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Force PPC Darwin to use fork instead of vfork. This change

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requires both the parent and child process to explicitly set
the process group id. Vfork guarantees the child process 
runs to the exec before it releases the parent process.  
Now that we use fork instead of vfork, it's possible for the 
parent to wait on the child process without having the child 
setpgid on itself.  This eliminates spurious hangs on ppc
darwin caused by either a race condition between vfork and
execvp, or a bug in the vfork implementation.

Added a test to ensure we don't try to read from the
stderr pipe descriptor if the descriptor's not valid.



[SVN r43176]
This commit is contained in:
K. Noel Belcourt
2008-02-08 16:32:35 +00:00
parent 70a5f0acfd
commit 23aa013e45
1 changed files with 14 additions and 6 deletions
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20
src/engine/execunix.c
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@@ -25,6 +25,10 @@
# ifdef USE_EXECUNIX
# include <sys/times.h>
# if defined(__APPLE__) && defined(__ppc__)
# define NO_VFORK
# endif
# ifdef NO_VFORK
# define vfork() fork()
# endif
@@ -211,6 +215,8 @@ execcmd(
if ((cmdtab[slot].pid = vfork()) == 0)
{
int pid = getpid();
close(out[0]);
close(err[0]);
@@ -239,17 +245,19 @@ execcmd(
r_limit.rlim_max = globs.timeout;
setrlimit(RLIMIT_CPU, &r_limit);
}
setpgid(cmdtab[slot].pid, cmdtab[slot].pid);
execvp( argv[0], argv );
_exit(127);
}
setpgid(pid,pid);
execvp( argv[0], argv );
perror( "execvp" );
_exit(127);
}
else if( cmdtab[slot].pid == -1 )
{
perror( "vfork" );
exit( EXITBAD );
}
setpgid(cmdtab[slot].pid, cmdtab[slot].pid);
/* close write end of pipes */
close(out[1]);
close(err[1]);
@@ -458,7 +466,7 @@ execwait()
if (FD_ISSET(cmdtab[i].fd[OUT], &fds))
out = read_descriptor(i, OUT);
if (FD_ISSET(cmdtab[i].fd[ERR], &fds))
if ((globs.pipe_action != 0) && (FD_ISSET(cmdtab[i].fd[ERR], &fds)))
err = read_descriptor(i, ERR);
/* if feof on either descriptor, then we're done */