Re: [PATCH v2] semihosting: add O_BINARY flag in host_open for NT compatibility

[Peter Maydell]

On Fri, 6 Jan 2023 at 10:21, Evgeny Iakovlev
<eiakovlev@linux.microsoft.com> wrote:
>
> Windows open(2) implementation opens files in text mode by default and
> needs a Windows-only O_BINARY flag to open files as binary. QEMU already
> knows about that flag in osdep and it is defined to 0 on non-Windows,
> so we can just add it to the host_flags for better compatibility.
>
> Signed-off-by: Evgeny Iakovlev <eiakovlev@linux.microsoft.com>
> Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
> Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
> ---
>  semihosting/syscalls.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/semihosting/syscalls.c b/semihosting/syscalls.c
> index 508a0ad88c..b621d78c2d 100644
> --- a/semihosting/syscalls.c
> +++ b/semihosting/syscalls.c
> @@ -253,7 +253,7 @@ static void host_open(CPUState *cs, 
> gdb_syscall_complete_cb complete,
>  {
>      CPUArchState *env G_GNUC_UNUSED = cs->env_ptr;
>      char *p;
> -    int ret, host_flags;
> +    int ret, host_flags = O_BINARY;

The semihosting API, at least for Arm, has a modeflags string so the
guest can say whether it wants to open O_BINARY or not:
https://github.com/ARM-software/abi-aa/blob/main/semihosting/semihosting.rst#sys-open-0x01

So we need to plumb that down through the common semihosting code
into this function and set O_BINARY accordingly. Otherwise guest
code that asks for a text-mode file won't get one.

I don't know about other semihosting APIs, so those would need
to be checked to see what they should do.

thanks
-- PMM