[logging] use program name for log id (#1953)

On Android, we use the "ot-daemon" name for the runnable program
and we want the syslog id be updated to "ot-daemon" as well.
Instead of hardcoding the syslog id, this commit derive the id
from the program name so it works for both linux and Android.

src/agent/main.cpp

@@ -58,7 +58,6 @@
 #include "common/types.hpp"
 #include "ncp/ncp_openthread.hpp"
 
-static const char kSyslogIdent[] = "otbr-agent";
 static const char kDefaultInterfaceName[] = "wpan0";
 
 // Port number used by Rest server.
@@ -268,7 +267,7 @@ static int realmain(int argc, char *argv[])
  }
  }
 
- otbrLogInit(kSyslogIdent, logLevel, verbose);
+ otbrLogInit(argv[0], logLevel, verbose);
  otbrLogNotice("Running %s", OTBR_PACKAGE_VERSION);
  otbrLogNotice("Thread version: %s", otbr::Ncp::ControllerOpenThread::GetThreadVersion());
  otbrLogNotice("Thread interface: %s", interfaceName);

src/common/logging.cpp

@@ -78,12 +78,17 @@ void otbrLogSetLevel(otbrLogLevel aLevel)
 }
 
 /** Initialize logging */
-void otbrLogInit(const char *aIdent, otbrLogLevel aLevel, bool aPrintStderr)
+void otbrLogInit(const char *aProgramName, otbrLogLevel aLevel, bool aPrintStderr)
 {
- assert(aIdent);
+ const char *ident;
+
+ assert(aProgramName != nullptr);
  assert(aLevel >= OTBR_LOG_EMERG && aLevel <= OTBR_LOG_DEBUG);
 
- openlog(aIdent, (LOG_CONS | LOG_PID) | (aPrintStderr ? LOG_PERROR : 0), OTBR_SYSLOG_FACILITY_ID);
+ ident = strrchr(aProgramName, '/');
+ ident = (ident != nullptr) ? ident + 1 : aProgramName;
+
+ openlog(ident, (LOG_CONS | LOG_PID) | (aPrintStderr ? LOG_PERROR : 0), OTBR_SYSLOG_FACILITY_ID);
  sLevel = aLevel;
  sDefaultLevel = sLevel;
 }

src/common/logging.hpp

@@ -86,12 +86,12 @@ void otbrLogEnableSyslog(bool aEnabled);
 /**
  * This function initialize the logging service.
  *
- * @param[in] aIdent Identity of the logger.
+ * @param[in] aProgramName The name of this runnable program.
  * @param[in] aLevel Log level of the logger.
  * @param[in] aPrintStderr Whether to log to stderr.
  *
  */
-void otbrLogInit(const char *aIdent, otbrLogLevel aLevel, bool aPrintStderr);
+void otbrLogInit(const char *aProgramName, otbrLogLevel aLevel, bool aPrintStderr);
 
 /**
  * This function log at level @p aLevel.

src/web/main.cpp

@@ -46,7 +46,6 @@
 #include "common/logging.hpp"
 #include "web/web-service/web_server.hpp"
 
-static const char kSyslogIdent[] = "otbr-web";
 static const char kDefaultInterfaceName[] = "wpan0";
 static const char kDefaultListenAddr[] = "::";
 
@@ -112,7 +111,7 @@ int main(int argc, char **argv)
  }
  }
 
- otbrLogInit(kSyslogIdent, logLevel, true);
+ otbrLogInit(argv[0], logLevel, true);
  otbrLogInfo("Running %s", OTBR_PACKAGE_VERSION);
 
  if (interfaceName == nullptr)