Remove dependency on signal() function

Replaces uses of signal() with sigaction() which should be far
more portable.

Author: matt335672

common/os_calls.c

@@ -2987,10 +2987,28 @@ g_set_alarm(void (*func)(int), unsigned int secs)
 #if defined(_WIN32)
     return 0;
 #else
+    struct sigaction action;
+
     /* Cancel any previous alarm to prevent a race */
     unsigned int rv = alarm(0);
-    signal(SIGALRM, func);
-    (void)alarm(secs);
+
+    if (func == NULL)
+    {
+        action.sa_handler = SIG_DFL;
+        action.sa_flags = 0;
+    }
+    else
+    {
+        action.sa_handler = func;
+        action.sa_flags = SA_RESTART;
+    }
+    sigemptyset (&action.sa_mask);
+
+    sigaction(SIGALRM, &action, NULL);
+    if (func != NULL && secs > 0)
+    {
+        (void)alarm(secs);
+    }
     return rv;
 #endif
 }
@@ -3002,7 +3020,22 @@ g_signal_child_stop(void (*func)(int))
 {
 #if defined(_WIN32)
 #else
-    signal(SIGCHLD, func);
+    struct sigaction action;
+
+    if (func == NULL)
+    {
+        action.sa_handler = SIG_DFL;
+        action.sa_flags = 0;
+    }
+    else
+    {
+        action.sa_handler = func;
+        // Don't need to know when children are stopped or started
+        action.sa_flags = (SA_RESTART | SA_NOCLDSTOP);
+    }
+    sigemptyset (&action.sa_mask);
+
+    sigaction(SIGCHLD, &action, NULL);
 #endif
 }
 
@@ -3013,7 +3046,21 @@ g_signal_segfault(void (*func)(int))
 {
 #if defined(_WIN32)
 #else
-    signal(SIGSEGV, func);
+    struct sigaction action;
+
+    if (func == NULL)
+    {
+        action.sa_handler = SIG_DFL;
+        action.sa_flags = 0;
+    }
+    else
+    {
+        action.sa_handler = func;
+        action.sa_flags = SA_RESETHAND; // This is a one-shot
+    }
+    sigemptyset (&action.sa_mask);
+
+    sigaction(SIGSEGV, &action, NULL);
 #endif
 }
 
@@ -3024,7 +3071,21 @@ g_signal_hang_up(void (*func)(int))
 {
 #if defined(_WIN32)
 #else
-    signal(SIGHUP, func);
+    struct sigaction action;
+
+    if (func == NULL)
+    {
+        action.sa_handler = SIG_DFL;
+        action.sa_flags = 0;
+    }
+    else
+    {
+        action.sa_handler = func;
+        action.sa_flags = SA_RESTART;
+    }
+    sigemptyset (&action.sa_mask);
+
+    sigaction(SIGHUP, &action, NULL);
 #endif
 }
 
@@ -3035,7 +3096,21 @@ g_signal_user_interrupt(void (*func)(int))
 {
 #if defined(_WIN32)
 #else
-    signal(SIGINT, func);
+    struct sigaction action;
+
+    if (func == NULL)
+    {
+        action.sa_handler = SIG_DFL;
+        action.sa_flags = 0;
+    }
+    else
+    {
+        action.sa_handler = func;
+        action.sa_flags = SA_RESTART;
+    }
+    sigemptyset (&action.sa_mask);
+
+    sigaction(SIGINT, &action, NULL);
 #endif
 }
 
@@ -3046,7 +3121,21 @@ g_signal_terminate(void (*func)(int))
 {
 #if defined(_WIN32)
 #else
-    signal(SIGTERM, func);
+    struct sigaction action;
+
+    if (func == NULL)
+    {
+        action.sa_handler = SIG_DFL;
+        action.sa_flags = 0;
+    }
+    else
+    {
+        action.sa_handler = func;
+        action.sa_flags = SA_RESTART;
+    }
+    sigemptyset (&action.sa_mask);
+
+    sigaction(SIGTERM, &action, NULL);
 #endif
 }
 
@@ -3057,7 +3146,21 @@ g_signal_pipe(void (*func)(int))
 {
 #if defined(_WIN32)
 #else
-    signal(SIGPIPE, func);
+    struct sigaction action;
+
+    if (func == NULL)
+    {
+        action.sa_handler = SIG_DFL;
+        action.sa_flags = 0;
+    }
+    else
+    {
+        action.sa_handler = func;
+        action.sa_flags = SA_RESTART;
+    }
+    sigemptyset (&action.sa_mask);
+
+    sigaction(SIGPIPE, &action, NULL);
 #endif
 }
 
