286 lines
8.7 KiB
C
286 lines
8.7 KiB
C
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/*
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* Copyright (c) 2000 Silicon Graphics, Inc. All Rights Reserved.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of version 2 of the GNU General Public License as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it would be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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*
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* Further, this software is distributed without any warranty that it is
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* free of the rightful claim of any third person regarding infringement
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* or the like. Any license provided herein, whether implied or
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* otherwise, applies only to this software file. Patent licenses, if
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* any, provided herein do not apply to combinations of this program with
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* other software, or any other product whatsoever.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write the Free Software Foundation, Inc., 59
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* Temple Place - Suite 330, Boston MA 02111-1307, USA.
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*
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* Contact information: Silicon Graphics, Inc., 1600 Amphitheatre Pkwy,
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* Mountain View, CA 94043, or:
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*
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* http://www.sgi.com
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*
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* For further information regarding this notice, see:
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*
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* http://oss.sgi.com/projects/GenInfo/NoticeExplan/
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*/
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/**************************************************************
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*
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* OS Testing - Silicon Graphics, Inc.
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*
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* FUNCTION NAME : forker
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* background
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*
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* FUNCTION TITLE : fork desired number of copies of the current process
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* fork a process and return control to caller
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*
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* SYNOPSIS:
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* int forker(ncopies, mode, prefix)
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* int ncopies;
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* int mode;
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* char *prefix;
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*
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* int background(prefix);
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* char *prefix;
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*
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* extern int Forker_pids[];
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* extern int Forker_npids;
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*
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* AUTHOR : Richard Logan
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*
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* CO-PILOT(s) : Dean Roehrich
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*
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* INITIAL RELEASE : UNICOS 8.0
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*
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* DESIGN DESCRIPTION
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* The background function will do a fork of the current process.
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* The parent process will then exit, thus orphaning the
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* child process. Doing this will not nice the child process
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* like executing a cmd in the background using "&" from the shell.
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* If the fork fails and prefix is not NULL, a error message is printed
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* to stderr and the process will exit with a value of errno.
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*
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* The forker function will fork <ncopies> minus one copies
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* of the current process. There are two modes in how the forks
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* will be done. Mode 0 (default) will have all new processes
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* be childern of the parent process. Using Mode 1,
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* the parent process will have one child and that child will
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* fork the next process, if necessary, and on and on.
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* The forker function will return the number of successful
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* forks. This value will be different for the parent and each child.
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* Using mode 0, the parent will get the total number of successful
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* forks. Using mode 1, the newest child will get the total number
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* of forks. The parent will get a return value of 1.
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*
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* The forker function also updates the global variables
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* Forker_pids[] and Forker_npids. The Forker_pids array will
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* be updated to contain the pid of each new process. The
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* Forker_npids variable contains the number of entries
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* in Forker_pids. Note, not all processes will have
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* access to all pids via Forker_pids. If using mode 0, only the
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* parent process and the last process will have all information.
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* If using mode 1, only the last child process will have all information.
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*
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* If the prefix parameter is not NULL and the fork system call fails,
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* a error message will be printed to stderr. The error message
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* the be preceeded with prefix string. If prefix is NULL,
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* no error message is printed.
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*
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* SPECIAL REQUIREMENTS
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* None.
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*
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* UPDATE HISTORY
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* This should contain the description, author, and date of any
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* "interesting" modifications (i.e. info should helpful in
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* maintaining/enhancing this module).
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* username description
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* ----------------------------------------------------------------
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* rrl This functions will first written during
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* the SFS testing days, 1993.
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*
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* BUGS/LIMITATIONS
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* The child pids are stored in the fixed array, Forker_pids.
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* The array only has space for 4098 pids. Only the first
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* 4098 pids will be stored in the array.
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*
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**************************************************************/
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#include <stdio.h>
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#include <errno.h>
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#include <unistd.h> /* fork, getpid, sleep */
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#include <string.h>
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#include "forker.h"
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extern int errno;
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int Forker_pids[FORKER_MAX_PIDS]; /* holds pids of forked processes */
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int Forker_npids=0; /* number of entries in Forker_pids */
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/***********************************************************************
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*
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* This function will fork and the parent will exit zero and
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* the child will return. This will orphan the returning process
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* putting it in the background.
