remove legacy clock_gettime and gettimeofday from public syscall.h

some nontrivial number of applications have historically performed
direct syscalls for these operations rather than using the public
functions. such usage is invalid now that time_t is 64-bit and these
syscalls no longer match the types they are used with, and it was
already harmful before (by suppressing use of vdso).

since syscall() has no type safety, incorrect usage of these syscalls
can't be caught at compile-time. so, without manually inspecting or
running additional tools to check sources, the risk of such errors
slipping through is high.

this patch renames the syscalls on 32-bit archs to clock_gettime32 and
gettimeofday_time32, so that applications using the original names
will fail to build without being fixed.

note that there are a number of other syscalls that may also be unsafe
to use directly after the time64 switchover, but (1) these are the
main two that seem to be in widespread use, and (2) most of the others
continue to have valid usage with a null timeval/timespec argument, as
the argument is an optional timeout or similar.

1 files changed, 7 insertions, 0 deletions

diff --git a/src/internal/syscall.h b/src/internal/syscall.h
index d768fb64..0b61f34e 100644
--- a/src/internal/syscall.h
+++ b/src/internal/syscall.h
@@ -193,6 +193,13 @@ hidden long __syscall_ret(unsigned long),
 #define SYS_sendfile SYS_sendfile64
 #endif
 
+#ifndef SYS_clock_gettime
+#define SYS_clock_gettime SYS_clock_gettime32
+#endif
+
+#ifndef SYS_gettimeofday
+#define SYS_gettimeofday SYS_gettimeofday_time32
+#endif
 
 /* Ensure that the plain syscall names are defined even for "time64-only"
  * archs. These facilitate callers passing null time arguments, and make