When cross-compiling, we cannot run a test program to check whether a siginfo_t provides the signal sender PID, so we fall back to assuming that it does, and also check that SA_SIGINFO is declared so compilation will not fail on systems without it (#120).

configure.ac

@@ -40,6 +40,7 @@ AC_CHECK_HEADERS([sys/ioctl.h])
 AC_CHECK_HEADERS([libintl.h locale.h])
 AC_CHECK_HEADERS([sys/sysmacros.h])
 AC_CHECK_MEMBERS([struct stat.st_blksize])
+AC_CHECK_DECLS([SA_SIGINFO], [], [], [[#include <signal.h>]])
 
 AC_SEARCH_LIBS([sqrtl],[m])
 AC_CHECK_HEADERS([math.h])
@@ -98,7 +99,11 @@ AC_MSG_RESULT([yes])
 AC_DEFINE([SIGINFO_PROVIDES_PID], [1], [Signal handlers can determine the sending PID])
 ], [
 AC_MSG_RESULT([no])
-])
+], [
+AC_MSG_RESULT([cannot check, assuming yes])
+AC_DEFINE([SIGINFO_PROVIDES_PID], [1], [Signal handlers can determine the sending PID])
+]
+)
 
 AH_BOTTOM([#include "config-aux.h"])
 

src/include/config-aux.h

@@ -43,3 +43,11 @@ typedef bool _Bool;
 # define true 1
 # define __bool_true_false_are_defined 1
 #endif
+
+/* Whether "--remote" should be available. */
+#undef PV_REMOTE_CONTROL
+#if HAVE_DECL_SA_SIGINFO
+# if SIGINFO_PROVIDES_PID
+#define PV_REMOTE_CONTROL 1
+# endif
+#endif

src/include/config.h.in

@@ -28,6 +28,10 @@
    */
 #undef HAVE_DCGETTEXT
 
+/* Define to 1 if you have the declaration of `SA_SIGINFO', and to 0 if you
+   don't. */
+#undef HAVE_DECL_SA_SIGINFO
+
 /* Define to 1 if you have the `dup2' function. */
 #undef HAVE_DUP2
 

src/include/pv-internal.h

@@ -159,13 +159,13 @@ struct pvstate_s {
 		struct sigaction old_sigint;
 		struct sigaction old_sighup;
 		struct sigaction old_sigterm;
-#ifdef SIGINFO_PROVIDES_PID
+#ifdef PV_REMOTE_CONTROL
 		struct sigaction old_sigusr2;
 #endif
 		struct sigaction old_sigalrm;
 		struct timespec tstp_time;	 /* see pv_sig_tstp() / __cont() */
 		struct timespec toffset;	 /* total time spent stopped */
-#ifdef SIGINFO_PROVIDES_PID
+#ifdef PV_REMOTE_CONTROL
 		volatile sig_atomic_t rxusr2;	 /* whether SIGUSR2 was received */
 		volatile pid_t sender;		 /* PID of sending process for SIGUSR2 */
 #endif

src/include/pv.h

@@ -238,7 +238,7 @@ extern off_t pv_calc_total_size(pvstate_t);
  */
 extern void pv_sig_init(pvstate_t);
 
-#ifdef SIGINFO_PROVIDES_PID
+#ifdef PV_REMOTE_CONTROL
 /*
  * Return true if SIGUSR2 has been received, and indicate the sender.
  */

src/main/help.c

@@ -405,11 +405,11 @@ void display_help(void)
 		{ "-d", "--watchfd", N_("PID[:FD]"),
 		 N_("watch file FD opened by process PID"),
 		 { 0, 0, 0, 0} },
-#ifdef SIGINFO_PROVIDES_PID
+#ifdef PV_REMOTE_CONTROL
 		{ "-R", "--remote", N_("PID"),
 		 N_("update settings of process PID"),
 		 { 0, 0, 0, 0} },
-#endif				/* SIGINFO_PROVIDES_PID */
+#endif				/* PV_REMOTE_CONTROL */
 		{ "", NULL, NULL, NULL, { 0, 0, 0, 0} },
 		{ "-P", "--pidfile", N_("FILE"),
 		 N_("save process ID in FILE"),

src/main/remote.c

@@ -21,7 +21,7 @@
 #include <sys/time.h>
 #include <sys/stat.h>
 
-#ifdef SIGINFO_PROVIDES_PID
+#ifdef PV_REMOTE_CONTROL
 void pv_error(pvstate_t, char *, ...);
 
 struct remote_msg {
@@ -407,10 +407,10 @@ void pv_remote_fini(void)
 {
 }
 
-#else				/* !SIGINFO_PROVIDES_PID */
+#else				/* !PV_REMOTE_CONTROL */
 
 /*
- * Dummy stubs for remote control when we don't have SIGINFO_PROVIDES_PID.
+ * Dummy stubs for remote control when we don't have PV_REMOTE_CONTROL.
  */
 void pv_remote_init(void)
 {

src/pv/signal.c

@@ -226,7 +226,7 @@ static void pv_sig_term( /*@unused@ */  __attribute__((unused))
 }
 
 
-#ifdef SIGINFO_PROVIDES_PID
+#ifdef PV_REMOTE_CONTROL
 /*
  * Handle a SIGUSR2 by setting a flag to say we received it, after recording
  * the sending PID.
@@ -375,7 +375,7 @@ void pv_sig_init(pvstate_t state)
 	sa.sa_flags = 0;
 	(void) sigaction(SIGTERM, &sa, &(pv_sig_state->signal.old_sigterm));
 
-#ifdef SIGINFO_PROVIDES_PID
+#ifdef PV_REMOTE_CONTROL
 	/*
 	 * Handle SIGUSR2 by setting a flag to say the signal has been
 	 * received, and storing the sending process's PID.
@@ -431,7 +431,7 @@ void pv_sig_fini( /*@unused@ */  __attribute__((unused)) pvstate_t state)
 	(void) sigaction(SIGINT, &(pv_sig_state->signal.old_sigint), NULL);
 	(void) sigaction(SIGHUP, &(pv_sig_state->signal.old_sighup), NULL);
 	(void) sigaction(SIGTERM, &(pv_sig_state->signal.old_sigterm), NULL);
-#ifdef SIGINFO_PROVIDES_PID
+#ifdef PV_REMOTE_CONTROL
 	(void) sigaction(SIGUSR2, &(pv_sig_state->signal.old_sigusr2), NULL);
 #endif
 	(void) sigaction(SIGALRM, &(pv_sig_state->signal.old_sigalrm), NULL);