io + socket: make pipes and sockets nonblocking by default

All normal Ruby IO methods (IO#read, IO#gets, IO#write, ...) are
all capable of appearing to be "blocking" when presented with a
file description with the O_NONBLOCK flag set; so there is
little risk of incompatibility within Ruby-using programs.

The biggest compatibility risk is when spawning external
programs.  As a result, stdin, stdout, and stderr are now always
made blocking before exec-family calls.

This change will make an event-oriented MJIT usable if it is
waiting on pipes on POSIX_like platforms.

It is ALSO necessary to take advantage of (proposed lightweight
concurrency (aka "auto-Fiber") or any similar proposal for
network concurrency: https://bugs.ruby-lang.org/issues/13618

Named-pipe (FIFO) are NOT yet non-blocking by default since
they are rarely-used and may introduce compatibility problems
and extra syscall overhead for a common path.

Please revert this commit if there are problems and if I am afk
since I am afk a lot, lately.

[ruby-core:89950] [Bug #14968]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@65922 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

3 files changed, 16 insertions, 8 deletions

diff --git a/ext/socket/init.c b/ext/socket/init.c
index 157d6706a6..24b9b00e15 100644
--- a/ext/socket/init.c
+++ b/ext/socket/init.c
@@ -435,7 +435,7 @@ rsock_socket0(int domain, int type, int proto)
     static int cloexec_state = -1; /* <0: unknown, 0: ignored, >0: working */
 
     if (cloexec_state > 0) { /* common path, if SOCK_CLOEXEC is defined */
-        ret = socket(domain, type|SOCK_CLOEXEC, proto);
+        ret = socket(domain, type|SOCK_CLOEXEC|SOCK_NONBLOCK, proto);
         if (ret >= 0) {
             if (ret <= 2)
                 goto fix_cloexec;
@@ -443,7 +443,7 @@ rsock_socket0(int domain, int type, int proto)
         }
     }
     else if (cloexec_state < 0) { /* usually runs once only for detection */
-        ret = socket(domain, type|SOCK_CLOEXEC, proto);
+        ret = socket(domain, type|SOCK_CLOEXEC|SOCK_NONBLOCK, proto);
         if (ret >= 0) {
             cloexec_state = rsock_detect_cloexec(ret);
             if (cloexec_state == 0 || ret <= 2)
@@ -466,6 +466,7 @@ rsock_socket0(int domain, int type, int proto)
         return -1;
 fix_cloexec:
     rb_maygvl_fd_fix_cloexec(ret);
+    rsock_make_fd_nonblock(ret);
 update_max_fd:
     rb_update_max_fd(ret);
 
@@ -632,8 +633,8 @@ rsock_connect(int fd, const struct sockaddr *sockaddr, int len, int socks)
     return status;
 }
 
-static void
-make_fd_nonblock(int fd)
+void
+rsock_make_fd_nonblock(int fd)
 {
     int flags;
 #ifdef F_GETFL
@@ -659,6 +660,7 @@ cloexec_accept(int socket, struct sockaddr *address, socklen_t *address_len,
 #ifdef HAVE_ACCEPT4
     static int try_accept4 = 1;
 #endif
+    nonblock = 1; /* TODO remove parameter */
     if (address_len) len0 = *address_len;
 #ifdef HAVE_ACCEPT4
     if (try_accept4) {
@@ -678,7 +680,7 @@ cloexec_accept(int socket, struct sockaddr *address, socklen_t *address_len,
                 rb_maygvl_fd_fix_cloexec(ret);
 #ifndef SOCK_NONBLOCK
             if (nonblock) {
-                make_fd_nonblock(ret);
+                rsock_make_fd_nonblock(ret);
             }
 #endif
             if (address_len && len0 < *address_len) *address_len = len0;
@@ -695,7 +697,7 @@ cloexec_accept(int socket, struct sockaddr *address, socklen_t *address_len,
     if (address_len && len0 < *address_len) *address_len = len0;
     rb_maygvl_fd_fix_cloexec(ret);
     if (nonblock) {
-        make_fd_nonblock(ret);
+        rsock_make_fd_nonblock(ret);
     }
     return ret;
 }
diff --git a/ext/socket/rubysocket.h b/ext/socket/rubysocket.h
index 88143bfe0e..bccea8732f 100644
--- a/ext/socket/rubysocket.h
+++ b/ext/socket/rubysocket.h
@@ -433,6 +433,8 @@ static inline void rsock_maybe_wait_fd(int fd) { }
 VALUE rsock_read_nonblock(VALUE sock, VALUE length, VALUE buf, VALUE ex);
 VALUE rsock_write_nonblock(VALUE sock, VALUE buf, VALUE ex);
 
+void rsock_make_fd_nonblock(int fd);
+
 #if !defined HAVE_INET_NTOP && ! defined _WIN32
 const char *inet_ntop(int, const void *, char *, size_t);
 #elif defined __MINGW32__
diff --git a/ext/socket/socket.c b/ext/socket/socket.c
index ead3592d8a..ad2ca5fc67 100644
--- a/ext/socket/socket.c
+++ b/ext/socket/socket.c
@@ -177,14 +177,14 @@ rsock_socketpair0(int domain, int type, int protocol, int sv[2])
     static int cloexec_state = -1; /* <0: unknown, 0: ignored, >0: working */
 
     if (cloexec_state > 0) { /* common path, if SOCK_CLOEXEC is defined */
-        ret = socketpair(domain, type|SOCK_CLOEXEC, protocol, sv);
+        ret = socketpair(domain, type|SOCK_CLOEXEC|SOCK_NONBLOCK, protocol, sv);
         if (ret == 0 && (sv[0] <= 2 || sv[1] <= 2)) {
             goto fix_cloexec; /* highly unlikely */
         }
         goto update_max_fd;
     }
     else if (cloexec_state < 0) { /* usually runs once only for detection */
-        ret = socketpair(domain, type|SOCK_CLOEXEC, protocol, sv);
+        ret = socketpair(domain, type|SOCK_CLOEXEC|SOCK_NONBLOCK, protocol, sv);
         if (ret == 0) {
             cloexec_state = rsock_detect_cloexec(sv[0]);
             if ((cloexec_state == 0) || (sv[0] <= 2 || sv[1] <= 2))
@@ -213,6 +213,8 @@ rsock_socketpair0(int domain, int type, int protocol, int sv[2])
 fix_cloexec:
     rb_maygvl_fd_fix_cloexec(sv[0]);
     rb_maygvl_fd_fix_cloexec(sv[1]);
+    rsock_make_fd_nonblock(sv[0]);
+    rsock_make_fd_nonblock(sv[1]);
 
 update_max_fd:
     rb_update_max_fd(sv[0]);
@@ -231,6 +233,8 @@ rsock_socketpair0(int domain, int type, int protocol, int sv[2])
 
     rb_fd_fix_cloexec(sv[0]);
     rb_fd_fix_cloexec(sv[1]);
+    rsock_make_fd_nonblock(sv[0]);
+    rsock_make_fd_nonblock(sv[1]);
     return ret;
 }
 #endif /* !SOCK_CLOEXEC */