Initial revision

1 files changed, 170 insertions, 0 deletions

diff --git a/compat/waitpid.c b/compat/waitpid.c
new file mode 100644
index 0000000..179d5de
--- /dev/null
+++ b/compat/waitpid.c
@@ -0,0 +1,170 @@
+/* 
+ * 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.
+ *
+ * SCCS: @(#) waitpid.c 1.9 96/02/15 12:08:26
+ */
+
+#include "tclInt.h"
+#include "tclPort.h"
+
+/*
+ * 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 {
+    int 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
+
+int
+waitpid(pid, statusPtr, options)
+    int 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;
+    int 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;
+    }
+}