462 lines
11 KiB
C
462 lines
11 KiB
C
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/*
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* $Id: server.c,v 1.1 1998/03/20 16:19:41 korbb Exp $
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*
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* Server Handling copyright 1992-1998 Bruce Korb
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*
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* Server Handling is free software.
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* You may redistribute it and/or modify it under the terms of the
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* GNU General Public License, as published by the Free Software
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* Foundation; either version 2, or (at your option) any later version.
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*
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* Server Handling is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with Server Handling. See the file "COPYING". If not,
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* write to: The Free Software Foundation, Inc.,
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* 59 Temple Place - Suite 330,
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* Boston, MA 02111-1307, USA.
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*
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* As a special exception, Bruce Korb gives permission for additional
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* uses of the text contained in his release of ServerHandler.
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*
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* The exception is that, if you link the ServerHandler library with other
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* files to produce an executable, this does not by itself cause the
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* resulting executable to be covered by the GNU General Public License.
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* Your use of that executable is in no way restricted on account of
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* linking the ServerHandler library code into it.
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*
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* This exception does not however invalidate any other reasons why
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* the executable file might be covered by the GNU General Public License.
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*
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* This exception applies only to the code released by Bruce Korb under
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* the name ServerHandler. If you copy code from other sources under the
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* General Public License into a copy of ServerHandler, as the General Public
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* License permits, the exception does not apply to the code that you add
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* in this way. To avoid misleading anyone as to the status of such
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* modified files, you must delete this exception notice from them.
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*
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* If you write modifications of your own for ServerHandler, it is your
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* choice whether to permit this exception to apply to your modifications.
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* If you do not wish that, delete this exception notice.
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*/
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#include <fcntl.h>
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#include <errno.h>
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#include <signal.h>
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#include <stdlib.h>
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#include <string.h>
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#include <ctype.h>
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#include <sys/param.h>
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#include "server.h"
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#ifdef DEBUG
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#define STATIC
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#else
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#define STATIC static
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#endif
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#ifndef tSCC
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#define tSCC static const char
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#endif
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#ifndef NUL
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#define NUL '\0'
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#endif
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STATIC bool readPipeTimeout;
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STATIC tpChar defArgs[] =
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{(char *) NULL, "-p", (char *) NULL};
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STATIC tpfPair serverPair =
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{(FILE *) NULL, (FILE *) NULL};
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STATIC pid_t serverId = NULLPROCESS;
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/*
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* Arbitrary text that should not be found in the shell output.
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* It must be a single line and appear verbatim at the start of
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* the terminating output line.
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*/
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tSCC zDone[] = "ShElL-OuTpUt-HaS-bEeN-cOmPlEtEd";
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STATIC tpChar pCurDir = (char *) NULL;
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/*
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* chainOpen
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*
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* Given an FD for an inferior process to use as stdin,
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* start that process and return a NEW FD that that process
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* will use for its stdout. Requires the argument vector
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* for the new process and, optionally, a pointer to a place
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* to store the child's process id.
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*/
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int
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chainOpen (stdinFd, ppArgs, pChild)
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int stdinFd;
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tpChar *ppArgs;
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pid_t *pChild;
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{
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tFdPair stdoutPair =
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{-1, -1};
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pid_t chId;
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char *pzCmd;
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/*
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* Create a pipe it will be the child process' stdout,
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* and the parent will read from it.
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*/
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if ((pipe ((int *) &stdoutPair) < 0))
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{
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if (pChild != (pid_t *) NULL)
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*pChild = NOPROCESS;
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return -1;
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}
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/*
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* If we did not get an arg list, use the default
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*/
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if (ppArgs == (tpChar *) NULL)
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ppArgs = defArgs;
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/*
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* If the arg list does not have a program,
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* assume the "SHELL" from the environment, or, failing
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* that, then sh. Set argv[0] to whatever we decided on.
