| /* |
| * 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 */ |
| } |