root/jmemname.c
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DEFINITIONS
This source file includes following definitions.
- select_file_name
- select_file_name
- GLOBAL
- jpeg_free_small
- GLOBAL
- jpeg_free_large
- jpeg_mem_available
- METHODDEF
- METHODDEF
- METHODDEF
- jpeg_open_backing_store
- jpeg_mem_init
- jpeg_mem_term
/*
* jmemname.c
*
* Copyright (C) 1992-1997, 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
#ifdef VMS /* VMS is very nonstandard */
#define READ_BINARY "rb", "ctx=stm"
#define RW_BINARY "w+b", "ctx=stm"
#else /* standard ANSI-compliant case */
#define READ_BINARY "rb"
#define RW_BINARY "w+b"
#endif
#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
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
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);
}
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);
}
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
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.
*/
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.
*/
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 */
}
void
jpeg_mem_term (j_common_ptr cinfo)
{
/* no work */
}