Re: [PATCH 1/5] connect: split git:// setup into a separate function

Jonathan Nieder [off-list ref] writes:

The git_connect function is growing long.  Split the
PROTO_GIT-specific portion to a separate function to make it easier to
read.

No functional change intended.

Signed-off-by: Jonathan Nieder <redacted>
Reviewed-by: Stefan Beller <redacted>
---
As before, except with sbeller's Reviewed-by.

I found this quite nice, except for one thing.

+/*
+ * Open a connection using Git's native protocol.
+ *
+ * The caller is responsible for freeing hostandport, but this function may
+ * modify it (for example, to truncate it to remove the port part).
+ */
+static struct child_process *git_connect_git(int fd[2], char *hostandport,
+					     const char *path, const char *prog,
+					     int flags)
+{
+	struct child_process *conn = &no_fork;
+	struct strbuf request = STRBUF_INIT;

As this one decides what "conn" to return, including the fallback
&no_fork instance,...

Each of the if/elseif/ cascade, one of which calls the new helper,
now makes an explicit assignment to "conn" declared in
git_connect().

Which means the defaulting of git_connect::conn to &no_fork is now
unneeded.  One of the things that made the original cascade a bit
harder to follow than necessary, aside from the physical length of
the PROTO_GIT part, was that the case where conn remains to point at
no_fork looked very special and it was buried in that long PROTO_GIT
part.  Now the main source of that issue is fixed, it would make it
clear to leave conn uninitialized (or initialize to NULL---but leaving
it uninitialized would make the intention of the code more clear, I
would think, that each of the if/elseif/ cascade must assign to it).

 		printf("Diag: path=%s\n", path ? path : "NULL");
 		conn = NULL;
 	} else if (protocol == PROTO_GIT) {
-		struct strbuf request = STRBUF_INIT;
-...
+		conn = git_connect_git(fd, hostandport, path, prog, flags);
 	} else {
 		struct strbuf cmd = STRBUF_INIT;
 		const char *const *var;

Hi,

On Oct 24, 2017, Junio C Hamano wrote:

Jonathan Nieder [off-list ref] writes:

quoted

+static struct child_process *git_connect_git(int fd[2], char *hostandport,
+					     const char *path, const char *prog,
+					     int flags)
+{
+	struct child_process *conn = &no_fork;
+	struct strbuf request = STRBUF_INIT;

As this one decides what "conn" to return, including the fallback
&no_fork instance,...

quoted

+	...
+	return conn;
+}
+
 /*
  * This returns a dummy child_process if the transport protocol does not
  * need fork(2), or a struct child_process object if it does.  Once done,

@@ -881,50 +939,7 @@ struct child_process *git_connect(int fd[2], const char *url,

Each of the if/elseif/ cascade, one of which calls the new helper,
now makes an explicit assignment to "conn" declared in
git_connect().

Which means the defaulting of git_connect::conn to &no_fork is now
unneeded.  One of the things that made the original cascade a bit
harder to follow than necessary, aside from the physical length of
the PROTO_GIT part, was that the case where conn remains to point at
no_fork looked very special and it was buried in that long PROTO_GIT
part.

Good idea.  Here's what I'll include in the reroll.

-- >8 --
Subject: connect: move no_fork fallback to git_tcp_connect

git_connect has the structure

	struct child_process *conn = &no_fork;

	...
	switch (protocol) {
	case PROTO_GIT:
		if (git_use_proxy(hostandport))
			conn = git_proxy_connect(fd, hostandport);
		else
			git_tcp_connect(fd, hostandport, flags);
		...
		break;
	case PROTO_SSH:
		conn = xmalloc(sizeof(*conn));
		child_process_init(conn);
		argv_array_push(&conn->args, ssh);
		...
		break;
	...
	return conn;

In all cases except the git_tcp_connect case, conn is explicitly
assigned a value. Make the code clearer by explicitly assigning
'conn = &no_fork' in the tcp case and eliminating the default so the
compiler can ensure conn is always correctly assigned.

Noticed-by: Junio C Hamano [off-list ref]
Signed-off-by: Jonathan Nieder <redacted>
---
 connect.c | 22 ++++++++++++----------
 1 file changed, 12 insertions(+), 10 deletions(-)

diff --git a/connect.c b/connect.c
index 7fbd396b35..b6accf71cb 100644
--- a/connect.c
+++ b/connect.c

@@ -582,12 +582,21 @@ static int git_tcp_connect_sock(char *host, int flags)
 #endif /* NO_IPV6 */
 
 
-static void git_tcp_connect(int fd[2], char *host, int flags)
+static struct child_process no_fork = CHILD_PROCESS_INIT;
+
+int git_connection_is_socket(struct child_process *conn)
+{
+	return conn == &no_fork;
+}
+
+static struct child_process *git_tcp_connect(int fd[2], char *host, int flags)
 {
 	int sockfd = git_tcp_connect_sock(host, flags);
 
 	fd[0] = sockfd;
 	fd[1] = dup(sockfd);
+
+	return &no_fork;
 }
 
 

@@ -761,8 +770,6 @@ static enum protocol parse_connect_url(const char *url_orig, char **ret_host,
 	return protocol;
 }
 
-static struct child_process no_fork = CHILD_PROCESS_INIT;
-
 static const char *get_ssh_command(void)
 {
 	const char *ssh;

@@ -865,7 +872,7 @@ struct child_process *git_connect(int fd[2], const char *url,
 				  const char *prog, int flags)
 {
 	char *hostandport, *path;
-	struct child_process *conn = &no_fork;
+	struct child_process *conn;
 	enum protocol protocol;
 
 	/* Without this we cannot rely on waitpid() to tell

@@ -901,7 +908,7 @@ struct child_process *git_connect(int fd[2], const char *url,
 		if (git_use_proxy(hostandport))
 			conn = git_proxy_connect(fd, hostandport);
 		else
-			git_tcp_connect(fd, hostandport, flags);
+			conn = git_tcp_connect(fd, hostandport, flags);
 		/*
 		 * Separate original protocol components prog and path
 		 * from extended host header with a NUL byte.

@@ -1041,11 +1048,6 @@ struct child_process *git_connect(int fd[2], const char *url,
 	return conn;
 }
 
-int git_connection_is_socket(struct child_process *conn)
-{
-	return conn == &no_fork;
-}
-
 int finish_connect(struct child_process *conn)
 {
 	int code;

-- 
2.15.0.448.gf294e3d99a