Use docker run to compile C code not docker build

C version of #1006

Note that I switched all the C builds to use -O2 and that meant
that the compiler found some more warnings so I also fixed these
up. The possibly undefined ones were harmless, the aliasing one
is now more correct.

As these are small programs, the caching from `docker build` makes
no real difference, and worst case compile time is much better.

Signed-off-by: Justin Cormack <justin.cormack@docker.com>

alpine/base/c-compile/Dockerfile

@@ -0,0 +1,15 @@
+FROM alpine:3.5
+RUN \
+  apk update && apk upgrade && \
+  apk add \
+  curl \
+  gcc \
+  git \
+  libc-dev \
+  linux-headers \
+  util-linux-dev \
+  && true
+
+COPY compile.sh /usr/bin/
+
+ENTRYPOINT ["/usr/bin/compile.sh"]

alpine/base/c-compile/Makefile

@@ -0,0 +1,29 @@
+.PHONY: tag push
+
+BASE=alpine:3.5
+IMAGE=c-compile
+
+default: push
+
+hash: Dockerfile compile.sh 
+	DOCKER_CONTENT_TRUST=1 docker pull $(BASE)
+	tar cf - $^ | docker build --no-cache -t $(IMAGE):build -
+	docker run --rm --entrypoint=/bin/sh $(IMAGE):build -c 'cat /lib/apk/db/installed /usr/bin/compile.sh | sha1sum' | sed 's/ .*//' > hash
+
+push: hash
+	docker pull mobylinux/$(IMAGE):$(shell cat hash) || \
+		(docker tag $(IMAGE):build mobylinux/$(IMAGE):$(shell cat hash) && \
+		 docker push mobylinux/$(IMAGE):$(shell cat hash))
+	docker rmi $(IMAGE):build
+	rm -f hash
+
+tag: hash
+	docker pull mobylinux/$(IMAGE):$(shell cat hash) || \
+		docker tag $(IMAGE):build mobylinux/$(IMAGE):$(shell cat hash)
+	docker rmi $(IMAGE):build
+	rm -f hash
+
+clean:
+	rm -f hash
+
+.DELETE_ON_ERROR:

alpine/base/c-compile/compile.sh

@@ -0,0 +1,56 @@
+#!/bin/sh
+
+# This is designed to compile a single package to a single binary
+# so it makes some assumptions about things to simplify config
+# to output a single binary (in a tarball) just use -o file
+# use --docker to output a tarball for input to docker build -
+
+set -e
+
+usage() {
+	echo "Usage: -o file"
+	exit 1
+}
+
+[ $# = 0 ] && usage
+
+while [ $# -gt 0 ]
+do
+	flag="$1"
+	case "$flag" in
+	-o)
+		[ $# -eq 1 ] && usage
+		out="$2"
+		mkdir -p "$(dirname $2)"
+		shift
+	;;
+	-l*)
+		LIBS="$LIBS $1"
+		shift
+	;;
+	*)
+		echo "Unknown option $1"
+		exit 1
+	esac
+	shift
+done
+
+[ -z "$out" ] && usage
+
+package=$(basename "$out")
+
+dir="/src/$package"
+
+mkdir -p $dir
+
+# untar input
+tar xf - -C $dir
+
+(
+	cd $dir
+	CFILES=$(find . -name '*.c')
+	cc -static -O2 -Wall -Werror -o ../../$out $CFILES $LIBS
+)
+
+tar cf - $out
+exit 0

alpine/packages/9pmount-vsock/Dockerfile

@@ -1,10 +0,0 @@
-# Tag: b77cfc4ad0033d4366df830ed697afc7bab458a2
-FROM mobylinux/alpine-build-c@sha256:53739ea6042cb0ac39cf6e262012c1c4224206b2c9b719569fe7efa3a381348c
-
-COPY . /9pmount-vsock
-
-WORKDIR /9pmount-vsock
-
-RUN cc -Wall -Werror 9pmount-vsock.c hvsock.c -lpthread -o 9pmount-vsock
-
-CMD ["tar", "cf", "-", "9pmount-vsock"]

alpine/packages/9pmount-vsock/Makefile

@@ -1,12 +1,13 @@
-DEPS=Dockerfile $(wildcard *.c *.h)
+# Tag: ac075fed7c87e4af30d8490ae0504166cceb0df3
+C_COMPILE=mobylinux/c-compile@sha256:0e82d441ce112d638f904a08199c76b022c065a2dbf8908bb366755267d4417f
 
