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/* exec.cxx
$Id: exec.cxx,v 1.7 2002/01/15 06:38:20 elf Exp $
written by Oscar Levi
8 December 1998
This file is part of the project BSIGN. See the file README for
more information.
Copyright (C) 1998 The Buici Company.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
-----------
DESCRIPTION
-----------
Support for executing a child process and managing IO streams for
that child.
*/
#include "standard.h"
#include "exec.h"
#include "sys/types.h"
#include "sys/wait.h"
#include "sys/time.h"
#include "errno.h"
int ExStream::exec (const char* szCommand, ExStream** rgpexs, int cStream)
{
// extern bool g_fDebug;
// if (g_fDebug)
// fprintf (stderr, "execute: '%s'\n", szCommand);
#if 0
for (int i = 0; i < cStream; ++i) {
ExStream& exs = *rgpexs[i];
fprintf (stderr, "%sing %d %d\n", exs.m_fWrite ? "writ" : "read",
exs.m_rgfd[0], exs.m_rgfd[1]);
}
#endif
int pid = fork ();
int status = 0; // Child's exit status
if (pid == 0) { // Child
for (int i = 0; i < cStream; ++i) { // Perform redirection
ExStream& exs = *rgpexs[i];
if (exs.m_fdTarget != -1) {
// fprintf (stderr, "%d: child closing %d\n", i, exs.m_fdTarget);
close (exs.m_fdTarget);
// fprintf (stderr, "%d: child duping %d to %d\n", i,
// exs.fd_child (), exs.m_fdTarget);
int result = dup2 (exs.fd_child (), exs.m_fdTarget);
// if (result == -1)
// fprintf (stderr, "dup2 failed %d %d\n", result, errno);
// fprintf (stderr, "%d: child closing %d\n", i, exs.fd_child ());
close (exs.fd_child ());
}
// fprintf (stderr, "%d: child closing parent's %d\n", i, exs.fd_parent ());
close (exs.fd_parent ());
}
// sleep (1);
// fprintf (stderr, "child command '%s'\n", szCommand);
int result = execl ("/bin/sh", "sh", "-c", szCommand, NULL);
fprintf (stderr, "child terminated unexpectedly result %d errno %d\n",
result, errno);
_exit (127); // *** FIXME, why this constant?
}
else { // Parent
// sleep (1);
for (int i = 0; i < cStream; ++i) { // Make everything non-block
ExStream& exs = *rgpexs[i];
// fprintf (stderr, "parent O_NONBLOCKING %d\n", exs.fd_parent ());
fcntl (exs.fd_parent (), F_SETFL, O_NONBLOCK);
// fprintf (stderr, "parent closing %d\n", exs.fd_child ());
close (exs.fd_child ());
}
bool fQuitChild = false;
bool fQuitIO = false;
while (!fQuitChild || !fQuitIO) {
fd_set fdsetRead;
FD_ZERO (&fdsetRead);
fd_set fdsetWrite;
FD_ZERO (&fdsetWrite);
int n = 0; // Highest numbered descriptor for select
for (int i = 0; i < cStream; ++i) { // Make everything non-block
ExStream& exs = *rgpexs[i];
if (!exs.is_active ())
continue;
FD_SET (exs.fd_parent (), exs.m_fWrite ? &fdsetWrite : &fdsetRead);
if (exs.fd_parent () > n)
n = exs.fd_parent ();
}
// Work the fd's until we kenna do it no more
struct timeval tv;
tv.tv_sec = 0;
tv.tv_usec = 100000; // 1/10th of a second
int result = select (n + 1, &fdsetRead, &fdsetWrite, NULL, &tv);
if (result == 0 && fQuitChild)
fQuitIO = true;
for (int i = 0; i < cStream; ++i) { // Make everything non-block
ExStream& exs = *rgpexs[i];
if (FD_ISSET (exs.fd_parent (),
exs.m_fWrite ? &fdsetWrite : &fdsetRead)) {
if (exs.m_fWrite) {
int cb = write (exs.fd_parent (), exs.m_pb + exs.m_cbUsed,
exs.m_cb - exs.m_cbUsed);
// fprintf (stderr, "parent writing to %d (%d bytes)\n",
// exs.fd_parent (), cb);
exs.m_cbUsed += cb;
if (exs.m_cb == exs.m_cbUsed) {
// fprintf (stderr, "parent closing to %d (EOF)\n",
// exs.fd_parent ());
close (exs.fd_parent ());
}
}
else {
int cb = read (exs.fd_parent (), exs.m_pb + exs.m_cbUsed,
exs.m_cb - exs.m_cbUsed);
// fprintf (stderr, "parent reading from %d (%d bytes, %d total)\n",
// exs.fd_parent (), cb, exs.m_cbUsed + cb);
exs.m_cbUsed += cb;
if (cb == 0)
exs.m_fClosed = true;
}
}
}
if (waitpid (pid, &status, WNOHANG) == pid) {
fQuitChild = true;
// fprintf (stderr, "child exited with status 0x%x (%d)\n",
// status, status);
status = WEXITSTATUS (status);
}
} // while
}
return status;
}
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