Date: Mon, 29 Mar 2004 20:32:47 -0600 From: "Jacques A. Vidrine" <nectar@FreeBSD.org> To: Daniel Eischen <eischen@vigrid.com> Cc: Sean McNeil <sean@mcneil.com> Subject: Re: nss_ldap broken Message-ID: <20040330023247.GA5637@madman.celabo.org> In-Reply-To: <Pine.GSO.4.10.10403261747480.16871-100000@pcnet5.pcnet.com> References: <1080334840.11426.12.camel@server.mcneil.com> <Pine.GSO.4.10.10403261747480.16871-100000@pcnet5.pcnet.com>
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On Fri, Mar 26, 2004 at 05:51:02PM -0500, Daniel Eischen wrote:
> I think I made a comment about how you should always
> prefix _pthread_foo() calls with 'if (__isthreaded)'.
Yes, I'm sure you did. My recollection was that it was an
optimization only, but it seems either I misunderstood or my
recollection is poor (or both) :-)
> When the thread libraries are initialized, then overrwrite
> the function pointers in libc's thread jumptable. If you
> unload the library, libc still retains those pointers.
OK, so we guard calls to threading routines with __isthreaded. (Patch
below.) Uglifies things a bit, but I can deal. Maybe some day we'll
rewrite reentrant.h so that it doesn't lose the return code (they
should all be like mutex_trylock?).
So, if I understand correctly:
(1) __isthreaded starts out 0
(2) When a threading library is loaded (by any cause? DT_NEEDED?
dlopen RTLD_GLOBAL? dlopen RTLD_LOCAL?), __isthreaded is set
to 1
(3) When a threading library is unloaded, __isthreaded is reset to 0
Only, I don't immediately see where (3) happens...
Sean, could you report how this patch works for you? Hmm, actually, it
looks almost identical to what you posted :-) Is there a reason that
you stored the value of `__isthreaded' in a local variable? Did that
make a difference for your case?
Cheers,
--
Jacques Vidrine / nectar@celabo.org / jvidrine@verio.net / nectar@freebsd.org
Index: net/nsdispatch.c
===================================================================
RCS file: /home/ncvs/src/lib/libc/net/nsdispatch.c,v
retrieving revision 1.10
diff -c -r1.10 nsdispatch.c
*** net/nsdispatch.c 15 Mar 2004 08:14:35 -0000 1.10
--- net/nsdispatch.c 30 Mar 2004 02:19:19 -0000
***************
*** 319,324 ****
--- 319,325 ----
int result;
const char *path;
+ result = 0;
#if defined(_NSS_DEBUG) && defined(_NSS_SHOOT_FOOT)
/* NOTE WELL: THIS IS A SECURITY HOLE. This must only be built
* for debugging purposes and MUST NEVER be used in production.
***************
*** 331,346 ****
return (0);
if (statbuf.st_mtime <= confmod)
return (0);
! result = _pthread_mutex_trylock(&conf_lock);
! if (result != 0)
! return (0);
! (void)_pthread_rwlock_unlock(&nss_lock);
! result = _pthread_rwlock_wrlock(&nss_lock);
! if (result != 0)
! goto fin2;
_nsyyin = fopen(path, "r");
! if (_nsyyin == NULL)
goto fin;
VECTOR_FREE(_nsmap, &_nsmapsize, sizeof(*_nsmap),
(vector_free_elem)ns_dbt_free);
VECTOR_FREE(_nsmod, &_nsmodsize, sizeof(*_nsmod),
--- 332,351 ----
return (0);
if (statbuf.st_mtime <= confmod)
return (0);
! if (__isthreaded) {
! result = _pthread_mutex_trylock(&conf_lock);
! if (result != 0)
! return (0);
! (void)_pthread_rwlock_unlock(&nss_lock);
! result = _pthread_rwlock_wrlock(&nss_lock);
! if (result != 0)
! goto fin2;
! }
_nsyyin = fopen(path, "r");
! if (_nsyyin == NULL) {
! result = errno;
goto fin;
+ }
VECTOR_FREE(_nsmap, &_nsmapsize, sizeof(*_nsmap),