@@ -3068,7 +3171,21 @@ g_signal_usr1(void (*func)(int))
 {
 #if defined(_WIN32)
 #else
-    signal(SIGUSR1, func);
+    struct sigaction action;
+
+    if (func == NULL)
+    {
+        action.sa_handler = SIG_DFL;
+        action.sa_flags = 0;
+    }
+    else
+    {
+        action.sa_handler = func;
+        action.sa_flags = SA_RESTART;
+    }
+    sigemptyset (&action.sa_mask);
+
+    sigaction(SIGUSR1, &action, NULL);
 #endif
 }
 

common/os_calls.h

@@ -176,6 +176,14 @@ g_sck_get_peer_ip_address(int sck,
 const char *
 g_sck_get_peer_description(int sck,
                            char *desc, unsigned int bytes);
+/**
+ * Sleep for the specified number of milli-seconds
+ * @param msecs Milli-seconds
+ *
+ * If a signal is processed, it is possible that this call will
+ * sleep for less than the specified number of milli-seconds. This
+ * is platform-specific
+ */
 void     g_sleep(int msecs);
 int      g_pipe(int fd[2]);
 
@@ -275,13 +283,56 @@ int      g_execvp(const char *p1, char *args[]);
  */
 int      g_execvp_list(const char *file, struct list *argv);
 int      g_execlp3(const char *a1, const char *a2, const char *a3);
+/**
+ * Set an alarm using SIGALRM
+ * @param func Signal handler, or NULL to cancel an alarm
+ * @param secs Number of seconds until an alarm is raised
+ * @return Number of seconds remaining before a previously requested
+ *         alarm is raised
+ */
 unsigned int g_set_alarm(void (*func)(int), unsigned int secs);
+/**
+ * Set a handler up for SIGCHLD
+ * @param func signal handler, or NULL to restore the default handler
+ * The handler remains in place until explicitly replaced.
+ */
 void     g_signal_child_stop(void (*func)(int));
+/**
+ * Set a handler up for SIGSEGV
+ * @param func signal handler, or NULL to restore the default handler
+ * The handler can only be called once, at which point the
+ * default handler is restored. This is to avoid infinite loops
+ */
 void     g_signal_segfault(void (*func)(int));
+/**
+ * Set a handler up for SIGHUP
+ * @param func signal handler, or NULL to restore the default handler
+ * The handler remains in place until explicitly replaced.
+ */
 void     g_signal_hang_up(void (*func)(int));
+/**
+ * Set a handler up for SIGINT
+ * @param func signal handler, or NULL to restore the default handler
+ * The handler remains in place until explicitly replaced.
+ */
 void     g_signal_user_interrupt(void (*func)(int));
+/**
+ * Set a handler up for SIGTERM
+ * @param func signal handler, or NULL to restore the default handler
+ * The handler remains in place until explicitly replaced.
+ */
 void     g_signal_terminate(void (*func)(int));
+/**
+ * Set a handler up for SIGPIPE
+ * @param func signal handler, or NULL to restore the default handler
+ * The handler remains in place until explicitly replaced.
+ */
 void     g_signal_pipe(void (*func)(int));
+/**
+ * Set a handler up for SIGUSR1
+ * @param func signal handler, or NULL to restore the default handler
+ * The handler remains in place until explicitly replaced.
+ */
 void     g_signal_usr1(void (*func)(int));
 int      g_fork(void);
 int      g_setgid(int pid);

tests/common/Makefile.am

@@ -18,6 +18,7 @@ test_common_SOURCES = \
     test_list_calls.c \
     test_string_calls.c \
     test_os_calls.c \
+    test_os_calls_signals.c \
     test_ssl_calls.c \
     test_base64.c \
     test_guid.c

tests/common/test_common.h

@@ -15,4 +15,9 @@ Suite *make_suite_test_ssl_calls(void);
 Suite *make_suite_test_base64(void);
 Suite *make_suite_test_guid(void);
 
+TCase *make_tcase_test_os_calls_signals(void);
+
+void os_calls_signals_init(void);
+void os_calls_signals_deinit(void);
+
 #endif /* TEST_COMMON_H */

tests/common/test_common_main.c

@@ -64,14 +64,17 @@ int main (void)
      * reporting when running in libcheck fork mode */
     setvbuf(stdout, NULL, _IONBF, 0);
 
-    /* Initialise the ssl module */
+    /* Initialise modules */
     ssl_init();
+    os_calls_signals_init();
 
     srunner_run_all (sr, CK_ENV);
     number_failed = srunner_ntests_failed(sr);
     srunner_free(sr);
 
     ssl_finish();
+    os_calls_signals_deinit();
+
     log_end();
     return (number_failed == 0) ? EXIT_SUCCESS : EXIT_FAILURE;
 }

tests/common/test_os_calls.c

@@ -512,5 +512,9 @@ make_suite_test_os_calls(void)
     tcase_add_test(tc_os_calls, test_g_file_is_open);
     tcase_add_test(tc_os_calls, test_g_sck_fd_passing);
     tcase_add_test(tc_os_calls, test_g_sck_fd_overflow);
+
+    // Add other test cases in other files
+    suite_add_tcase(s, make_tcase_test_os_calls_signals());
+
     return s;
 }