glibc string.h declares memcpy() with attribute(nonnull(1,2)), causing
calls with NULL arguments to be treated as undefined behaviour.
This is consistent with ISO C99 and C11, which state that passing 0
to string functions as an array length does not remove the requirement
that the pointer to the array is a valid pointer.
gcc -fsanitize=undefined catches this while running OSTree's test suite.
Similarly, running the GLib test suite reports similar issues for
qsort(), memmove(), memcmp().
(This is a partial cherry-pick of commit e5ed410c8c0fe823883 from GLib.)
Signed-off-by: Simon McVittie <smcv@debian.org>
Bug: https://bugzilla.gnome.org/show_bug.cgi?id=775510
Reviewed-by: Colin Walters
Our hashing of non-ASCII strings was undefined due to the fact that
'char' is signed on some platforms, unsigned on others. Always use a
signed char.
Discovered by Alexander Larsson.
https://bugzilla.gnome.org/show_bug.cgi?id=658806
