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NAME | INVOCATION | ENVIRONMENT | OPTIONS | RETURN VALUES | USAGE EXAMPLES | AUTHOR | COPYRIGHT | COLOPHON |
ABIDIFF(1) Libabigail ABIDIFF(1)
abidiff - compare ABIs of ELF files
abidiff compares the Application Binary Interfaces (ABI) of two
shared libraries in ELF format. It emits a meaningful report
describing the differences between the two ABIs.
This tool can also compare the textual representations of the ABI of
two ELF binaries (as emitted by abidw) or an ELF binary against a
textual representation of another ELF binary.
For a comprehensive ABI change report that includes changes about
function and variable sub-types, the two input shared libraries must
be accompanied with their debug information in DWARF format. Other‐
wise, only ELF symbols that were added or removed are reported.
abidiff [options] <first-shared-library> <second-shared-library>
abidiff loads two default suppression specifications files, merges
their content and use it to filter out ABI change reports that might
be considered as false positives to users.
· Default system-wide suppression specification file
It's located by the optional environment variable
LIBABIGAIL_DEFAULT_SYSTEM_SUPPRESSION_FILE. If that environment
variable is not set, then abidiff tries to load the suppression
file $libdir/libabigail/libabigail-default.abignore. If that file
is not present, then no default system-wide suppression
specification file is loaded.
· Default user suppression specification file.
It's located by the optional environment
LIBABIGAIL_DEFAULT_USER_SUPPRESSION_FILE. If that environment
variable is not set, then abidiff tries to load the suppression
file $HOME/.abignore. If that file is not present, then no default
user suppression specification is loaded.
· --help | -h
Display a short help about the command and exit.
· --version | -v
Display the version of the program and exit.
· --debug-info-dir1 | --d1 <di-path1>
For cases where the debug information for first-shared-library
is split out into a separate file, tells abidiff where to find
that separate debug information file.
Note that di-path must point to the root directory under which
the debug information is arranged in a tree-like manner. Under
Red Hat based systems, that directory is usually
<root>/usr/lib/debug.
Note also that this option is not mandatory for split debug
information installed by your system's package manager because
then abidiff knows where to find it.
· --debug-info-dir2 | --d2 <di-path2>
Like --debug-info-dir1, this options tells abidiff where to find
the split debug information for the second-shared-library file.
· --headers-dir1 | --hd1 <headers-directory-path-1>
Specifies where to find the public headers of the first shared
library that the tool has to consider. The tool will thus
filter out ABI changes on types that are not defined in public
headers.
· --headers-dir2 | --hd2 <headers-directory-path-1>
Specifies where to find the public headers of the second shared
library that the tool has to consider. The tool will thus
filter out ABI changes on types that are not defined in public
headers.
· --no-linux-kernel-mode
Without this option, if abidiff detects that the binaries it is
looking at are Linux Kernel binaries (either vmlinux or modules)
then it only considers functions and variables which ELF symbols
are listed in the __ksymtab and __ksymtab_gpl sections.
With this option, abidiff considers the binary as a non-special
ELF binary. It thus considers functions and variables which are
defined and exported in the ELF sense.
· --kmi-whitelist | -kaw <path-to-whitelist>
When analyzing a Linux kernel binary, this option points to the
white list of names of ELF symbols of functions and variables
which ABI must be considered. That white list is called a
"Kernel Module Interface white list". This is because for the
Kernel, we don't talk about ABI; we rather talk about the
interface between the Kernel and its module. Hence the term KMI
rather than ABI.
Any other function or variable which ELF symbol are not present
in that white list will not be considered by this tool.
If this option is not provided -- thus if no white list is
provided -- then the entire KMI, that is, the set of all
publicly defined and exported functions and global variables by
the Linux Kernel binaries, is considered.
· --drop-private-types
This option is to be used with the --headers-dir1 and
--headers-dir2 options. With this option, types that are NOT
defined in the headers are entirely dropped from the internal
representation build by Libabigail to represent the ABI. They
thus don't have to be filtered out from the final ABI change
report because they are not even present in Libabigail's
representation.
