Merge branch 'jk/push-client-deadlock-fix' into HEAD

Some Windows SDK lacks pthread_sigmask() implementation and fails
to compile the recently updated "git push" codepath that uses it.

* jk/push-client-deadlock-fix:
  Windows: only add a no-op pthread_sigmask() when needed
  Windows: add pthread_sigmask() that does nothing
  t5504: drop sigpipe=ok from push tests
  fetch-pack: isolate sigpipe in demuxer thread
  send-pack: isolate sigpipe in demuxer thread
  run-command: teach async threads to ignore SIGPIPE
  send-pack: close demux pipe before finishing async process

compat/mingw.h

@@ -142,6 +142,7 @@ static inline int fcntl(int fd, int cmd, ...)
 #define sigemptyset(x) (void)0
 static inline int sigaddset(sigset_t *set, int signum)
 { return 0; }
+#define SIG_BLOCK 0
 #define SIG_UNBLOCK 0
 static inline int sigprocmask(int how, const sigset_t *set, sigset_t *oldset)
 { return 0; }

compat/win32/pthread.h

@@ -104,4 +104,11 @@ static inline void *pthread_getspecific(pthread_key_t key)
 	return TlsGetValue(key);
 }
 
+#ifndef __MINGW64_VERSION_MAJOR
+static inline int pthread_sigmask(int how, const sigset_t *set, sigset_t *oset)
+{
+	return 0;
+}
+#endif
+
 #endif /* PTHREAD_H */

fetch-pack.c

@@ -15,7 +15,6 @@
 #include "version.h"
 #include "prio-queue.h"
 #include "sha1-array.h"
-#include "sigchain.h"
 
 static int transfer_unpack_limit = -1;
 static int fetch_unpack_limit = -1;
@@ -674,10 +673,8 @@ static int sideband_demux(int in, int out, void *data)
 	int *xd = data;
 	int ret;
 
-	sigchain_push(SIGPIPE, SIG_IGN);
 	ret = recv_sideband("fetch-pack", xd[0], out);
 	close(out);
-	sigchain_pop(SIGPIPE);
 	return ret;
 }
 
@@ -701,6 +698,7 @@ static int get_pack(struct fetch_pack_args *args,
 		demux.proc = sideband_demux;
 		demux.data = xd;
 		demux.out = -1;
+		demux.isolate_sigpipe = 1;
 		if (start_async(&demux))
 			die("fetch-pack: unable to fork off sideband"
 			    " demultiplexer");

run-command.c

@@ -590,6 +590,16 @@ static void *run_thread(void *data)
 	struct async *async = data;
 	intptr_t ret;
 
+	if (async->isolate_sigpipe) {
+		sigset_t mask;
+		sigemptyset(&mask);
+		sigaddset(&mask, SIGPIPE);
+		if (pthread_sigmask(SIG_BLOCK, &mask, NULL) < 0) {
+			ret = error("unable to block SIGPIPE in async thread");
+			return (void *)ret;
+		}
+	}
+
 	pthread_setspecific(async_key, async);
 	ret = async->proc(async->proc_in, async->proc_out, async->data);
 	return (void *)ret;

run-command.h

@@ -116,6 +116,7 @@ struct async {
 	int proc_in;
 	int proc_out;
 #endif
+	int isolate_sigpipe;
 };
 
 int start_async(struct async *async);

send-pack.c

@@ -518,6 +518,7 @@ int send_pack(struct send_pack_args *args,
 		demux.proc = sideband_demux;
 		demux.data = fd;
 		demux.out = -1;
+		demux.isolate_sigpipe = 1;
 		if (start_async(&demux))
 			die("send-pack: unable to fork off sideband demultiplexer");
 		in = demux.out;
@@ -531,8 +532,10 @@ int send_pack(struct send_pack_args *args,
 				close(out);
 			if (git_connection_is_socket(conn))
 				shutdown(fd[0], SHUT_WR);
-			if (use_sideband)
+			if (use_sideband) {
+				close(demux.out);
 				finish_async(&demux);
+			}
 			fd[1] = -1;
 			return -1;
 		}
@@ -551,11 +554,11 @@ int send_pack(struct send_pack_args *args,
 		packet_flush(out);
 
 	if (use_sideband && cmds_sent) {
+		close(demux.out);
 		if (finish_async(&demux)) {
 			error("error in sideband demultiplexer");
 			ret = -1;
 		}
-		close(demux.out);
 	}
 
 	if (ret < 0)

t/t5504-fetch-receive-strict.sh

@@ -100,11 +100,8 @@ test_expect_success 'push with receive.fsckobjects' '
 		git config receive.fsckobjects true &&
 		git config transfer.fsckobjects false
 	) &&
-	test_must_fail ok=sigpipe git push --porcelain dst master:refs/heads/test >act &&
+	test_must_fail git push --porcelain dst master:refs/heads/test >act &&
-	{
+	test_cmp exp act
-		test_cmp exp act ||
-		! test -s act
-	}
 '
 
 test_expect_success 'push with transfer.fsckobjects' '
@@ -114,7 +111,8 @@ test_expect_success 'push with transfer.fsckobjects' '
 		cd dst &&
 		git config transfer.fsckobjects true
 	) &&
-	test_must_fail ok=sigpipe git push --porcelain dst master:refs/heads/test >act
+	test_must_fail git push --porcelain dst master:refs/heads/test >act &&
+	test_cmp exp act
 '
 
 cat >bogus-commit <<\EOF