(vector_free_elem)ns_dbt_free);
VECTOR_FREE(_nsmod, &_nsmodsize, sizeof(*_nsmod),
***************
*** 353,362 ****
(void)atexit(nss_atexit);
confmod = statbuf.st_mtime;
fin:
! (void)_pthread_rwlock_unlock(&nss_lock);
! result = _pthread_rwlock_rdlock(&nss_lock);
fin2:
! (void)_pthread_mutex_unlock(&conf_lock);
return (result);
}
--- 358,371 ----
(void)atexit(nss_atexit);
confmod = statbuf.st_mtime;
fin:
! if (__isthreaded) {
! (void)_pthread_rwlock_unlock(&nss_lock);
! if (result == 0)
! result = _pthread_rwlock_rdlock(&nss_lock);
! }
fin2:
! if (__isthreaded)
! (void)_pthread_mutex_unlock(&conf_lock);
return (result);
}
***************
*** 510,521 ****
static void
nss_atexit(void)
{
! (void)_pthread_rwlock_wrlock(&nss_lock);
VECTOR_FREE(_nsmap, &_nsmapsize, sizeof(*_nsmap),
(vector_free_elem)ns_dbt_free);
VECTOR_FREE(_nsmod, &_nsmodsize, sizeof(*_nsmod),
(vector_free_elem)ns_mod_free);
! (void)_pthread_rwlock_unlock(&nss_lock);
}
--- 519,532 ----
static void
nss_atexit(void)
{
! if (__isthreaded)
! (void)_pthread_rwlock_wrlock(&nss_lock);
VECTOR_FREE(_nsmap, &_nsmapsize, sizeof(*_nsmap),
(vector_free_elem)ns_dbt_free);
VECTOR_FREE(_nsmod, &_nsmodsize, sizeof(*_nsmod),
(vector_free_elem)ns_mod_free);
! if (__isthreaded)
! (void)_pthread_rwlock_unlock(&nss_lock);
}
***************
*** 571,580 ****
int serrno, i, result, srclistsize;
serrno = errno;
! result = _pthread_rwlock_rdlock(&nss_lock);
! if (result != 0) {
! result = NS_UNAVAIL;
! goto fin;
}
result = nss_configure();
if (result != 0) {
--- 582,593 ----
int serrno, i, result, srclistsize;
serrno = errno;
! if (__isthreaded) {
! result = _pthread_rwlock_rdlock(&nss_lock);
! if (result != 0) {
! result = NS_UNAVAIL;
! goto fin;
! }
}
result = nss_configure();
if (result != 0) {
***************
*** 604,610 ****
break;
}
}
! (void)_pthread_rwlock_unlock(&nss_lock);
fin:
errno = serrno;
return (result);
--- 617,624 ----
break;
}
}
! if (__isthreaded)
! (void)_pthread_rwlock_unlock(&nss_lock);
fin:
errno = serrno;
return (result);
Index: net/nss_compat.c
===================================================================
RCS file: /home/ncvs/src/lib/libc/net/nss_compat.c,v
retrieving revision 1.2
diff -c -r1.2 nss_compat.c
*** net/nss_compat.c 9 Jan 2004 13:43:49 -0000 1.2
--- net/nss_compat.c 30 Mar 2004 02:16:03 -0000
***************
*** 41,46 ****
--- 41,47 ----
#include <pthread.h>
#include <pthread_np.h>
#include "un-namespace.h"
+ #include "libc_private.h"
struct group;
***************
*** 60,66 ****
#define SET_TERMINATOR(x, y) \
do { \
! if (_pthread_main_np()) \
_term_main_##x = (y); \
else { \
(void)_pthread_once(&_term_once_##x, _term_create_##x); \
--- 61,67 ----
#define SET_TERMINATOR(x, y) \
do { \
! if (!__isthreaded || _pthread_main_np()) \
_term_main_##x = (y); \
else { \
(void)_pthread_once(&_term_once_##x, _term_create_##x); \
***************
*** 69,75 ****
} while (0)
#define CHECK_TERMINATOR(x) \
! (_pthread_main_np() ? \
(_term_main_##x) : \
((void)_pthread_once(&_term_once_##x, _term_create_##x), \
_pthread_getspecific(_term_key_##x)))
--- 70,76 ----
} while (0)
#define CHECK_TERMINATOR(x) \
! (!__isthreaded || _pthread_main_np() ? \
(_term_main_##x) : \
((void)_pthread_once(&_term_once_##x, _term_create_##x), \
_pthread_getspecific(_term_key_##x)))
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