Implement "info proc mappings" for NetBSD

Define nbsd_nat_target::find_memory_regions and
nbsd_nat_target::info_proc. info_proc handles as of now only
the "mappings" command.

Define a local static function kinfo_get_vmmap() that reads
the process memory layout of a specified process.
kinfo_get_vmmap() wraps the sysctl(3) call.

nbsd-tdep.c defines now utility functions for printing the
process memory layout:
 * nbsd_info_proc_mappings_header()
 * nbsd_vm_map_entry_flags()
 * nbsd_info_proc_mappings_entry()

gdb/ChangeLog:

	* nbsd-nat.c; Include "nbsd-tdep.h" and "gdbarch.h".
	* nbsd-nat.c (nbsd_nat_target::find_memory_regions)
	(nbsd_nat_target::info_proc): New functions.
	* nbsd-nat.c (kinfo_get_vmmap): New function.
	* nbsd-nat.c (nbsd_nat_target::info_proc) Use
	nbsd_info_proc_mappings_header and nbsd_info_proc_mappings_entry.
	* nbsd-tdep.c (nbsd_info_proc_mappings_header)
	(nbsd_info_proc_mappings_entry, nbsd_vm_map_entry_flags): New
	functions.
	* nbsd-tdep.c (KINFO_VME_PROT_READ, KINFO_VME_PROT_WRITE)
	(KINFO_VME_PROT_EXEC, KINFO_VME_FLAG_COW)
	(KINFO_VME_FLAG_NEEDS_COPY, KINFO_VME_FLAG_NOCOREDUMP)
	(KINFO_VME_FLAG_PAGEABLE, KINFO_VME_FLAG_GROWS_UP)
	(KINFO_VME_FLAG_GROWS_DOWN): New.

gdb/nbsd-nat.c

@@ -21,7 +21,9 @@
 
 #include "nbsd-nat.h"
 #include "gdbthread.h"
+#include "nbsd-tdep.h"
 #include "inferior.h"
+#include "gdbarch.h"
 
 #include <sys/types.h>
 #include <sys/ptrace.h>
@@ -199,3 +201,150 @@ nbsd_nat_target::pid_to_str (ptid_t ptid)
 
   return normal_pid_to_str (ptid);
 }
+
+/* Retrieve all the memory regions in the specified process.  */
+
+static gdb::unique_xmalloc_ptr<struct kinfo_vmentry[]>
+nbsd_kinfo_get_vmmap (pid_t pid, size_t *size)
+{
+  int mib[5] = {CTL_VM, VM_PROC, VM_PROC_MAP, pid,
+		sizeof (struct kinfo_vmentry)};
+
+  size_t length = 0;
+  if (sysctl (mib, ARRAY_SIZE (mib), NULL, &length, NULL, 0))
+    {
+      *size = 0;
+      return NULL;
+    }
+
+  /* Prereserve more space.  The length argument is volatile and can change
+     between the sysctl(3) calls as this function can be called against a
+     running process.  */
+  length = length * 5 / 3;
+
+  gdb::unique_xmalloc_ptr<struct kinfo_vmentry[]> kiv
+    (XNEWVAR (kinfo_vmentry, length));
+
+  if (sysctl (mib, ARRAY_SIZE (mib), kiv.get (), &length, NULL, 0))
+    {
+      *size = 0;
+      return NULL;
+    }
+
+  *size = length / sizeof (struct kinfo_vmentry);
+  return kiv;
+}
+
+/* Iterate over all the memory regions in the current inferior,
+   calling FUNC for each memory region.  OBFD is passed as the last
+   argument to FUNC.  */
+
+int
+nbsd_nat_target::find_memory_regions (find_memory_region_ftype func,
+				      void *data)
+{
+  pid_t pid = inferior_ptid.pid ();
+
+  size_t nitems;
+  gdb::unique_xmalloc_ptr<struct kinfo_vmentry[]> vmentl
+    = nbsd_kinfo_get_vmmap (pid, &nitems);
+  if (vmentl == NULL)
+    perror_with_name (_("Couldn't fetch VM map entries."));
+
+  for (size_t i = 0; i < nitems; i++)
+    {
+      struct kinfo_vmentry *kve = &vmentl[i];
+
+      /* Skip unreadable segments and those where MAP_NOCORE has been set.  */
+      if (!(kve->kve_protection & KVME_PROT_READ)
+	  || kve->kve_flags & KVME_FLAG_NOCOREDUMP)
+	continue;
+
+      /* Skip segments with an invalid type.  */
+      switch (kve->kve_type)
+	{
+	case KVME_TYPE_VNODE:
+	case KVME_TYPE_ANON:
+	case KVME_TYPE_SUBMAP:
+	case KVME_TYPE_OBJECT:
+	  break;
+	default:
+	  continue;
+	}
+
+      size_t size = kve->kve_end - kve->kve_start;
+      if (info_verbose)
+	{
+	  fprintf_filtered (gdb_stdout,
+			    "Save segment, %ld bytes at %s (%c%c%c)\n",
+			    (long) size,
+			    paddress (target_gdbarch (), kve->kve_start),
+			    kve->kve_protection & KVME_PROT_READ ? 'r' : '-',
+			    kve->kve_protection & KVME_PROT_WRITE ? 'w' : '-',
+			    kve->kve_protection & KVME_PROT_EXEC ? 'x' : '-');
+	}
+
+      /* Invoke the callback function to create the corefile segment.
+	 Pass MODIFIED as true, we do not know the real modification state.  */
+      func (kve->kve_start, size, kve->kve_protection & KVME_PROT_READ,
+	    kve->kve_protection & KVME_PROT_WRITE,
+	    kve->kve_protection & KVME_PROT_EXEC, 1, data);
+    }
+  return 0;
+}
+
+/* Implement the "info_proc" target_ops method.  */
+
+bool
+nbsd_nat_target::info_proc (const char *args, enum info_proc_what what)
+{
+  pid_t pid;
+  bool do_mappings = false;
+
+  switch (what)
+    {
+    case IP_MAPPINGS:
+      do_mappings = true;
+      break;
+    default:
+      error (_("Not supported on this target."));
+    }
+
+  gdb_argv built_argv (args);
+  if (built_argv.count () == 0)
+    {
+      pid = inferior_ptid.pid ();
+      if (pid == 0)
+        error (_("No current process: you must name one."));
+    }
+  else if (built_argv.count () == 1 && isdigit (built_argv[0][0]))
+    pid = strtol (built_argv[0], NULL, 10);
+  else
+    error (_("Invalid arguments."));
+
+  printf_filtered (_("process %d\n"), pid);
+
+  if (do_mappings)
+    {
+      size_t nvment;
+      gdb::unique_xmalloc_ptr<struct kinfo_vmentry[]> vmentl
+	= nbsd_kinfo_get_vmmap (pid, &nvment);
+
+      if (vmentl != nullptr)
+	{
+	  int addr_bit = TARGET_CHAR_BIT * sizeof (void *);
+	  nbsd_info_proc_mappings_header (addr_bit);
+
+	  struct kinfo_vmentry *kve = vmentl.get ();
+	  for (int i = 0; i < nvment; i++, kve++)
+	    nbsd_info_proc_mappings_entry (addr_bit, kve->kve_start,
+					   kve->kve_end, kve->kve_offset,
+					   kve->kve_flags, kve->kve_protection,
+					   kve->kve_path);
+	}
+      else
+	warning (_("unable to fetch virtual memory map"));
+    }
+
+  return true;
+}