[PATCH 2/3] connect: let callers know if connection is a socket

They might care because they want to do a half-duplex close. With pipes, that means simply closing the output descriptor; with a socket, you must actually call shutdown.

Instead of exposing the magic no_fork child_process struct, let's encapsulate the test in a function.

Signed-off-by: Jeff King <peff@peff.net>
---
An more object-oriented refactoring would be something like:

  struct git_connection {
    struct child_process child;
    int in;
    int out;
  };

  void git_connection_read_fd(struct git_connection *c)
  {
          return c->in;
  }

  void git_connect_write_fd(struct git_connect *c)
  {
          return c->child.pid ? c->out : c->in;
  }

  void git_connection_half_duplex_close(struct git_connection *c)
  {
          if (!c->child.pid)
                  shutdown(c->in, SHUT_WR);
          else
                  close(c->out);
  }

but the idea that a git connection is defined by two file descriptors runs throughout the code (in fact, we don't even explicitly do the half-duplex close in the pipe case; we hand the descriptor off to the pack-objects run-command, which takes ownership). So trying to be fancy and abstracted is not worth it in this case.

 cache.h   |    1 +
 connect.c |    7 ++++++-
 2 files changed, 7 insertions(+), 1 deletions(-)