Commit Graph

18 Commits

Author SHA1 Message Date
Omar Sandoval
c0d8709b45 Update copyright headers to Meta
Signed-off-by: Omar Sandoval <osandov@osandov.com>
2021-11-21 15:59:44 -08:00
Omar Sandoval
a4b9d68a8c Use GPL-3.0-or-later license identifier instead of GPL-3.0+
Apparently the latter is deprecated and the former is preferred.

Signed-off-by: Omar Sandoval <osandov@osandov.com>
2021-04-03 01:10:35 -07:00
Omar Sandoval
30cfa40a72 libdrgn: rename "unavailable" objects to "absent" objects
I was going to add an Object.available_ attribute, but that made me
realize that the naming is somewhat ambiguous, as a reference object
with an invalid address might also be considered "unavailable" by users.
Use the name "absent" instead, which is more clear: the object isn't
there at all.

Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-12-29 14:58:26 -08:00
Omar Sandoval
6bd0c2b4d2 libdrgn: add concept of "unavailable" objects
There are some situations where we can find an object but can't
determine its value, like local variables that have been optimized out,
inlined functions without a concrete instance, and pure virtual methods.
It's still useful to get some information from these objects, namely
their types. Let's add the concept of an "unavailable" object, which is
an object with a known type but unknown value/address.

Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-12-04 13:58:19 -08:00
Omar Sandoval
286c09844e Clean up #includes with include-what-you-use
I recently hit a couple of CI failures caused by relying on transitive
includes that weren't always present. include-what-you-use is a
Clang-based tool that helps with this. It's a bit finicky and noisy, so
this adds scripts/iwyu.py to make running it more convenient (but not
reliable enough to automate it in Travis).

This cleans up all reasonable include-what-you-use warnings and
reorganizes a few header files.

Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-23 16:29:42 -07:00
Omar Sandoval
d512964c1e libdrgn: add drgn_error_copy()
This is needed for a future change where we'll want to save an error and
return it multiple times.

Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-02 17:13:16 -07:00
Omar Sandoval
8b264f8823 Update copyright headers to Facebook and add missing headers
drgn was originally my side project, but for awhile now it's also been
my work project. Update the copyright headers to reflect this, and add a
copyright header to various files that were missing it.
2020-05-15 15:13:02 -07:00
Serapheim Dimitropoulos
80fef04c70 Add address attribute to FaultError exception 2020-02-04 14:59:31 -08:00
Omar Sandoval
698991b27b Get rid of DRGN_ERROR_{ELF,DWARF}_ERROR and FileFormatError
We're too inconsistent with how we use these for them to be useful (and
it's impossible to distinguish between a format error and some other
error from libelf/libdw/libdwfl), so let's just get rid of them and make
it all DRGN_ERROR_OTHER/Exception.
2019-08-15 15:03:42 -07:00
Omar Sandoval
62ff4e1dba libdrgn: indicate finder lookup failure with special error
Currently, finders indicate a non-fatal lookup error by setting the type
member to NULL. This won't work when we replace the symbol finder with
an object finder (which shouldn't modify the object on failure).
Instead, use a static error for this purpose.
2019-07-29 17:04:47 -07:00
Omar Sandoval
e5874ad18a libdrgn: use libdwfl
libdwfl is the elfutils "DWARF frontend library". It has high-level
functionality for looking up symbols, walking stack traces, etc. In
order to use this functionality, we need to report our debugging
information through libdwfl. For userspace programs, libdwfl has a much
better implementation than drgn for automatically finding debug
information from a core dump or PID. However, for the kernel, libdwfl
has a few issues:

- It only supports finding debug information for the running kernel, not
  vmcores.
- It determines the vmlinux address range by reading /proc/kallsyms,
  which is slow (~70ms on my machine).
- If separate debug information isn't available for a kernel module, it
  finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated
  for every module.
- It doesn't find kernel modules with names containing both dashes and
  underscores (e.g., aes-x86_64).

Luckily, drgn already solved all of these problems, and with some
effort, we can keep doing it ourselves and report it to libdwfl.

The conversion replaces a bunch of code for dealing with userspace core
dump notes, /proc/$pid/maps, and relocations.
2019-07-15 12:27:48 -07:00
Omar Sandoval
e2a27e7f59 libdrgn: add drgn_error_format_os()
There are some cases where we format a path (e.g., with asprintf()) and
keep it around only in case of errors. Add drgn_error_format_os() so we
can just reformat it if we hit the error, which simplifies cleanup.
2019-07-11 16:19:18 -07:00
Omar Sandoval
74c0aa8612 libdrgn: reorder drgn_error_create_os() arguments
To make it more consistent with the upcoming drgn_error_format_os().
2019-07-11 16:12:56 -07:00
Omar Sandoval
efaec41ca2 libdrgn: add string_builder_append_error() 2019-05-14 11:49:52 -07:00
Omar Sandoval
e21ed988fb libdrgn: add drgn_error_from_string_builder()
And use that instead of exposing drgn_error_create_nodup().
2019-05-14 10:16:01 -07:00
Omar Sandoval
b0f10d3b58 libdrgn: pass enum drgn_error_code to error constructors 2019-05-14 10:13:05 -07:00
Omar Sandoval
15bc0286b9 libdrgn: add drgn_error_create_nodup() 2019-05-09 16:35:14 -07:00
Omar Sandoval
75c3679147 Rewrite drgn core in C
The current mixed Python/C implementation works well, but it has a
couple of important limitations:

- It's too slow for some common use cases, like iterating over large
  data structures.
- It can't be reused in utilities written in other languages.

This replaces the internals with a new library written in C, libdrgn. It
includes Python bindings with mostly the same public interface as
before, with some important improvements:

- Types are now represented by a single Type class rather than the messy
  polymorphism in the Python implementation.
- Qualifiers are a bitmask instead of a set of strings.
- Bit fields are not considered a separate type.
- The lvalue/rvalue terminology is replaced with reference/value.
- Structure, union, and array values are better supported.
- Function objects are supported.
- Program distinguishes between lookups of variables, constants, and
  functions.

The C rewrite is about 6x as fast as the original Python when using the
Python bindings, and about 8x when using the C API directly.

Currently, the exposed API in C is fairly conservative. In the future,
the memory reader, type index, and object index APIs will probably be
exposed for more flexibility.
2019-04-02 14:12:07 -07:00