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Index: lib/libc/sys/ptrace.2
===================================================================
--- lib/libc/sys/ptrace.2
+++ lib/libc/sys/ptrace.2
@@ -163,6 +163,40 @@
initial thread,
and exiting processes do not report an event for the termination of the
last thread.
+.It Dv PTRACE_VFORK
+Report a stop event when a parent process resumes after a
+.Xr vfork 2 .
+.Pp
+When
+.Dv PTRACE_FORK
+is active,
+the parent process reports an event with
+.Dv PL_FLAG_FORKED
+set when the child process is created.
+If a debugger is not tracing the new child process,
+it must ensure that no breakpoints are enabled in the shared process
+memory before detaching from the new child process.
+This means that no breakpoints are enabled in the parent process either.
+.Pp
+The
+.Dv PTRACE_VFORK
+flag enables a new stop that indicates when the new child process stops
+sharing the process memory of the parent process.
+A debugger can reinsert breakpoints in the parent process and resume it
+in response to this event.
+This event is indicated by setting the
+.Dv PL_FLAG_VFORK_DONE
+flag.
+In addition,
+if
+.Dv PTRACE_FORK
+is active,
+the initial fork event will include the
+.Dv PL_FLAG_VFORKED
+flag in addition to
+.Dv PL_FLAG_FORKED
+when a traced process creates a new process via
+.Xr vfork 2 .
.El
.Pp
The default tracing event mask when attaching to a process via
@@ -491,6 +525,16 @@
Note that this event is not reported when the last LWP in a process exits.
The termination of the last thread is reported via a normal process exit
event.
+.It PL_FLAG_VFORKED
+Indicates that the thread is returning from a call to
+.Xr vfork 2
+that created a new child process.
+This flag is set in addition to
+.Dv PL_FLAG_FORKED .
+.It PL_FLAG_VFORK_DONE
+Indicates that the thread has resumed after a child process created via
+.Xr vfork 2
+has stopped sharing its address space with the traced process.
.El
.It pl_sigmask
The current signal mask of the LWP
Index: sys/kern/kern_fork.c
===================================================================
--- sys/kern/kern_fork.c
+++ sys/kern/kern_fork.c
@@ -735,6 +735,7 @@
if (fr->fr_flags & RFPPWAIT) {
td->td_pflags |= TDP_RFPPWAIT;
td->td_rfppwait_p = p2;
+ td->td_dbgflags |= TDB_VFORK;
}
PROC_UNLOCK(p2);
Index: sys/kern/subr_syscall.c
===================================================================
--- sys/kern/subr_syscall.c
+++ sys/kern/subr_syscall.c
@@ -242,5 +242,13 @@
cv_timedwait(&p2->p_pwait, &p2->p_mtx, hz);
}
PROC_UNLOCK(p2);
+
+ if (td->td_dbgflags & TDB_VFORK) {
+ PROC_LOCK(p);
+ if (p->p_ptevents & PTRACE_VFORK)
+ ptracestop(td, SIGTRAP);
+ td->td_dbgflags &= ~TDB_VFORK;
+ PROC_UNLOCK(p);
+ }
}
}
Index: sys/kern/sys_process.c
===================================================================
--- sys/kern/sys_process.c
+++ sys/kern/sys_process.c
@@ -993,7 +993,7 @@
}
tmp = *(int *)addr;
if ((tmp & ~(PTRACE_EXEC | PTRACE_SCE | PTRACE_SCX |
- PTRACE_FORK | PTRACE_LWP)) != 0) {
