archie/tcl7.6/unix/tclUnixPipe.c

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/*
* tclUnixPipe.c -- This file implements the UNIX-specific exec pipeline
* functions.
*
* Copyright (c) 1991-1994 The Regents of the University of California.
* Copyright (c) 1994-1996 Sun Microsystems, Inc.
*
* See the file "license.terms" for information on usage and redistribution
* of this file, and for a DISCLAIMER OF ALL WARRANTIES.
*
* SCCS: @(#) tclUnixPipe.c 1.30 96/09/12 14:57:15
*/
#include "tclInt.h"
#include "tclPort.h"
/*
* Declarations for local procedures defined in this file:
*/
static void RestoreSignals _ANSI_ARGS_((void));
static int SetupStdFile _ANSI_ARGS_((Tcl_File file, int type));
/*
*----------------------------------------------------------------------
*
* TclpCreateProcess --
*
* Create a child process that has the specified files as its
* standard input, output, and error. The child process runs
* asynchronously and runs with the same environment variables
* as the creating process.
*
* The path is searched to find the specified executable.
*
* Results:
* The return value is TCL_ERROR and an error message is left in
* interp->result if there was a problem creating the child
* process. Otherwise, the return value is TCL_OK and *pidPtr is
* filled with the process id of the child process.
*
* Side effects:
* A process is created.
*
*----------------------------------------------------------------------
*/
/* ARGSUSED */
int
TclpCreateProcess(interp, argc, argv, inputFile, outputFile, errorFile,
inputFileName, outputFileName, errorFileName, pidPtr)
Tcl_Interp *interp; /* Interpreter in which to leave errors that
* occurred when creating the child process.
* Error messages from the child process
* itself are sent to errorFile. */
int argc; /* Number of arguments in following array. */
char **argv; /* Array of argument strings. argv[0]
* contains the name of the executable
* converted to native format (using the
* Tcl_TranslateFileName call). Additional
* arguments have not been converted. */
Tcl_File inputFile; /* If non-NULL, gives the file to use as
* input for the child process. If inputFile
* file is not readable or is NULL, the child
* will receive no standard input. */
Tcl_File outputFile; /* If non-NULL, gives the file that
* receives output from the child process. If
* outputFile file is not writeable or is
* NULL, output from the child will be
* discarded. */
Tcl_File errorFile; /* If non-NULL, gives the file that
* receives errors from the child process. If
* errorFile file is not writeable or is NULL,
* errors from the child will be discarded.
* errorFile may be the same as outputFile. */
char *inputFileName; /* If non-NULL, gives the name of the disk
* file that corresponds to inputFile
* (unused). */
char *outputFileName; /* If non-NULL, gives the name of the disk
* file that corresponds to outputFile
* (unused). */
char *errorFileName; /* If non-NULL, gives the name of the disk
* file that corresponds to errorFile
* (unused). */
int *pidPtr; /* If this procedure is successful, pidPtr
* is filled with the process id of the child
* process. */
{
Tcl_File errPipeIn, errPipeOut;
int pid, joinThisError, count, status;
char errSpace[200];
errPipeIn = NULL;
errPipeOut = NULL;
pid = -1;
/*
* Create a pipe that the child can use to return error
* information if anything goes wrong.
*/
if (TclCreatePipe(&errPipeIn, &errPipeOut) == 0) {
Tcl_AppendResult(interp, "couldn't create pipe: ",
Tcl_PosixError(interp), (char *) NULL);
goto error;
}
joinThisError = (errorFile == outputFile);
pid = vfork();
if (pid == 0) {
/*
* Set up stdio file handles for the child process.
*/
if (!SetupStdFile(inputFile, TCL_STDIN)
|| !SetupStdFile(outputFile, TCL_STDOUT)
|| (!joinThisError && !SetupStdFile(errorFile, TCL_STDERR))
|| (joinThisError &&
((dup2(1,2) == -1) ||
(fcntl(2, F_SETFD, 0) != 0)))) {
sprintf(errSpace,
"%dforked process couldn't set up input/output: ",
errno);
TclWriteFile(errPipeOut, 1, errSpace, (int) strlen(errSpace));
_exit(1);
}
/*
* Close the input side of the error pipe.
*/
RestoreSignals();
execvp(argv[0], &argv[0]);
sprintf(errSpace, "%dcouldn't execute \"%.150s\": ", errno,
argv[0]);
TclWriteFile(errPipeOut, 1, errSpace, (int) strlen(errSpace));
_exit(1);
}
if (pid == -1) {
Tcl_AppendResult(interp, "couldn't fork child process: ",
Tcl_PosixError(interp), (char *) NULL);
goto error;
}
/*
* Read back from the error pipe to see if the child startup
* up OK. The info in the pipe (if any) consists of a decimal
* errno value followed by an error message.
*/
TclCloseFile(errPipeOut);
errPipeOut = NULL;
count = TclReadFile(errPipeIn, 1, errSpace,
(size_t) (sizeof(errSpace) - 1));
if (count > 0) {
char *end;
errSpace[count] = 0;
errno = strtol(errSpace, &end, 10);
Tcl_AppendResult(interp, end, Tcl_PosixError(interp),
(char *) NULL);
goto error;
}
TclCloseFile(errPipeIn);
*pidPtr = pid;
return TCL_OK;
error:
if (pid != -1) {
/*
* Reap the child process now if an error occurred during its
* startup.
