2 * Copyright (c) 2000 Silicon Graphics, Inc. All Rights Reserved.
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16 * any, provided herein do not apply to combinations of this program with
17 * other software, or any other product whatsoever.
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32 /**************************************************************
34 * OS Testing - Silicon Graphics, Inc.
36 * FUNCTION NAME : forker
39 * FUNCTION TITLE : fork desired number of copies of the current process
40 * fork a process and return control to caller
43 * int forker(ncopies, mode, prefix)
48 * int background(prefix);
51 * extern int Forker_pids[];
52 * extern int Forker_npids;
54 * AUTHOR : Richard Logan
56 * CO-PILOT(s) : Dean Roehrich
58 * INITIAL RELEASE : UNICOS 8.0
61 * The background function will do a fork of the current process.
62 * The parent process will then exit, thus orphaning the
63 * child process. Doing this will not nice the child process
64 * like executing a cmd in the background using "&" from the shell.
65 * If the fork fails and prefix is not NULL, a error message is printed
66 * to stderr and the process will exit with a value of errno.
68 * The forker function will fork <ncopies> minus one copies
69 * of the current process. There are two modes in how the forks
70 * will be done. Mode 0 (default) will have all new processes
71 * be childern of the parent process. Using Mode 1,
72 * the parent process will have one child and that child will
73 * fork the next process, if necessary, and on and on.
74 * The forker function will return the number of successful
75 * forks. This value will be different for the parent and each child.
76 * Using mode 0, the parent will get the total number of successful
77 * forks. Using mode 1, the newest child will get the total number
78 * of forks. The parent will get a return value of 1.
80 * The forker function also updates the global variables
81 * Forker_pids[] and Forker_npids. The Forker_pids array will
82 * be updated to contain the pid of each new process. The
83 * Forker_npids variable contains the number of entries
84 * in Forker_pids. Note, not all processes will have
85 * access to all pids via Forker_pids. If using mode 0, only the
86 * parent process and the last process will have all information.
87 * If using mode 1, only the last child process will have all information.
89 * If the prefix parameter is not NULL and the fork system call fails,
90 * a error message will be printed to stderr. The error message
91 * the be preceeded with prefix string. If prefix is NULL,
92 * no error message is printed.
94 * SPECIAL REQUIREMENTS
98 * This should contain the description, author, and date of any
99 * "interesting" modifications (i.e. info should helpful in
100 * maintaining/enhancing this module).
101 * username description
102 * ----------------------------------------------------------------
103 * rrl This functions will first written during
104 * the SFS testing days, 1993.
107 * The child pids are stored in the fixed array, Forker_pids.
108 * The array only has space for 4098 pids. Only the first
109 * 4098 pids will be stored in the array.
111 **************************************************************/
115 #include <unistd.h> /* fork, getpid, sleep */
121 int Forker_pids[FORKER_MAX_PIDS]; /* holds pids of forked processes */
122 int Forker_npids=0; /* number of entries in Forker_pids */
124 /***********************************************************************
126 * This function will fork and the parent will exit zero and
127 * the child will return. This will orphan the returning process
128 * putting it in the background.
131 * 0 : if fork did not fail
132 * !0 : if fork failed, the return value will be the errno.
133 ***********************************************************************/
140 if ( prefix != NULL )
141 fprintf(stderr, "%s: In %s background(), fork() failed, errno:%d %s\n",
142 prefix, __FILE__, errno, strerror(errno));
145 case 0: /* child process */
154 } /* end of background */
156 /***********************************************************************
157 * Forker will fork ncopies-1 copies of self.
159 ***********************************************************************/
161 forker(ncopies, mode, prefix)
163 int mode; /* 0 - all childern of parent, 1 - only 1 direct child */
164 char *prefix; /* if ! NULL, an message will be printed to stderr */
165 /* if fork fails. The prefix (program name) will */
166 /* preceed the message */
174 for ( cnt=1; cnt < ncopies; cnt++ ) {
177 case 1 : /* only 1 direct child */
178 if ( (pid = fork()) == -1 ) {
179 if ( prefix != NULL )
180 fprintf(stderr, "%s: %s,forker(): fork() failed, errno:%d %s\n",
181 prefix, __FILE__, errno, strerror(errno));
187 case 0: /* child - continues the forking */
189 if ( Forker_npids < FORKER_MAX_PIDS )
190 Forker_pids[Forker_npids-1]=getpid();
193 default: /* parent - stop the forking */
194 if ( Forker_npids < FORKER_MAX_PIDS )
195 Forker_pids[Forker_npids-1]=pid;
201 default : /* all new processes are childern of parent */
202 if ( (pid = fork()) == -1 ) {
203 if ( prefix != NULL )
204 fprintf(stderr, "%s: %s,forker(): fork() failed, errno:%d %s\n",
205 prefix, __FILE__, errno, strerror(errno));
211 case 0: /* child - stops the forking */
212 if ( Forker_npids < FORKER_MAX_PIDS )
213 Forker_pids[Forker_npids-1]=getpid();
216 default: /* parent - continues the forking */
217 if ( Forker_npids < FORKER_MAX_PIDS )
218 Forker_pids[Forker_npids-1]=pid;
225 if ( Forker_npids < FORKER_MAX_PIDS )
226 Forker_pids[Forker_npids]=0;
229 } /* end of forker */
235 * The following is a unit test main for the background and forker
250 printf("Usage: %s ncopies [mode]\n", argv[0]);
254 if ( sscanf(argv[1], "%i", &ncopies) != 1 ) {
255 printf("%s: ncopies argument must be integer\n", argv[0]);
260 if ( sscanf(argv[2], "%i", &mode) != 1 ) {
261 printf("%s: mode argument must be integer\n", argv[0]);
265 printf("Starting Pid = %d\n", getpid());
266 ret=background(argv[0]);
267 printf("After background() ret:%d, pid = %d\n", ret, getpid());
269 ret=forker(ncopies, mode, argv[0]);
271 printf("forker(%d, %d, %s) ret:%d, pid = %d, sleeping 30 seconds.\n",
272 ncopies, mode, argv[0], ret, getpid());
274 printf("%d My version of Forker_pids[], Forker_npids = %d\n",
275 getpid(), Forker_npids);
277 for (ind=0; ind<Forker_npids; ind++){
278 printf("%d ind:%-2d pid:%d\n", getpid(), ind, Forker_pids[ind]);
285 #endif /* UNIT_TEST */