Add bpf_object__open_file() and bpf_object__open_mem() APIs that use a new
approach to providing future-proof non-ABI-breaking API changes. It relies on
APIs accepting optional self-describing "opts" struct, containing its own
size, filled out and provided by potentially outdated (as well as
newer-than-libbpf) user application. A set of internal helper macros
(OPTS_VALID, OPTS_HAS, and OPTS_GET) streamline and simplify a graceful
handling forward and backward compatibility for user applications dynamically
linked against different versions of libbpf shared library.
Users of libbpf are provided with convenience macro LIBBPF_OPTS that takes
care of populating correct structure size and zero-initializes options struct,
which helps avoid obscure issues of unitialized padding. Uninitialized padding
in a struct might turn into garbage-populated new fields understood by future
versions of libbpf.
Patch #1 removes enforcement of kern_version in libbpf and always populates
correct one on behalf of users.
Patch #2 defines necessary infrastructure for options and two new open APIs
relying on it.
Patch #3 fixes bug in bpf_object__name().
Patch #4 switches two of test_progs' tests to use new APIs as a validation
that they work as expected.
v2->v3:
- fix LIBBPF_OPTS() to ensure zero-initialization of padded bytes;
- pass through name override and relaxed maps flag for open_file() (Toke);
- fix bpf_object__name() to actually return object name;
- don't bother parsing and verifying version section (John);
v1->v2:
- use better approach for tracking last field in opts struct;
- convert few tests to new APIs for validation;
- fix bug with using offsetof(last_field) instead of offsetofend(last_field).
Andrii Nakryiko (4):
libbpf: stop enforcing kern_version, populate it for users
libbpf: add bpf_object__open_{file,mem} w/ extensible opts
libbpf: fix bpf_object__name() to actually return object name
selftests/bpf: switch tests to new bpf_object__open_{file,mem}() APIs
tools/lib/bpf/libbpf.c | 183 +++++++++---------
tools/lib/bpf/libbpf.h | 48 ++++-
tools/lib/bpf/libbpf.map | 3 +
tools/lib/bpf/libbpf_internal.h | 32 +++
tools/testing/selftests/bpf/Makefile | 2 +-
.../selftests/bpf/prog_tests/attach_probe.c | 49 ++++-
.../bpf/prog_tests/reference_tracking.c | 16 +-
.../selftests/bpf/progs/test_attach_probe.c | 1 -
.../bpf/progs/test_get_stack_rawtp.c | 1 -
.../selftests/bpf/progs/test_perf_buffer.c | 1 -
.../selftests/bpf/progs/test_stacktrace_map.c | 1 -
11 files changed, 226 insertions(+), 111 deletions(-)
--
2.17.1
