From b70d6dd8e6b775fe31d42b3f5bd3227803f736c7 Mon Sep 17 00:00:00 2001 From: Hallvard Furuseth Date: Wed, 5 Apr 2006 20:08:34 +0000 Subject: [PATCH] LDAP_RDWR_DEBUG update: - Avoid buffer overrun when too many readers. - When remoinv reader ID, move one ID instead of all later IDs in array. - assert(correct lock owner) before unlocking a write lock. --- libraries/libldap_r/rdwr.c | 36 +++++++++++++++++++++++------------- 1 file changed, 23 insertions(+), 13 deletions(-) diff --git a/libraries/libldap_r/rdwr.c b/libraries/libldap_r/rdwr.c index 45f642de4f..de6b23cb4a 100644 --- a/libraries/libldap_r/rdwr.c +++ b/libraries/libldap_r/rdwr.c @@ -64,6 +64,7 @@ struct ldap_int_thread_rdwr_s { #ifdef LDAP_RDWR_DEBUG /* keep track of who has these locks */ #define MAX_READERS 32 + int ltrw_more_readers; /* Set if ltrw_readers[] is incomplete */ ldap_pvt_thread_t ltrw_readers[MAX_READERS]; ldap_pvt_thread_t ltrw_writer; #endif @@ -173,7 +174,10 @@ int ldap_pvt_thread_rdwr_rlock( ldap_pvt_thread_rdwr_t *rwlock ) } #ifdef LDAP_RDWR_DEBUG - rw->ltrw_readers[rw->ltrw_r_active] = ldap_pvt_thread_self(); + if( rw->ltrw_r_active < MAX_READERS ) + rw->ltrw_readers[rw->ltrw_r_active] = ldap_pvt_thread_self(); + else + rw->ltrw_more_readers = 1; #endif rw->ltrw_r_active++; @@ -209,7 +213,10 @@ int ldap_pvt_thread_rdwr_rtrylock( ldap_pvt_thread_rdwr_t *rwlock ) } #ifdef LDAP_RDWR_DEBUG - rw->ltrw_readers[rw->ltrw_r_active] = ldap_pvt_thread_self(); + if( rw->ltrw_r_active < MAX_READERS ) + rw->ltrw_readers[rw->ltrw_r_active] = ldap_pvt_thread_self(); + else + rw->ltrw_more_readers = 1; #endif rw->ltrw_r_active++; @@ -233,23 +240,25 @@ int ldap_pvt_thread_rdwr_runlock( ldap_pvt_thread_rdwr_t *rwlock ) ldap_pvt_thread_mutex_lock( &rw->ltrw_mutex ); + rw->ltrw_r_active--; #ifdef LDAP_RDWR_DEBUG /* Remove us from the list of readers */ - { int i, j; - ldap_pvt_thread_t self = ldap_pvt_thread_self(); - - for (i=0; iltrw_r_active;i++) { - if (rw->ltrw_readers[i] == self) { - for (j=i; jltrw_r_active-1; j++) - rw->ltrw_readers[j] = rw->ltrw_readers[j+1]; - rw->ltrw_readers[j] = 0; - break; + ldap_pvt_thread_t self = ldap_pvt_thread_self(); + int i, j; + for( i = j = rw->ltrw_r_active; i >= 0; i--) { + if (rw->ltrw_readers[i] == self) { + rw->ltrw_readers[i] = rw->ltrw_readers[j]; + rw->ltrw_readers[j] = 0; + break; + } } - } + if( !rw->ltrw_more_readers ) + assert( i >= 0 ); + else if( j == 0 ) + rw->ltrw_more_readers = 0; } #endif - rw->ltrw_r_active--; assert( rw->ltrw_w_active >= 0 ); assert( rw->ltrw_w_wait >= 0 ); @@ -372,6 +381,7 @@ int ldap_pvt_thread_rdwr_wunlock( ldap_pvt_thread_rdwr_t *rwlock ) } #ifdef LDAP_RDWR_DEBUG + assert( rw->ltrw_writer == ldap_pvt_thread_self() ); rw->ltrw_writer = 0; #endif ldap_pvt_thread_mutex_unlock( &rw->ltrw_mutex ); -- 2.39.5