git_connect: clarify conn->use_shell flag

When executing user-specified programs, we generally always
want to use a shell, for flexibility and consistency. One
big exception is executing $GIT_SSH, which for historical
reasons must not use a shell.

Once upon a time the logic in git_connect looked like:

  if (protocol == PROTO_SSH) {
	  ... setup ssh ...
  } else {
	  ... setup local connection ...
	  conn->use_shell = 1;
  }

But over time the PROTO_SSH block has grown, and the "local"
block has shrunk so that it contains only conn->use_shell;
it's easy to miss at the end of the large block.  Moreover,
PROTO_SSH now also sometimes sets use_shell, when the new
GIT_SSH_COMMAND is used.

Let's just set conn->use_shell when we're setting up the "conn"
struct, and unset it (with a comment) in the historical GIT_SSH
case.  This will make the flow easier to follow.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/connect.c b/connect.c
index 962f990..acd39d7 100644 (file)
--- a/connect.c
+++ b/connect.c
@@ -723,10 +723,11 @@ struct child_process *git_connect(int fd[2], const char *url,
 
                /* remove repo-local variables from the environment */
                conn->env = local_repo_env;
+               conn->use_shell = 1;
                conn->in = conn->out = -1;
                if (protocol == PROTO_SSH) {
                        const char *ssh;
-                       int putty, tortoiseplink = 0;
+                       int putty = 0, tortoiseplink = 0;
                        char *ssh_host = hostandport;
                        const char *port = NULL;
                        get_host_and_port(&ssh_host, &port);
@@ -748,13 +749,17 @@ struct child_process *git_connect(int fd[2], const char *url,
                        }
 
                        ssh = getenv("GIT_SSH_COMMAND");
-                       if (ssh) {
-                               conn->use_shell = 1;
-                               putty = 0;
-                       } else {
+                       if (!ssh) {
                                const char *base;
                                char *ssh_dup;
 
+                               /*
+                                * GIT_SSH is the no-shell version of
+                                * GIT_SSH_COMMAND (and must remain so for
+                                * historical compatibility).
+                                */
+                               conn->use_shell = 0;
+
                                ssh = getenv("GIT_SSH");
                                if (!ssh)
                                        ssh = "ssh";
@@ -764,8 +769,9 @@ struct child_process *git_connect(int fd[2], const char *url,
 
                                tortoiseplink = !strcasecmp(base, "tortoiseplink") ||
                                        !strcasecmp(base, "tortoiseplink.exe");
-                               putty = !strcasecmp(base, "plink") ||
-                                       !strcasecmp(base, "plink.exe") || tortoiseplink;
+                               putty = tortoiseplink ||
+                                       !strcasecmp(base, "plink") ||
+                                       !strcasecmp(base, "plink.exe");
 
                                free(ssh_dup);
                        }
@@ -779,8 +785,6 @@ struct child_process *git_connect(int fd[2], const char *url,
                                argv_array_push(&conn->args, port);
                        }
                        argv_array_push(&conn->args, ssh_host);
-               } else {
-                       conn->use_shell = 1;
                }
                argv_array_push(&conn->args, cmd.buf);