In general, the patch adds indirection to minimize the amount of code
that needs to know about differences between v2 and v3. Specifically,
some new ctf_get_ctt_* functions are added, and new LCTF_* macros are
added to use the underlying container's version to do the right thing.
CTF containers can have parent/child relationships, wherein a type ID in
one container refers to a type in the parent. It is permitted for the
parent and child to have different versions.
MFC after: 1 month
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D34363
CTFv1 was obsolete before libctf was imported into FreeBSD, and
ctfconvert/ctfmerge can emit only CTFv2. Make ctf.h a bit easier to
maintain by ripping v1 support out. No functional change intended.
MFC after: 1 week
Sponsored by: The FreeBSD Foundation
For consistency with other CTF toolchain code. No functional change
intended.
Fixes: 105fd928b0 ("libctf: Improve check for duplicate SOU definitions in ctf_add_type()")
MFC after: 1 week
When copying a struct or union from one CTF container to another,
ctf_add_type() checks whether it matches an existing type in the
destination container. It does so by looking for a type with the same
name and kind as the new type, and if one exists, it iterates over all
members of the source type and checks whether a member with matching
name and offset exists in the matched destination type. This can
produce false positives, for example because member types are not
compared, but this is not expected to arise in practice. If the match
fails, ctf_add_type() returns an error.
The procedure used for member comparison breaks down in the face of
anonymous struct and union members. ctf_member_iter() visits each
member in the source definition and looks up the corresponding member in
the desination definition by name using ctf_member_info(), but this
function will descend into anonymous members and thus fail to match.
Fix the problem by introducing a custom comparison routine which does
not assume member names are unique. This should also be faster for
types with many members; in the previous scheme, membcmp() would perform
a linear scan of the desination type's members to perform a lookup by
name. The new routine steps through the members of both types in a
single loop.
PR: 258763
MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation
When prefixes such as struct, union, etc. are compared with the current
type (e.g. struct foo), a comparison is made with the prefix. The code
currently assumes that every type is a valid C type with a prefix,
however at times, garbage ends up in this function causing an
unpredictable crash with DTrace due to the isspace(*p) call or
subsequent calls. An example that I've seen of this is the letter 's'
being passed in, comparing true with struct as the comparison size was
(q - p) == 1, but then we increment p with the length of "struct",
resulting in an out of bounds read.
Reviewed by: markj
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D29435
encode 0-length (i.e. "") structure and union member names as offset 0.
This ensures that we don't confuse other parts of the CTF code which
expect this encoding.
This resolves a Dtrace error resolving members of anonymous structs/unions
within the (struct mbuf) type which some users were seeing after r366908.
While here, update the code in ctf_add_generic() to encode 0-length type
names as offset 0.
Reviewed by: markj
MFC after: 2 weeks
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D27246
always copy intrinsic data types before copying bitfields which are
based on those types. This ensures the type ordering in the destination
CTF container matches the assumption made elsewhere in the CTF code
that instrinsic data types will always appear before bitfields based on
those types.
This resolves the following error message some users have seen after
r366908:
"/usr/lib/dtrace/ipfw.d", line 121: failed to copy type of 'ip6p':
Conflicting type is already defined
Reviewed by: markj
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D27213
Previously, ctf_member_info() would ignore members belonging to an
anonymous struct or union. This made it impossible to, for example, trace
the m_next field of an mbuf using DTrace.
Reported and tested by: gallatin
MFC after: 2 weeks
list of pending dynamic type definitions, a match on the type name is not
sufficient - we need to compare the type encodings as well. For example,
bitfields have their own distinct type definitions which share the name of
the underlying integer type, and these types aren't generally
interchangeable.
This bug was causing the following libdtrace error when attempting to trace
the th_flags member of a struct tcphdr:
cg: bad field: off 104 type <32877> bits 539620016
Reported by: rwatson
MFC after: 3 weeks
ctf_add_type() first performs a by-name lookup of the type in the
destination container. If this lookup returns a forward declaration for an
enum, struct, or union, reset dst_type back to CTF_ERR, indicating that the
source type is not in fact present in the destination container. This
ensures that ctf_add_type() will also search the destination container's
dynamic type list for the source type.
Without this change, a pair of mutually recursive struct definitions could
cause infinite recursion in ctf_add_type() if the destination container
only contained forward declarations for the struct types: ctf_add_type()
recursively calls itself on each struct member's type, and the forward
declarations meant that the dynamic type list search would be skipped.
MFC after: 2 weeks
Sponsored by: EMC / Isilon Storage Division
indicates the range of type indices which have been committed to the
container by ctf_update(). However, the top bit of the dtd_type field is
not part of the type index; rather, it is a flag used to indicate that the
corresponding CTF container is a parent. This is why the maximum CTF type
index is 2^15 - 1 rather than 2^16 - 1. Therefore, this flag must be masked
off (using the CTF_TYPE_TO_INDEX macro) when comparing a type index with the
ctf_dtoldid field of a container.
This bug was causing libctf to erroneously free committed type definitions
in ctf_discard(). libdtrace holds some references to such types, resulting
in a use-after-free.
MFC after: 2 weeks
Sponsored by: EMC / Isilon Storage Division
we end up skipping a dynamic type because it has already been committed to
the container, we would previously either set the loop variable to an
uninitialized local variable, or set it to itself, resulting in an infinite
loop.
MFC after: 2 weeks
Sponsored by: EMC / Isilon Storage Division
Illumos DTrace issues:
3089 want ::typedef
3094 libctf should support removing a dynamic type
3095 libctf does not validate arrays correctly
3096 libctf does not validate function types correctly
