From 701a9b33fd43f5a2adc773e95b72e12d7ab6e8a7 Mon Sep 17 00:00:00 2001
From: Runxi Yu <me@runxiyu.org>
Date: Sat, 29 Mar 2025 21:15:24 +0800
Subject: [PATCH] Attempt to make hookc.c portable

---
 hookc/hookc.c | 63 ++++++++++++++++++++++++++++++++++++++++++++++++-----

diff --git a/hookc/hookc.c b/hookc/hookc.c
index 9921edf5912f486ada0bc69890a7fcb60776395e..14acc0100093efb311fced22005eecc4e99a39a8 100644
--- a/hookc/hookc.c
+++ b/hookc/hookc.c
@@ -15,11 +15,13 @@ #include <sys/stat.h>
 #include <string.h>
 #include <fcntl.h>
 #include <signal.h>
-
-/*
- * FIXME: splice(2) is not portable and will only work on Linux. Alternative
- * implementations should be supplied for other environments.
- */
+#ifdef __linux__
+#include <linux/limits.h>
+#include <sys/sendfile.h>
+#define USE_SPLICE 1
+#else
+#define USE_SPLICE 0
+#endif
 
 int main(int argc, char *argv[]) {
 	if (signal(SIGPIPE, SIG_IGN) == SIG_ERR) {
@@ -56,11 +58,20 @@ 	if (!S_ISFIFO(stdin_stat.st_mode)) {
 		dprintf(STDERR_FILENO, "stdin must be a pipe\n");
 		return EXIT_FAILURE;
 	}
+	#if USE_SPLICE
 	int stdin_pipe_size = fcntl(STDIN_FILENO, F_GETPIPE_SZ);
 	if (stdin_pipe_size == -1) {
 		perror("fcntl on stdin");
 		return EXIT_FAILURE;
 	}
+#else
+	int stdin_pipe_size = 65536;
+#endif
+
+	if (stdin_pipe_size == -1) {
+		perror("fcntl on stdin");
+		return EXIT_FAILURE;
+	}
 
 	/*
 	 * Same for stderr.
@@ -74,7 +85,15 @@ 	if (!S_ISFIFO(stderr_stat.st_mode)) {
 		dprintf(STDERR_FILENO, "stderr must be a pipe\n");
 		return EXIT_FAILURE;
 	}
+#if USE_SPLICE
 	int stderr_pipe_size = fcntl(STDERR_FILENO, F_GETPIPE_SZ);
+	if (stderr_pipe_size == -1) {
+		perror("fcntl on stderr");
+		return EXIT_FAILURE;
+	}
+#else
+	int stderr_pipe_size = 65536;
+#endif
 	if (stderr_pipe_size == -1) {
 		perror("fcntl on stderr");
 		return EXIT_FAILURE;
@@ -182,6 +201,7 @@ 	/*
 	 * Splice stdin to the daemon. For pre-receive it's just old/new/ref.
 	 */
 	ssize_t stdin_bytes_spliced;
+#if USE_SPLICE
 	while ((stdin_bytes_spliced = splice(STDIN_FILENO, NULL, sock, NULL, stdin_pipe_size, SPLICE_F_MORE)) > 0) {
 	}
 	if (stdin_bytes_spliced == -1) {
@@ -189,6 +209,22 @@ 		perror("splice stdin to internal socket");
 		close(sock);
 		return EXIT_FAILURE;
 	}
+#else
+	char buf[65536];
+	ssize_t n;
+	while ((n = read(STDIN_FILENO, buf, sizeof(buf))) > 0) {
+		if (write(sock, buf, n) != n) {
+			perror("write to internal socket");
+			close(sock);
+			return EXIT_FAILURE;
+		}
+	}
+	if (n < 0) {
+		perror("read from stdin");
+		close(sock);
+		return EXIT_FAILURE;
+	}
+#endif
 
 	/*
 	 * The sending part of the UNIX socket should be shut down, to let
@@ -237,13 +273,28 @@ 	 * We usually don't actually use this as the daemon could easily write
 	 * to the SSH connection's stderr directly anyway.
 	 */
 	ssize_t stderr_bytes_spliced;
+#if USE_SPLICE
 	while ((stderr_bytes_spliced = splice(sock, NULL, STDERR_FILENO, NULL, stderr_pipe_size, SPLICE_F_MORE)) > 0) {
 	}
-	if (stdin_bytes_spliced == -1 && errno != ECONNRESET) {
+	if (stderr_bytes_spliced == -1 && errno != ECONNRESET) {
 		perror("splice internal socket to stderr");
 		close(sock);
 		return EXIT_FAILURE;
 	}
+#else
+	while ((n = read(sock, buf, sizeof(buf))) > 0) {
+		if (write(STDERR_FILENO, buf, n) != n) {
+			perror("write to stderr");
+			close(sock);
+			return EXIT_FAILURE;
+		}
+	}
+	if (n < 0 && errno != ECONNRESET) {
+		perror("read from internal socket");
+		close(sock);
+		return EXIT_FAILURE;
+	}
+#endif
 
 	close(sock);
 	return *status_buf;

-- 
2.48.1