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Add pthread_getname_np and pthread_setname_np

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This patch adds pthread_getname_np and pthread_setname_np.

These were added to glibc in 2.12[1] and are also present in some form on
NetBSD and several UNIXes.

The code is based on NetBSD's implementation with changes to better match
Linux behaviour.

Implementation quirks:

* pthread_setname_np with a NULL pointer segfaults (as linux)

* pthread_setname_np returns ERANGE for names longer than 16 characters (as
linux)

* pthread_getname_np with a NULL pointer returns EFAULT (as linux)

* pthread_getname_np with a buffer length of less than 16 returns ERANGE (as
linux)

* pthread_getname_np truncates the thread name to fit the buffer length.
This guarantees success even when the default thread name is longer than 16
characters, but means there is no way to discover the actual length of the
thread name. (Linux always truncates the thread name to 16 characters)

* Changing program_invocation_short_name changes the default thread name (on
linux, it has no effect on the default thread name)

I'll leave it up to you to decide if any of these matter.

This is implemented via class pthread_attr to make it easier to add
pthread_attr_[gs]etname_np (present in NetBSD and some UNIXes) should it
ever be added to Linux (or we decide we want it anyway).

[1] https://sourceware.org/git/?p=glibc.git;a=blob;f=NEWS
This commit is contained in:
Jon Turney
2016-08-22 18:43:05 +01:00
parent fb8e88815e
commit fdb7df230d
8 changed files with 78 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

65
winsup/cygwin/thread.cc
View File

@@ -1106,7 +1106,7 @@ pthread::resume ()
pthread_attr::pthread_attr ():verifyable_object (PTHREAD_ATTR_MAGIC),
joinable (PTHREAD_CREATE_JOINABLE), contentionscope (PTHREAD_SCOPE_PROCESS),
inheritsched (PTHREAD_INHERIT_SCHED), stackaddr (NULL), stacksize (0),
guardsize (wincap.def_guard_page_size ())
guardsize (wincap.def_guard_page_size ()), name (NULL)
{
schedparam.sched_priority = 0;
}
@@ -2576,6 +2576,69 @@ pthread_getattr_np (pthread_t thread, pthread_attr_t *attr)
return 0;
}
/* For Linux compatibility, the length of a thread name is 16 characters. */
#define THRNAMELEN 16
extern "C" int
pthread_getname_np (pthread_t thread, char *buf, size_t buflen)
{
char *name;
if (!pthread::is_good_object (&thread))
return ESRCH;
if (!thread->attr.name)
name = program_invocation_short_name;
else
name = thread->attr.name;
/* Return ERANGE if the provided buffer is less than THRNAMELEN. Truncate
and zero-terminate the name to fit in buf. This means we always return
something if the buffer is THRNAMELEN or larger, but there is no way to
tell if we have the whole name. */
if (buflen < THRNAMELEN)
return ERANGE;
int ret = 0;
__try
{
strlcpy (buf, name, buflen);
}
__except (NO_ERROR)
{
ret = EFAULT;
}
__endtry
return ret;
}
extern "C" int
pthread_setname_np (pthread_t thread, const char *name)
{
char *oldname, *cp;
if (!pthread::is_good_object (&thread))
return ESRCH;
if (strlen (name) > THRNAMELEN)
return ERANGE;
cp = strdup (name);
if (!cp)
return ENOMEM;
oldname = thread->attr.name;
thread->attr.name = cp;
if (oldname)
free (oldname);
return 0;
}
#undef THRNAMELEN
/* provided for source level compatability.
See http://www.opengroup.org/onlinepubs/007908799/xsh/pthread_getconcurrency.html
*/