Closes osandov#96.

Signed-off-by: Omar Sandoval <[email protected]>

Signed-off-by: Davide Cavalca <[email protected]>

Signed-off-by: Davide Cavalca <[email protected]>

It's undefined behavior to pass NULL to memcpy() even if the length is
zero. See also commit a17215e ("libdrgn: dwarf_index: fix memcpy()
undefined behavior").

Signed-off-by: Omar Sandoval <[email protected]>

drgn_object_reinit() and drgn_object_copy() can both load from an
uninitialized little_endian field, causing UBSan errors like:

  libdrgn/object.h:105:27: runtime error: load of value 68, which is not a valid value for type '_Bool'

This only happens when little_endian isn't valid for the type and won't
be used anyways, but it's easy enough to work around.

Signed-off-by: Omar Sandoval <[email protected]>

There are a couple of places where we compute `NULL + 0`, which is
undefined behavior. Add a helper to do this safely.

Signed-off-by: Omar Sandoval <[email protected]>

See commit 0cb77b3 ("libdrgn: work around Clang __muloti4 again")
and commit 2dd14ad ("libdrgn: work around "undefined reference to
'__muloti4'" when using Clang"). These keep sneaking in because I don't
have an old enough version of Clang lying around.

Signed-off-by: Omar Sandoval <[email protected]>

Clang enables -Wgnu-variable-sized-type-not-at-end by default, which
warns for DRGN_CFI_ROW():

  arch_x86_64.c:735:27: warning: field 'row' with variable sized type 'struct drgn_cfi_row' not at the end of a struct or class is a GNU extension
        [-Wgnu-variable-sized-type-not-at-end]
          .default_dwarf_cfi_row = DRGN_CFI_ROW(

DRGN_CFI_ROW() is gnarly anyways, so instead of having it expand to a
pointer expression relying on this GCC extension, make it expand to an
initializer. Then, we can initialize default_dwarf_cfi_row as a separate
variable rather than directly in the initializer for struct
drgn_architecture_info.

This still relies on a GCC extension for static initialization of
flexible array members, but apparently Clang is okay with that one by
default (-Wgnu-flexible-array-initializer must be enabled explictly or
by -Wgnu or -Wpedantic).

Signed-off-by: Omar Sandoval <[email protected]>

The folly implementation calls this elsewhere, but we only need it in
table##_chunk_mark_eof(), so it was folded in there.

Signed-off-by: Omar Sandoval <[email protected]>

GCC doesn't warn about table##_delete_iterator() being unused because it
is inline, but Clang does, so add the unused attribute.

Signed-off-by: Omar Sandoval <[email protected]>

Everytime I try to build drgn with Clang, there are a few things that
need fixing. Let's test it so that it stays in good shape.

Signed-off-by: Omar Sandoval <[email protected]>

This is the documented way that drgn should be built for development, so
let's enforce it.

Signed-off-by: Omar Sandoval <[email protected]>

Apparently the latter is deprecated and the former is preferred.

Signed-off-by: Omar Sandoval <[email protected]>

We don't actually want make clean to remove the generated files that are
included in a distribution tarball, because then the user will need to
regenerate them, and they might not have the dependencies installed.

Signed-off-by: Omar Sandoval <[email protected]>

Signed-off-by: Omar Sandoval <[email protected]>

With the added Clang tests, apparently vmtest is generating excessive
traffic on Dropbox. Disable it on GitHub Actions until I can work out a
new solution.

Signed-off-by: Omar Sandoval <[email protected]>