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NAME | INVOCATION | ENVIRONMENT | OPTIONS | RETURN VALUES | USAGE EXAMPLES | AUTHOR | COPYRIGHT | COLOPHON |
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ABIDIFF(1) Libabigail ABIDIFF(1)
abidiff - compare ABIs of ELF files
abidiff compares the Application Binary Interfaces (ABI) of two
shared libraries in ]8;;http://en.wikipedia.org/wiki/Executable_and_Linkable_Format\ELF]8;;\ 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 between two input shared
libraries that includes changes about function and variable
sub-types, abidiff uses by default, debug information in ]8;;http://www.dwarfstd.org\DWARF]8;;\
format, if present, otherwise it compares interfaces using debug
information in ]8;;https://raw.githubusercontent.com/wiki/oracle/binutils-gdb/files/ctf-spec.pdf\CTF]8;;\ or ]8;;https://docs.kernel.org/bpf/btf.html\BTF]8;;\ formats, if present. Finally, if no
debug info in these formats is found, it only considers ]8;;http://en.wikipedia.org/wiki/Executable_and_Linkable_Format\ELF]8;;\
symbols and report about their addition or removal.
This tool uses the libabigail library to analyze the binary as
well as its associated debug information. Here is its general
mode of operation.
When instructed to do so, a binary and its associated debug
information is read and analyzed. To that effect, libabigail
analyzes by default the descriptions of the types reachable by the
interfaces (functions and variables) that are visible outside of
their translation unit. Once that analysis is done, an
Application Binary Interface Corpus is constructed by only
considering the subset of types reachable from interfaces
associated to ]8;;http://en.wikipedia.org/wiki/Executable_and_Linkable_Format\ELF]8;;\ symbols that are defined and exported by the
binary. It's that final ABI corpus which libabigail considers as
representing the ABI of the analyzed binary.
Libabigail then has capabilities to generate textual
representations of ABI Corpora, compare them, analyze their
changes and report about them.
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.
• --add-binaries1 <bin1,bin2,bin3,..>
For each of the comma-separated binaries given in argument to
this option, if the binary is found in the directory
specified by the --added-binaries-dir1 option, then abidiff
loads the ABI corpus of the binary and adds it to a set of
corpora (called an ABI Corpus Group) that includes the first
argument of abidiff.
That ABI corpus group is then compared against the second
corpus group given in argument to abidiff.
• --add-binaries2 <bin1,bin2,bin3,..>
For each of the comma-separated binaries given in argument to
this option, if the binary is found in the directory
specified by the --added-binaries-dir2 option, then abidiff
loads the ABI corpus of the binary and adds it to a set of
corpora(called an ABI Corpus Group) that includes the second
argument of abidiff.
That ABI corpus group is then compared against the first
corpus group given in argument to abidiff.
• --added-binaries-dir1 | --abd1 <added-binaries-directory-1>
This option is to be used in conjunction with the
--add-binaries1, --follow-dependencies and
--list-dependencies options. Binaries referred to by these
options, if found in the directory
added-binaries-directory-1, are loaded as ABI corpus and are
added to the first ABI corpus group that is to be used in the
comparison.
• --added-binaries-dir2 | --abd2 <added-binaries-directory-2>
This option is to be used in conjunction with the
--add-binaries2, --follow-dependencies and
--list-dependencies options. Binaries referred to by these
options, if found in the directory
added-binaries-directory-2, are loaded as ABI corpus and are
added to the second ABI corpus group to be used in the
comparison.
• --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.
• --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.
• --allow-non-exported-interfaces
When looking at the debug information accompanying a binary,
this tool analyzes the descriptions of the types reachable by
the interfaces (functions and variables) that are visible
outside of their translation unit. Once that analysis is
done, an ABI corpus is constructed by only considering the
subset of types reachable from interfaces associated to ]8;;http://en.wikipedia.org/wiki/Executable_and_Linkable_Format\ELF]8;;\
symbols that are defined and exported by the binary. It's
those final ABI Corpora that are compared by this tool.
The problem with that approach however is that analyzing all
the interfaces that are visible from outside their
translation unit can amount to a lot of data, especially when
those binaries are applications, as opposed to shared
libraries. One example of such applications is the ]8;;https://kernel.org/\Linux
Kernel]8;;\. Analyzing massive ABI Corpora like these can be
extremely slow.
In the presence of an "average sized" binary however one can
afford having libabigail analyze all interfaces that are
visible outside of their translation unit, using this option.
