[PATCH] Use kinfo_getfile to implement fdwalk on FreeBSD.

[John Baldwin]

kinfo_getfile() requires a couple of system calls to fetch the list of
open file descriptors. This can be much cheaper than invoking fstat
on all of the values from 0 to the open file resource limit maximum.

gdb/ChangeLog:

* common/filestuff.c [HAVE_KINFO_GETFILE]: Include headers.
(fdwalk) [HAVE_KINFO_GETFILE]: Use kinfo_getfile.
---
gdb/ChangeLog | 5 +++++
gdb/common/filestuff.c | 26 ++++++++++++++++++++++++++
2 files changed, 31 insertions(+)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 348eb65ec7..f88cc16b4d 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,8 @@
[phone] John Baldwin <***@FreeBSD.org>
+
+ * common/filestuff.c [HAVE_KINFO_GETFILE]: Include headers.
+ (fdwalk) [HAVE_KINFO_GETFILE]: Use kinfo_getfile.
+
2018-11-30 John Baldwin <***@FreeBSD.org>

* fbsd-nat.c [__FreeBSD_version >= 700009] (USE_SIGINFO): Macro
diff --git a/gdb/common/filestuff.c b/gdb/common/filestuff.c
index 0db5c6936b..48b0487f54 100644
--- a/gdb/common/filestuff.c
+++ b/gdb/common/filestuff.c
@@ -36,6 +36,11 @@
#define HAVE_SOCKETS 1
#endif

+#ifdef HAVE_KINFO_GETFILE
+#include <sys/user.h>
+#include <libutil.h>
+#endif
+
#ifdef HAVE_SYS_RESOURCE_H
#include <sys/resource.h>
#endif /* HAVE_SYS_RESOURCE_H */
@@ -108,6 +113,27 @@ fdwalk (int (*func) (void *, int), void *arg)
}
/* We may fall through to the next case. */
#endif
+#ifdef HAVE_KINFO_GETFILE
+ gdb::unique_xmalloc_ptr<struct kinfo_file> fdtbl;
+ int nfd;
+ fdtbl.reset (kinfo_getfile (getpid (), &nfd));
+ if (fdtbl != NULL)
+ {
+ int result = 0;
+ struct kinfo_file *kf = fdtbl.get ();
+ for (int i = 0; i < nfd; i++, kf++)
+ {
+ if (kf->kf_fd >= 0)
+ {
+ result = func (arg, kf->kf_fd);
+ if (result != 0)
+ break;
+ }
+ }
+ return result;
+ }
+ /* We may fall through to the next case. */
+#endif

{
int max, fd;

[Tom Tromey]

John> kinfo_getfile() requires a couple of system calls to fetch the list of
John> open file descriptors. This can be much cheaper than invoking fstat
John> on all of the values from 0 to the open file resource limit maximum.

John> gdb/ChangeLog:

John> * common/filestuff.c [HAVE_KINFO_GETFILE]: Include headers.
John> (fdwalk) [HAVE_KINFO_GETFILE]: Use kinfo_getfile.

Thanks.

John> +#ifdef HAVE_KINFO_GETFILE
John> + gdb::unique_xmalloc_ptr<struct kinfo_file> fdtbl;
John> + int nfd;
John> + fdtbl.reset (kinfo_getfile (getpid (), &nfd));

I think this should be combined with the declaration; no need to call
reset.

This is ok with that change.

Tom

[Pedro Alves]

Post by Tom Tromey
John> +#ifdef HAVE_KINFO_GETFILE
John> + gdb::unique_xmalloc_ptr<struct kinfo_file> fdtbl;
John> + int nfd;
John> + fdtbl.reset (kinfo_getfile (getpid (), &nfd));
I think this should be combined with the declaration; no need to call
reset.

If you want, you can also use the array-version of unique_ptr
and eliminate some variables:

int nfd;
gdb::unique_xmalloc_ptr<struct kinfo_file[]> fdtbl
(kinfo_getfile (getpid (), &nfd));
if (fdtbl != NULL)
{
for (int i = 0; i < nfd; i++)
{
if (fdtbl[i]->kf_fd >= 0)
{
int result = func (arg, fdtbl[i]->kf_fd);
if (result != 0)
return result;
}
}
return 0;
}

Thanks,
Pedro Alves

[John Baldwin]

Post by Pedro Alves

Post by Tom Tromey
John> +#ifdef HAVE_KINFO_GETFILE
John> + gdb::unique_xmalloc_ptr<struct kinfo_file> fdtbl;
John> + int nfd;
John> + fdtbl.reset (kinfo_getfile (getpid (), &nfd));
I think this should be combined with the declaration; no need to call
reset.

If you want, you can also use the array-version of unique_ptr
int nfd;
gdb::unique_xmalloc_ptr<struct kinfo_file[]> fdtbl
(kinfo_getfile (getpid (), &nfd));
if (fdtbl != NULL)
{
for (int i = 0; i < nfd; i++)
{
if (fdtbl[i]->kf_fd >= 0)
{
int result = func (arg, fdtbl[i]->kf_fd);
if (result != 0)
return result;
}
}
return 0;
}

Thanks. This is what I pushed (modulo using fdtbl[i]. rather than
fdtbl[i]->).