Re: [PATCH 12/19] block: Update block to compile with Emscripten

[Philippe Mathieu-Daudé]

On 16/4/25 11:00, Philippe Mathieu-Daudé wrote:
> On 16/4/25 10:14, Kohei Tokunaga wrote:
> > emscripten exposes copy_file_range declaration but doesn't provide the
> > implementation in the final link. Define the emscripten-specific stub
> > function to avoid type conflict with the emscripten's header.
> >
> > Signed-off-by: Kohei Tokunaga <ktokunaga.mail@gmail.com>
> > ---
> >   block/file-posix.c |  6 ++++++
> >   stubs/emscripten.c | 13 +++++++++++++
> >   2 files changed, 19 insertions(+)
> >   create mode 100644 stubs/emscripten.c
> >
> > diff --git a/block/file-posix.c b/block/file-posix.c
> > index 56d1972d15..22e0ed5069 100644
> > --- a/block/file-posix.c
> > +++ b/block/file-posix.c
> > @@ -110,6 +110,10 @@
> >   #include <sys/diskslice.h>
> >   #endif
> > +#ifdef EMSCRIPTEN
> > +#include <sys/ioctl.h>
> > +#endif
> > +
> >   /* OS X does not have O_DSYNC */
> >   #ifndef O_DSYNC
> >   #ifdef O_SYNC
> > @@ -2010,6 +2014,7 @@ static int handle_aiocb_write_zeroes_unmap(void 
> > *opaque)
> >       return handle_aiocb_write_zeroes(aiocb);
> >   }
> > +#ifndef EMSCRIPTEN
> >   #ifndef HAVE_COPY_FILE_RANGE
> >   static off_t copy_file_range(int in_fd, off_t *in_off, int out_fd,
> >                                off_t *out_off, size_t len, unsigned 
> > int flags)
> > @@ -2023,6 +2028,7 @@ static off_t copy_file_range(int in_fd, off_t 
> > *in_off, int out_fd,
> >   #endif
> >   }
> >   #endif
> > +#endif
> >   /*
> >    * parse_zone - Fill a zone descriptor
> > diff --git a/stubs/emscripten.c b/stubs/emscripten.c
> > new file mode 100644
> > index 0000000000..2157d6349b
> > --- /dev/null
> > +++ b/stubs/emscripten.c
> > @@ -0,0 +1,13 @@
> > +/* SPDX-License-Identifier: GPL-2.0-or-later */
> > +#include "qemu/osdep.h"
> > +/*
> > + * emscripten exposes copy_file_range declaration but doesn't provide 
> > the
> > + * implementation in the final link. Define the stub here but avoid type
> > + * conflict with the emscripten's header.
> > + */
> > +ssize_t copy_file_range(int in_fd, off_t *in_off, int out_fd,
> > +                             off_t *out_off, size_t len, unsigned int 
> > flags)
> > +{
> > +    errno = ENOSYS;
> > +    return -1;
> > +}
>
> I'd include in this patch this hunk from patch 17:
>
> -- >8 --
> diff --git a/stubs/meson.build b/stubs/meson.build
> index 63392f5e78..4fd4d362f9 100644
> --- a/stubs/meson.build
> +++ b/stubs/meson.build
> @@ -89,3 +89,7 @@ if have_system or have_user
>     stub_ss.add(files('hotplug-stubs.c'))
>     stub_ss.add(files('sysbus.c'))
>   endif
> +
> +if host_os == 'emscripten'
> +  stub_ss.add(files('emscripten.c'))
> +endif
> ---

Actually what about checking the symbol presence in meson?
Something like (untested):

-- >8 --
diff --git a/meson.build b/meson.build
index b18c46d16a2..33185fdf315 100644
--- a/meson.build
+++ b/meson.build
@@ -2654,3 +2654,2 @@ config_host_data.set('CONFIG_TIMERFD', 
cc.has_function('timerfd_create'))
 config_host_data.set('CONFIG_GETLOADAVG', cc.has_function('getloadavg'))
-config_host_data.set('HAVE_COPY_FILE_RANGE', 
cc.has_function('copy_file_range'))
 config_host_data.set('HAVE_GETIFADDRS', cc.has_function('getifaddrs'))
@@ -2756,2 +2755,6 @@ config_host_data.set('HAVE_UTMPX',

+config_host_data.set('HAVE_COPY_FILE_RANGE', cc.links(gnu_source_prefix 
+ '''
+  #include <unistd.h>
+  int main(void) { return copy_file_range(-1, NULL, -1, NULL, 0, 0); }'''))
 config_host_data.set('CONFIG_EVENTFD', cc.links('''
---