Update libc crate to 0.2.55

This change updates the libc crate to version 0.2.55.

Import subrepo libc/:libc at caf17a0641d29dc624621177f5756804dd180c13

1 files changed, 28 insertions, 0 deletions

diff --git a/libc/libc-test/src/cmsg.c b/libc/libc-test/src/cmsg.c
new file mode 100644
index 0000000..a8b1c37
--- /dev/null
+++ b/libc/libc-test/src/cmsg.c
@@ -0,0 +1,28 @@
+#include <sys/param.h>
+#include <sys/socket.h>
+
+// Since the cmsg(3) macros are macros instead of functions, they aren't
+// available to FFI.  libc must reimplement them, which is error-prone.  This
+// file provides FFI access to the actual macros so they can be tested against
+// the Rust reimplementations.
+
+struct cmsghdr *cmsg_firsthdr(struct msghdr *msgh) {
+	return CMSG_FIRSTHDR(msgh);
+}
+
+struct cmsghdr *cmsg_nxthdr(struct msghdr *msgh, struct cmsghdr *cmsg) {
+	return CMSG_NXTHDR(msgh, cmsg);
+}
+
+size_t cmsg_space(size_t length) {
+	return CMSG_SPACE(length);
+}
+
+size_t cmsg_len(size_t length) {
+	return CMSG_LEN(length);
+}
+
+unsigned char *cmsg_data(struct cmsghdr *cmsg) {
+	return CMSG_DATA(cmsg);
+}
+