diff options
Diffstat (limited to 'tcl8.6/compat/waitpid.c')
| -rw-r--r-- | tcl8.6/compat/waitpid.c | 168 |
1 files changed, 168 insertions, 0 deletions
diff --git a/tcl8.6/compat/waitpid.c b/tcl8.6/compat/waitpid.c new file mode 100644 index 0000000..e03275a --- /dev/null +++ b/tcl8.6/compat/waitpid.c @@ -0,0 +1,168 @@ +/* + * waitpid.c -- + * + * This procedure emulates the POSIX waitpid kernel call on BSD systems + * that don't have waitpid but do have wait3. This code is based on a + * prototype version written by Mark Diekhans and Karl Lehenbauer. + * + * Copyright (c) 1993 The Regents of the University of California. + * Copyright (c) 1994 Sun Microsystems, Inc. + * + * See the file "license.terms" for information on usage and redistribution of + * this file, and for a DISCLAIMER OF ALL WARRANTIES. + */ + +#include "tclPort.h" + +#ifndef pid_t +#define pid_t int +#endif + +/* + * A linked list of the following structures is used to keep track of + * processes for which we received notification from the kernel, but the + * application hasn't waited for them yet (this can happen because wait may + * not return the process we really want). We save the information here until + * the application finally does wait for the process. + */ + +typedef struct WaitInfo { + pid_t pid; /* Pid of process that exited. */ + WAIT_STATUS_TYPE status; /* Status returned when child exited or + * suspended. */ + struct WaitInfo *nextPtr; /* Next in list of exited processes. */ +} WaitInfo; + +static WaitInfo *deadList = NULL; + /* First in list of all dead processes. */ + +/* + *---------------------------------------------------------------------- + * + * waitpid -- + * + * This procedure emulates the functionality of the POSIX waitpid kernel + * call, using the BSD wait3 kernel call. Note: it doesn't emulate + * absolutely all of the waitpid functionality, in that it doesn't + * support pid's of 0 or < -1. + * + * Results: + * -1 is returned if there is an error in the wait kernel call. Otherwise + * the pid of an exited or suspended process is returned and *statusPtr + * is set to the status value of the process. + * + * Side effects: + * None. + * + *---------------------------------------------------------------------- + */ + +#ifdef waitpid +# undef waitpid +#endif + +pid_t +waitpid( + pid_t pid, /* The pid to wait on. Must be -1 or greater + * than zero. */ + int *statusPtr, /* Where to store wait status for the + * process. */ + int options) /* OR'ed combination of WNOHANG and + * WUNTRACED. */ +{ + register WaitInfo *waitPtr, *prevPtr; + pid_t result; + WAIT_STATUS_TYPE status; + + if ((pid < -1) || (pid == 0)) { + errno = EINVAL; + return -1; + } + + /* + * See if there's a suitable process that has already stopped or exited. + * If so, remove it from the list of exited processes and return its + * information. + */ + + for (waitPtr = deadList, prevPtr = NULL; waitPtr != NULL; + prevPtr = waitPtr, waitPtr = waitPtr->nextPtr) { + if ((pid != waitPtr->pid) && (pid != -1)) { + continue; + } + if (!(options & WUNTRACED) && (WIFSTOPPED(waitPtr->status))) { + continue; + } + result = waitPtr->pid; + *statusPtr = *((int *) &waitPtr->status); + if (prevPtr == NULL) { + deadList = waitPtr->nextPtr; + } else { + prevPtr->nextPtr = waitPtr->nextPtr; + } + ckfree((char *) waitPtr); + return result; + } + + /* + * Wait for any process to stop or exit. If it's an acceptable one then + * return it to the caller; otherwise store information about it in the + * list of exited processes and try again. On systems that have only wait + * but not wait3, there are several situations we can't handle, but we do + * the best we can (e.g. can still handle some combinations of options by + * invoking wait instead of wait3). + */ + + while (1) { +#if NO_WAIT3 + if (options & WNOHANG) { + return 0; + } + if (options != 0) { + errno = EINVAL; + return -1; + } + result = wait(&status); +#else + result = wait3(&status, options, 0); +#endif + if ((result == -1) && (errno == EINTR)) { + continue; + } + if (result <= 0) { + return result; + } + + if ((pid != result) && (pid != -1)) { + goto saveInfo; + } + if (!(options & WUNTRACED) && (WIFSTOPPED(status))) { + goto saveInfo; + } + *statusPtr = *((int *) &status); + return result; + + /* + * Can't return this info to caller. Save it in the list of stopped or + * exited processes. Tricky point: first check for an existing entry + * for the process and overwrite it if it exists (e.g. a previously + * stopped process might now be dead). + */ + + saveInfo: + for (waitPtr = deadList; waitPtr != NULL; waitPtr = waitPtr->nextPtr) { + if (waitPtr->pid == result) { + waitPtr->status = status; + goto waitAgain; + } + } + waitPtr = (WaitInfo *) ckalloc(sizeof(WaitInfo)); + waitPtr->pid = result; + waitPtr->status = status; + waitPtr->nextPtr = deadList; + deadList = waitPtr; + + waitAgain: + continue; + } +} |