Re: fix build error on MinGW (HAVE_READLINK) undefined

[Eli Zaretskii <eliz@gnu.org>]

> Date: Fri, 27 Jan 2012 10:07:26 +0800
> From: asmwarrior <asmwarrior@gmail.com>
> 
> diff --git a/gdb/gdbserver/hostio.c b/gdb/gdbserver/hostio.c
> index 34e4fa8..7575fb1 100644
> --- a/gdb/gdbserver/hostio.c
> +++ b/gdb/gdbserver/hostio.c
> @@ -459,6 +459,7 @@ handle_unlink (char *own_buf)
>   static void
>   handle_readlink (char *own_buf, int *new_packet_len)
>   {
> +#if defined (HAVE_READLINK) && defined (PATH_MAX)
>     char filename[PATH_MAX], linkname[PATH_MAX];
>     char *p;
>     int ret, bytes_sent;
> @@ -485,6 +486,10 @@ handle_readlink (char *own_buf, int *new_packet_len)
>        to return a partial response, but simply fail.  */
>     if (bytes_sent < ret)
>       sprintf (own_buf, "F-1,%x", FILEIO_ENAMETOOLONG);
> +#else
> +   hostio_error (own_buf);
> +   return;
> +#endif

I think you need to set errno to EINVAL in the #else branch, because
the meaning of that error on systems that do have readlink is "the
named file is not a symbolic link".

On second thought, perhaps a better way would be to define a readlink
for MinGW that always sets errno to EINVAL and returns -1.  Then the
ugly #ifdef can go away.

> static char *
> inf_child_fileio_readlink (const char *filename, int *target_errno)
> {
>    /* We support readlink only on systems that also provide a compile-time
>       maximum path length (MAXPATHLEN), at least for now.  */
> #if defined (HAVE_READLINK) && defined (MAXPATHLEN)
>    char buf[MAXPATHLEN];
>    int len;
>    char *ret;
> 
>    len = readlink (filename, buf, sizeof buf);

Here too.