Modernize: use sigaction() whenever possible. Remove uses of common.

bsd_signal() may not be defined, and there is really no reason to even
try to use it if sigaction() is avaiable; using sigaction() guarantees
the semantics we really want.

Replace uses of common variables with explicit instantiation and
extern declarations in a header file.

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

common/Makefile

@@ -4,7 +4,7 @@ VERSION = $(shell cat ../version)
 -include ../MCONFIG
 include ../MRULES
 
-OBJS = tftpsubs.$(O)
+OBJS = tftpsubs.$(O) signal.$(O)
 LIB  = libcommon.a
 
 all: $(LIB)

common/signal.c

@@ -0,0 +1,42 @@
+/*
+ * signal.c
+ *
+ * Use sigaction() to simulate BSD signal()
+ */
+
+#include "config.h"
+
+#ifdef HAVE_SIGACTION
+
+sighandler_t tftp_signal(int signum, sighandler_t handler)
+{
+    struct sigaction action, oldaction;
+
+    memset(&action, 0, sizeof action);
+    action.sa_handler = handler;
+    sigemptyset(&action.sa_mask);
+    sigaddset(&action.sa_mask, signum);
+    action.sa_flags = SA_RESTART;
+
+    if (sigaction(signum, &action, &oldaction))
+	return SIG_ERR;
+
+    return oldaction.sa_handler;
+}
+
+#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

@@ -1,6 +1,6 @@
 /* -*- c -*- ------------------------------------------------------------- *
  *
- *   Copyright 2001-2006 H. Peter Anvin - All Rights Reserved
+ *   Copyright 2001-2024 H. Peter Anvin - All Rights Reserved
  *
  *   This program is free software available under the same license
  *   as the "OpenBSD" operating system, distributed at
@@ -279,9 +279,14 @@ typedef int socklen_t;
 void *xmalloc(size_t);
 char *xstrdup(const char *);
 
-#ifndef HAVE_BSD_SIGNAL
-void (*bsd_signal(int, void (*)(int))) (int);
+#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);
+
 #ifndef HAVE_DUP2
 int dup2(int, int);
 #endif

configure.ac

@@ -89,6 +89,9 @@ AC_CHECK_FUNCS(setreuid)
 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.
 AC_CHECK_FUNCS(strtoumax)
@@ -120,7 +123,6 @@ OBJROOT=`pwd`
 XTRA=false
 PA_SEARCH_LIBS_AND_ADD(xmalloc, iberty)
 PA_SEARCH_LIBS_AND_ADD(xstrdup, iberty)
-PA_SEARCH_LIBS_AND_ADD(bsd_signal, bsd, bsdsignal)
 PA_SEARCH_LIBS_AND_ADD(getopt_long, getopt, getopt_long)
 PA_SEARCH_LIBS_AND_ADD(getaddrinfo, [nsl resolv])
 if $pa_add_getaddrinfo

lib/Makefile

@@ -25,5 +25,3 @@ libxtra.a: $(LIBOBJS)
 	-rm -f libxtra.a
 	$(AR) libxtra.a $(LIBOBJS)
 	$(RANLIB) libxtra.a
-
-

lib/bsdsignal.c

@@ -1,27 +0,0 @@
-/*
- * bsdsignal.c
- *
- * Use sigaction() to simulate BSD signal()
- */
-
-#include "config.h"
-
-void (*bsd_signal(int signum, void (*handler) (int))) (int) {
-    struct sigaction action, oldaction;
-
-    memset(&action, 0, sizeof action);
-    action.sa_handler = handler;
-    sigemptyset(&action.sa_mask);
-    sigaddset(&action.sa_mask, signum);
-    action.sa_flags = SA_RESTART;
-
-    if (sigaction(signum, &action, &oldaction) == -1) {
-#ifdef SIG_ERR
-        return SIG_ERR;
-#else
-        return NULL;
-#endif
-    }
-
-    return oldaction.sa_handler;
-}

tftp/extern.h

@@ -31,10 +31,13 @@
  * SUCH DAMAGE.
  */
 
-#ifndef RECVFILE_H
-#define RECVFILE_H
+#ifndef EXTERN_H
+#define EXTERN_H
+
+#include "config.h"
 
 void tftp_recvfile(int, const char *, const char *);
 void tftp_sendfile(int, const char *, const char *);
+extern sigjmp_buf toplevel;
 
 #endif

tftp/main.c

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

tftp/tftp.c

@@ -48,8 +48,7 @@ extern int maxtimeout;
 #define PKTSIZE    SEGSIZE+4
 char ackbuf[PKTSIZE];
 int timeout;
-sigjmp_buf toplevel;
-sigjmp_buf timeoutbuf;
+static sigjmp_buf timeoutbuf;
 
 static void nak(int, const char *);
 static int makerequest(int, const char *, struct tftphdr *, const char *);
@@ -85,7 +84,7 @@ void tftp_sendfile(int fd, const char *name, const char *mode)
     is_request = 1;             /* First packet is the actual WRQ */
     amount = 0;
 
-    bsd_signal(SIGALRM, timer);
+    tftp_signal(SIGALRM, timer);
     do {
         if (is_request) {
             size = makerequest(WRQ, name, dp, mode) - 4;
@@ -191,7 +190,7 @@ void tftp_recvfile(int fd, const char *name, const char *mode)
     firsttrip = 1;
     amount = 0;
 
-    bsd_signal(SIGALRM, timer);
+    tftp_signal(SIGALRM, timer);
     do {
         if (firsttrip) {
             size = makerequest(RRQ, name, ap, mode);