Without this option however, those private types are kept in the
internal representation and later filtered out from the report.
This options thus potentially makes Libabigail consume less
memory. It's meant to be mainly used to optimize the memory
consumption of the tool on binaries with a lot of publicly
defined and exported types.
· --stat
Rather than displaying the detailed ABI differences between
first-shared-library and second-shared-library, just display
some summary statistics about these differences.
· --symtabs
Only display the symbol tables of the first-shared-library and
second-shared-library.
· --deleted-fns
In the resulting report about the differences between
first-shared-library and second-shared-library, only display the
globally defined functions that got deleted from
first-shared-library.
· --changed-fns
In the resulting report about the differences between
first-shared-library and second-shared-library, only display the
changes in sub-types of the global functions defined in
first-shared-library.
· --added-fns
In the resulting report about the differences between
first-shared-library and second-shared-library, only display the
globally defined functions that were added to
second-shared-library.
· --deleted-vars
In the resulting report about the differences between
first-shared-library and second-shared-library, only display the
globally defined variables that were deleted from
first-shared-library.
· --changed-vars
In the resulting report about the differences between
first-shared-library and second-shared-library, only display the
changes in the sub-types of the global variables defined in
first-shared-library
· --added-vars
In the resulting report about the differences between
first-shared-library and second-shared-library, only display the
global variables that were added (defined) to
second-shared-library.
· --no-added-syms
In the resulting report about the differences between
first-shared-library and second-shared-library, do not display
added functions or variables. Do not display added functions or
variables ELF symbols either. All other kinds of changes are
displayed unless they are explicitely forbidden by other options
on the command line.
· --no-linkage-name
In the resulting report, do not display the linkage names of the
added, removed, or changed functions or variables.
· --no-show-locs
Do not show information about where in the second shared
library the respective type was changed.
· --no-show-relative-offset-changes
Without this option, when the offset of a data member changes,
the change report not only mentions the older and newer offset,
but it also mentions by how many bits the data member changes.
With this option, the latter is not shown.
· --no-unreferenced-symbols
In the resulting report, do not display change information about
function and variable symbols that are not referenced by any
debug information. Note that for these symbols not referenced
by any debug information, the change information displayed is
either added or removed symbols.
· --no-default-suppression
Do not load the default suppression specification files.
· --suppressions | --suppr <path-to-suppressions>
Use a suppression specification file located at
path-to-suppressions. Note that this option can appear multiple
times on the command line. In that case, all of the provided
suppression specification files are taken into account.
Please note that, by default, if this option is not provided,
then the default suppression specification files are loaded .
· --drop <regex>
When reading the first-shared-library and second-shared-library
ELF input files, drop the globally defined functions and
variables which name match the regular expression regex. As a
result, no change involving these functions or variables will be
emitted in the diff report.
· --drop-fn <regex>
When reading the first-shared-library and second-shared-library
ELF input files, drop the globally defined functions which name
match the regular expression regex. As a result, no change
involving these functions will be emitted in the diff report.
· --drop-var <regex>
When reading the first-shared-library and second-shared-library
ELF input files, drop the globally defined variables matching a
the regular expression regex.
· --keep <regex>
When reading the first-shared-library and second-shared-library
ELF input files, keep the globally defined functions and
variables which names match the regular expression regex. All
other functions and variables are dropped on the floor and will
thus not appear in the resulting diff report.
· --keep-fn <regex>
When reading the first-shared-library and second-shared-library
ELF input files, keep the globally defined functions which name
match the regular expression regex. All other functions are
dropped on the floor and will thus not appear in the resulting
diff report.
· --keep-var <regex>
When reading the first-shared-library and second-shared-library
ELF input files, keep the globally defined which names match the
regular expression regex. All other variables are dropped on
the floor and will thus not appear in the resulting diff report.
· --harmless
In the diff report, display only the harmless changes. By
default, the harmless changes are filtered out of the diff
report keep the clutter to a minimum and have a greater chance
to spot real ABI issues.
