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277 lines
8.5 KiB
C
277 lines
8.5 KiB
C
/*
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* jmemname.c
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*
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* Copyright (C) 1992-1997, Thomas G. Lane.
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* This file is part of the Independent JPEG Group's software.
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* For conditions of distribution and use, see the accompanying README file.
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*
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* This file provides a generic implementation of the system-dependent
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* portion of the JPEG memory manager. This implementation assumes that
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* you must explicitly construct a name for each temp file.
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* Also, the problem of determining the amount of memory available
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* is shoved onto the user.
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*/
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#define JPEG_INTERNALS
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#include "jinclude.h"
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#include "jpeglib.h"
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#include "jmemsys.h" /* import the system-dependent declarations */
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#ifndef HAVE_STDLIB_H /* <stdlib.h> should declare malloc(),free() */
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extern void * malloc JPP((size_t size));
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extern void free JPP((void *ptr));
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#endif
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#ifndef SEEK_SET /* pre-ANSI systems may not define this; */
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#define SEEK_SET 0 /* if not, assume 0 is correct */
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#endif
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#ifdef DONT_USE_B_MODE /* define mode parameters for fopen() */
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#define READ_BINARY "r"
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#define RW_BINARY "w+"
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#else
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#ifdef VMS /* VMS is very nonstandard */
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#define READ_BINARY "rb", "ctx=stm"
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#define RW_BINARY "w+b", "ctx=stm"
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#else /* standard ANSI-compliant case */
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#define READ_BINARY "rb"
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#define RW_BINARY "w+b"
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#endif
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#endif
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/*
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* Selection of a file name for a temporary file.
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* This is system-dependent!
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*
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* The code as given is suitable for most Unix systems, and it is easily
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* modified for most non-Unix systems. Some notes:
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* 1. The temp file is created in the directory named by TEMP_DIRECTORY.
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* The default value is /usr/tmp, which is the conventional place for
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* creating large temp files on Unix. On other systems you'll probably
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* want to change the file location. You can do this by editing the
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* #define, or (preferred) by defining TEMP_DIRECTORY in jconfig.h.
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*
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* 2. If you need to change the file name as well as its location,
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* you can override the TEMP_FILE_NAME macro. (Note that this is
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* actually a printf format string; it must contain %s and %d.)
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* Few people should need to do this.
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*
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* 3. mktemp() is used to ensure that multiple processes running
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* simultaneously won't select the same file names. If your system
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* doesn't have mktemp(), define NO_MKTEMP to do it the hard way.
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* (If you don't have <errno.h>, also define NO_ERRNO_H.)
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*
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* 4. You probably want to define NEED_SIGNAL_CATCHER so that cjpeg.c/djpeg.c
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* will cause the temp files to be removed if you stop the program early.
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*/
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#ifndef TEMP_DIRECTORY /* can override from jconfig.h or Makefile */
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#define TEMP_DIRECTORY "/usr/tmp/" /* recommended setting for Unix */
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#endif
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static int next_file_num; /* to distinguish among several temp files */
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#ifdef NO_MKTEMP
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#ifndef TEMP_FILE_NAME /* can override from jconfig.h or Makefile */
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#define TEMP_FILE_NAME "%sJPG%03d.TMP"
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#endif
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#ifndef NO_ERRNO_H
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#include <errno.h> /* to define ENOENT */
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#endif
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/* ANSI C specifies that errno is a macro, but on older systems it's more
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* likely to be a plain int variable. And not all versions of errno.h
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* bother to declare it, so we have to in order to be most portable. Thus:
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*/
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#ifndef errno
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extern int errno;
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#endif
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LOCAL(void)
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select_file_name (char * fname)
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{
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FILE * tfile;
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/* Keep generating file names till we find one that's not in use */
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for (;;) {
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next_file_num++; /* advance counter */
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sprintf(fname, TEMP_FILE_NAME, TEMP_DIRECTORY, next_file_num);
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if ((tfile = fopen(fname, READ_BINARY)) == NULL) {
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/* fopen could have failed for a reason other than the file not
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* being there; for example, file there but unreadable.
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* If <errno.h> isn't available, then we cannot test the cause.
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*/
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#ifdef ENOENT
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if (errno != ENOENT)
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continue;
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#endif
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break;
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}
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fclose(tfile); /* oops, it's there; close tfile & try again */
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}
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}
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#else /* ! NO_MKTEMP */
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/* Note that mktemp() requires the initial filename to end in six X's */
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#ifndef TEMP_FILE_NAME /* can override from jconfig.h or Makefile */
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#define TEMP_FILE_NAME "%sJPG%dXXXXXX"
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#endif
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LOCAL(void)
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select_file_name (char * fname)
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{
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next_file_num++; /* advance counter */
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sprintf(fname, TEMP_FILE_NAME, TEMP_DIRECTORY, next_file_num);
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mktemp(fname); /* make sure file name is unique */
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/* mktemp replaces the trailing XXXXXX with a unique string of characters */
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}
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#endif /* NO_MKTEMP */
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/*
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* Memory allocation and freeing are controlled by the regular library
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* routines malloc() and free().
