From abe187d253e3547ab5dabce9128b973679442baf Mon Sep 17 00:00:00 2001 From: Thomas Munro Date: Mon, 6 Feb 2023 14:54:03 +1300 Subject: [PATCH v3 3/3] Use newer client socket options where available. As a recent commit did for the server side, we can now also try to set client sockets to nonblocking and close-on-exit atomically when creating the socket. This uses flags expected in the next POSIX revision, but already widely available on common platforms. This saves a couple of fcntl() calls, and plugs a tiny window for resource leaks in multi-threaded programs that might fork-and-exec while another thread would otherwise have to run socket() and then fcntl(). Discussion: https://postgr.es/m/CA%2BhUKGKb6FsAdQWcRL35KJsftv%2B9zXqQbzwkfRf1i0J2e57%2BhQ%40mail.gmail.com --- src/interfaces/libpq/fe-connect.c | 23 ++++++++++++++++++++++- 1 file changed, 22 insertions(+), 1 deletion(-) diff --git a/src/interfaces/libpq/fe-connect.c b/src/interfaces/libpq/fe-connect.c index 50b5df3490..953abc640f 100644 --- a/src/interfaces/libpq/fe-connect.c +++ b/src/interfaces/libpq/fe-connect.c @@ -2464,6 +2464,7 @@ keep_going: /* We will come back to here until there is { struct addrinfo *addr_cur = conn->addr_cur; char host_addr[NI_MAXHOST]; + int sock_type; /* * Advance to next possible host, if we've tried all of @@ -2494,7 +2495,23 @@ keep_going: /* We will come back to here until there is conn->connip = strdup(host_addr); /* Try to create the socket */ - conn->sock = socket(addr_cur->ai_family, SOCK_STREAM, 0); + sock_type = SOCK_STREAM; +#ifdef SOCK_CLOEXEC + /* + * Atomically mark close-on-exec, if possible on this + * platform, for the benefit of multi-threaded programs. + * Otherwise see below. + */ + sock_type |= SOCK_CLOEXEC; +#endif +#ifdef SOCK_NONBLOCK + /* + * We might as well skip a system call for nonblocking + * mode too, if we can. + */ + sock_type |= SOCK_NONBLOCK; +#endif + conn->sock = socket(addr_cur->ai_family, sock_type, 0); if (conn->sock == PGINVALID_SOCKET) { int errorno = SOCK_ERRNO; @@ -2540,6 +2557,7 @@ keep_going: /* We will come back to here until there is goto keep_going; } } +#ifndef SOCK_NONBLOCK if (!pg_set_noblock(conn->sock)) { libpq_append_conn_error(conn, "could not set socket to nonblocking mode: %s", @@ -2547,7 +2565,9 @@ keep_going: /* We will come back to here until there is conn->try_next_addr = true; goto keep_going; } +#endif +#ifndef SOCK_CLOEXEC #ifdef F_SETFD if (fcntl(conn->sock, F_SETFD, FD_CLOEXEC) == -1) { @@ -2557,6 +2577,7 @@ keep_going: /* We will come back to here until there is goto keep_going; } #endif /* F_SETFD */ +#endif if (addr_cur->ai_family != AF_UNIX) { -- 2.39.1