· --no-harmful
In the diff report, do not display the harmful changes. By
default, only the harmful changes are displayed in diff report.
· --redundant
In the diff report, do display redundant changes. A redundant
change is a change that has been displayed elsewhere in the
report.
· --no-redundant
In the diff report, do NOT display redundant changes. A
redundant change is a change that has been displayed elsewhere
in the report. This option is switched on by default.
· --no-architecture
Do not take architecture in account when comparing ABIs.
· --no-corpus-path
Do not emit the path attribute for the ABI corpus.
· --dump-diff-tree
After the diff report, emit a textual representation of the
diff nodes tree used by the comparison engine to represent the
changed functions and variables. That representation is
emitted to the error output for debugging purposes. Note that
this diff tree is relevant only to functions and variables
that have some sub-type changes. Added or removed functions
and variables do not have any diff nodes tree associated to
them.
· --stats
Emit statistics about various internal things.
· --verbose
Emit verbose logs about the progress of miscellaneous internal
things.
The exit code of the abidiff command is either 0 if the ABI of the
binaries being compared are equal, or non-zero if they differ or if
the tool encountered an error.
In the later case, the exit code is a 8-bits-wide bit field in which
each bit has a specific meaning.
The first bit, of value 1, named ABIDIFF_ERROR means there was an
error.
The second bit, of value 2, named ABIDIFF_USAGE_ERROR means there was
an error in the way the user invoked the tool. It might be set, for
instance, if the user invoked the tool with an unknown command line
switch, with a wrong number or argument, etc. If this bit is set,
then the ABIDIFF_ERROR bit must be set as well.
The third bit, of value 4, named ABIDIFF_ABI_CHANGE means the ABI of
the binaries being compared are different.
The fourth bit, of value 8, named ABIDIFF_ABI_INCOMPATIBLE_CHANGE
means the ABI of the binaries compared are different in an
incompatible way. If this bit is set, then the ABIDIFF_ABI_CHANGE
bit must be set as well. If the ABIDIFF_ABI_CHANGE is set and the
ABIDIFF_INCOMPATIBLE_CHANGE is NOT set, then it means that the ABIs
being compared might or might not be compatible. In that case, a
human being needs to review the ABI changes to decide if they are
compatible or not.
Note that, at the moment, there are only a few kinds of ABI changes
that would result in setting the flag
ABIDIFF_ABI_INCOMPATIBLE_CHANGE. Those ABI changes are either:
· the removal of the symbol of a function or variable that has
been defined and exported.
· the modification of the index of a member of a virtual function
table (for C++ programs and libraries).
With time, when more ABI change patterns are found to always
constitute incompatible ABI changes, we will adapt the code to
recognize those cases and set the ABIDIFF_ABI_INCOMPATIBLE_CHANGE
accordingly. So, if you find such patterns, please let us know.
The remaining bits are not used for the moment.
1. Detecting a change in a sub-type of a function:
$ cat -n test-v0.cc
1 // Compile this with:
2 // g++ -g -Wall -shared -o libtest-v0.so test-v0.cc
3
4 struct S0
5 {
6 int m0;
7 };
8
9 void
10 foo(S0* /*parameter_name*/)
11 {
12 // do something with parameter_name.
13 }
$
$ cat -n test-v1.cc
1 // Compile this with:
2 // g++ -g -Wall -shared -o libtest-v1.so test-v1.cc
3
4 struct type_base
5 {
6 int inserted;
7 };
8
9 struct S0 : public type_base
10 {
11 int m0;
12 };
13
14 void
15 foo(S0* /*parameter_name*/)
16 {
17 // do something with parameter_name.