+ PTRACE_FORK | PTRACE_LWP | PTRACE_VFORK)) != 0) {
error = EINVAL;
break;
}
@@ -1303,7 +1303,11 @@
if (td2->td_dbgflags & TDB_FORK) {
pl->pl_flags |= PL_FLAG_FORKED;
pl->pl_child_pid = td2->td_dbg_forked;
- }
+ if (td2->td_dbgflags & TDB_VFORK)
+ pl->pl_flags |= PL_FLAG_VFORKED;
+ } else if ((td2->td_dbgflags & (TDB_SCX | TDB_VFORK)) ==
+ TDB_VFORK)
+ pl->pl_flags |= PL_FLAG_VFORK_DONE;
if (td2->td_dbgflags & TDB_CHILD)
pl->pl_flags |= PL_FLAG_CHILD;
if (td2->td_dbgflags & TDB_BORN)
Index: sys/sys/proc.h
===================================================================
--- sys/sys/proc.h
+++ sys/sys/proc.h
@@ -422,6 +422,7 @@
#define TDB_CHILD 0x00000100 /* New child indicator for ptrace() */
#define TDB_BORN 0x00000200 /* New LWP indicator for ptrace() */
#define TDB_EXIT 0x00000400 /* Exiting LWP indicator for ptrace() */
+#define TDB_VFORK 0x00000800 /* vfork indicator for ptrace() */
/*
* "Private" flags kept in td_pflags:
Index: sys/sys/ptrace.h
===================================================================
--- sys/sys/ptrace.h
+++ sys/sys/ptrace.h
@@ -89,6 +89,7 @@
#define PTRACE_SYSCALL (PTRACE_SCE | PTRACE_SCX)
#define PTRACE_FORK 0x0008
#define PTRACE_LWP 0x0010
+#define PTRACE_VFORK 0x0020
#define PTRACE_DEFAULT (PTRACE_EXEC)
@@ -124,6 +125,8 @@
#define PL_FLAG_CHILD 0x80 /* I am from child */
#define PL_FLAG_BORN 0x100 /* new LWP */
#define PL_FLAG_EXITED 0x200 /* exiting LWP */
+#define PL_FLAG_VFORKED 0x400 /* new child via vfork */
+#define PL_FLAG_VFORK_DONE 0x800 /* vfork parent has resumed */
sigset_t pl_sigmask; /* LWP signal mask */
sigset_t pl_siglist; /* LWP pending signal */
struct __siginfo pl_siginfo; /* siginfo for signal */
Index: tests/sys/kern/ptrace_test.c
===================================================================
--- tests/sys/kern/ptrace_test.c
+++ tests/sys/kern/ptrace_test.c
@@ -1549,6 +1549,130 @@
ATF_REQUIRE(errno == ECHILD);
}
+/*
+ * Verify that the expected ptrace events are reported for PTRACE_VFORK.
+ */
+ATF_TC_WITHOUT_HEAD(ptrace__ptrace_vfork);
+ATF_TC_BODY(ptrace__ptrace_vfork, tc)
+{
+ struct ptrace_lwpinfo pl;
+ pid_t fpid, wpid;
+ int events, status;
+
+ ATF_REQUIRE((fpid = fork()) != -1);
+ if (fpid == 0) {
+ trace_me();
+ follow_fork_parent(true);
+ }
+
+ /* The first wait() should report the stop from SIGSTOP. */
+ wpid = waitpid(fpid, &status, 0);
+ ATF_REQUIRE(wpid == fpid);
+ ATF_REQUIRE(WIFSTOPPED(status));
+ ATF_REQUIRE(WSTOPSIG(status) == SIGSTOP);
+
+ ATF_REQUIRE(ptrace(PT_GET_EVENT_MASK, fpid, (caddr_t)&events,
+ sizeof(events)) == 0);
+ events |= PTRACE_VFORK;
+ ATF_REQUIRE(ptrace(PT_SET_EVENT_MASK, fpid, (caddr_t)&events,
+ sizeof(events)) == 0);
+
+ /* Continue the child ignoring the SIGSTOP. */
+ ATF_REQUIRE(ptrace(PT_CONTINUE, fpid, (caddr_t)1, 0) != -1);
+
+ /* The next event should report the end of the vfork. */
+ wpid = wait(&status);
+ ATF_REQUIRE(wpid == fpid);
+ ATF_REQUIRE(WIFSTOPPED(status));
+ ATF_REQUIRE(WSTOPSIG(status) == SIGTRAP);