Note that this option is turned on by default, unless we are
in the presence of the ]8;;https://kernel.org/\Linux Kernel]8;;\.
• --btf
When comparing binaries, extract ABI information from ]8;;https://docs.kernel.org/bpf/btf.html\BTF]8;;\
debug information, if present.
• --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.
• --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
• --ctf
When comparing binaries, extract ABI information from ]8;;https://raw.githubusercontent.com/wiki/oracle/binutils-gdb/files/ctf-spec.pdf\CTF]8;;\
debug information, if present.
• --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.
This option can be provided several times with different root
directories. In that case, abidiff will potentially look
into all those root directories to find the split debug info
for first-shared-library.
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.
This option can be provided several times with different root
directories. In that case, abidiff will potentially look
into all those root directories to find the split debug info
for second-shared-library.
• --debug-self-comparison
In this mode, error messages are emitted for types which fail
type canonicalization, in some circumstances, when comparing
a binary against itself.
When comparing a binary against itself, canonical types of
the second binary should be equal (as much as possible) to
canonical types of the first binary. When some discrepancies
are detected in this mode, an abort signal is emitted and
execution is halted. This option should be used while
executing the tool in a debugger, for troubleshooting
purposes.
This is an optional debugging and sanity check option. To
enable it the libabigail package needs to be configured with
the --enable-debug-self-comparison configure option.
• --debug-tc
In this mode, the process of type canonicalization is put
under heavy scrutiny. Basically, during type
canonicalization, each type comparison is performed twice:
once in a structural mode (comparing every sub-type
member-wise), and once using canonical comparison. The two
comparisons should yield the same result. Otherwise, an
abort signal is emitted and the process can be debugged to
understand why the two kinds of comparison yield different
results.
This is an optional debugging and sanity check option. To
enable it the libabigail package needs to be configured with
the --enable-debug-type-canonicalization configure option.
• --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.
• --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.
• --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.
• --drop-private-types
This option is to be used with the --headers-dir1,
header-file1, header-file2 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.
• --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.
• --exported-interfaces-only
By default, when looking at the debug information
accompanying a binary, this tool analyzes the descriptions of
the types reachable by the interfaces (functions and
variables) that are visible outside of their translation
unit. Once that analysis is done, an ABI corpus is
constructed by only considering the subset of types reachable
from interfaces associated to ]8;;http://en.wikipedia.org/wiki/Executable_and_Linkable_Format\ELF]8;;\ symbols that are defined
and exported by the binary. It's those final ABI Corpora
that are compared by this tool.
The problem with that approach however is that analyzing all
the interfaces that are visible from outside their
translation unit can amount to a lot of data, especially when
those binaries are applications, as opposed to shared
libraries. One example of such applications is the ]8;;https://kernel.org/\Linux
Kernel]8;;\. Analyzing massive ABI corpora like these can be
extremely slow.
To mitigate that performance issue, this option allows
libabigail to only analyze types that are reachable from
interfaces associated with defined and exported ]8;;http://en.wikipedia.org/wiki/Executable_and_Linkable_Format\ELF]8;;\ symbols.
Note that this option is turned on by default when analyzing
the ]8;;https://kernel.org/\Linux Kernel]8;;\. Otherwise, it's turned off by default.
• --fail-no-debug-info
If no debug info was found, then this option makes the
program to fail. Otherwise, without this option, the program
will attempt to compare properties of the binaries that are
not related to debug info, like pure ELF properties.
• --follow-dependencies | --fdeps
For each dependency of the first argument of abidiff, if it's
found in the directory specified by the --added-binaries-dir1
option, then construct an ABI corpus out of the dependency,
add it to a set of corpora (called an ABI Corpus Group) that
includes the first argument of abidiff.
Similarly, for each dependency of the second argument of
abidiff, if it's found in the directory specified by the
--added-binaries-dir2 option, then construct an ABI corpus
out of the dependency, add it to an ABI corpus group that
includes the second argument of abidiff.
These two ABI corpus groups are then compared against each
other.
Said otherwise, this makes abidiff compare the set of its
first input and its dependencies against the set of its
second input and its dependencies.
• --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.
• --headers-dir1 | --hd1 <headers-directory-path-1>
Specifies where to find the public headers of the first
shared library (or binary in general) that the tool has to
consider. The tool will thus filter out ABI changes on types
that are not defined in public headers.
