server/fs_log: merge labels using 'label_prefix'

Policies are no longer partially matched against 'label' attributes.
New test at run/fs_log.

Issue #1766

repos/os/run/fs_log.run

@@ -0,0 +1,72 @@
+#
+# Test logging to file system
+#
+
+build {
+	core init drivers/timer
+	server/vfs server/fs_log
+	test/bomb
+}
+
+set timeout 240
+set rounds 20
+
+set config {
+<config prio_levels="2">
+	<parent-provides>
+		<service name="CAP"/>
+		<service name="CPU"/>
+		<service name="LOG"/>
+		<service name="PD"/>
+		<service name="RAM"/>
+		<service name="RM"/>
+		<service name="ROM"/>
+		<service name="SIGNAL"/>
+	</parent-provides>
+	<default-route>
+		<any-service> <parent/> <any-child/> </any-service>
+	</default-route>
+	<start name="timer">
+		<resource name="CPU" quantum="10"/>
+		<resource name="RAM" quantum="1M"/>
+		<provides><service name="Timer"/></provides>
+	</start>
+	<start name="vfs">
+		<resource name="RAM" quantum="2M"/>
+		<provides><service name="File_system"/></provides>
+		<config>
+			<vfs>
+				<log name="bomb-master.log"/>
+				<dir name="bomb-master"> <log name="bomb_g5.log"/> </dir>
+			</vfs>
+			<policy label="fs_log" writeable="yes"/>
+		</config>
+	</start>
+	<start name="fs_log">
+		<resource name="RAM" quantum="2M"/>
+		<provides><service name="LOG"/></provides>
+		<config>
+			<policy label="bomb-master"/>
+			<policy label_prefix="bomb-master" merge="true"/>
+		</config>
+	</start>
+	<start name="bomb-master" priority="-1">
+		<binary name="bomb"/>
+		<resource name="CPU" quantum="90"/>
+		<resource name="RAM" quantum="2G"/>
+		<route>
+			<any-service> <any-child/> <parent/> </any-service>
+		</route>
+		<config rounds="1" generations="1" sleep="500"/>
+	</start>
+</config>}
+
+create_boot_directory
+
+install_config $config
+
+build_boot_image "core init ld.lib.so bomb timer vfs fs_log"
+
+append qemu_args " -nographic"
+
+run_genode_until "Done\. Going to sleep\." $timeout

repos/os/src/server/fs_log/README

@@ -15,8 +15,8 @@ trailing "->", the log filename takes the name of the next label element.
 !   <provides><service name="LOG"/></provides>
 !   <config>
 !     <policy label="nic_drv" truncate="no"/>
-!     <policy label="cli_monitor -> " merge="yes"/>
+!     <policy label_prefix="cli_monitor -> " merge="yes"/>
-!     <policy label="" truncate="yes"/>
+!     <policy truncate="yes"/>
 !   </config>
 ! </start>
 

repos/os/src/server/fs_log/main.cc

@@ -12,6 +12,7 @@
  */
 
 /* Genode includes */
+#include <os/path.h>
 #include <file_system_session/connection.h>
 #include <file_system/util.h>
 #include <root/component.h>
@@ -37,6 +38,8 @@ namespace Fs_log {
 		TX_BUF_SIZE = BLOCK_SIZE * (QUEUE_SIZE*2 + 1)
 	};
 
+	typedef Genode::Path<File_system::MAX_PATH_LEN> Path;
+
 }
 
 class Fs_log::Root_component :
@@ -71,61 +74,38 @@ class Fs_log::Root_component :
 			bool truncate = false;
 			Session_label session_label(args);
 			char const *label_str = session_label.string();
-			char const *label_prefix = nullptr;
+			char const *label_prefix = "";
+
+			strncpy(dir_path+1, label_str, MAX_PATH_LEN-1);
 
 			try {
 				Session_policy policy(session_label);
-				try {
+				truncate = policy.attribute_value("truncate", truncate);
-					truncate = policy.attribute("truncate").has_value("yes");
+
-				} catch (Xml_node::Nonexistent_attribute) { }
+				if (policy.attribute_value("merge", false)
+				 && policy.has_attribute("label_prefix")) {
 