18 }
$
$ g++ -g -Wall -shared -o libtest-v0.so test-v0.cc
$ g++ -g -Wall -shared -o libtest-v1.so test-v1.cc
$
$ ../build/tools/abidiff libtest-v0.so libtest-v1.so
Functions changes summary: 0 Removed, 1 Changed, 0 Added function
Variables changes summary: 0 Removed, 0 Changed, 0 Added variable
1 function with some indirect sub-type change:
[C]'function void foo(S0*)' has some indirect sub-type changes:
parameter 0 of type 'S0*' has sub-type changes:
in pointed to type 'struct S0':
size changed from 32 to 64 bits
1 base class insertion:
struct type_base
1 data member change:
'int S0::m0' offset changed from 0 to 32
$
2. Detecting another change in a sub-type of a function:
$ cat -n test-v0.cc
1 // Compile this with:
2 // g++ -g -Wall -shared -o libtest-v0.so test-v0.cc
3
4 struct S0
5 {
6 int m0;
7 };
8
9 void
10 foo(S0& /*parameter_name*/)
11 {
12 // do something with parameter_name.
13 }
$
$ cat -n test-v1.cc
1 // Compile this with:
2 // g++ -g -Wall -shared -o libtest-v1.so test-v1.cc
3
4 struct S0
5 {
6 char inserted_member;
7 int m0;
8 };
9
10 void
11 foo(S0& /*parameter_name*/)
12 {
13 // do something with parameter_name.
14 }
$
$ g++ -g -Wall -shared -o libtest-v0.so test-v0.cc
$ g++ -g -Wall -shared -o libtest-v1.so test-v1.cc
$
$ ../build/tools/abidiff libtest-v0.so libtest-v1.so
Functions changes summary: 0 Removed, 1 Changed, 0 Added function
Variables changes summary: 0 Removed, 0 Changed, 0 Added variable
1 function with some indirect sub-type change:
[C]'function void foo(S0&)' has some indirect sub-type changes:
parameter 0 of type 'S0&' has sub-type changes:
in referenced type 'struct S0':
size changed from 32 to 64 bits
1 data member insertion:
'char S0::inserted_member', at offset 0 (in bits)
1 data member change:
'int S0::m0' offset changed from 0 to 32
$
3. Detecting that functions got removed or added to a library:
$ cat -n test-v0.cc
1 // Compile this with:
2 // g++ -g -Wall -shared -o libtest-v0.so test-v0.cc
3
4 struct S0
5 {
6 int m0;
7 };
8
9 void
10 foo(S0& /*parameter_name*/)
11 {
12 // do something with parameter_name.
13 }
$
$ cat -n test-v1.cc
1 // Compile this with:
2 // g++ -g -Wall -shared -o libtest-v1.so test-v1.cc
3
4 struct S0
5 {
6 char inserted_member;
7 int m0;
8 };
9
10 void
11 bar(S0& /*parameter_name*/)
12 {
13 // do something with parameter_name.
14 }
$
$ g++ -g -Wall -shared -o libtest-v0.so test-v0.cc
$ g++ -g -Wall -shared -o libtest-v1.so test-v1.cc
$
$ ../build/tools/abidiff libtest-v0.so libtest-v1.so
Functions changes summary: 1 Removed, 0 Changed, 1 Added functions
Variables changes summary: 0 Removed, 0 Changed, 0 Added variable
1 Removed function:
'function void foo(S0&)' {_Z3fooR2S0}
1 Added function:
'function void bar(S0&)' {_Z3barR2S0}
$
Dodji Seketeli
2014-2016, Red Hat, Inc.
This page is part of the libabigail (ABI Generic Analysis and
Instrumentation Library) project. Information about the project can
be found at ⟨https://sourceware.org/libabigail/⟩. If you have a bug
report for this manual page, see
⟨http://sourceware.org/bugzilla/enter_bug.cgi?product=libabigail⟩.
This page was obtained from the project's upstream Git repository
⟨git://sourceware.org/git/libabigail.git⟩ on 2017-07-05. If you dis‐
cover any rendering problems in this HTML version of the page, or you
believe there is a better or more up-to-date source for the page, or
you have corrections or improvements to the information in this
COLOPHON (which is not part of the original manual page), send a mail
to man-pages@man7.org
Jul 05, 2017 ABIDIFF(1)