-9pmount-vsock: $(DEPS)
+default: sbin/9pmount-vsock
-	mkdir -p sbin
-	BUILD=$$( tar cf - $(DEPS) | docker build -q - ) && \
-	[ -n "$$BUILD" ] && \
-	echo "Built $$BUILD" && \
-	docker run --rm --net=none $$BUILD | tar xf - -C sbin
 
+DEPS=$(wildcard *.c *.h)
+
+sbin/9pmount-vsock: $(DEPS)
+	mkdir -p $(dir $@)
+	tar cf - $(DEPS) | docker run --rm --net=none --log-driver=none -i $(C_COMPILE) -o $@ -lpthread | tar xf -
 
 clean:
 	rm -rf sbin

alpine/packages/nc-vsock/Dockerfile

@@ -1,10 +0,0 @@
-# Tag: b77cfc4ad0033d4366df830ed697afc7bab458a2
-FROM mobylinux/alpine-build-c@sha256:53739ea6042cb0ac39cf6e262012c1c4224206b2c9b719569fe7efa3a381348c
-
-COPY . /nc-vsock
-
-WORKDIR /nc-vsock
-
-RUN cc -Wall -Werror -o nc-vsock nc-vsock.c -luuid
-
-CMD ["tar", "cf", "-", "nc-vsock"]

alpine/packages/nc-vsock/Makefile

@@ -1,11 +1,13 @@
-DEPS=Dockerfile $(wildcard *.c *.h)
+# Tag: ac075fed7c87e4af30d8490ae0504166cceb0df3
+C_COMPILE=mobylinux/c-compile@sha256:0e82d441ce112d638f904a08199c76b022c065a2dbf8908bb366755267d4417f
+
+default: usr/bin/nc-vsock
+
+DEPS=$(wildcard *.c *.h)
 
 usr/bin/nc-vsock: $(DEPS)
-	mkdir -p usr/bin
+	mkdir -p $(dir $@)
-	BUILD=$$( tar cf - $(DEPS) | docker build -q - ) && \
+	tar cf - $(DEPS) | docker run --rm --net=none --log-driver=none -i $(C_COMPILE) -o $@ -luuid | tar xf -
-	[ -n "$$BUILD" ] && \
-	echo "Built $$BUILD" && \
-	docker run --rm --net=none $$BUILD | tar xf - -C usr/bin
 
 clean:
 	rm -rf usr

alpine/packages/nc-vsock/nc-vsock.c

@@ -193,7 +193,7 @@ static int hvsock_listen(const char *port_str)
 
 static int tcp_connect(const char *node, const char *service)
 {
-	int fd;
+	int fd = -1;
 	int ret;
 	const struct addrinfo hints = {
 		.ai_family = AF_INET,

alpine/packages/tap-vsockd/Dockerfile

@@ -1,10 +0,0 @@
-# Tag: b77cfc4ad0033d4366df830ed697afc7bab458a2
-FROM mobylinux/alpine-build-c@sha256:53739ea6042cb0ac39cf6e262012c1c4224206b2c9b719569fe7efa3a381348c
-
-COPY . /tap-vsockd
-
-WORKDIR /tap-vsockd
-
-RUN cc -Wall -Werror tap-vsockd.c hvsock.c protocol.c -lpthread -o tap-vsockd
-
-CMD ["tar", "cf", "-", "tap-vsockd"]

alpine/packages/tap-vsockd/Makefile

@@ -1,11 +1,13 @@
-DEPS=Dockerfile $(wildcard *.c *.h)
+# Tag: ac075fed7c87e4af30d8490ae0504166cceb0df3
+C_COMPILE=mobylinux/c-compile@sha256:0e82d441ce112d638f904a08199c76b022c065a2dbf8908bb366755267d4417f
+
+default: sbin/tap-vsockd
+
+DEPS=$(wildcard *.c *.h)
 
