serialise: Split functions user for serialisation from util.c

The read_all_buf() and write_all_buf() functions in util.c are
primarily used for serialising data structures to a stream during
migraiton.  We're going to have further use for such serialisation
when we add dynamic configuration updates, where we'll want to share
the code with the client program.

To make that easier move the functions into a new serialise.c
file, and rename thematically.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

9 files changed, 113 insertions, 76 deletions

diff --git a/Makefile b/Makefile
index 513dc6c..5b6891d 100644
--- a/Makefile
+++ b/Makefile
@@ -40,8 +40,8 @@ FLAGS += -DDUAL_STACK_SOCKETS=$(DUAL_STACK_SOCKETS)
 PASST_SRCS = arch.c arp.c checksum.c conf.c dhcp.c dhcpv6.c epoll_ctl.c \
 	flow.c fwd.c icmp.c igmp.c inany.c iov.c ip.c isolation.c lineread.c \
 	log.c mld.c ndp.c netlink.c migrate.c packet.c passt.c pasta.c pcap.c \
-	pif.c repair.c tap.c tcp.c tcp_buf.c tcp_splice.c tcp_vu.c udp.c \
-	udp_flow.c udp_vu.c util.c vhost_user.c virtio.c vu_common.c
+	pif.c repair.c serialise.c tap.c tcp.c tcp_buf.c tcp_splice.c tcp_vu.c \
+	udp.c udp_flow.c udp_vu.c util.c vhost_user.c virtio.c vu_common.c
 QRAP_SRCS = qrap.c
 PASST_REPAIR_SRCS = passt-repair.c
 SRCS = $(PASST_SRCS) $(QRAP_SRCS) $(PASST_REPAIR_SRCS)
@@ -51,9 +51,10 @@ MANPAGES = passt.1 pasta.1 qrap.1 passt-repair.1
 PASST_HEADERS = arch.h arp.h checksum.h conf.h dhcp.h dhcpv6.h epoll_ctl.h \
 	flow.h fwd.h flow_table.h icmp.h icmp_flow.h inany.h iov.h ip.h \
 	isolation.h lineread.h log.h migrate.h ndp.h netlink.h packet.h \
-	passt.h pasta.h pcap.h pif.h repair.h siphash.h tap.h tcp.h tcp_buf.h \
-	tcp_conn.h tcp_internal.h tcp_splice.h tcp_vu.h udp.h udp_flow.h \
-	udp_internal.h udp_vu.h util.h vhost_user.h virtio.h vu_common.h
+	passt.h pasta.h pcap.h pif.h repair.h serialise.h siphash.h tap.h tcp.h \
+	tcp_buf.h tcp_conn.h tcp_internal.h tcp_splice.h tcp_vu.h udp.h \
+	udp_flow.h udp_internal.h udp_vu.h util.h vhost_user.h virtio.h \
+	vu_common.h
 HEADERS = $(PASST_HEADERS) seccomp.h
 
 C := \#include <sys/random.h>\nint main(){int a=getrandom(0, 0, 0);}
diff --git a/flow.c b/flow.c
index 4282da2..25a6f1a 100644
--- a/flow.c
+++ b/flow.c
@@ -21,6 +21,7 @@
 #include "flow_table.h"
 #include "repair.h"
 #include "epoll_ctl.h"
+#include "serialise.h"
 
 const char *flow_state_str[] = {
 	[FLOW_STATE_FREE]	= "FREE",
diff --git a/migrate.c b/migrate.c
index 1e8858a..8937b85 100644
--- a/migrate.c
+++ b/migrate.c
@@ -24,6 +24,7 @@
 
 #include "migrate.h"
 #include "repair.h"
+#include "serialise.h"
 
 /* Magic identifier for migration data */
 #define MIGRATE_MAGIC		0xB1BB1D1B0BB1D1B0
diff --git a/pcap.c b/pcap.c
index 54fba5c..a026f17 100644
--- a/pcap.c
+++ b/pcap.c
@@ -34,6 +34,7 @@
 #include "pcap.h"
 #include "iov.h"
 #include "tap.h"
+#include "serialise.h"
 
