[PATCH 01/24] iov: add some functions to manage iovec

[Laurent Vivier <lvivier@redhat.com>]

Signed-off-by: Laurent Vivier <lvivier@redhat.com>
---
 Makefile |  4 +--
 iov.c    | 78 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 iov.h    | 46 +++++++++++++++++++++++++++++++++
 3 files changed, 126 insertions(+), 2 deletions(-)
 create mode 100644 iov.c
 create mode 100644 iov.h

diff --git a/Makefile b/Makefile
index af4fa87e7e13..c1138fb91d26 100644
--- a/Makefile
+++ b/Makefile
@@ -47,7 +47,7 @@ FLAGS += -DDUAL_STACK_SOCKETS=$(DUAL_STACK_SOCKETS)
 PASST_SRCS = arch.c arp.c checksum.c conf.c dhcp.c dhcpv6.c flow.c icmp.c \
 	igmp.c isolation.c lineread.c log.c mld.c ndp.c netlink.c packet.c \
 	passt.c pasta.c pcap.c pif.c port_fwd.c tap.c tcp.c tcp_splice.c udp.c \
-	util.c
+	util.c iov.c
 QRAP_SRCS = qrap.c
 SRCS = $(PASST_SRCS) $(QRAP_SRCS)
 
@@ -56,7 +56,7 @@ MANPAGES = passt.1 pasta.1 qrap.1
 PASST_HEADERS = arch.h arp.h checksum.h conf.h dhcp.h dhcpv6.h flow.h \
 	flow_table.h icmp.h inany.h isolation.h lineread.h log.h ndp.h \
 	netlink.h packet.h passt.h pasta.h pcap.h pif.h port_fwd.h siphash.h \
-	tap.h tcp.h tcp_conn.h tcp_splice.h udp.h util.h
+	tap.h tcp.h tcp_conn.h tcp_splice.h udp.h util.h iov.h
 HEADERS = $(PASST_HEADERS) seccomp.h
 
