signals: require and always use sigaction()

tftpd already requires sigaction() to compile, so there is no reason
to use anything else. It also allows for nicer combination of flags.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

common/signal.c

@@ -1,42 +1,19 @@
 /*
  * signal.c
  *
- * Use sigaction() to simulate BSD signal()
+ * User-friendly wrapper around sigaction().
  */
 
 #include "config.h"
 
-#ifdef HAVE_SIGACTION
-
-sighandler_t tftp_signal(int signum, sighandler_t handler)
+int tftp_signal(int signum, sighandler_t handler, int flags)
 {
-    struct sigaction action, oldaction;
+    struct sigaction sa;
 
-    memset(&action, 0, sizeof action);
-    action.sa_handler = handler;
-    sigemptyset(&action.sa_mask);
-    sigaddset(&action.sa_mask, signum);
-    action.sa_flags = SA_RESTART;
+    memset(&sa, 0, sizeof sa);
+    sa.sa_handler = handler;
+    sigemptyset(&sa.sa_mask);
+    sa.sa_flags = flags;
 
-    if (sigaction(signum, &action, &oldaction))
-	return SIG_ERR;
-
-    return oldaction.sa_handler;
+    return sigaction(signum, &sa, NULL);
 }
-
-#elif defined(HAVE_BSD_SIGNAL)
-
-sighandler_t tftp_signal(int signum, sighandler_t handler)
-{
-    return bsd_signal(signum, handler);
-}
-
-#else
-
-/* This is dangerous at best. Let's hope it works. */
-sighandler_t tftp_signal(int signum, sighandler_t handler)
-{
-    return signal(signum, handler);
-}
-
-#endif

config.h

@@ -282,10 +282,7 @@ char *xstrdup(const char *);
 #ifndef HAVE_SIGHANDLER_T
 typedef void (*sighandler_t)(int);
 #endif
-#ifndef SIG_ERR
-#define SIG_ERR NULL
-#endif
-sighandler_t tftp_signal(int, sighandler_t);
+int tftp_signal(int, sighandler_t, int);
 
 #ifndef HAVE_DUP2
 int dup2(int, int);

configure.ac

@@ -74,9 +74,12 @@ dnl but POSIX requires <sys/socket.h> for socklen_t to be defined.
 dnl
 AC_CHECK_TYPES(socklen_t,,,
 [AC_INCLUDES_DEFAULT
-#if HAVE_SYS_TYPES_H
+#ifdef HAVE_SYS_TYPES_H
 # include <sys/types.h>
 #endif
+#ifdef HAVE_SYS_SOCKET_H
+# include <sys/socket.h>
+#endif
 ])
 
 AC_SEARCH_LIBS(socket, [socket ws2_32 wsock32], , [AC_MSG_ERROR(socket library not found)])
@@ -85,14 +88,12 @@ AC_CHECK_FUNCS(fcntl)
 AC_CHECK_FUNCS(setsid)
 AC_CHECK_FUNCS(recvmsg)
 AC_CHECK_FUNCS(ftruncate)
-AC_CHECK_FUNCS(setreuid)
 AC_CHECK_FUNCS(setresuid)
-AC_CHECK_FUNCS(setregid)
+AC_CHECK_FUNCS(setreuid)
 AC_CHECK_FUNCS(setresgid)
+AC_CHECK_FUNCS(setregid)
 AC_CHECK_FUNCS(initgroups)
 AC_CHECK_FUNCS(setgroups)
-AC_CHECK_FUNCS(sigaction)
-AC_CHECK_FUNCS(bsd_signal)
 AC_CHECK_TYPES(sighandler_t)
 
 dnl Solaris 8 has [u]intmax_t but not strtoumax().  How utterly braindamaged.

tftp/main.c

@@ -305,7 +305,7 @@ int main(int argc, char *argv[])
         sp->s_proto = (char *)"udp";
     }
 
-    tftp_signal(SIGINT, intr);
+    tftp_signal(SIGINT, intr, 0);
 
     if (peerargc) {
         /* Set peer */
@@ -768,8 +768,8 @@ void intr(int sig)
 {
     (void)sig;                  /* Quiet unused warning */
 
-    tftp_signal(SIGALRM, SIG_IGN);
     alarm(0);
+    tftp_signal(SIGALRM, SIG_DFL, 0);
     siglongjmp(toplevel, -1);
 }
 

tftp/tftp.c

@@ -84,7 +84,7 @@ void tftp_sendfile(int fd, const char *name, const char *mode)
     is_request = 1;             /* First packet is the actual WRQ */
     amount = 0;
 
-    tftp_signal(SIGALRM, timer);
+    tftp_signal(SIGALRM, timer, 0);
     do {
         if (is_request) {
             size = makerequest(WRQ, name, dp, mode) - 4;
@@ -190,7 +190,7 @@ void tftp_recvfile(int fd, const char *name, const char *mode)
     firsttrip = 1;
     amount = 0;
 
-    tftp_signal(SIGALRM, timer);
+    tftp_signal(SIGALRM, timer, 0);
     do {
         if (firsttrip) {
             size = makerequest(RRQ, name, ap, mode);

tftpd/misc.c

@@ -19,19 +19,11 @@
 #include "tftpd.h"
 
 /*
- * Set the signal handler and flags.  Basically a user-friendly
- * wrapper around sigaction().
+ * Set the signal handler and flags, and error out on failure.
  */
-void set_signal(int signum, void (*handler) (int), int flags)
+void set_signal(int signum, sighandler_t handler, int flags)
 {
-    struct sigaction sa;
-
-    memset(&sa, 0, sizeof sa);
-    sa.sa_handler = handler;
-    sigemptyset(&sa.sa_mask);
-    sa.sa_flags = flags;
-
-    if (sigaction(signum, &sa, NULL)) {
+    if (tftp_signal(signum, handler, flags)) {
         syslog(LOG_ERR, "sigaction: %m");
         exit(EX_OSERR);
     }