 #define PCAP_VERSION_MINOR 4
 
diff --git a/serialise.c b/serialise.c
new file mode 100644
index 0000000..f162eeb
--- /dev/null
+++ b/serialise.c
@@ -0,0 +1,88 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+/* PASST - Plug A Simple Socket Transport
+ *  for qemu/UNIX domain socket mode
+ *
+ * PASTA - Pack A Subtle Tap Abstraction
+ *  for network namespace/tap device mode
+ *
+ * serialise.c - Serialisation of data structures over bytestreams
+ *
+ * Copyright Red Hat
+ * Author: David Gibson <david@gibson.dropbear.id.au>
+ */
+
+#include <assert.h>
+#include <errno.h>
+#include <unistd.h>
+
+#include "serialise.h"
+
+/**
+ * read_all_buf() - Fill a whole buffer from a file descriptor
+ * @fd:		File descriptor
+ * @buf:	Pointer to base of buffer
+ * @len:	Length of buffer
+ *
+ * Return: 0 on success, -1 on error (with errno set)
+ *
+ * #syscalls read
+ */
+int read_all_buf(int fd, void *buf, size_t len)
+{
+	size_t left = len;
+	char *p = buf;
+
+	while (left) {
+		ssize_t rc;
+
+		assert(left <= len);
+
+		do
+			rc = read(fd, p, left);
+		while ((rc < 0) && errno == EINTR);
+
+		if (rc < 0)
+			return -1;
+
+		if (rc == 0) {
+			errno = ENODATA;
+			return -1;
+		}
+
+		p += rc;
+		left -= rc;
+	}
+	return 0;
+}
+
+/**
+ * write_all_buf() - write all of a buffer to an fd
+ * @fd:		File descriptor
+ * @buf:	Pointer to base of buffer
+ * @len:	Length of buffer
+ *
+ * Return: 0 on success, -1 on error (with errno set)
+ *
+ * #syscalls write
+ */
+int write_all_buf(int fd, const void *buf, size_t len)
+{
+	const char *p = buf;
+	size_t left = len;
+
+	while (left) {
+		ssize_t rc;
+
+		do
+			rc = write(fd, p, left);
+		while ((rc < 0) && errno == EINTR);
+
+		if (rc < 0)
+			return -1;
+
+		p += rc;
+		left -= rc;
+	}
+	return 0;
+}
diff --git a/serialise.h b/serialise.h
new file mode 100644
index 0000000..251c772
--- /dev/null
+++ b/serialise.h
@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later
+ * Copyright Red Hat
+ * Author: David Gibson <david@gibson.dropbear.id.au>
+ */
+
+#ifndef SERIALISE_H
+#define SERIALISE_H
+
+#include <stddef.h>
+
+int read_all_buf(int fd, void *buf, size_t len);
+int write_all_buf(int fd, const void *buf, size_t len);
+
+#endif /* SERIALISE_H */
diff --git a/tcp.c b/tcp.c
index b145862..8ea9be8 100644
--- a/tcp.c
+++ b/tcp.c
@@ -308,6 +308,7 @@
 #include "flow.h"
 #include "repair.h"
 #include "linux_dep.h"
+#include "serialise.h"
 
 #include "flow_table.h"
 #include "tcp_internal.h"
diff --git a/util.c b/util.c
index 22318c0..faa2c6a 100644
--- a/util.c
+++ b/util.c
@@ -37,6 +37,7 @@
 #include "pcap.h"
 #include "epoll_ctl.h"
 #include "pasta.h"
+#include "serialise.h"
 #ifdef HAS_GETRANDOM
 #include <sys/random.h>
 #endif
@@ -800,37 +801,6 @@ int do_clone(int (*fn)(void *), char *stack_area, size_t stack_size, int flags,
 }
 
 /**
- * write_all_buf() - write all of a buffer to an fd
- * @fd:		File descriptor
- * @buf:	Pointer to base of buffer
- * @len:	Length of buffer
- *
- * Return: 0 on success, -1 on error (with errno set)
- *
- * #syscalls write
- */
-int write_all_buf(int fd, const void *buf, size_t len)
-{
-	const char *p = buf;
-	size_t left = len;
-
-	while (left) {
-		ssize_t rc;
-
-		do
-			rc = write(fd, p, left);
-		while ((rc < 0) && errno == EINTR);
-
-		if (rc < 0)
-			return -1;
-
-		p += rc;
-		left -= rc;
-	}
-	return 0;
-}
-
-/**
  * write_remainder() - write the tail of an IO vector to an fd
  * @fd:		File descriptor
  * @iov:	IO vector
@@ -867,44 +837,6 @@ int write_remainder(int fd, const struct iovec *iov, size_t iovcnt, size_t skip)
 }
 
 /**
- * read_all_buf() - Fill a whole buffer from a file descriptor
- * @fd:		File descriptor
- * @buf:	Pointer to base of buffer
- * @len:	Length of buffer
- *
- * Return: 0 on success, -1 on error (with errno set)
- *
- * #syscalls read
- */
-int read_all_buf(int fd, void *buf, size_t len)
-{
-	size_t left = len;
-	char *p = buf;
-
-	while (left) {
-		ssize_t rc;
-
-		assert(left <= len);
-
-		do
-			rc = read(fd, p, left);
-		while ((rc < 0) && errno == EINTR);
-
-		if (rc < 0)
-			return -1;
-
-		if (rc == 0) {
-			errno = ENODATA;
-			return -1;
-		}
-
-		p += rc;
-		left -= rc;
-	}
-	return 0;
-}
-
-/**
  * read_remainder() - Read the tail of an IO vector from a file descriptor
  * @fd:		File descriptor
  * @iov:	IO vector
diff --git a/util.h b/util.h
index 2fc5cd7..cb66910 100644
--- a/util.h
+++ b/util.h
@@ -245,9 +245,7 @@ int fls(unsigned long x);
 int ilog2(unsigned long x);
 int write_file(const char *path, const char *buf);
 intmax_t read_file_integer(const char *path, intmax_t fallback);
-int write_all_buf(int fd, const void *buf, size_t len);
 int write_remainder(int fd, const struct iovec *iov, size_t iovcnt, size_t skip);
-int read_all_buf(int fd, void *buf, size_t len);
 int read_remainder(int fd, const struct iovec *iov, size_t cnt, size_t skip);
 void close_open_files(int argc, char **argv);
 bool snprintf_check(char *str, size_t size, const char *format, ...);