Mercurial > hg > octave-lyh > gnulib-hg
changeset 4847:80786047b412
Use waitid if possible.
author | Bruno Haible <bruno@clisp.org> |
---|---|
date | Mon, 03 Nov 2003 20:47:02 +0000 |
parents | 8a8f6899a8f8 |
children | c9f50d6e7732 |
files | lib/ChangeLog lib/wait-process.c m4/ChangeLog m4/wait-process.m4 |
diffstat | 4 files changed, 105 insertions(+), 5 deletions(-) [+] |
line wrap: on
line diff
--- a/lib/ChangeLog +++ b/lib/ChangeLog @@ -1,3 +1,9 @@ +2003-10-31 Bruno Haible <bruno@clisp.org> + + * wait-process.c (wait_process): Use waitid with WNOWAIT if available, + to avoid (extremely rare) race condition. + Suggested by Paul Eggert. + 2003-11-03 Jim Meyering <jim@meyering.net> * userspec.c: Include "userspec.h".
--- a/lib/wait-process.c +++ b/lib/wait-process.c @@ -101,6 +101,15 @@ #define SIZEOF(a) (sizeof(a) / sizeof(a[0])) +#if defined _MSC_VER || defined __MINGW32__ + +/* The return value of spawnvp() is really a process handle as returned + by CreateProcess(). Therefore we can kill it using TerminateProcess. */ +#define kill(pid,sig) TerminateProcess ((HANDLE) (pid), sig) + +#endif + + /* Type of an entry in the slaves array. The 'used' bit determines whether this entry is currently in use. (If pid_t was an atomic type like sig_atomic_t, we could just set the @@ -243,6 +252,85 @@ bool null_stderr, bool slave_process, bool exit_on_error) { +#if HAVE_WAITID && defined WNOWAIT + /* Use of waitid() with WNOWAIT avoids a race condition: If slave_process is + true, and this process sleeps a very long time between the return from + waitpid() and the execution of unregister_slave_subprocess(), and + meanwhile another process acquires the same PID as child, and then - still + before unregister_slave_subprocess() - this process gets a fatal signal, + it would kill the other totally unrelated process. */ + siginfo_t info; + for (;;) + { + if (waitid (P_PID, child, &info, slave_process ? WNOWAIT : 0) < 0) + { +# ifdef EINTR + if (errno == EINTR) + continue; +# endif + if (exit_on_error || !null_stderr) + error (exit_on_error ? EXIT_FAILURE : 0, errno, + _("%s subprocess"), progname); + return 127; + } + + /* info.si_code is set to one of CLD_EXITED, CLD_KILLED, CLD_DUMPED, + CLD_TRAPPED, CLD_STOPPED, CLD_CONTINUED. Loop until the program + terminates. */ + if (info.si_code == CLD_EXITED + || info.si_code == CLD_KILLED || info.si_code == CLD_DUMPED) + break; + } + + /* The child process has exited or was signalled. */ + + if (slave_process) + { + /* Unregister the child from the list of slave subprocesses, so that + later, when we exit, we don't kill a totally unrelated process which + may have acquired the same pid. */ + unregister_slave_subprocess (child); + + /* Now remove the zombie from the process list. */ + for (;;) + { + if (waitid (P_PID, child, &info, 0) < 0) + { +# ifdef EINTR + if (errno == EINTR) + continue; +# endif + if (exit_on_error || !null_stderr) + error (exit_on_error ? EXIT_FAILURE : 0, errno, + _("%s subprocess"), progname); + return 127; + } + break; + } + } + + switch (info.si_code) + { + case CLD_KILLED: + case CLD_DUMPED: + if (exit_on_error || !null_stderr) + error (exit_on_error ? EXIT_FAILURE : 0, 0, + _("%s subprocess got fatal signal %d"), + progname, info.si_status); + return 127; + case CLD_EXITED: + if (info.si_status == 127) + { + if (exit_on_error || !null_stderr) + error (exit_on_error ? EXIT_FAILURE : 0, 0, + _("%s subprocess failed"), progname); + return 127; + } + return info.si_status; + default: + abort (); + } +#else /* waitpid() is just as portable as wait() nowadays. */ WAIT_T status; @@ -253,11 +341,11 @@ if (result != child) { -#ifdef EINTR +# ifdef EINTR if (errno == EINTR) continue; -#endif -#if 0 /* defined ECHILD */ +# endif +# if 0 /* defined ECHILD */ if (errno == ECHILD) { /* Child process nonexistent?! Assume it terminated @@ -265,7 +353,7 @@ *(int *) &status = 0; break; } -#endif +# endif if (exit_on_error || !null_stderr) error (exit_on_error ? EXIT_FAILURE : 0, errno, _("%s subprocess"), progname); @@ -302,4 +390,5 @@ return 127; } return WEXITSTATUS (status); +#endif }
--- a/m4/ChangeLog +++ b/m4/ChangeLog @@ -1,3 +1,7 @@ +2003-11-03 Bruno Haible <bruno@clisp.org> + + * wait-process.m4 (gl_WAIT_PROCESS): Also check for waitid. + 2003-10-30 Paul Eggert <eggert@cs.ucla.edu> * host-os.m4 (UTILS_HOST_OS): Change netbsd*-gnu pattern back to
--- a/m4/wait-process.m4 +++ b/m4/wait-process.m4 @@ -1,4 +1,4 @@ -# wait-process.m4 serial 1 +# wait-process.m4 serial 2 dnl Copyright (C) 2003 Free Software Foundation, Inc. dnl This file is free software, distributed under the terms of the GNU dnl General Public License. As a special exception to the GNU General @@ -12,4 +12,5 @@ AC_CHECK_HEADERS_ONCE(unistd.h) dnl Prerequisites of lib/wait-process.c. AC_REQUIRE([gt_TYPE_SIG_ATOMIC_T]) + AC_CHECK_FUNCS(waitid) ])