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*/
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GLOBAL(void *)
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jpeg_get_small (j_common_ptr cinfo, size_t sizeofobject)
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{
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return (void *) malloc(sizeofobject);
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}
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GLOBAL(void)
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jpeg_free_small (j_common_ptr cinfo, void * object, size_t sizeofobject)
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{
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free(object);
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}
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/*
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* "Large" objects are treated the same as "small" ones.
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* NB: although we include FAR keywords in the routine declarations,
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* this file won't actually work in 80x86 small/medium model; at least,
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* you probably won't be able to process useful-size images in only 64KB.
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*/
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GLOBAL(void FAR *)
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jpeg_get_large (j_common_ptr cinfo, size_t sizeofobject)
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{
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return (void FAR *) malloc(sizeofobject);
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}
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GLOBAL(void)
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jpeg_free_large (j_common_ptr cinfo, void FAR * object, size_t sizeofobject)
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{
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free(object);
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}
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/*
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* This routine computes the total memory space available for allocation.
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* It's impossible to do this in a portable way; our current solution is
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* to make the user tell us (with a default value set at compile time).
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* If you can actually get the available space, it's a good idea to subtract
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* a slop factor of 5% or so.
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*/
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#ifndef DEFAULT_MAX_MEM /* so can override from makefile */
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#define DEFAULT_MAX_MEM 1000000L /* default: one megabyte */
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#endif
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GLOBAL(long)
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jpeg_mem_available (j_common_ptr cinfo, long min_bytes_needed,
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long max_bytes_needed, long already_allocated)
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{
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return cinfo->mem->max_memory_to_use - already_allocated;
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}
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/*
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* Backing store (temporary file) management.
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* Backing store objects are only used when the value returned by
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* jpeg_mem_available is less than the total space needed. You can dispense
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* with these routines if you have plenty of virtual memory; see jmemnobs.c.
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*/
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METHODDEF(void)
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read_backing_store (j_common_ptr cinfo, backing_store_ptr info,
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void FAR * buffer_address,
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long file_offset, long byte_count)
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{
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if (fseek(info->temp_file, file_offset, SEEK_SET))
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ERREXIT(cinfo, JERR_TFILE_SEEK);
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if (JFREAD(info->temp_file, buffer_address, byte_count)
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!= (size_t) byte_count)
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ERREXIT(cinfo, JERR_TFILE_READ);
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}
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METHODDEF(void)
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write_backing_store (j_common_ptr cinfo, backing_store_ptr info,
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void FAR * buffer_address,
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long file_offset, long byte_count)
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{
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if (fseek(info->temp_file, file_offset, SEEK_SET))
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ERREXIT(cinfo, JERR_TFILE_SEEK);
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if (JFWRITE(info->temp_file, buffer_address, byte_count)
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!= (size_t) byte_count)
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ERREXIT(cinfo, JERR_TFILE_WRITE);
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}
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METHODDEF(void)
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close_backing_store (j_common_ptr cinfo, backing_store_ptr info)
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{
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fclose(info->temp_file); /* close the file */
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unlink(info->temp_name); /* delete the file */
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/* If your system doesn't have unlink(), use remove() instead.
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* remove() is the ANSI-standard name for this function, but if
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* your system was ANSI you'd be using jmemansi.c, right?
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*/
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TRACEMSS(cinfo, 1, JTRC_TFILE_CLOSE, info->temp_name);
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}
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/*
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* Initial opening of a backing-store object.
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*/
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GLOBAL(void)
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jpeg_open_backing_store (j_common_ptr cinfo, backing_store_ptr info,
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long total_bytes_needed)
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{
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select_file_name(info->temp_name);
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if ((info->temp_file = fopen(info->temp_name, RW_BINARY)) == NULL)
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ERREXITS(cinfo, JERR_TFILE_CREATE, info->temp_name);
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info->read_backing_store = read_backing_store;
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info->write_backing_store = write_backing_store;
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info->close_backing_store = close_backing_store;
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TRACEMSS(cinfo, 1, JTRC_TFILE_OPEN, info->temp_name);
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}
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/*
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* These routines take care of any system-dependent initialization and
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* cleanup required.
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*/
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GLOBAL(long)
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jpeg_mem_init (j_common_ptr cinfo)
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{
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next_file_num = 0; /* initialize temp file name generator */
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return DEFAULT_MAX_MEM; /* default for max_memory_to_use */
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}
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GLOBAL(void)
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jpeg_mem_term (j_common_ptr cinfo)
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{
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/* no work */
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}
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