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[Darwin 2/4] Do not crash (failed assertion) after PT_KILL ptrace error
- From: Joel Brobecker <brobecker at adacore dot com>
- To: gdb-patches at sourceware dot org
- Cc: Joel Brobecker <brobecker at adacore dot com>
- Date: Fri, 1 Jul 2011 12:03:24 -0700
- Subject: [Darwin 2/4] Do not crash (failed assertion) after PT_KILL ptrace error
- References: <1309547006-21412-1-git-send-email-brobecker@adacore.com>
This is something I noticed while reading the code. Putting an
assertion that the PT_KILL ptrace call never returns an error
is too strong. It might not be a debugger bug that caused the
PT_KILL ptrace operation to fail, so a failed-assertion "crash"
would not be justified. It also seems easy enough to continue
and get ready for the next debugging session. So this patch
changes the assertion into a warning.
This patch also tries to handle the case where ptrace return -1,
but left errno set to zero. According to the ptrace man page,
it is possible for some ptrace operations to return -1 in non-error
situations, and to detect those situations, it explains that errno
should be set prior to calling ptrace, and then checked again after.
gdb/ChangeLog:
* darwin-nat.c (darwin_ptrace): Add documentation.
Set errno to zero before calling ptrace. If ptrace returns
-1 and errno is zero, then change then return zero.
(darwin_kill_inferior): Issue a warning instead of triggering
a failed assertion when the PT_KILL ptrace operations returned
nonzero.
Tested on x86_64-darwin. Checked in.
---
gdb/ChangeLog | 9 +++++++++
gdb/darwin-nat.c | 17 ++++++++++++++++-
2 files changed, 25 insertions(+), 1 deletions(-)
diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 5be8066..ce522fb 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,14 @@
2011-07-01 Joel Brobecker <brobecker@adacore.com>
+ * darwin-nat.c (darwin_ptrace): Add documentation.
+ Set errno to zero before calling ptrace. If ptrace returns
+ -1 and errno is zero, then change then return zero.
+ (darwin_kill_inferior): Issue a warning instead of triggering
+ a failed assertion when the PT_KILL ptrace operations returned
+ nonzero.
+
+2011-07-01 Joel Brobecker <brobecker@adacore.com>
+
* darwin-nat.c (darwin_detach): Call darwin_resume_inferior
only when inf->private->no_ptrace.
diff --git a/gdb/darwin-nat.c b/gdb/darwin-nat.c
index fc5263a..27c6e2c 100644
--- a/gdb/darwin-nat.c
+++ b/gdb/darwin-nat.c
@@ -233,13 +233,25 @@ unparse_exception_type (unsigned int i)
}
}
+/* Set errno to zero, and then call ptrace with the given arguments.
+ If inferior debugging traces are on, then also print a debug
+ trace.
+
+ The returned value is the same as the value returned by ptrace,
+ except in the case where that value is -1 but errno is zero.
+ This case is documented to be a non-error situation, so we
+ return zero in that case. */
+
static int
darwin_ptrace (const char *name,
int request, int pid, PTRACE_TYPE_ARG3 arg3, int arg4)
{
int ret;
+ errno = 0;
ret = ptrace (request, pid, (caddr_t) arg3, arg4);
+ if (ret == -1 && errno == 0)
+ ret = 0;
inferior_debug (4, _("ptrace (%s, %d, 0x%x, %d): %d (%s)\n"),
name, pid, arg3, arg4, ret,
@@ -1301,7 +1313,10 @@ darwin_kill_inferior (struct target_ops *ops)
darwin_stop_inferior (inf);
res = PTRACE (PT_KILL, inf->pid, 0, 0);
- gdb_assert (res == 0);
+ if (res != 0)
+ warning (_("Failed to kill inferior: ptrace returned %d "
+ "[%s] (pid=%d)"),
+ res, safe_strerror (errno), inf->pid);
darwin_reply_to_all_pending_messages (inf);
--
1.7.1