| // +build !plan9 |
| // +build !windows |
| |
| /* |
| Plan 9 from User Space src/lib9/rfork.c |
| http://code.swtch.com/plan9port/src/tip/src/lib9/rfork.c |
| |
| Copyright 2001-2007 Russ Cox. All Rights Reserved. |
| |
| Permission is hereby granted, free of charge, to any person obtaining a copy |
| of this software and associated documentation files (the "Software"), to deal |
| in the Software without restriction, including without limitation the rights |
| to use, copy, modify, merge, publish, distribute, sublicense, and/or sell |
| copies of the Software, and to permit persons to whom the Software is |
| furnished to do so, subject to the following conditions: |
| |
| The above copyright notice and this permission notice shall be included in |
| all copies or substantial portions of the Software. |
| |
| THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
| IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
| FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE |
| AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
| LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, |
| OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN |
| THE SOFTWARE. |
| */ |
| |
| #include <u.h> |
| #include <sys/wait.h> |
| #include <signal.h> |
| #include <libc.h> |
| #undef rfork |
| |
| static void |
| nop(int x) |
| { |
| USED(x); |
| } |
| |
| int |
| p9rfork(int flags) |
| { |
| int pid, status; |
| int p[2]; |
| int n; |
| char buf[128], *q; |
| extern char **environ; |
| |
| if((flags&(RFPROC|RFFDG|RFMEM)) == (RFPROC|RFFDG)){ |
| /* check other flags before we commit */ |
| flags &= ~(RFPROC|RFFDG|RFENVG); |
| n = (flags & ~(RFNOTEG|RFNAMEG|RFNOWAIT|RFCENVG)); |
| if(n){ |
| werrstr("unknown flags %08ux in rfork", n); |
| return -1; |
| } |
| if(flags&RFNOWAIT){ |
| /* |
| * BUG - should put the signal handler back after we |
| * finish, but I just don't care. If a program calls with |
| * NOWAIT once, they're not likely to want child notes |
| * after that. |
| */ |
| signal(SIGCHLD, nop); |
| if(pipe(p) < 0) |
| return -1; |
| } |
| pid = fork(); |
| if(pid == -1) |
| return -1; |
| if(flags&RFNOWAIT){ |
| flags &= ~RFNOWAIT; |
| if(pid){ |
| /* |
| * Parent - wait for child to fork wait-free child. |
| * Then read pid from pipe. Assume pipe buffer can absorb the write. |
| */ |
| close(p[1]); |
| status = 0; |
| if(wait4(pid, &status, 0, 0) < 0){ |
| werrstr("pipe dance - wait4 - %r"); |
| close(p[0]); |
| return -1; |
| } |
| n = (int)readn(p[0], buf, sizeof buf-1); |
| close(p[0]); |
| if(!WIFEXITED(status) || WEXITSTATUS(status)!=0 || n <= 0){ |
| if(!WIFEXITED(status)) |
| werrstr("pipe dance - !exited 0x%ux", status); |
| else if(WEXITSTATUS(status) != 0) |
| werrstr("pipe dance - non-zero status 0x%ux", status); |
| else if(n < 0) |
| werrstr("pipe dance - pipe read error - %r"); |
| else if(n == 0) |
| werrstr("pipe dance - pipe read eof"); |
| else |
| werrstr("pipe dance - unknown failure"); |
| return -1; |
| } |
| buf[n] = 0; |
| if(buf[0] == 'x'){ |
| werrstr("%s", buf+2); |
| return -1; |
| } |
| pid = (int)strtol(buf, &q, 0); |
| }else{ |
| /* |
| * Child - fork a new child whose wait message can't |
| * get back to the parent because we're going to exit! |
| */ |
| signal(SIGCHLD, SIG_IGN); |
| close(p[0]); |
| pid = fork(); |
| if(pid){ |
| /* Child parent - send status over pipe and exit. */ |
| if(pid > 0) |
| fprint(p[1], "%d", pid); |
| else |
| fprint(p[1], "x %r"); |
| close(p[1]); |
| _exit(0); |
| }else{ |
| /* Child child - close pipe. */ |
| close(p[1]); |
| } |
| } |
| } |
| if(pid != 0) |
| return pid; |
| if(flags&RFCENVG) |
| if(environ) |
| *environ = nil; |
| } |
| if(flags&RFPROC){ |
| werrstr("cannot use rfork for shared memory -- use libthread"); |
| return -1; |
| } |
| if(flags&RFNAMEG){ |
| /* XXX set $NAMESPACE to a new directory */ |
| flags &= ~RFNAMEG; |
| } |
| if(flags&RFNOTEG){ |
| setpgid(0, getpid()); |
| flags &= ~RFNOTEG; |
| } |
| if(flags&RFNOWAIT){ |
| werrstr("cannot use RFNOWAIT without RFPROC"); |
| return -1; |
| } |
| if(flags){ |
| werrstr("unknown flags %08ux in rfork", flags); |
| return -1; |
| } |
| return 0; |
| } |