#include "git-compat-util.h"

#include "strbuf.h"

#include "unix-socket.h"

#define DEFAULT_UNIX_STREAM_LISTEN_BACKLOG (5)

static int chdir_len(const char *orig, int len)

{

  char *path = xmemdupz(orig, len);

  int r = chdir(path);

  free(path);

  return r;

}

struct unix_sockaddr_context {

  char *orig_dir;

};

static void unix_sockaddr_cleanup(struct unix_sockaddr_context *ctx)

{

  if (!ctx->orig_dir)

    return;

  /*

   * If we fail, we can't just return an error, since we have

   * moved the cwd of the whole process, which could confuse calling

   * code.  We are better off to just die.

   */

  if (chdir(ctx->orig_dir) < 0)

    die("unable to restore original working directory");

  free(ctx->orig_dir);

}

static int unix_sockaddr_init(struct sockaddr_un *sa, const char *path,

            struct unix_sockaddr_context *ctx,

            int disallow_chdir)

{

  int size = strlen(path) + 1;

  ctx->orig_dir = NULL;

  if (size > sizeof(sa->sun_path)) {

    const char *slash;

    const char *dir;

    struct strbuf cwd = STRBUF_INIT;

    if (disallow_chdir) {

      errno = ENAMETOOLONG;

      return -1;

    }

    slash = find_last_dir_sep(path);

    if (!slash) {

      errno = ENAMETOOLONG;

      return -1;

    }

    dir = path;

    path = slash + 1;

    size = strlen(path) + 1;

    if (size > sizeof(sa->sun_path)) {

      errno = ENAMETOOLONG;

      return -1;

    }

    if (strbuf_getcwd(&cwd))

      return -1;

    ctx->orig_dir = strbuf_detach(&cwd, NULL);

    if (chdir_len(dir, slash - dir) < 0)

      return -1;

  }

  memset(sa, 0, sizeof(*sa));

  sa->sun_family = AF_UNIX;

  memcpy(sa->sun_path, path, size);

  return 0;

}

int unix_stream_connect(const char *path, int disallow_chdir)

{

  int fd = -1, saved_errno;

  struct sockaddr_un sa;

  struct unix_sockaddr_context ctx;

  if (unix_sockaddr_init(&sa, path, &ctx, disallow_chdir) < 0)

    return -1;

  fd = socket(AF_UNIX, SOCK_STREAM, 0);

  if (fd < 0)

    goto fail;

  if (connect(fd, (struct sockaddr *)&sa, sizeof(sa)) < 0)

    goto fail;

  unix_sockaddr_cleanup(&ctx);

  return fd;

fail:

  saved_errno = errno;

  if (fd != -1)

    close(fd);

  unix_sockaddr_cleanup(&ctx);

  errno = saved_errno;

  return -1;

}

int unix_stream_listen(const char *path,

           const struct unix_stream_listen_opts *opts)

{

  int fd = -1, saved_errno;

  int backlog;

  struct sockaddr_un sa;

  struct unix_sockaddr_context ctx;

  unlink(path);

  if (unix_sockaddr_init(&sa, path, &ctx, opts->disallow_chdir) < 0)

    return -1;

  fd = socket(AF_UNIX, SOCK_STREAM, 0);

  if (fd < 0)

    goto fail;

  if (bind(fd, (struct sockaddr *)&sa, sizeof(sa)) < 0)

    goto fail;

  backlog = opts->listen_backlog_size;

  if (backlog <= 0)

    backlog = DEFAULT_UNIX_STREAM_LISTEN_BACKLOG;

  if (listen(fd, backlog) < 0)

    goto fail;

  unix_sockaddr_cleanup(&ctx);

  return fd;

fail:

  saved_errno = errno;

  if (fd != -1)

    close(fd);

  unix_sockaddr_cleanup(&ctx);

  errno = saved_errno;

  return -1;

}