fix race condition in signal handler

Closes: #269

5 files changed, 16 insertions, 4 deletions

diff --git a/src/daemon.c b/src/daemon.c
index cbec849..9df4f7f 100644
--- a/src/daemon.c
+++ b/src/daemon.c
@@ -108,6 +108,7 @@ static int dcc_setup_startup_log(void)
         rs_add_logger(rs_logger_file, RS_LOG_DEBUG, 0, STDERR_FILENO);
     } else {
         openlog("distccd", LOG_PID, LOG_DAEMON);
+        rs_trace_syslog = TRUE;
         rs_add_logger(rs_logger_syslog, RS_LOG_DEBUG, NULL, 0);
     }
 
@@ -304,6 +305,7 @@ static void dcc_setup_real_log(void)
 
     rs_remove_all_loggers();
     openlog("distccd", LOG_PID, LOG_DAEMON);
+    rs_trace_syslog = TRUE;
     rs_add_logger(rs_logger_syslog, opt_log_level_num, NULL, 0);
 }
 
diff --git a/src/dparent.c b/src/dparent.c
index f8dc534..485f9c4 100644
--- a/src/dparent.c
+++ b/src/dparent.c
@@ -324,7 +324,9 @@ void dcc_remove_pid(void)
     if (!arg_pid_file)
         return;
 
-    if (unlink(arg_pid_file)) {
+                                /* this may be called from a signal handler,
+                                   and syslog is not safe from signal handler */
+    if (unlink(arg_pid_file) && !rs_trace_syslog) {
         rs_log_warning("failed to remove pid file %s: %s",
                        arg_pid_file, strerror(errno));
     }
diff --git a/src/dsignal.c b/src/dsignal.c
index de033b7..018ff04 100644
--- a/src/dsignal.c
+++ b/src/dsignal.c
@@ -120,7 +120,8 @@ static RETSIGTYPE dcc_daemon_terminate(int whichsig)
 
     am_parent = getpid() == dcc_master_pid;
 
-    if (am_parent) {
+    /* syslog is not safe from a signal handler */
+    if (am_parent && !rs_trace_syslog) {
 #ifdef HAVE_STRSIGNAL
         rs_log_info("%s", strsignal(whichsig));
 #else
@@ -139,6 +140,9 @@ static RETSIGTYPE dcc_daemon_terminate(int whichsig)
 
     raise(whichsig);
 
+/* malloc() stuff not safe from a signal handler, but keep this here in case
+   this memory non-leak is to be fixed in the future. */
+/*
 #ifdef HAVE_GSSAPI
     if (dcc_auth_enabled) {
         dcc_gssapi_release_credentials();
@@ -147,5 +151,5 @@ static RETSIGTYPE dcc_daemon_terminate(int whichsig)
             dcc_gssapi_free_list();
         }
     }
-#endif
+#endif*/
 }
diff --git a/src/trace.c b/src/trace.c
index c5f148b..8b64e29 100644
--- a/src/trace.c
+++ b/src/trace.c
@@ -39,6 +39,7 @@
 #include <stdarg.h>
 #include <syslog.h>
 
+#include "distcc.h"
 #include "trace.h"
 #include "snprintf.h"
 #include "va_copy.h"
@@ -53,7 +54,8 @@ struct rs_logger_list {
 
 static struct rs_logger_list *logger_list = NULL;
 
-
+/* really bool */
+int rs_trace_syslog = FALSE;
 int rs_trace_level = RS_LOG_NOTICE;
 
 #ifdef UNUSED
diff --git a/src/trace.h b/src/trace.h
index f01b1f2..0db4c7f 100644
--- a/src/trace.h
+++ b/src/trace.h
@@ -210,6 +210,8 @@ void rs_log0_nofn(int level, char const *fmt, ...);
  * messages.
  */
 
+/* really bool */
+extern int rs_trace_syslog;
 extern int rs_trace_level;
 
 #ifdef DO_RS_TRACE