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*
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* Return Value
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* 0 : if fork did not fail
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* !0 : if fork failed, the return value will be the errno.
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***********************************************************************/
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int
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background(prefix)
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char *prefix;
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{
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switch (fork()) {
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case -1:
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if ( prefix != NULL )
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fprintf(stderr, "%s: In %s background(), fork() failed, errno:%d %s\n",
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prefix, __FILE__, errno, strerror(errno));
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exit(errno);
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case 0: /* child process */
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break;
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default:
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exit(0);
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}
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return 0;
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} /* end of background */
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/***********************************************************************
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* Forker will fork ncopies-1 copies of self.
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*
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***********************************************************************/
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int
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forker(ncopies, mode, prefix)
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int ncopies;
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int mode; /* 0 - all childern of parent, 1 - only 1 direct child */
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char *prefix; /* if ! NULL, an message will be printed to stderr */
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/* if fork fails. The prefix (program name) will */
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/* preceed the message */
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{
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int cnt;
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int pid;
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static int ind = 0;
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Forker_pids[ind]=0;
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for ( cnt=1; cnt < ncopies; cnt++ ) {
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switch ( mode ) {
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case 1 : /* only 1 direct child */
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if ( (pid = fork()) == -1 ) {
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if ( prefix != NULL )
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fprintf(stderr, "%s: %s,forker(): fork() failed, errno:%d %s\n",
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prefix, __FILE__, errno, strerror(errno));
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return 0;
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}
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Forker_npids++;
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switch (pid ) {
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case 0: /* child - continues the forking */
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if ( Forker_npids < FORKER_MAX_PIDS )
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Forker_pids[Forker_npids-1]=getpid();
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break;
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default: /* parent - stop the forking */
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if ( Forker_npids < FORKER_MAX_PIDS )
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Forker_pids[Forker_npids-1]=pid;
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return cnt-1;
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}
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break;
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default : /* all new processes are childern of parent */
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if ( (pid = fork()) == -1 ) {
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if ( prefix != NULL )
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fprintf(stderr, "%s: %s,forker(): fork() failed, errno:%d %s\n",
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prefix, __FILE__, errno, strerror(errno));
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return cnt-1;
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}
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Forker_npids++;
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switch (pid ) {
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case 0: /* child - stops the forking */
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if ( Forker_npids < FORKER_MAX_PIDS )
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Forker_pids[Forker_npids-1]=getpid();
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return cnt;
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default: /* parent - continues the forking */
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if ( Forker_npids < FORKER_MAX_PIDS )
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Forker_pids[Forker_npids-1]=pid;
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break;
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}
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break;
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}
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}
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if ( Forker_npids < FORKER_MAX_PIDS )
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Forker_pids[Forker_npids]=0;
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return cnt-1;
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} /* end of forker */
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#if UNIT_TEST
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/*
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* The following is a unit test main for the background and forker
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* functions.
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*/
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int
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main(argc, argv)
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int argc;
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char **argv;
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{
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int ncopies=1;
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int mode=0;
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int ret;
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int ind;
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if ( argc == 1 ) {
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printf("Usage: %s ncopies [mode]\n", argv[0]);
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exit(1);
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}
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if ( sscanf(argv[1], "%i", &ncopies) != 1 ) {
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printf("%s: ncopies argument must be integer\n", argv[0]);
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exit(1);
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}
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if ( argc == 3 )
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if ( sscanf(argv[2], "%i", &mode) != 1 ) {
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printf("%s: mode argument must be integer\n", argv[0]);
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exit(1);
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}
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printf("Starting Pid = %d\n", getpid());
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ret=background(argv[0]);
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printf("After background() ret:%d, pid = %d\n", ret, getpid());
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ret=forker(ncopies, mode, argv[0]);
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printf("forker(%d, %d, %s) ret:%d, pid = %d, sleeping 30 seconds.\n",
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ncopies, mode, argv[0], ret, getpid());
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printf("%d My version of Forker_pids[], Forker_npids = %d\n",
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getpid(), Forker_npids);
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for (ind=0; ind<Forker_npids; ind++){
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printf("%d ind:%-2d pid:%d\n", getpid(), ind, Forker_pids[ind]);
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}
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sleep(30);
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exit(0);
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}
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#endif /* UNIT_TEST */
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