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Use spawnve on cygwin.
* configure.ac (AC_CHECK_HEADERS): Add process.h. (checkfuncs): Add dup3, spawnve, spawnvpe; sort the list. (AC_CHECK_FUNCS): Add dup3, spawnve, spawnvpe. * configure, config.in: Rebuild. * pex-unix.c [HAVE_SPAWNVE] (pex_unix_exec_child): New function. [HAVE_SPAWNVE] (save_and_install_fd, restore_fd): New functions.
This commit is contained in:
Richard Henderson
@@ -55,7 +55,9 @@ extern int errno;
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#ifdef HAVE_SYS_STAT_H
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#include <sys/stat.h>
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#endif
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#ifdef HAVE_PROCESS_H
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#include <process.h>
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#endif
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#ifdef vfork /* Autoconf may define this to fork for us. */
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# define VFORK_STRING "fork"
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@@ -387,6 +389,202 @@ pex_child_error (struct pex_obj *obj, const char *executable,
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extern char **environ;
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#if defined(HAVE_SPAWNVE) && defined(HAVE_SPAWNVPE)
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/* Implementation of pex->exec_child using the Cygwin spawn operation. */
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/* Subroutine of pex_unix_exec_child. Move OLD_FD to a new file descriptor
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to be stored in *PNEW_FD, save the flags in *PFLAGS, and arrange for the
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saved copy to be close-on-exec. Move CHILD_FD into OLD_FD. If CHILD_FD
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is -1, OLD_FD is to be closed. Return -1 on error. */
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static int
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save_and_install_fd(int *pnew_fd, int *pflags, int old_fd, int child_fd)
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{
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int new_fd, flags;
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flags = fcntl (old_fd, F_GETFD);
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/* If we could not retrieve the flags, then OLD_FD was not open. */
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if (flags < 0)
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{
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new_fd = -1, flags = 0;
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if (child_fd >= 0 && dup2 (child_fd, old_fd) < 0)
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return -1;
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}
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/* If we wish to close OLD_FD, just mark it CLOEXEC. */
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else if (child_fd == -1)
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{
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new_fd = old_fd;
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if ((flags & FD_CLOEXEC) == 0 && fcntl (old_fd, F_SETFD, FD_CLOEXEC) < 0)
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return -1;
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}
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/* Otherwise we need to save a copy of OLD_FD before installing CHILD_FD. */
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else
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{
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#ifdef F_DUPFD_CLOEXEC
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new_fd = fcntl (old_fd, F_DUPFD_CLOEXEC, 3);
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if (new_fd < 0)
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return -1;
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#else
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/* Prefer F_DUPFD over dup in order to avoid getting a new fd
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in the range 0-2, right where a new stderr fd might get put. */
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new_fd = fcntl (old_fd, F_DUPFD, 3);
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if (new_fd < 0)
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return -1;
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if (fcntl (new_fd, F_SETFD, FD_CLOEXEC) < 0)
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return -1;
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#endif
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if (dup2 (child_fd, old_fd) < 0)
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return -1;
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}
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*pflags = flags;
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if (pnew_fd)
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*pnew_fd = new_fd;
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else if (new_fd != old_fd)
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abort ();
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return 0;
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}
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/* Subroutine of pex_unix_exec_child. Move SAVE_FD back to OLD_FD
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restoring FLAGS. If SAVE_FD < 0, OLD_FD is to be closed. */
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static int
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restore_fd(int old_fd, int save_fd, int flags)
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{
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/* For SAVE_FD < 0, all we have to do is restore the
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"closed-ness" of the original. */
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if (save_fd < 0)
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return close (old_fd);
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/* For SAVE_FD == OLD_FD, all we have to do is restore the
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original setting of the CLOEXEC flag. */
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if (save_fd == old_fd)
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{
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if (flags & FD_CLOEXEC)
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return 0;
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return fcntl (old_fd, F_SETFD, flags);
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}
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/* Otherwise we have to move the descriptor back, restore the flags,
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and close the saved copy. */
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#ifdef HAVE_DUP3
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if (flags == FD_CLOEXEC)
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{
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if (dup3 (save_fd, old_fd, O_CLOEXEC) < 0)
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return -1;
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}
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else
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#endif
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{
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if (dup2 (save_fd, old_fd) < 0)
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return -1;
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if (flags != 0 && fcntl (old_fd, F_SETFD, flags) < 0)
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return -1;
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}
