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Re: RFC: close-on-exec internal file descriptors
- From: Joel Brobecker <brobecker at adacore dot com>
- To: Tom Tromey <tromey at redhat dot com>
- Cc: gdb-patches at sourceware dot org
- Date: Tue, 7 May 2013 10:45:59 +0400
- Subject: Re: RFC: close-on-exec internal file descriptors
- References: <874njjs1aa dot fsf at fleche dot redhat dot com> <m2vcbzui0o dot fsf at igel dot home> <87fw32p00e dot fsf at fleche dot redhat dot com> <874niy6y35 dot fsf at fleche dot redhat dot com> <87d2tmsey0 dot fsf at fleche dot redhat dot com> <20130501144722 dot GA10034 at adacore dot com> <874negym65 dot fsf at fleche dot redhat dot com>
> Sorry Joel.
> I did not even consider this possibility.
No worries at all!
> Could you try the appended? I can't even build parts of it, so...
>
> I think it is pretty ugly, since it is a layer on top of the
> kernel-level cloexec flags. However, that is another discussion, from
> the earlier reviews.
Yeah, hard to see an alternative based on the decisions made.
Seems OK to me.
I tested the patches, and they look good to me, except for the fact
that we were missing the #include of filestuff.h. Attached is patch
that builds and tests fine on x86_64-darwin and ia64-hpux...
--
Joel
>From 7118b53028599be9b5d2957bd1676c48ca87970b Mon Sep 17 00:00:00 2001
From: Joel Brobecker <brobecker@adacore.com>
Date: Tue, 7 May 2013 02:33:02 -0400
Subject: [PATCH] Do not close pipes used to communicate with child during inferior fork
---
gdb/common/filestuff.c | 27 +++++++++++++++++++++++++++
gdb/common/filestuff.h | 10 ++++++++++
gdb/darwin-nat.c | 7 +++++++
gdb/inf-ttrace.c | 11 +++++++++++
4 files changed, 55 insertions(+), 0 deletions(-)
diff --git a/gdb/common/filestuff.c b/gdb/common/filestuff.c
index 68f66ca..e7af3a5 100644
--- a/gdb/common/filestuff.c
+++ b/gdb/common/filestuff.c
@@ -177,6 +177,33 @@ notice_open_fds (void)
fdwalk (do_mark_open_fd, NULL);
}
+/* See filestuff.h. */
+
+void
+mark_fd_no_cloexec (int fd)
+{
+ do_mark_open_fd (NULL, fd);
+}
+
+/* See filestuff.h. */
+
+void
+unmark_fd_no_cloexec (int fd)
+{
+ int i, val;
+
+ for (i = 0; VEC_iterate (int, open_fds, i, val); ++i)
+ {
+ if (fd == val)
+ {
+ VEC_unordered_remove (int, open_fds, i);
+ return;
+ }
+ }
+
+ gdb_assert_not_reached (_("fd not found in open_fds"));
+}
+
/* Helper function for close_most_fds that closes the file descriptor
if appropriate. */
diff --git a/gdb/common/filestuff.h b/gdb/common/filestuff.h
index 0db33f0..b162a0c 100644
--- a/gdb/common/filestuff.h
+++ b/gdb/common/filestuff.h
@@ -24,6 +24,16 @@
extern void notice_open_fds (void);
+/* Mark a file descriptor as inheritable across an exec. */
+
+extern void mark_fd_no_cloexec (int fd);
+
+/* Mark a file descriptor as no longer being inheritable across an
+ exec. This is only meaningful when FD was previously passed to
+ mark_fd_no_cloexec. */
+
+extern void unmark_fd_no_cloexec (int fd);
+
/* Close all open file descriptors other than those marked by
'notice_open_fds', and stdin, stdout, and stderr. Errors that
occur while closing are ignored. */
diff --git a/gdb/darwin-nat.c b/gdb/darwin-nat.c
index acdbf36..a2da924 100644
--- a/gdb/darwin-nat.c
+++ b/gdb/darwin-nat.c
@@ -66,6 +66,7 @@
#include <mach/port.h>
#include "darwin-nat.h"
+#include "common/filestuff.h"
/* Quick overview.
Darwin kernel is Mach + BSD derived kernel. Note that they share the
@@ -1516,6 +1517,9 @@ darwin_pre_ptrace (void)
ptrace_fds[1] = -1;
error (_("unable to create a pipe: %s"), safe_strerror (errno));
}
+
+ mark_fd_no_cloexec (ptrace_fds[0]);
+ mark_fd_no_cloexec (ptrace_fds[1]);
}
static void
@@ -1533,6 +1537,9 @@ darwin_ptrace_him (int pid)
close (ptrace_fds[0]);
close (ptrace_fds[1]);
+ unmark_fd_no_cloexec (ptrace_fds[0]);
+ unmark_fd_no_cloexec (ptrace_fds[1]);
+
darwin_init_thread_list (inf);
startup_inferior (START_INFERIOR_TRAPS_EXPECTED);
diff --git a/gdb/inf-ttrace.c b/gdb/inf-ttrace.c
index 96b473d..2ecf482 100644
--- a/gdb/inf-ttrace.c
+++ b/gdb/inf-ttrace.c
@@ -38,6 +38,7 @@
#include "inf-child.h"
#include "inf-ttrace.h"
+#include "common/filestuff.h"
@@ -558,6 +559,11 @@ do_cleanup_pfds (void *dummy)
close (inf_ttrace_pfd1[1]);
close (inf_ttrace_pfd2[0]);
close (inf_ttrace_pfd2[1]);
+
+ unmark_fd_no_cloexec (inf_ttrace_pfd1[0]);
+ unmark_fd_no_cloexec (inf_ttrace_pfd1[1]);
+ unmark_fd_no_cloexec (inf_ttrace_pfd2[0]);
+ unmark_fd_no_cloexec (inf_ttrace_pfd2[1]);
}
static void
@@ -572,6 +578,11 @@ inf_ttrace_prepare (void)
close (inf_ttrace_pfd2[0]);
perror_with_name (("pipe"));
}
+
+ mark_fd_no_cloexec (inf_ttrace_pfd1[0]);
+ mark_fd_no_cloexec (inf_ttrace_pfd1[1]);
+ mark_fd_no_cloexec (inf_ttrace_pfd2[0]);
+ mark_fd_no_cloexec (inf_ttrace_pfd2[1]);
}
/* Prepare to be traced. */
--
1.7.0.4