[PATCH] Rewrite nbsd_nat_target::pid_to_exec_file to sysctl(3)

[Kamil Rytarowski <n54@gmx.com>]

procfs on NetBSD is optional and not recommended.

	* nbsd-nat.c: Include <sys/types.h>, <sys/ptrace.h> and
	<sys/sysctl.h>.
	* nbsd-nat.c (nbsd_nat_target::pid_to_exec_file): Rewrite.
---
 gdb/ChangeLog  |  6 ++++++
 gdb/nbsd-nat.c | 22 ++++++++++------------
 2 files changed, 16 insertions(+), 12 deletions(-)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index a0d97584189..358d49755bf 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,9 @@
+2020-03-14  Kamil Rytarowski  <n54@gmx.com>
+
+	* nbsd-nat.c: Include <sys/types.h>, <sys/ptrace.h> and
+	<sys/sysctl.h>.
+	* nbsd-nat.c (nbsd_nat_target::pid_to_exec_file): Rewrite.
+
 2020-03-14  Tom Tromey  <tom@tromey.com>

 	* c-typeprint.c (cp_type_print_method_args): Print "__restrict__"
diff --git a/gdb/nbsd-nat.c b/gdb/nbsd-nat.c
index e7f91bebb0d..5e881883a1f 100644
--- a/gdb/nbsd-nat.c
+++ b/gdb/nbsd-nat.c
@@ -21,23 +21,21 @@

 #include "nbsd-nat.h"

+#include <sys/types.h>
+#include <sys/ptrace.h>
+#include <sys/sysctl.h>
+
 /* Return the name of a file that can be opened to get the symbols for
    the child process identified by PID.  */

 char *
 nbsd_nat_target::pid_to_exec_file (int pid)
 {
-  ssize_t len;
   static char buf[PATH_MAX];
-  char name[PATH_MAX];
-
-  xsnprintf (name, PATH_MAX, "/proc/%d/exe", pid);
-  len = readlink (name, buf, PATH_MAX - 1);
-  if (len != -1)
-    {
-      buf[len] = '\0';
-      return buf;
-    }
-
-  return NULL;
+  size_t buflen;
+  int mib[4] = {CTL_KERN, KERN_PROC_ARGS, pid, KERN_PROC_PATHNAME};
+  buflen = sizeof(buf);
+  if (sysctl (mib, ARRAY_SIZE (mib), buf, &buflen, NULL, 0))
+    return NULL;
+  return buf;
 }
--
2.25.0