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*/
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if (pzCmd = *ppArgs,
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(pzCmd == (char *) NULL) || (*pzCmd == '\0'))
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{
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pzCmd = getenv ("SHELL");
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if (pzCmd == (char *) NULL)
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pzCmd = "sh";
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}
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#ifdef DEBUG_PRINT
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printf ("START: %s\n", pzCmd);
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{
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int idx = 0;
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while (ppArgs[++idx] != (char *) NULL)
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printf (" ARG %2d: %s\n", idx, ppArgs[idx]);
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}
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#endif
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/*
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* Call fork() and see which process we become
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*/
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chId = fork ();
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switch (chId)
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{
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case NOPROCESS: /* parent - error in call */
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close (stdoutPair.readFd);
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close (stdoutPair.writeFd);
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if (pChild != (pid_t *) NULL)
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*pChild = NOPROCESS;
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return -1;
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default: /* parent - return opposite FD's */
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if (pChild != (pid_t *) NULL)
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*pChild = chId;
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#ifdef DEBUG_PRINT
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printf ("for pid %d: stdin from %d, stdout to %d\n"
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"for parent: read from %d\n",
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chId, stdinFd, stdoutPair.writeFd, stdoutPair.readFd);
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#endif
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close (stdinFd);
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close (stdoutPair.writeFd);
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return stdoutPair.readFd;
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case NULLPROCESS: /* child - continue processing */
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break;
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}
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/*
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* Close the pipe end handed back to the parent process
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*/
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close (stdoutPair.readFd);
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/*
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* Close our current stdin and stdout
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*/
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close (STDIN_FILENO);
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close (STDOUT_FILENO);
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/*
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* Make the fd passed in the stdin, and the write end of
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* the new pipe become the stdout.
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*/
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fcntl (stdoutPair.writeFd, F_DUPFD, STDOUT_FILENO);
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fcntl (stdinFd, F_DUPFD, STDIN_FILENO);
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if (*ppArgs == (char *) NULL)
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*ppArgs = pzCmd;
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execvp (pzCmd, ppArgs);
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fprintf (stderr, "Error %d: Could not execvp( '%s', ... ): %s\n",
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errno, pzCmd, strerror (errno));
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exit (EXIT_PANIC);
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}
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/*
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* p2open
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*
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* Given a pointer to an argument vector, start a process and
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* place its stdin and stdout file descriptors into an fd pair
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* structure. The "writeFd" connects to the inferior process
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* stdin, and the "readFd" connects to its stdout. The calling
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* process should write to "writeFd" and read from "readFd".
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* The return value is the process id of the created process.
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*/
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pid_t
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p2open (pPair, ppArgs)
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tFdPair *pPair;
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tpChar *ppArgs;
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{
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pid_t chId;
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/*
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* Create a bi-directional pipe. Writes on 0 arrive on 1
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* and vice versa, so the parent and child processes will
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* read and write to opposite FD's.
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*/
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if (pipe ((int *) pPair) < 0)
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return NOPROCESS;
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pPair->readFd = chainOpen (pPair->readFd, ppArgs, &chId);
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if (chId == NOPROCESS)
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close (pPair->writeFd);
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return chId;
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}
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/*
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* p2fopen
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*
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* Identical to "p2open()", except that the "fd"'s are "fdopen(3)"-ed
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* into file pointers instead.
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*/
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pid_t
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p2fopen (pfPair, ppArgs)
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tpfPair *pfPair;
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tpChar *ppArgs;
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{
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tFdPair fdPair;
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pid_t chId = p2open (&fdPair, ppArgs);
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if (chId == NOPROCESS)
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return chId;
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pfPair->pfRead = fdopen (fdPair.readFd, "r");
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pfPair->pfWrite = fdopen (fdPair.writeFd, "w");
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return chId;
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}
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/*
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* loadData
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*
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* Read data from a file pointer (a pipe to a process in this context)
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* until we either get EOF or we get a marker line back.
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* The read data are stored in a malloc-ed string that is truncated
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* to size at the end. Input is assumed to be an ASCII string.