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return close (save_fd);
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}
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static pid_t
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pex_unix_exec_child (struct pex_obj *obj ATTRIBUTE_UNUSED,
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int flags, const char *executable,
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char * const * argv, char * const * env,
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int in, int out, int errdes, int toclose,
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const char **errmsg, int *err)
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{
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int fl_in = 0, fl_out = 0, fl_err = 0, fl_tc = 0;
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int save_in = -1, save_out = -1, save_err = -1;
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int max, retries;
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pid_t pid;
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if (flags & PEX_STDERR_TO_STDOUT)
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errdes = out;
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/* We need the three standard file descriptors to be set up as for
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the child before we perform the spawn. The file descriptors for
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the parent need to be moved and marked for close-on-exec. */
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if (in != STDIN_FILE_NO
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&& save_and_install_fd (&save_in, &fl_in, STDIN_FILE_NO, in) < 0)
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goto error_dup2;
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if (out != STDOUT_FILE_NO
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&& save_and_install_fd (&save_out, &fl_out, STDOUT_FILE_NO, out) < 0)
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goto error_dup2;
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if (errdes != STDERR_FILE_NO
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&& save_and_install_fd (&save_err, &fl_err, STDERR_FILE_NO, errdes) < 0)
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goto error_dup2;
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if (toclose >= 0
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&& save_and_install_fd (NULL, &fl_tc, toclose, -1) < 0)
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goto error_dup2;
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/* Now that we've moved the file descriptors for the child into place,
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close the originals. Be careful not to close any of the standard
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file descriptors that we just set up. */
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max = -1;
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if (errdes >= 0)
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max = STDERR_FILE_NO;
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else if (out >= 0)
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max = STDOUT_FILE_NO;
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else if (in >= 0)
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max = STDIN_FILE_NO;
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if (in > max)
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close (in);
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if (out > max)
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close (out);
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if (errdes > max && errdes != out)
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close (errdes);
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/* If we were not given an environment, use the global environment. */
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if (env == NULL)
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env = environ;
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/* Launch the program. If we get EAGAIN (normally out of pid's), try
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again a few times with increasing backoff times. */
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retries = 0;
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while (1)
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{
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typedef const char * const *cc_cp;
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if (flags & PEX_SEARCH)
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pid = spawnvpe (_P_NOWAITO, executable, (cc_cp)argv, (cc_cp)env);
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else
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pid = spawnve (_P_NOWAITO, executable, (cc_cp)argv, (cc_cp)env);
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if (pid > 0)
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break;
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*err = errno;
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*errmsg = "spawn";
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if (errno != EAGAIN || ++retries == 4)
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return (pid_t) -1;
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sleep (1 << retries);
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}
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/* Success. Restore the parent's file descriptors that we saved above. */
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if (toclose >= 0
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&& restore_fd (toclose, toclose, fl_tc) < 0)
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goto error_dup2;
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if (in != STDIN_FILE_NO
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&& restore_fd (STDIN_FILE_NO, save_in, fl_in) < 0)
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goto error_dup2;
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if (out != STDOUT_FILE_NO
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&& restore_fd (STDOUT_FILE_NO, save_out, fl_out) < 0)
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goto error_dup2;
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if (errdes != STDERR_FILE_NO
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&& restore_fd (STDERR_FILE_NO, save_err, fl_err) < 0)
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goto error_dup2;
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return pid;
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error_dup2:
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*err = errno;
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*errmsg = "dup2";
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return (pid_t) -1;
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}
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#else
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/* Implementation of pex->exec_child using standard vfork + exec. */
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static pid_t
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pex_unix_exec_child (struct pex_obj *obj, int flags, const char *executable,
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char * const * argv, char * const * env,
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@@ -521,6 +719,7 @@ pex_unix_exec_child (struct pex_obj *obj, int flags, const char *executable,
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return pid;
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}
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}
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#endif /* SPAWN */
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/* Wait for a child process to complete. */
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