git_connect: use argv_array

This avoids magic numbers when we allocate fixed-size argv
arrays, and makes it more obvious that we are not
overflowing.

It is also the first step to fixing a memory leak. When
git_connect returns a child_process struct, the argv array
in the struct is dynamically allocated, but the individual
strings are not (they are either owned elsewhere, or are
freed). Later, in finish_connect, we free the array but
leave the strings alone.

This works for the child_process created by git_connect, but
if we use transport_take_over, we may also end up with a
child_process created by transport-helper's get_helper.
In that case, the strings are freshly allocated, and we
would want to free them.  However, we have no idea in
finish_connect which type we have.

By consistently using run-command's internal argv-array, we
do not have to worry about this issue at all; finish_command
takes care of it for us, and we can drop our manual free
entirely.

Note that this actually makes the get_helper leak slightly
worse; now we are leaking both the strings and the array.
But when we adjust it in a future patch, that leak will go
away entirely.

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 a983d061a90f0b720afa1a9b50247da299164d79..94a66502464400d5dfc47a4151cc2fd01780a0a4 100644 (file)
--- a/connect.c
+++ b/connect.c
@@ -534,22 +534,18 @@ static int git_use_proxy(const char *host)
 static struct child_process *git_proxy_connect(int fd[2], char *host)
 {
        const char *port = STR(DEFAULT_GIT_PORT);
-       const char **argv;
        struct child_process *proxy;
 
        get_host_and_port(&host, &port);
 
-       argv = xmalloc(sizeof(*argv) * 4);
-       argv[0] = git_proxy_command;
-       argv[1] = host;
-       argv[2] = port;
-       argv[3] = NULL;
        proxy = xcalloc(1, sizeof(*proxy));
-       proxy->argv = argv;
+       argv_array_push(&proxy->args, git_proxy_command);
+       argv_array_push(&proxy->args, host);
+       argv_array_push(&proxy->args, port);
        proxy->in = -1;
        proxy->out = -1;
        if (start_command(proxy))
-               die("cannot start proxy %s", argv[0]);
+               die("cannot start proxy %s", git_proxy_command);
        fd[0] = proxy->out; /* read from proxy stdout */
        fd[1] = proxy->in;  /* write to proxy stdin */
        return proxy;
@@ -663,7 +659,6 @@ struct child_process *git_connect(int fd[2], const char *url,
        char *hostandport, *path;
        struct child_process *conn = &no_fork;
        enum protocol protocol;
-       const char **arg;
        struct strbuf cmd = STRBUF_INIT;
 
        /* Without this we cannot rely on waitpid() to tell
@@ -707,7 +702,6 @@ struct child_process *git_connect(int fd[2], const char *url,
                sq_quote_buf(&cmd, path);
 
                conn->in = conn->out = -1;
-               conn->argv = arg = xcalloc(7, sizeof(*arg));
                if (protocol == PROTO_SSH) {
                        const char *ssh = getenv("GIT_SSH");
                        int putty = ssh && strcasestr(ssh, "plink");
@@ -718,22 +712,21 @@ struct child_process *git_connect(int fd[2], const char *url,
 
                        if (!ssh) ssh = "ssh";
 
-                       *arg++ = ssh;
+                       argv_array_push(&conn->args, ssh);
                        if (putty && !strcasestr(ssh, "tortoiseplink"))
-                               *arg++ = "-batch";
+                               argv_array_push(&conn->args, "-batch");
                        if (port) {
                                /* P is for PuTTY, p is for OpenSSH */
-                               *arg++ = putty ? "-P" : "-p";
-                               *arg++ = port;
+                               argv_array_push(&conn->args, putty ? "-P" : "-p");
+                               argv_array_push(&conn->args, port);
                        }
-                       *arg++ = ssh_host;
+                       argv_array_push(&conn->args, ssh_host);
                } else {
                        /* remove repo-local variables from the environment */
                        conn->env = local_repo_env;
                        conn->use_shell = 1;
                }
-               *arg++ = cmd.buf;
-               *arg = NULL;
+               argv_array_push(&conn->args, cmd.buf);
 
                if (start_command(conn))
                        die("unable to fork");
@@ -759,7 +752,6 @@ int finish_connect(struct child_process *conn)
                return 0;
 
        code = finish_command(conn);
-       free(conn->argv);
        free(conn);
        return code;
 }