From fe1b3794de3944967bd4ebce46dd0dc0d3449a17 Mon Sep 17 00:00:00 2001 From: Hallvard Furuseth Date: Mon, 17 Sep 2012 15:42:15 +0200 Subject: [PATCH] ITS#7364 Limit mdb lock upgrade before sem_unlink. Do not try shared lock when closing or after error. Track file lock state to decide. Change meaning of *excl to reflect file lock state. --- libraries/libmdb/mdb.c | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-) diff --git a/libraries/libmdb/mdb.c b/libraries/libmdb/mdb.c index 9546d01f47..b00e0767f8 100644 --- a/libraries/libmdb/mdb.c +++ b/libraries/libmdb/mdb.c @@ -2775,6 +2775,9 @@ mdb_env_share_locks(MDB_env *env) return rc; } +/** Try to get exlusive lock, otherwise shared. + * Maintain *excl = -1: no/unknown lock, 0: shared, 1: exclusive. + */ static int mdb_env_excl_lock(MDB_env *env, int *excl) { @@ -2798,7 +2801,11 @@ mdb_env_excl_lock(MDB_env *env, int *excl) lock_info.l_len = 1; if (!fcntl(env->me_lfd, F_SETLK, &lock_info)) { *excl = 1; - } else { + } else +# ifdef MDB_USE_POSIX_SEM + if (*excl < 0) /* always true when !MDB_USE_POSIX_SEM */ +# endif + { lock_info.l_type = F_RDLCK; while ((rc = fcntl(env->me_lfd, F_SETLKW, &lock_info)) && (rc = ErrCode()) == EINTR) ; @@ -2896,7 +2903,7 @@ mdb_env_setup_locks(MDB_env *env, char *lpath, int mode, int *excl) int rc; off_t size, rsize; - *excl = 0; + *excl = -1; #ifdef _WIN32 if ((env->me_lfd = CreateFile(lpath, GENERIC_READ|GENERIC_WRITE, @@ -2934,7 +2941,7 @@ mdb_env_setup_locks(MDB_env *env, char *lpath, int mode, int *excl) size = lseek(env->me_lfd, 0, SEEK_END); #endif rsize = (env->me_maxreaders-1) * sizeof(MDB_reader) + sizeof(MDB_txninfo); - if (size < rsize && *excl) { + if (size < rsize && *excl > 0) { #ifdef _WIN32 SetFilePointer(env->me_lfd, rsize, NULL, 0); if (!SetEndOfFile(env->me_lfd)) { @@ -2978,7 +2985,7 @@ mdb_env_setup_locks(MDB_env *env, char *lpath, int mode, int *excl) env->me_txns = m; #endif } - if (*excl) { + if (*excl > 0) { #ifdef _WIN32 BY_HANDLE_FILE_INFORMATION stbuf; struct { @@ -3205,7 +3212,7 @@ mdb_env_open(MDB_env *env, const char *path, unsigned int flags, mode_t mode) goto leave; } #endif - if (excl) { + if (excl > 0) { rc = mdb_env_share_locks(env); if (rc) goto leave; -- 2.39.5