*/
Tcl_WaitPid(pid, &status, WNOHANG);
}
if (errPipeIn) {
TclCloseFile(errPipeIn);
}
if (errPipeOut) {
TclCloseFile(errPipeOut);
}
return TCL_ERROR;
}
/*
*----------------------------------------------------------------------
*
* RestoreSignals --
*
* This procedure is invoked in a forked child process just before
* exec-ing a new program to restore all signals to their default
* settings.
*
* Results:
* None.
*
* Side effects:
* Signal settings get changed.
*
*----------------------------------------------------------------------
*/
static void
RestoreSignals()
{
#ifdef SIGABRT
signal(SIGABRT, SIG_DFL);
#endif
#ifdef SIGALRM
signal(SIGALRM, SIG_DFL);
#endif
#ifdef SIGFPE
signal(SIGFPE, SIG_DFL);
#endif
#ifdef SIGHUP
signal(SIGHUP, SIG_DFL);
#endif
#ifdef SIGILL
signal(SIGILL, SIG_DFL);
#endif
#ifdef SIGINT
signal(SIGINT, SIG_DFL);
#endif
#ifdef SIGPIPE
signal(SIGPIPE, SIG_DFL);
#endif
#ifdef SIGQUIT
signal(SIGQUIT, SIG_DFL);
#endif
#ifdef SIGSEGV
signal(SIGSEGV, SIG_DFL);
#endif
#ifdef SIGTERM
signal(SIGTERM, SIG_DFL);
#endif
#ifdef SIGUSR1
signal(SIGUSR1, SIG_DFL);
#endif
#ifdef SIGUSR2
signal(SIGUSR2, SIG_DFL);
#endif
#ifdef SIGCHLD
signal(SIGCHLD, SIG_DFL);
#endif
#ifdef SIGCONT
signal(SIGCONT, SIG_DFL);
#endif
#ifdef SIGTSTP
signal(SIGTSTP, SIG_DFL);
#endif
#ifdef SIGTTIN
signal(SIGTTIN, SIG_DFL);
#endif
#ifdef SIGTTOU
signal(SIGTTOU, SIG_DFL);
#endif
}
/*
*----------------------------------------------------------------------
*
* SetupStdFile --
*
* Set up stdio file handles for the child process, using the
* current standard channels if no other files are specified.
* If no standard channel is defined, or if no file is associated
* with the channel, then the corresponding standard fd is closed.
*
* Results:
* Returns 1 on success, or 0 on failure.
*
* Side effects:
* Replaces stdio fds.
*
*----------------------------------------------------------------------
*/
static int
SetupStdFile(file, type)
Tcl_File file; /* File to dup, or NULL. */
int type; /* One of TCL_STDIN, TCL_STDOUT, TCL_STDERR */
{
Tcl_Channel channel;
int fd;
int targetFd = 0; /* Initializations here needed only to */
int direction = 0; /* prevent warnings about using uninitialized
* variables. */
switch (type) {
case TCL_STDIN:
targetFd = 0;
direction = TCL_READABLE;
break;
case TCL_STDOUT:
targetFd = 1;
direction = TCL_WRITABLE;
break;
case TCL_STDERR:
targetFd = 2;
direction = TCL_WRITABLE;
break;
}
if (!file) {
channel = Tcl_GetStdChannel(type);
if (channel) {
file = Tcl_GetChannelFile(channel, direction);
}
}
if (file) {
fd = (int)Tcl_GetFileInfo(file, NULL);
if (fd != targetFd) {
if (dup2(fd, targetFd) == -1) {
return 0;
}
/*
* Must clear the close-on-exec flag for the target FD, since
* some systems (e.g. Ultrix) do not clear the CLOEXEC flag on
* the target FD.
*/
fcntl(targetFd, F_SETFD, 0);
} else {
int result;
/*
* Since we aren't dup'ing the file, we need to explicitly clear
* the close-on-exec flag.
*/
result = fcntl(fd, F_SETFD, 0);
}
} else {
close(targetFd);
}
return 1;
}
/*
*----------------------------------------------------------------------
*
* TclCreatePipe --
*
* Creates a pipe - simply calls the pipe() function.
*
* Results:
* Returns 1 on success, 0 on failure.
*
* Side effects:
* Creates a pipe.
*
*----------------------------------------------------------------------
*/
int
TclCreatePipe(readPipe, writePipe)
Tcl_File *readPipe; /* Location to store file handle for
* read side of pipe. */
Tcl_File *writePipe; /* Location to store file handle for
* write side of pipe. */
{
int pipeIds[2];
if (pipe(pipeIds) != 0) {
return 0;
}
fcntl(pipeIds[0], F_SETFD, FD_CLOEXEC);
fcntl(pipeIds[1], F_SETFD, FD_CLOEXEC);
*readPipe = Tcl_GetFile((ClientData)pipeIds[0], TCL_UNIX_FD);
*writePipe = Tcl_GetFile((ClientData)pipeIds[1], TCL_UNIX_FD);
return 1;
}