error building tmate-ssh-server

[ScrumpyJack]

I get this error building tmate-ssh-server from latest source using musl-linux c libraries.

Any suggestions would be welcome

CC tmate-main.o
tmate-main.c: In function 'get_in_jail':
tmate-main.c:245:6: warning: implicit declaration of function 'unshare'; did you mean 'usage'? [-Wimplicit-function-declaration]
if (unshare(CLONE_NEWPID | CLONE_NEWIPC | CLONE_NEWNS | CLONE_NEWNET) < 0)
^~~~~~~
usage
tmate-main.c:245:6: warning: nested extern declaration of 'unshare' [-Wnested-externs]
tmate-main.c:245:14: error: 'CLONE_NEWPID' undeclared (first use in this function)
if (unshare(CLONE_NEWPID | CLONE_NEWIPC | CLONE_NEWNS | CLONE_NEWNET) < 0)
^~~~~~~~~~~~
tmate-main.c:245:14: note: each undeclared identifier is reported only once for each function it appears in
tmate-main.c:245:29: error: 'CLONE_NEWIPC' undeclared (first use in this function)
if (unshare(CLONE_NEWPID | CLONE_NEWIPC | CLONE_NEWNS | CLONE_NEWNET) < 0)
^~~~~~~~~~~~
tmate-main.c:245:44: error: 'CLONE_NEWNS' undeclared (first use in this function)
if (unshare(CLONE_NEWPID | CLONE_NEWIPC | CLONE_NEWNS | CLONE_NEWNET) < 0)
^~~~~~~~~~~
tmate-main.c:245:58: error: 'CLONE_NEWNET' undeclared (first use in this function); did you mean 'SOL_DECNET'?
if (unshare(CLONE_NEWPID | CLONE_NEWIPC | CLONE_NEWNS | CLONE_NEWNET) < 0)
^~~~~~~~~~~~
SOL_DECNET
tmate-main.c:253:6: warning: implicit declaration of function 'setresgid'; did you mean 'setregid'? [-Wimplicit-function-declaration]
if (setresgid(gid, gid, gid) < 0)
^~~~~~~~~
setregid
tmate-main.c:253:6: warning: nested extern declaration of 'setresgid' [-Wnested-externs]
tmate-main.c:264:6: warning: implicit declaration of function 'setresuid'; did you mean 'setreuid'? [-Wimplicit-function-declaration]
if (setresuid(uid, uid, uid) < 0)
^~~~~~~~~
setreuid
tmate-main.c:264:6: warning: nested extern declaration of 'setresuid' [-Wnested-externs]
tmate-main.c: At top level:
cc1: warning: unrecognized command line option '-Wno-null-pointer-arithmetic'
make: *** [Makefile:992: tmate-main.o] Error 1

[jsarenik]

On Alpine Linux x86_64 I use following patch. Only two lines are really fixing this, the rest is updating configure.ac for Autoconf to be happy.

commit 4941e65b
Author: Jan Sarenik <[email protected]>
Date:   Thu Aug 25 10:14:55 2022 +0000

    Fix musl-libc compilation and update autoconf

diff --git a/Makefile.am b/Makefile.am
index 91ba01bd..afc80146 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -17,9 +17,7 @@ CPPFLAGS += @XOPEN_DEFINES@ -DTMUX_CONF="\"$(sysconfdir)/tmux.conf\""
 
 # glibc as usual does things ass-backwards and hides useful things by default,
 # so everyone has to add this.
-if IS_GLIBC
 CFLAGS += -D_GNU_SOURCE
-endif
 
 if IS_DEVENV
 CFLAGS += -DDEVENV
diff --git a/configure.ac b/configure.ac
index 2035470f..bd1565ed 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1,6 +1,6 @@
 # configure.ac
 
-AC_INIT(tmate-ssh-server, 2.3.0)
+AC_INIT([tmate-ssh-server],[2.3.0])
 
