util/osdep: Avoid madvise proto on modern Solaris
On older Solaris releases (before Solaris 11), we didn't get a
prototype for madvise, and so util/osdep.c provides its own prototype.
Some time between the public Solaris 11.4 release and Solaris 11.4.42
CBE, we started getting an madvise prototype that looks like this:
extern int madvise(void *, size_t, int);
which conflicts with the prototype in util/osdeps.c. Instead of always
declaring this prototype, check if we're missing the madvise()
prototype, and only declare it ourselves if the prototype is missing.
Move the prototype to include/qemu/osdep.h, the normal place to handle
platform-specific header quirks.
The 'missing_madvise_proto' meson check contains an obviously wrong
prototype for madvise. So if that code compiles and links, we must be
missing the actual prototype for madvise.
Signed-off-by: Andrew Deason <adeason@sinenomine.net>
Message-id: 20220316035227.3702-2-adeason@sinenomine.net
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
diff --git a/meson.build b/meson.build
index bae62ef..282e7c4 100644
--- a/meson.build
+++ b/meson.build
@@ -1715,11 +1715,30 @@
#error Not supported
#endif
}'''))
-config_host_data.set('CONFIG_MADVISE', cc.links(gnu_source_prefix + '''
+
+has_madvise = cc.links(gnu_source_prefix + '''
#include <sys/types.h>
#include <sys/mman.h>
#include <stddef.h>
- int main(void) { return madvise(NULL, 0, MADV_DONTNEED); }'''))
+ int main(void) { return madvise(NULL, 0, MADV_DONTNEED); }''')
+missing_madvise_proto = false
+if has_madvise
+ # Some platforms (illumos and Solaris before Solaris 11) provide madvise()
+ # but forget to prototype it. In this case, has_madvise will be true (the
+ # test program links despite a compile warning). To detect the
+ # missing-prototype case, we try again with a definitely-bogus prototype.
+ # This will only compile if the system headers don't provide the prototype;
+ # otherwise the conflicting prototypes will cause a compiler error.
+ missing_madvise_proto = cc.links(gnu_source_prefix + '''
+ #include <sys/types.h>
+ #include <sys/mman.h>
+ #include <stddef.h>
+ extern int madvise(int);
+ int main(void) { return madvise(0); }''')
+endif
+config_host_data.set('CONFIG_MADVISE', has_madvise)
+config_host_data.set('HAVE_MADVISE_WITHOUT_PROTOTYPE', missing_madvise_proto)
+
config_host_data.set('CONFIG_MEMFD', cc.links(gnu_source_prefix + '''
#include <sys/mman.h>
int main(void) { return memfd_create("foo", MFD_ALLOW_SEALING); }'''))
