From: Ken Raeburn <raeburn@mit.edu>
Date: Sat, 20 Aug 2005 04:22:42 +0000 (+0000)
Subject: * kdb_db2.c (MAX_LOCK_TRIES): New macro.
X-Git-Tag: ms-bug-test-20060525~170
X-Git-Url: http://git.tremily.us/?a=commitdiff_plain;h=0853f66e3e5c38870f640c34187b67d6a3d963e1;p=krb5.git

* kdb_db2.c (MAX_LOCK_TRIES): New macro.
(krb5_db2_db_lock): Always make non-blocking attempts to acquire the lock.
Retry up to MAX_LOCK_TRIES times on failure.

git-svn-id: svn://anonsvn.mit.edu/krb5/trunk@17339 dc483132-0cff-0310-8789-dd5450dbe970
---

diff --git a/src/lib/kdb/kdb_db2/ChangeLog b/src/lib/kdb/kdb_db2/ChangeLog
index 1e23fa368..865aeef2d 100644
--- a/src/lib/kdb/kdb_db2/ChangeLog
+++ b/src/lib/kdb/kdb_db2/ChangeLog
@@ -1,3 +1,9 @@
+2005-08-19  Ken Raeburn  <raeburn@mit.edu>
+
+	* kdb_db2.c (MAX_LOCK_TRIES): New macro.
+	(krb5_db2_db_lock): Always make non-blocking attempts to acquire
+	the lock.  Retry up to MAX_LOCK_TRIES times on failure.
+
 2005-07-06  Ken Raeburn  <raeburn@mit.edu>
 
 	* Makefile.in (LIBBASE): Change to db2.
diff --git a/src/lib/kdb/kdb_db2/kdb_db2.c b/src/lib/kdb/kdb_db2/kdb_db2.c
index 2bcfae1aa..dc41a081c 100644
--- a/src/lib/kdb/kdb_db2/kdb_db2.c
+++ b/src/lib/kdb/kdb_db2/kdb_db2.c
@@ -531,6 +531,8 @@ krb5_db2_db_end_update(krb5_context context)
     return (retval);
 }
 
+#define MAX_LOCK_TRIES 5
+
 krb5_error_code
 krb5_db2_db_lock(krb5_context context, int in_mode)
 {
@@ -540,7 +542,7 @@ krb5_db2_db_lock(krb5_context context, int in_mode)
     krb5_error_code retval;
     time_t  mod_time;
     kdb5_dal_handle *dal_handle;
-    int     mode = in_mode & ~KRB5_DB_LOCKMODE_PERMANENT;	/* permanent is not available for principal db */
+    int     mode, gotlock, tries;
 
     switch (in_mode) {
     case KRB5_DB_LOCKMODE_PERMANENT:
@@ -571,20 +573,24 @@ krb5_db2_db_lock(krb5_context context, int in_mode)
     if ((mode != KRB5_LOCKMODE_SHARED) && (mode != KRB5_LOCKMODE_EXCLUSIVE))
 	return KRB5_KDB_BADLOCKMODE;
 
-    if (db_ctx->db_nb_locks)
-	krb5_lock_mode = mode | KRB5_LOCKMODE_DONTBLOCK;
-    else
-	krb5_lock_mode = mode;
-    retval = krb5_lock_file(context, db_ctx->db_lf_file, krb5_lock_mode);
-    switch (retval) {
-    case EBADF:
-	if (mode == KRB5_LOCKMODE_EXCLUSIVE)
+    krb5_lock_mode = mode | KRB5_LOCKMODE_DONTBLOCK;
+    for (gotlock = tries = 0; tries < MAX_LOCK_TRIES; tries++) {
+	retval = krb5_lock_file(context, db_ctx->db_lf_file, krb5_lock_mode);
+	if (retval == 0) {
+	    gotlock++;
+	    break;
+	} else if (retval == EBADF && mode == KRB5_DB_LOCKMODE_EXCLUSIVE)
+	    /* tried to exclusive-lock something we don't have */
+	    /* write access to */
 	    return KRB5_KDB_CANTLOCK_DB;
-    default:
-	return retval;
-    case 0:
-	break;
+	sleep(1);
     }
+    if (retval == EACCES)
+	return KRB5_KDB_CANTLOCK_DB;
+    else if (retval == EAGAIN || retval == EWOULDBLOCK)
+	return OSA_ADB_CANTLOCK_DB;
+    else if (retval != 0)
+	return retval;
 
     if ((retval = krb5_db2_db_get_age(context, NULL, &mod_time)))
 	goto lock_error;