[RFC] Support for pthread_setname_np / pthread_getname_np

[john stultz <johnstul at us dot ibm dot com>]

I've recently committed support to the Linux kernel for accessing and
setting a threads comm value via the proc interface. This should allow
for pthread_setname_np() / pthread_getname_np() functionality to be
implemented in glibc.

See the kernel git commit here:
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=4614a696bd1c3a9af3a08f0e5874830a85b889d4


I'm very unfamiliar with glibc and its coding conventions (I can't even
get it to build at the moment - probably too old of a distro :) but
wanted to send out a very raw first pass of how such functionality could
be (poorly) implemented.

Any feedback, suggestions or total rewrites by more skilled coders would
be welcome!

thanks
-john

Index: glibc-2.11/nptl/pthread_setname_np.c
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ glibc-2.11/nptl/pthread_setname_np.c	2010-01-06 18:24:09.000000000 -0800
@@ -0,0 +1,66 @@
+/*
+   This file is part of the GNU C Library.
+   Contributed by John Stultz <johnstul@us.ibm.com>, 2010.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+#include <errno.h>
+#include <inttypes.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include "pthreadP.h"
+
+
+int
+pthread_setname_np (thread_id, name)
+     pthread_t thread_id;
+     char *name;
+{
+  struct pthread *thread = (struct pthread *) thread_id;
+  int ret = 0;
+  char buf[255];
+  int fd;
+
+  if (INVALID_TD_P (thread))
+    return ESRCH;
+
+  lll_lock (thread->lock, LLL_PRIVATE);
+
+  sprintf(buf,"/proc/self/task/%i/comm", thread->tid);
+  fd = open(buf, O_WRONLY);
+  if (__builtin_expect (fd == -1, 0))
+    {
+      ret = errno;
+    }
+  else
+    {
+      ssize_t len = strlen(name);
+      ssize_t written = write(fd, name,len);
+      if (__builtin_expect (written != len, 0))
+        {
+           if (written == -1)
+             ret = errno;
+           else
+             ret = EIO;
+        }
+      close(fd);
+    }
+
+  lll_unlock (thread->lock, LLL_PRIVATE);
+
+  return ret;
+}
Index: glibc-2.11/nptl/Makefile
===================================================================
--- glibc-2.11.orig/nptl/Makefile	2009-10-30 10:17:08.000000000 -0700
+++ glibc-2.11/nptl/Makefile	2010-01-06 16:23:13.000000000 -0800
@@ -124,6 +124,8 @@ libpthread-routines = nptl-init vars eve
 		      pthread_mutexattr_setprotocol \
 		      pthread_mutexattr_getprioceiling \
 		      pthread_mutexattr_setprioceiling tpp \
+		      pthread_setname_np \
+		      pthread_getname_np \
 		      pthread_mutex_getprioceiling pthread_mutex_setprioceiling
 #		      pthread_setuid pthread_seteuid pthread_setreuid \
 #		      pthread_setresuid \
Index: glibc-2.11/nptl/sysdeps/pthread/pthread.h
===================================================================
--- glibc-2.11.orig/nptl/sysdeps/pthread/pthread.h	2009-10-30 10:17:08.000000000 -0700
+++ glibc-2.11/nptl/sysdeps/pthread/pthread.h	2010-01-06 16:23:13.000000000 -0800
@@ -1099,6 +1099,12 @@ extern int pthread_setspecific (pthread_
 				__const void *__pointer) __THROW ;
 
 
+extern int pthread_setname_np (pthread_t __th, char *__name)
+     __THROW __nonnull ((2));
+
+extern int pthread_getname_np (pthread_t __th, char *__name)
+     __THROW __nonnull ((2));
+
 #ifdef __USE_XOPEN2K
 /* Get ID of CPU-time clock for thread THREAD_ID.  */
 extern int pthread_getcpuclockid (pthread_t __thread_id,
Index: glibc-2.11/nptl/pthread_getname_np.c
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ glibc-2.11/nptl/pthread_getname_np.c	2010-01-06 18:20:00.000000000 -0800
@@ -0,0 +1,64 @@
+/*
+   This file is part of the GNU C Library.
+   Contributed by John Stultz <johnstul@us.ibm.com>, 2010.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+#include <errno.h>
+#include <inttypes.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include "pthreadP.h"
+
+
+int
+pthread_getname_np (thread_id, name)
+     pthread_t thread_id;
+     char *name;
+{
+  struct pthread *thread = (struct pthread *) thread_id;
+  int ret = 0;
+  char buf[255];
+  int fd;
+
+  if (INVALID_TD_P (thread))
+    return ESRCH;
+
+  /* Do something to validate name? */
+
+  lll_lock (thread->lock, LLL_PRIVATE);
+
+  sprintf(buf,"/proc/self/task/%i/comm", thread->tid);
+  fd = open(buf, O_WRONLY);
+  if (__builtin_expect (fd == -1, 0))
+    {
+      ret = errno;
+    }
+  else
+    {
+      ssize_t len  = read(fd, buf, sizeof buf);
+      if (__builtin_expect (len == -1, 0))
+        {
+          ret = errno;
+        }
+      close(fd);
+      strncpy(name, buf, 255);
+    }
+
+  lll_unlock (thread->lock, LLL_PRIVATE);
+
+  return ret;
+}