 sbin/tap-vsockd: $(DEPS)
-	mkdir -p sbin
+	mkdir -p $(dir $@)
-	BUILD=$$( tar cf - $(DEPS) | docker build -q - ) && \
+	tar cf - $(DEPS) | docker run --rm --net=none --log-driver=none -i $(C_COMPILE) -o $@ -lpthread | tar xf -
-	[ -n "$$BUILD" ] && \
-	echo "Built $$BUILD" && \
-	docker run --rm --net=none $$BUILD | tar xf - -C sbin
 
 clean:
 	rm -rf sbin

alpine/packages/transfused/Dockerfile

@@ -1,10 +0,0 @@
-# Tag: b77cfc4ad0033d4366df830ed697afc7bab458a2
-FROM mobylinux/alpine-build-c@sha256:53739ea6042cb0ac39cf6e262012c1c4224206b2c9b719569fe7efa3a381348c
-
-COPY . /transfused
-
-WORKDIR /transfused
-
-RUN cc -g -static -Wall -Werror -o transfused transfused.c transfused_log.c transfused_vsock.c
-
-CMD ["tar", "cf", "-", "transfused"]

alpine/packages/transfused/Makefile

@@ -1,11 +1,13 @@
-DEPS=Dockerfile $(wildcard *.c *.h)
+# Tag: ac075fed7c87e4af30d8490ae0504166cceb0df3
+C_COMPILE=mobylinux/c-compile@sha256:0e82d441ce112d638f904a08199c76b022c065a2dbf8908bb366755267d4417f
+
+default: sbin/transfused
+
+DEPS=$(wildcard *.c *.h)
 
 sbin/transfused: $(DEPS)
-	mkdir -p sbin
+	mkdir -p $(dir $@)
-	BUILD=$$( tar cf - $(DEPS) | docker build -q - ) && \
+	tar cf - $(DEPS) | docker run --rm --net=none --log-driver=none -i $(C_COMPILE) -o $@ | tar xf -
-	[ -n "$$BUILD" ] && \
-	echo "Built $$BUILD" && \
-	docker run --rm --net=none $$BUILD | tar xf - -C sbin
 
 clean:
 	rm -rf sbin

alpine/packages/transfused/transfused.c

@@ -97,7 +97,7 @@ void unlock(char *const descr, pthread_mutex_t *mutex)
 
 int bind_socket(const char *socket)
 {
-	int sock;
+	int sock = -1;
 
 	if (socket[0] == 0)
 		die(2, NULL, NULL, "Socket family required");
@@ -118,7 +118,7 @@ int bind_socket(const char *socket)
 
 int connect_socket(const char *socket)
 {
-	int sock;
+	int sock = -1;
 
 	if (socket[0] == 0)
 		die(2, NULL, NULL, "Socket family required");
@@ -549,12 +549,15 @@ void start_writer(connection_t *connection, int fuse)
 void negotiate_notify_channel(char *mount_point, int notify_sock)
 {
 	int len = strlen(mount_point);
-	char hdr[6];
+	struct {
+		uint32_t len;
+		uint16_t channel;
+	} __attribute__((packed)) hdr;
 
-	*((uint32_t *)hdr) = 6 + len;
+	hdr.len = 6 + len;
-	*((uint16_t *)(hdr + 4)) = TRANSFUSE_NOTIFY_CHANNEL;
+	hdr.channel = TRANSFUSE_NOTIFY_CHANNEL;
 
-	write_exactly("negotiate_notify_channel hdr", notify_sock, hdr, 6);
+	write_exactly("negotiate_notify_channel hdr", notify_sock, &hdr, 6);
 	write_exactly("negotiate_notify_channel mnt",
 		      notify_sock, mount_point, len);
 }
@@ -1087,7 +1090,7 @@ void serve(parameters *params)
 	char subproto_selector;
 	pthread_t child;
 	connection_t *conn;
-	void *(*connection_handler_thread)(void *);
+	void *(*connection_handler_thread)(void *) = NULL;
 
 	if (listen(params->data_sock, 16))
 		die(1, NULL, "listen", "");