do locking, found to be a problem for Panasas Inc

git-svn-id: svn://svn.h5l.se/heimdal/trunk/heimdal@13193 ec53bebd-3082-4978-b11e-865c3cabbd6b

lib/krb5/keytab_file.c

@@ -294,6 +294,7 @@ static krb5_error_code
 fkt_start_seq_get_int(krb5_context context, 
 		      krb5_keytab id, 
 		      int flags,
+		      int exclusive,
 		      krb5_kt_cursor *c)
 {
     int8_t pvno, tag;
@@ -307,16 +308,23 @@ fkt_start_seq_get_int(krb5_context context,
 			      strerror(ret));
 	return ret;
     }
+    ret = _krb5_xlock(context, c->fd, exclusive, d->filename);
+    if (ret) {
+	close(c->fd);
+	return ret;
+    }
     c->sp = krb5_storage_from_fd(c->fd);
     krb5_storage_set_eof_code(c->sp, KRB5_KT_END);
     ret = krb5_ret_int8(c->sp, &pvno);
     if(ret) {
 	krb5_storage_free(c->sp);
+	_krb5_xunlock(c->fd);
 	close(c->fd);
 	return ret;
     }
     if(pvno != 5) {
 	krb5_storage_free(c->sp);
+	_krb5_xunlock(c->fd);
 	close(c->fd);
 	krb5_clear_error_string (context);
 	return KRB5_KEYTAB_BADVNO;
@@ -324,6 +332,7 @@ fkt_start_seq_get_int(krb5_context context,
     ret = krb5_ret_int8(c->sp, &tag);
     if (ret) {
 	krb5_storage_free(c->sp);
+	_krb5_xunlock(c->fd);
 	close(c->fd);
 	return ret;
     }
@@ -337,7 +346,7 @@ fkt_start_seq_get(krb5_context context,
 		  krb5_keytab id, 
 		  krb5_kt_cursor *c)
 {
-    return fkt_start_seq_get_int(context, id, O_RDONLY | O_BINARY, c);
+    return fkt_start_seq_get_int(context, id, O_RDONLY | O_BINARY, 0, c);
 }
 
 static krb5_error_code
@@ -409,6 +418,7 @@ fkt_end_seq_get(krb5_context context,
 		krb5_kt_cursor *cursor)
 {
     krb5_storage_free(cursor->sp);
+    _krb5_xunlock(cursor->fd);
     close(cursor->fd);
     return 0;
 }
@@ -448,17 +458,25 @@ fkt_add_entry(krb5_context context,
 				  strerror(ret));
 	    return ret;
 	}
+	ret = _krb5_xlock(context, fd, 1, d->filename);
+	if (ret) {
+	    close(fd);
+	    return ret;
+	}
 	sp = krb5_storage_from_fd(fd);
 	krb5_storage_set_eof_code(sp, KRB5_KT_END);
 	ret = fkt_setup_keytab(context, id, sp);
 	if(ret) {
-	    krb5_storage_free(sp);
+	    goto out;
-	    close(fd);
-	    return ret;
 	}
 	storage_set_flags(context, sp, id->version);
     } else {
 	int8_t pvno, tag;
+	ret = _krb5_xlock(context, fd, 1, d->filename);
+	if (ret) {
+	    close(fd);
+	    return ret;
+	}
 	sp = krb5_storage_from_fd(fd);
 	krb5_storage_set_eof_code(sp, KRB5_KT_END);
 	ret = krb5_ret_int8(sp, &pvno);
@@ -469,28 +487,21 @@ fkt_add_entry(krb5_context context,
 	    if(ret) {
 		krb5_set_error_string(context, "%s: keytab is corrupted: %s", 
 				      d->filename, strerror(ret));
-		krb5_storage_free(sp);
+		goto out;
-		close(fd);
-		return ret;
 	    }
 	    storage_set_flags(context, sp, id->version);
 	} else {
 	    if(pvno != 5) {
-		krb5_storage_free(sp);
-		close(fd);
-		krb5_clear_error_string (context);
 		ret = KRB5_KEYTAB_BADVNO;
 		krb5_set_error_string(context, "%s: %s", 
 				      d->filename, strerror(ret));
-		return ret;
+		goto out;
 	    }
 	    ret = krb5_ret_int8 (sp, &tag);
 	    if (ret) {
 		krb5_set_error_string(context, "%s: reading tag: %s", 
 				      d->filename, strerror(ret));
-		krb5_storage_free(sp);
+		goto out;
-		close(fd);
-		return ret;
 	    }
 	    id->version = tag;
 	    storage_set_flags(context, sp, id->version);
@@ -559,6 +570,7 @@ fkt_add_entry(krb5_context context,
     krb5_data_free(&keytab);
   out:
     krb5_storage_free(sp);
+    _krb5_xunlock(fd);
     close(fd);
     return ret;
 }
@@ -574,7 +586,7 @@ fkt_remove_entry(krb5_context context,
     int found = 0;
     krb5_error_code ret;
     
-    ret = fkt_start_seq_get_int(context, id, O_RDWR | O_BINARY, &cursor);
+    ret = fkt_start_seq_get_int(context, id, O_RDWR | O_BINARY, 1, &cursor);
     if(ret != 0) 
 	goto out; /* return other error here? */
     while(fkt_next_entry_int(context, id, &e, &cursor,