Note that several public header directories can be specified
for the first shared library. In that case the
--headers-dir1 option should be present several times on the
command line, like in the following example:
$ abidiff --headers-dir1 /some/path \
--headers-dir1 /some/other/path \
binary-version-1 binary-version-2
• --headers-dir2 | --hd2 <headers-directory-path-2>
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.
Note that several public header directories can be specified
for the second shared library. In that case the
--headers-dir2 option should be present several times like in
the following example:
$ abidiff --headers-dir2 /some/path \
--headers-dir2 /some/other/path \
binary-version-1 binary-version-2
• --header-file1 | --hf1 <header-file-path-1>
Specifies where to find one public header 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.
• --header-file2 | --hf2 <header-file-path-2>
Specifies where to find one public header 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.
• --help | -h
Display a short help about the command and exit.
• --ignore-soname
Ignore differences in the SONAME when doing a comparison
• --impacted-interfaces
When showing leaf changes, this option instructs abidiff to
show the list of impacted interfaces. This option is thus to
be used in addition the --leaf-changes-only option,
otherwise, it's ignored.
• --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.
• --kmi-whitelist | -w <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.
• --leaf-changes-only|-l only show leaf changes, so don't show
impact analysis report. This option implies --redundant.
The typical output of abidiff when comparing two binaries
looks like this
$ 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 fn(C&)' at test-v1.cc:13:1 has some indirect sub-type changes:
parameter 1 of type 'C&' has sub-type changes:
in referenced type 'struct C' at test-v1.cc:7:1:
type size hasn't changed
1 data member change:
type of 'leaf* C::m0' changed:
in pointed to type 'struct leaf' at test-v1.cc:1:1:
type size changed from 32 to 64 bits
1 data member insertion:
'char leaf::m1', at offset 32 (in bits) at test-v1.cc:4:1
$
So in that example the report emits information about how the
data member insertion change of "struct leaf" is reachable
from function "void fn(C&)". In other words, the report not
only shows the data member change on "struct leaf", but it
also shows the impact of that change on the function "void
fn(C&)".
In abidiff parlance, the change on "struct leaf" is called a
leaf change. So the --leaf-changes-only
--impacted-interfaces options show, well, only the leaf
change. And it goes like this:
$ abidiff -l libtest-v0.so libtest-v1.so
'struct leaf' changed:
type size changed from 32 to 64 bits
1 data member insertion:
'char leaf::m1', at offset 32 (in bits) at test-v1.cc:4:1
one impacted interface:
function void fn(C&)
$
Note how the report ends by showing the list of interfaces
impacted by the leaf change.
Now if you don't want to see that list of impacted
interfaces, then you can just avoid using the
--impacted-interface option. You can learn about that option
below, in any case.
• --list-dependencies | --ldeps
This option lists all the dependencies of the input arguments
of abidiff that are found in the directories specified by the
options --added-binaries-dir1 and --added-binaries-dir2
• --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-assume-odr-for-cplusplus
When analyzing a binary originating from C++ code using ]8;;http://www.dwarfstd.org\DWARF]8;;\
debug information, libabigail assumes the ]8;;https://en.wikipedia.org/wiki/One_Definition_Rule\One Definition Rule]8;;\
to speed-up the analysis. In that case, when several types
have the same name in the binary, they are assumed to all be
equal.
This option disables that assumption and instructs libabigail
to actually actually compare the types to determine if they
are equal.
• --no-architecture
Do not take architecture in account when comparing ABIs.
• --no-change-categorization | -x
This option disables the categorization of changes into
harmless and harmful changes. Note that this categorization
is a pre-requisite for the filtering of changes so this
option disables that filtering. The goal of this option is
to speed-up the execution of the program for cases where the
graph of changes is huge and where the user is just
interested in looking at, for instance, leaf node changes
without caring about their possible impact on interfaces. In
that case, this option would be used along with the
--leaf-changes-only one.
• --no-corpus-path
Do not emit the path attribute for the ABI corpus.
• --no-default-suppression
Do not load the default suppression specification files.
• --no-harmful
In the diff report, do not display the harmful changes. By
default, only the harmful changes are displayed in diff
report.
• --no-leverage-dwarf-factorization
When analyzing a binary which ]8;;http://www.dwarfstd.org\DWARF]8;;\ debug information was
processed with the ]8;;https://sourceware.org/dwz\DWZ]8;;\ tool, the type information is supposed
to be already factorized. That context is used by libabigail
to perform some speed optimizations.