 C := \#include <linux/tcp.h>\nstruct tcp_info x = { .tcpi_snd_wnd = 0 };
diff --git a/iov.c b/iov.c
new file mode 100644
index 000000000000..38a8e7566021
--- /dev/null
+++ b/iov.c
@@ -0,0 +1,78 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+/* some parts copied from QEMU util/iov.c */
+
+#include <sys/socket.h>
+#include "util.h"
+#include "iov.h"
+
+size_t iov_from_buf_full(const struct iovec *iov, unsigned int iov_cnt,
+			 size_t offset, const void *buf, size_t bytes)
+{
+	size_t done;
+	unsigned int i;
+	for (i = 0, done = 0; (offset || done < bytes) && i < iov_cnt; i++) {
+		if (offset < iov[i].iov_len) {
+			size_t len = MIN(iov[i].iov_len - offset, bytes - done);
+			memcpy((char *)iov[i].iov_base + offset, (char *)buf + done, len);
+			done += len;
+			offset = 0;
+		} else {
+			offset -= iov[i].iov_len;
+		}
+	}
+	return done;
+}
+
+size_t iov_to_buf_full(const struct iovec *iov, const unsigned int iov_cnt,
+		       size_t offset, void *buf, size_t bytes)
+{
+	size_t done;
+	unsigned int i;
+	for (i = 0, done = 0; (offset || done < bytes) && i < iov_cnt; i++) {
+		if (offset < iov[i].iov_len) {
+			size_t len = MIN(iov[i].iov_len - offset, bytes - done);
+			memcpy((char *)buf + done, (char *)iov[i].iov_base + offset, len);
+			done += len;
+			offset = 0;
+		} else {
+			offset -= iov[i].iov_len;
+		}
+	}
+	return done;
+}
+
+size_t iov_size(const struct iovec *iov, const unsigned int iov_cnt)
+{
+	size_t len;
+	unsigned int i;
+
+	len = 0;
+	for (i = 0; i < iov_cnt; i++) {
+		len += iov[i].iov_len;
+	}
+	return len;
+}
+
+unsigned iov_copy(struct iovec *dst_iov, unsigned int dst_iov_cnt,
+		  const struct iovec *iov, unsigned int iov_cnt,
+		  size_t offset, size_t bytes)
+{
+	size_t len;
+	unsigned int i, j;
+	for (i = 0, j = 0;
+		 i < iov_cnt && j < dst_iov_cnt && (offset || bytes); i++) {
+		if (offset >= iov[i].iov_len) {
+			offset -= iov[i].iov_len;
+			continue;
+		}
+		len = MIN(bytes, iov[i].iov_len - offset);
+
+		dst_iov[j].iov_base = (char *)iov[i].iov_base + offset;
+		dst_iov[j].iov_len = len;
+		j++;
+		bytes -= len;
+		offset = 0;
+	}
+	return j;
+}
diff --git a/iov.h b/iov.h
new file mode 100644
index 000000000000..31fbf6d0e1cf
--- /dev/null
+++ b/iov.h
@@ -0,0 +1,46 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+/* some parts copied from QEMU include/qemu/iov.h */
+
+#ifndef IOVEC_H
+#define IOVEC_H
+
+#include <unistd.h>
+#include <string.h>
+
+size_t iov_from_buf_full(const struct iovec *iov, unsigned int iov_cnt,
+			 size_t offset, const void *buf, size_t bytes);
+size_t iov_to_buf_full(const struct iovec *iov, const unsigned int iov_cnt,
+		       size_t offset, void *buf, size_t bytes);
+
+static inline size_t iov_from_buf(const struct iovec *iov,
+				  unsigned int iov_cnt, size_t offset,
+				  const void *buf, size_t bytes)
+{
+	if (__builtin_constant_p(bytes) && iov_cnt &&
+		offset <= iov[0].iov_len && bytes <= iov[0].iov_len - offset) {
+		memcpy((char *)iov[0].iov_base + offset, buf, bytes);
+		return bytes;
+	} else {
+		return iov_from_buf_full(iov, iov_cnt, offset, buf, bytes);
+	}
+}
+
+static inline size_t iov_to_buf(const struct iovec *iov,
+				const unsigned int iov_cnt, size_t offset,
+				void *buf, size_t bytes)
+{
+	if (__builtin_constant_p(bytes) && iov_cnt &&
+		offset <= iov[0].iov_len && bytes <= iov[0].iov_len - offset) {
+		memcpy(buf, (char *)iov[0].iov_base + offset, bytes);
+		return bytes;
+	} else {
+		return iov_to_buf_full(iov, iov_cnt, offset, buf, bytes);
+	}
+}
+
+size_t iov_size(const struct iovec *iov, const unsigned int iov_cnt);
+unsigned iov_copy(struct iovec *dst_iov, unsigned int dst_iov_cnt,
+		  const struct iovec *iov, unsigned int iov_cnt,
+		  size_t offset, size_t bytes);
+#endif
-- 
@@ -0,0 +1,46 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+/* some parts copied from QEMU include/qemu/iov.h */
+
+#ifndef IOVEC_H
+#define IOVEC_H
+
+#include <unistd.h>
+#include <string.h>
+
+size_t iov_from_buf_full(const struct iovec *iov, unsigned int iov_cnt,
+			 size_t offset, const void *buf, size_t bytes);
+size_t iov_to_buf_full(const struct iovec *iov, const unsigned int iov_cnt,
+		       size_t offset, void *buf, size_t bytes);
+
+static inline size_t iov_from_buf(const struct iovec *iov,
+				  unsigned int iov_cnt, size_t offset,
+				  const void *buf, size_t bytes)
+{
+	if (__builtin_constant_p(bytes) && iov_cnt &&
+		offset <= iov[0].iov_len && bytes <= iov[0].iov_len - offset) {
+		memcpy((char *)iov[0].iov_base + offset, buf, bytes);
+		return bytes;
+	} else {
+		return iov_from_buf_full(iov, iov_cnt, offset, buf, bytes);
+	}
+}
+
+static inline size_t iov_to_buf(const struct iovec *iov,
+				const unsigned int iov_cnt, size_t offset,
+				void *buf, size_t bytes)
+{
+	if (__builtin_constant_p(bytes) && iov_cnt &&
+		offset <= iov[0].iov_len && bytes <= iov[0].iov_len - offset) {
+		memcpy(buf, (char *)iov[0].iov_base + offset, bytes);
+		return bytes;
+	} else {
+		return iov_to_buf_full(iov, iov_cnt, offset, buf, bytes);
+	}
+}
+
+size_t iov_size(const struct iovec *iov, const unsigned int iov_cnt);
+unsigned iov_copy(struct iovec *dst_iov, unsigned int dst_iov_cnt,
+		  const struct iovec *iov, unsigned int iov_cnt,
+		  size_t offset, size_t bytes);
+#endif
-- 
2.42.0