[PATCH v4 4/7] Display per-thread information for threads in FreeBSD cores.

[John Baldwin <jhb@FreeBSD.org>]

Display the LWP ID of each thread in a FreeBSD core.  Extract thread
names from the per-thread THRMISC note.

gdb/ChangeLog:

	* fbsd_tdep.c (fbsd_core_pid_to_str): New function.
	(fbsd_core_thread_name): New function.
	(fbsd_init_abi): Add "core_pid_to_str" gdbarch method.
	Add "core_thread_name" gdbarch method.
---
 gdb/ChangeLog   |  7 ++++++
 gdb/fbsd-tdep.c | 66 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 73 insertions(+)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index bbac503..8f0fd34 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,12 @@
 2016-01-16  John Baldwin  <jhb@FreeBSD.org>
 
+	* fbsd_tdep.c (fbsd_core_pid_to_str): New function.
+	(fbsd_core_thread_name): New function.
+	(fbsd_init_abi): Add "core_pid_to_str" gdbarch method.
+	Add "core_thread_name" gdbarch method.
+
+2016-01-16  John Baldwin  <jhb@FreeBSD.org>
+
 	* corelow.c (core_thread_name): New function.
 	(init_core_ops): Use "core_thread_name" for the "to_thread_name"
 	target op.
diff --git a/gdb/fbsd-tdep.c b/gdb/fbsd-tdep.c
index 0ef94d6..b4e7eff 100644
--- a/gdb/fbsd-tdep.c
+++ b/gdb/fbsd-tdep.c
@@ -28,6 +28,70 @@
 #include "fbsd-tdep.h"
 
 
+/* This is how we want PTIDs from core files to be printed.  */
+
+static char *
+fbsd_core_pid_to_str (struct gdbarch *gdbarch, ptid_t ptid)
+{
+  static char buf[80];
+
+  if (ptid_get_lwp (ptid) != 0)
+    {
+      xsnprintf (buf, sizeof buf, "LWP %ld", ptid_get_lwp (ptid));
+      return buf;
+    }
+
+  return normal_pid_to_str (ptid);
+}
+
+/* Extract the name assigned to a thread from a core.  Returns the
+   string in a static buffer.  */
+
+static const char *
+fbsd_core_thread_name (struct gdbarch *gdbarch, struct thread_info *thr)
+{
+  static char buf[80];
+  struct bfd_section *section;
+  bfd_size_type size;
+  char sectionstr[32];
+
+  if (ptid_get_lwp (thr->ptid) != 0)
+    {
+      /* FreeBSD includes a NT_FREEBSD_THRMISC note for each thread
+	 whose contents are defined by a "struct thrmisc" declared in
+	 <sys/procfs.h> on FreeBSD.  The per-thread name is stored as
+	 a null-terminated string as the first member of the
+	 structure.  Rather than define the full structure here, just
+	 extract the null-terminated name from the start of the
+	 note.  */
+      xsnprintf (sectionstr, sizeof sectionstr, ".thrmisc/%ld",
+		ptid_get_lwp (thr->ptid));
+      section = bfd_get_section_by_name (core_bfd, sectionstr);
+      if (section != NULL && bfd_section_size (core_bfd, section) > 0)
+	{
+	  /* Truncate the name if it is longer than "buf".  */
+	  size = bfd_section_size (core_bfd, section);
+	  if (size > sizeof buf - 1)
+	    size = sizeof buf - 1;
+	  if (bfd_get_section_contents (core_bfd, section, buf, (file_ptr) 0,
+					size)
+	      && buf[0] != '\0')
+	    {
+	      buf[size] = '\0';
+
+	      /* Note that each thread will report the process command
+		 as its thread name instead of an empty name if a name
+		 has not been set explicitly.  Return a NULL name in
+		 that case.  */
+	      if (strcmp (buf, elf_tdata (core_bfd)->core->program) != 0)
+		  return buf;
+	    }
+	}
+    }
+
+  return NULL;
+}
+
 static int
 find_signalled_thread (struct thread_info *info, void *data)
 {
@@ -132,5 +196,7 @@ fbsd_make_corefile_notes (struct gdbarch *gdbarch, bfd *obfd, int *note_size)
 void
 fbsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 {
+  set_gdbarch_core_pid_to_str (gdbarch, fbsd_core_pid_to_str);
+  set_gdbarch_core_thread_name (gdbarch, fbsd_core_thread_name);
   set_gdbarch_make_corefile_notes (gdbarch, fbsd_make_corefile_notes);
 }
-- 
2.7.0