Add a process library with some stubs that the DTrace client needs.

These will be fleshed out as part of the DTrace userland tracing
development.

For now, the kernel tracing part of DTrace requires minimal functionality
for this library.

The API for this library is deliberately different from the libproc in
OpenSolaris due to licensing restrictions.

1 files changed, 159 insertions, 0 deletions

diff --git a/lib/libproc/proc_create.c b/lib/libproc/proc_create.c
new file mode 100644
index 0000000..8648999
--- /dev/null
+++ b/lib/libproc/proc_create.c
@@ -0,0 +1,159 @@
+/*-
+ * Copyright (c) 2008 John Birrell (jb@freebsd.org)
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * $FreeBSD$
+ */
+
+#include "_libproc.h"
+#include <err.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/wait.h>
+
+int
+proc_attach(pid_t pid, int flags, struct proc_handle **pphdl)
+{
+	struct proc_handle *phdl;
+	struct kevent kev;
+	int error = 0;
+	int status;
+
+	if (pid == 0 || pphdl == NULL)
+		return (EINVAL);
+
+	/*
+	 * Allocate memory for the process handle, a structure containing
+	 * all things related to the process.
+	 */
+	if ((phdl = malloc(sizeof(struct proc_handle))) == NULL)
+		return (ENOMEM);
+
+	memset(phdl, 0, sizeof(struct proc_handle));
+	phdl->pid = pid;
+	phdl->flags = flags;
+	phdl->status = PS_RUN;
+
+	EV_SET(&kev, pid, EVFILT_PROC, EV_ADD | EV_ONESHOT, NOTE_EXIT,
+	    0, NULL);
+
+	if ((phdl->kq = kqueue()) == -1)
+		err(1, "ERROR: cannot create kernel evet queue");
+
+	if (kevent(phdl->kq, &kev, 1, NULL, 0, NULL) < 0)
+		err(2, "ERROR: cannot monitor child process %d", pid);
+
+	if (ptrace(PT_ATTACH, phdl->pid, NULL, 0) != 0)
+		error = errno;
+
+	/* Wait for the child process to stop. */
+	else if (waitpid(pid, &status, WUNTRACED) == -1)
+		err(3, "ERROR: child process %d didn't stop as expected", pid);
+
+	/* Check for an unexpected status. */
+	else if (WIFSTOPPED(status) == 0)
+		err(4, "ERROR: child process %d status 0x%x", pid, status);
+	else
+		phdl->status = PS_STOP;
+
+	if (error)
+		proc_free(phdl);
+	else
+		*pphdl = phdl;
+
+	return (error);
+}
+
+int
+proc_create(const char *file, char * const *argv, struct proc_handle **pphdl)
+{
+	struct proc_handle *phdl;
+	struct kevent kev;
+	int error = 0;
+	int status;
+	pid_t pid;
+
+	/*
+	 * Allocate memory for the process handle, a structure containing
+	 * all things related to the process.
+	 */
+	if ((phdl = malloc(sizeof(struct proc_handle))) == NULL)
+		return (ENOMEM);
+
+	/* Fork a new process. */
+	if ((pid = fork()) == -1)
+		error = errno;
+	else if (pid == 0) {
+		/* The child expects to be traced. */
+		if (ptrace(PT_TRACE_ME, 0, 0, 0) != 0)
+			_exit(1);
+
+		/* Execute the specified file: */
+		execvp(file, argv);
+
+		/* Couldn't execute the file. */
+		_exit(2);
+	} else {
+		/* The parent owns the process handle. */
+		memset(phdl, 0, sizeof(struct proc_handle));
+		phdl->pid = pid;
+		phdl->status = PS_IDLE;
+
+		EV_SET(&kev, pid, EVFILT_PROC, EV_ADD | EV_ONESHOT, NOTE_EXIT,
+		    0, NULL);
+
+		if ((phdl->kq = kqueue()) == -1)
+                	err(1, "ERROR: cannot create kernel evet queue");
+
+        	if (kevent(phdl->kq, &kev, 1, NULL, 0, NULL) < 0)
+                	err(2, "ERROR: cannot monitor child process %d", pid);
+
+		/* Wait for the child process to stop. */
+		if (waitpid(pid, &status, WUNTRACED) == -1)
+                	err(3, "ERROR: child process %d didn't stop as expected", pid);
+
+		/* Check for an unexpected status. */
+		if (WIFSTOPPED(status) == 0)
+                	err(4, "ERROR: child process %d status 0x%x", pid, status);
+		else
+			phdl->status = PS_STOP;
+	}
+
+	if (error)
+		proc_free(phdl);
+	else
+		*pphdl = phdl;
+
+	return (error);
+}
+
+void
+proc_free(struct proc_handle *phdl)
+{
+	free(phdl);
+}