fcgi_close() passes shutdown() a literal 1, which is SHUT_RD in WASI #24229

The quoted description below was written with an LLM (Claude). I reviewed it, and ran the checks it describes myself.

Description

fcgi_close() in main/fastcgi.c half-closes the connection with a literal 1:

if (!force) {
	char buf[8];

	shutdown(req->fd, 1);
	/* read any remaining data, it may be omitted */
	while (recv(req->fd, buf, sizeof(buf), 0) > 0) {}
}
close(req->fd);

1 means SHUT_WR only where SHUT_WR is 1. POSIX names the constants, but does not fix their values. Every platform PHP supports today uses 1, and Windows' SD_SEND is 1 too, so nothing breaks there.

WASI numbers them from 1 instead. wasi-libc's <__header_sys_socket.h> has:

#define SHUT_RD 1
#define SHUT_WR 2
#define SHUT_RDWR (SHUT_RD | SHUT_WR)

So a php-cgi built for wasm32-wasip1 shuts the reading side instead. The drain loop then ends at once, and close() runs while the web server's last FCGI_STDIN record may still be unread. Linux answers that with a reset, which discards the response that php-cgi already sent but the web server had not read yet. The web server sees a broken pipe, or a connection reset, instead of FCGI_END_REQUEST.

I hit this running php-cgi in FastCGI mode (-b) on wazero, a WebAssembly runtime, behind a Go FastCGI client. About 1 in 60 requests failed on Linux. macOS did not show it. With SHUT_WR, 600 requests in a row succeeded.

The fix is to use the constant, as the comment means:

-			shutdown(req->fd, 1);
+			shutdown(req->fd, SHUT_WR);

The _WIN32 branch has the same literal. SD_SEND would be the matching name there, though 1 is correct on Windows.

I know WASI is not a target PHP supports. I am reporting it because the change is one line, it says what the comment already says, and it costs nothing on the supported platforms. I can send a PR if that is welcome.

PHP Version

PHP 8.6.0RC3

The same literal is on master, PHP-8.6, PHP-8.5 and PHP-8.4 as of 2026-10-10.

Operating System

Only with WASI (wasm32-wasip1, built with wasi-sdk 34), here on Linux. Not reproducible on native builds.