/* * 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 /* 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) ERREXIT(methods, "Failed to create temporary file"); 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 */ }