+ ATF_REQUIRE(ptrace(PT_LWPINFO, wpid, (caddr_t)&pl, sizeof(pl)) != -1);
+ ATF_REQUIRE((pl.pl_flags & PL_FLAG_VFORK_DONE) != 0);
+
+ ATF_REQUIRE(ptrace(PT_CONTINUE, fpid, (caddr_t)1, 0) != -1);
+
+ wpid = wait(&status);
+ ATF_REQUIRE(wpid == fpid);
+ ATF_REQUIRE(WIFEXITED(status));
+ ATF_REQUIRE(WEXITSTATUS(status) == 1);
+
+ wpid = wait(&status);
+ ATF_REQUIRE(wpid == -1);
+ ATF_REQUIRE(errno == ECHILD);
+}
+
+ATF_TC_WITHOUT_HEAD(ptrace__ptrace_vfork_follow);
+ATF_TC_BODY(ptrace__ptrace_vfork_follow, tc)
+{
+ struct ptrace_lwpinfo pl[2];
+ pid_t children[2], fpid, wpid;
+ int events, status;
+
+ ATF_REQUIRE((fpid = fork()) != -1);
+ if (fpid == 0) {
+ trace_me();
+ follow_fork_parent(true);
+ }
+
+ /* Parent process. */
+ children[0] = fpid;
+
+ /* The first wait() should report the stop from SIGSTOP. */
+ wpid = waitpid(children[0], &status, 0);
+ ATF_REQUIRE(wpid == children[0]);
+ ATF_REQUIRE(WIFSTOPPED(status));
+ ATF_REQUIRE(WSTOPSIG(status) == SIGSTOP);
+
+ ATF_REQUIRE(ptrace(PT_GET_EVENT_MASK, children[0], (caddr_t)&events,
+ sizeof(events)) == 0);
+ events |= PTRACE_FORK | PTRACE_VFORK;
+ ATF_REQUIRE(ptrace(PT_SET_EVENT_MASK, children[0], (caddr_t)&events,
+ sizeof(events)) == 0);
+
+ /* Continue the child ignoring the SIGSTOP. */
+ ATF_REQUIRE(ptrace(PT_CONTINUE, children[0], (caddr_t)1, 0) != -1);
+
+ /* Wait for both halves of the fork event to get reported. */
+ children[1] = handle_fork_events(children[0], pl);
+ ATF_REQUIRE(children[1] > 0);
+
+ ATF_REQUIRE((pl[0].pl_flags & PL_FLAG_VFORKED) != 0);
+
+ ATF_REQUIRE(ptrace(PT_CONTINUE, children[0], (caddr_t)1, 0) != -1);
+ ATF_REQUIRE(ptrace(PT_CONTINUE, children[1], (caddr_t)1, 0) != -1);
+
+ /*
+ * The child can't exit until the grandchild reports status, so the
+ * grandchild should report its exit first to the debugger.
+ */
+ wpid = waitpid(children[1], &status, 0);
+ ATF_REQUIRE(wpid == children[1]);
+ ATF_REQUIRE(WIFEXITED(status));
+ ATF_REQUIRE(WEXITSTATUS(status) == 2);
+
+ /*
+ * The child should report it's vfork() completion before it
+ * exits.
+ */
+ wpid = wait(&status);
+ ATF_REQUIRE(wpid == children[0]);
+ ATF_REQUIRE(WIFSTOPPED(status));
+ ATF_REQUIRE(WSTOPSIG(status) == SIGTRAP);
+ ATF_REQUIRE(ptrace(PT_LWPINFO, wpid, (caddr_t)&pl[0], sizeof(pl[0])) !=
+ -1);
+ ATF_REQUIRE((pl[0].pl_flags & PL_FLAG_VFORK_DONE) != 0);
+
+ ATF_REQUIRE(ptrace(PT_CONTINUE, children[0], (caddr_t)1, 0) != -1);
+
+ wpid = wait(&status);
+ ATF_REQUIRE(wpid == children[0]);
+ ATF_REQUIRE(WIFEXITED(status));
+ ATF_REQUIRE(WEXITSTATUS(status) == 1);
+
+ wpid = wait(&status);
+ ATF_REQUIRE(wpid == -1);
+ ATF_REQUIRE(errno == ECHILD);
+}
+
ATF_TP_ADD_TCS(tp)
{
@@ -1574,6 +1698,8 @@
ATF_TP_ADD_TC(tp, ptrace__ptrace_exec_disable);
ATF_TP_ADD_TC(tp, ptrace__ptrace_exec_enable);
ATF_TP_ADD_TC(tp, ptrace__event_mask);
+ ATF_TP_ADD_TC(tp, ptrace__ptrace_vfork);
+ ATF_TP_ADD_TC(tp, ptrace__ptrace_vfork_follow);
return (atf_no_error());
}

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