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*/
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STATIC char *
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loadData (fp)
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FILE *fp;
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{
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char *pzText;
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size_t textSize;
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char *pzScan;
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char zLine[1024];
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textSize = sizeof (zLine) * 2;
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pzScan = \
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pzText = malloc (textSize);
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if (pzText == (char *) NULL)
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return pzText;
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for (;;)
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{
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size_t usedCt;
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alarm (10);
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readPipeTimeout = BOOL_FALSE;
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if (fgets (zLine, sizeof (zLine), fp) == (char *) NULL)
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break;
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if (strncmp (zLine, zDone, sizeof (zDone) - 1) == 0)
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break;
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strcpy (pzScan, zLine);
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pzScan += strlen (zLine);
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usedCt = (size_t) (pzScan - pzText);
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if (textSize - usedCt < sizeof (zLine))
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{
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size_t off = (size_t) (pzScan - pzText);
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void *p;
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textSize += 4096;
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p = realloc ((void *) pzText, textSize);
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if (p == (void *) NULL)
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{
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fprintf (stderr, "Failed to get 0x%08X bytes\n", textSize);
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free ((void *) pzText);
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return (char *) NULL;
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}
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pzText = (char *) p;
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pzScan = pzText + off;
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}
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}
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alarm (0);
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if (readPipeTimeout)
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{
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free ((void *) pzText);
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return (char *) NULL;
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}
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while ((pzScan > pzText) && isspace (pzScan[-1]))
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pzScan--;
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*pzScan = NUL;
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return realloc ((void *) pzText, strlen (pzText) + 1);
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}
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/*
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* SHELL SERVER PROCESS CODE
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*/
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#ifdef DONT_HAVE_SIGSEND
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typedef enum
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{
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P_ALL, P_PID, P_GID, P_UID, P_PGID, P_SID, P_CID
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}
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idtype_t;
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typedef long id_t;
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STATIC int
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sigsend (idtype, id, sig)
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idtype_t idtype;
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id_t id;
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int sig;
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{
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switch (idtype)
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{
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case P_PID:
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kill ((pid_t) id, sig);
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break;
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case P_ALL:
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case P_GID:
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case P_UID:
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case P_PGID:
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case P_SID:
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case P_CID:
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errno = EINVAL;
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return -1;
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/*NOTREACHED */
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}
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return 0;
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}
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#endif /* HAVE_SIGSEND */
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STATIC void
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closeServer ()
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{
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sigsend (P_PID, (id_t) serverId, SIGKILL);
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serverId = NULLPROCESS;
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fclose (serverPair.pfRead);
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fclose (serverPair.pfWrite);
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serverPair.pfRead = serverPair.pfWrite = (FILE *) NULL;
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}
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struct sigaction savePipeAction;
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struct sigaction saveAlrmAction;
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struct sigaction currentAction;
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STATIC void
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sigHandler (signo)
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int signo;
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{
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closeServer ();
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readPipeTimeout = BOOL_TRUE;
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}
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STATIC void
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serverSetup ()
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{
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currentAction.sa_sigaction =
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currentAction.sa_handler = sigHandler;
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currentAction.sa_flags = SA_SIGINFO;
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sigemptyset (¤tAction.sa_mask);
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sigaction (SIGPIPE, ¤tAction, &savePipeAction);
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sigaction (SIGALRM, ¤tAction, &saveAlrmAction);
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atexit (&closeServer);
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fputs ("trap : INT\n", serverPair.pfWrite);
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fflush (serverPair.pfWrite);
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pCurDir = getcwd ((char *) NULL, MAXPATHLEN + 1);
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}
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char *
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runShell (pzCmd)
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const char *pzCmd;
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{
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tSCC zNil[] = "";
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/*
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* IF the shell server process is not running yet,
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* THEN try to start it.
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*/
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if (serverId == NULLPROCESS)
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{
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serverId = p2fopen (&serverPair, defArgs);
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if (serverId > 0)
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serverSetup ();
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}
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/*
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* IF it is still not running,
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* THEN return the nil string.
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*/
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if (serverId <= 0)
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return (char *) zNil;
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/*
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* Make sure the process will pay attention to us,
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* send the supplied command, and then
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* have it output a special marker that we can find.
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*/
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fprintf (serverPair.pfWrite, "\\cd %s\n%s\n\necho\necho %s\n",
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pCurDir, pzCmd, zDone);
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fflush (serverPair.pfWrite);
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if (serverId == NULLPROCESS)
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return (char *) NULL;
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/*
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* Now try to read back all the data. If we fail due to either
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* a sigpipe or sigalrm (timeout), we will return the nil string.
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*/
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{
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char *pz = loadData (serverPair.pfRead);
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if (pz == (char *) NULL)
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{
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fprintf (stderr, "CLOSING SHELL SERVER - command failure:\n\t%s\n",
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pzCmd);
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closeServer ();
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pz = (char *) zNil;
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}
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return pz;
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}
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}
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