '-DTEMP_DIRECTORY="/tmp/"'
* Note that double quotes are needed in the text of the macro.
* With most make systems you have to put single quotes around the
* -D construct to preserve the double quotes.
* (Amiga SAS C has trouble with ":" and such in command-line options,
* so we've put in a special case for the preferred Amiga temp directory.)
*
* 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.
*
* 4. You probably want to define NEED_SIGNAL_CATCHER so that jcmain/jdmain
* will cause the temp files to be removed if you stop the program early.
*/
#ifndef TEMP_DIRECTORY /* so can override from Makefile */
#ifdef AMIGA
#define TEMP_DIRECTORY "JPEGTMP:" /* recommended setting for Amiga */
#else
#define TEMP_DIRECTORY "/usr/tmp/" /* recommended setting for Unix */
#endif
#endif
static int next_file_num; /* to distinguish among several temp files */
#ifdef NO_MKTEMP
#ifndef TEMP_FILE_NAME /* so can override from Makefile */
#define TEMP_FILE_NAME "%sJPG%03d.TMP"
#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)
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 /* so can override from 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 *
jget_small (size_t sizeofobject)
{
total_used += sizeofobject;
return (void *) malloc(sizeofobject);
}
GLOBAL void
jfree_small (void * object)
{
free(object);
}
/*
* We assume NEED_FAR_POINTERS is not defined and so the separate entry points
* jget_large, jfree_large are not needed.
*/
/*
* 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
jmem_available (long min_bytes_needed, long max_bytes_needed)
{
return methods->max_memory_to_use - total_used;
}
/*
* Backing store (temporary file) management.
* Backing store objects are only used when the value returned by
* jmem_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 (backing_store_ptr info, void FAR * buffer_address,
long file_offset, long byte_count)
{
if (fseek(info->temp_file, file_offset, SEEK_SET))
ERREXIT(methods, "fseek failed on temporary file");
if (JFREAD(info->temp_file, buffer_address, byte_count)
!= (size_t) byte_count)
ERREXIT(methods, "fread failed on temporary file");
}
METHODDEF void
write_backing_store (backing_store_ptr info, void FAR * buffer_address,
long file_offset, long byte_count)
{
if (fseek(info->temp_file, file_offset, SEEK_SET))
ERREXIT(methods, "fseek failed on temporary file");
if (JFWRITE(info->temp_file, buffer_address, byte_count)
!= (size_t) byte_count)
ERREXIT(methods, "fwrite failed on temporary file --- out of disk space?");
}
METHODDEF void
close_backing_store (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?
*/
}
GLOBAL void
jopen_backing_store (backing_store_ptr info, long total_bytes_needed)
{
char tracemsg[TEMP_NAME_LENGTH+40];
select_file_name(info->temp_name);
if ((info->temp_file = fopen(info->temp_name, RW_BINARY)) == NULL) {
/* hack to get around ERREXIT's inability to handle string parameters */
sprintf(tracemsg, "Failed to create temporary file %s", info->temp_name);
ERREXIT(methods, tracemsg);
}
info->read_backing_store = read_backing_store;
info->write_backing_store = write_backing_store;
info->close_backing_store = close_backing_store;
/* hack to get around TRACEMS' inability to handle string parameters */
sprintf(tracemsg, "Using temp file %s", info->temp_name);
TRACEMS(methods, 1, tracemsg);
}
/*
* These routines take care of any system-dependent initialization and
* cleanup required. Keep in mind that jmem_term may be called more than
* once.
*/
GLOBAL void
jmem_init (external_methods_ptr emethods)
{
methods = emethods; /* save struct addr for error exit access */
emethods->max_memory_to_use = DEFAULT_MAX_MEM;
total_used = 0;
next_file_num = 0;
}
GLOBAL void
jmem_term (void)
{
/* no work */
}
These are the contents of the former NiCE NeXT User Group NeXTSTEP/OpenStep software archive, currently hosted by Netfuture.ch.