-				bool merge = false;
-				try {
-					merge = policy.attribute("merge").has_value("yes");
-				} catch (Xml_node::Nonexistent_attribute) { }
-				if (merge) {
-					/*
-					 * Use the policy label that was matched rather than
-					 * full session label for the path of the log file.
-					 */
-					policy.attribute("label").value(dir_path+1, sizeof(dir_path)-1);
 					if (!dir_path[1]) {
 						PERR("cannot merge an empty policy label");
 						throw Root::Unavailable();
 					}
 
 					/*
-					 * If the policy has a trailing '->', move first element
+					 * split the label between what will be the log file
-					 * from the log prefix to the end of the log path.
+					 * and what will be prepended to messages in the file
 					 */
-					size_t label_len = strlen(dir_path);
+					size_t offset = policy.attribute("label_prefix").value_size();
-					label_prefix = label_str+(label_len-1);
+					for (size_t i = offset; i < session_label.length()-4; ++i) {
+						if (strcmp(label_str+i, " -> ", 4))
+							continue;
 
-					if ((strcmp((dir_path+label_len)-3, " ->", 4) == 0) ||
+						dir_path[i+1] = '\0';
-					    (strcmp((dir_path+label_len)-4, " -> ", 5) == 0)) {
+						label_prefix = label_str+i+4;
-
+						break;
-						for (size_t i = 0;; ++i) {
-							if (label_prefix[i] == '\0') {
-								strncpy(dir_path+1, label_str, MAX_PATH_LEN-1);
-								label_prefix = nullptr;
-								break;
-							}
-
-							if (strcmp(label_prefix+i, " -> ", 4))
-								continue;
-
-							strncpy(dir_path+label_len, label_prefix, i+1);
-							label_prefix += i+4;
-							break;
-						}
 					}
+				}
+			} catch (Session_policy::No_policy_defined) { }
 
-				} else
-					strncpy(dir_path+1, label_str, MAX_PATH_LEN-1);
-
-			} catch (Session_policy::No_policy_defined) {
-				strncpy(dir_path+1, label_str, MAX_PATH_LEN-1);
-			}
 
 			{
 				/* Parse out a directory and file name. */
@@ -171,6 +151,7 @@ class Fs_log::Root_component :
 						offset = _fs.status(handle).size;
 
 				} catch (File_system::Lookup_failed) {
+					PDBG("create");
 					handle = _fs.file(dir_handle, file_name,
 					                  File_system::WRITE_ONLY, true);
 				}
@@ -181,33 +162,29 @@ class Fs_log::Root_component :
 				_log_files.insert(file);
 
 			} catch (Permission_denied) {
-				PERR("%s:%s: permission denied", dir_path, file_name);
+				PERR("%s: permission denied", Path(file_name, dir_path).base());
-
-			} catch (Name_too_long) {
-				PERR("%s:%s: name too long", dir_path, file_name);
 
 			} catch (No_space) {
-				PERR("%s:%s: no space", dir_path, file_name);
+				PERR("file system out of space");
 
 			} catch (Out_of_node_handles) {
-				PERR("%s:%s: out of node handles", dir_path, file_name);
+				PERR("too many open file handles");
 
 			} catch (Invalid_name) {
-				PERR("%s:%s: invalid_name", dir_path, file_name);
+				PERR("%s: invalid path", Path(file_name, dir_path).base());
 
-			} catch (Size_limit_reached) {
+			} catch (Name_too_long) {
-				PERR("%s:%s: size limit reached", dir_path, file_name);
+				PERR("%s: name too long", Path(file_name, dir_path).base());
 
 			} catch (...) {
-				PERR("%s:%s: unknown error", dir_path, file_name);
+				PERR("cannot open log file %s", Path(file_name, dir_path).base());
 				throw;
 			}
-			if (!file) {
-				PERR("file was null");
-				throw Root::Unavailable();
-			}
 
-			if (label_prefix && *label_prefix)
+			if (!file)
+				throw Root::Unavailable();
+
+			if (*label_prefix)
 				return new (md_alloc()) Labeled_session_component(label_prefix, *file);
 			return new (md_alloc()) Unlabeled_session_component(*file);
 		}