 AM_SILENT_RULES([yes])
 AC_CONFIG_AUX_DIR(etc)
@@ -26,7 +26,7 @@ test "$sysconfdir" = '${prefix}/etc' && sysconfdir=/etc
 
 AC_ARG_ENABLE(
 	devenv,
-	AC_HELP_STRING(--enable-devenv, "dev env (port 2200, no random tokens)"),
+	AS_HELP_STRING([--enable-devenv],["dev env (port 2200, no random tokens)"]),
 	found_devenv=$enable_devenv
 )
 AM_CONDITIONAL(IS_DEVENV, test "x$found_devenv" = xyes)
@@ -35,7 +35,7 @@ AM_CONDITIONAL(IS_DEVENV, test "x$found_devenv" = xyes)
 found_debug=yes
 AC_ARG_ENABLE(
 	debug,
-	AC_HELP_STRING(--enable-debug, enable debug build flags),
+	AS_HELP_STRING([--enable-debug],[enable debug build flags]),
 	found_debug=$enable_debug
 )
 AM_CONDITIONAL(IS_DEBUG, test "x$found_debug" = xyes)
@@ -43,7 +43,7 @@ AM_CONDITIONAL(IS_DEBUG, test "x$found_debug" = xyes)
 # Is this --enable-coverage?
 AC_ARG_ENABLE(
 	coverage,
-	AC_HELP_STRING(--enable-coverage, enable coverage build flags),
+	AS_HELP_STRING([--enable-coverage],[enable coverage build flags]),
 	found_coverage=$enable_coverage
 )
 AM_CONDITIONAL(IS_COVERAGE, test "x$found_coverage" = xyes)
@@ -51,7 +51,7 @@ AM_CONDITIONAL(IS_COVERAGE, test "x$found_coverage" = xyes)
 # Is this a static build?
 AC_ARG_ENABLE(
 	static,
-	AC_HELP_STRING(--enable-static, create a static build),
+	AS_HELP_STRING([--enable-static],[create a static build]),
 	found_static=$enable_static
 )
 if test "x$found_static" = xyes; then
@@ -224,31 +224,23 @@ AC_CHECK_FUNCS([setresuid setresgid setreuid setregid])
 
 # Check for b64_ntop.
 AC_MSG_CHECKING(for b64_ntop)
-AC_TRY_LINK(
-	[
+AC_LINK_IFELSE([AC_LANG_PROGRAM([[
 		#include <sys/types.h>
 		#include <netinet/in.h>
 		#include <resolv.h>
-	],
-	[b64_ntop(NULL, 0, NULL, 0);],
-	found_b64_ntop=yes,
-	found_b64_ntop=no
-)
+	]], [[b64_ntop(NULL, 0, NULL, 0);]])],[found_b64_ntop=yes],[found_b64_ntop=no
+])
 if test "x$found_b64_ntop" = xno; then
 	AC_MSG_RESULT(no)
 
 	AC_MSG_CHECKING(for b64_ntop with -lresolv)
 	LIBS="$LIBS -lresolv"
-	AC_TRY_LINK(
-		[
+	AC_LINK_IFELSE([AC_LANG_PROGRAM([[
 			#include <sys/types.h>
 			#include <netinet/in.h>
 			#include <resolv.h>
-		],
-		[b64_ntop(NULL, 0, NULL, 0);],
-		found_b64_ntop=yes,
-		found_b64_ntop=no
-	)
+		]], [[b64_ntop(NULL, 0, NULL, 0);]])],[found_b64_ntop=yes],[found_b64_ntop=no
+	])
 	if test "x$found_b64_ntop" = xno; then
 		AC_MSG_RESULT(no)
 	fi
@@ -598,4 +590,5 @@ AM_CONDITIONAL(IS_HPUX, test "x$PLATFORM" = xhpux)
 AM_CONDITIONAL(IS_UNKNOWN, test "x$PLATFORM" = xunknown)
 
 # autoconf should create a Makefile.
-AC_OUTPUT(Makefile)
+AC_CONFIG_FILES([Makefile])
+AC_OUTPUT