This option disables those optimizations.
• --no-linkage-name
In the resulting report, do not display the linkage names of
the added, removed, or changed functions or variables.
• --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.
• --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-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.
• --non-reachable-types|-t
Analyze and emit change reports for all the types of the
binary, including those that are not reachable from global
functions and variables.
This option might incur some serious performance degradation
as the number of types analyzed can be huge. However, if
paired with the --headers-dir{1,2} and/or header-file{1,2}
options, the additional non-reachable types analyzed are
restricted to those defined in public headers files, thus
hopefully making the performance hit acceptable.
Also, using this option alongside suppression specifications
(by also using the --suppressions option) might help keep the
number of analyzed types (and the potential performance
degradation) in control.
Note that without this option, only types that are reachable
from global functions and variables are analyzed, so the tool
detects and reports changes on these reachable types only.
• --redundant
In the diff report, do display redundant changes. A
redundant change is a change that has been displayed
elsewhere in the report.
• --show-bits
Show sizes and offsets in bits, not bytes. This option is
activated by default.
• --show-bytes
Show sizes and offsets in bytes, not bits. By default, sizes
and offsets are shown in bits.
• --show-dec
Show sizes and offsets in decimal base. This option is
activated by default.
• --show-hex
Show sizes and offsets in hexadecimal base.
• --stat
Rather than displaying the detailed ABI differences between
first-shared-library and second-shared-library, just display
some summary statistics about these differences.
• --stats
Emit statistics about various internal things.
• --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 .
• --symtabs
Only display the symbol tables of the first-shared-library
and second-shared-library.
• --verbose
Emit verbose logs about the progress of miscellaneous
internal things.
• --version | -v
Display the version of the program and exit.
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 an ABI 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
$
$ abidiff libtest-v0.so libtest-v1.so; echo "exit code: $?"
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
exit code: 4
$
Note how the exit code is 4, meaning the third bit
ABIDIFF_ABI_CHANGE of value 4 is set to 1. This means the tool
categorizes the ABI change as harmful and thus requires a user
review.
2. Detecting an incompatible ABI change in the 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 S0
10 foo()
11 {
12 S0 s = {};
13 return s;
14 }
$
$ 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 S0
15 foo()
16 {
17 S0 s = {};
18 return s;
19 }
$
$ g++ -g -Wall -shared -o libtest-v0.so test-v0.cc
$ g++ -g -Wall -shared -o libtest-v1.so test-v1.cc
$
$ abidiff libtest-v0.so libtest-v1.so; echo "exit code: $?"
Functions changes summary: 0 Removed, 1 Changed, 0 Added function
Variables changes summary: 0 Removed, 0 Changed, 0 Added variable
1 function with incompatible sub-type changes:
[C] 'function S0 foo(void)' at test-v0.cc:10:1 has some sub-type changes:
return type changed:
type size changed from 32 to 64 (in bits)
1 base class insertion:
struct type_base at test-v1.cc:4:1
1 data member change:
'int m0' offset changed from 0 to 32 (in bits) (by +32 bits)
exit code: 12
$
Note how the exit code is 12, meaning both the third bit
ABIDIFF_ABI_CHANGE of value 4 and the fourth bit
ABIDIFF_ABI_INCOMPATIBLE_CHANGE of value 8 are set to 1. This
means the tool categorizes the ABI change as incompatible. It's
an ABI break.
3. 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
$
$ abidiff libtest-v0.so libtest-v1.so; echo "exit code: $?"
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
exit code: 4
$
4. 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
$
$ abidiff libtest-v0.so libtest-v1.so; echo "exit code: $?"
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}
exit code: 12
$
5. Comparing two sets of binaries that are passed on the
command line:
$ abidiff --add-binaries1=file2-v1 \
--add-binaries2=file2-v2,file2-v1 \
--added-binaries-dir1 dir1 \
--added-binaries-dir2 dir2 \
file1-v1 file1-v2
Note that the files file2-v1, and file2-v2 are to be found
in dir1 and dir2 or in the current directory.
6. Compare two libraries and their dependencies:
$ abidiff --follow-dependencies \
--added-binaries-dir1 /some/where \
--added-binaries-dir2 /some/where/else \
foo bar
This compares the set of binaries comprised by foo and its
dependencies against the set of binaries comprised by bar
and its dependencies.
Dodji Seketeli
2014-2025, 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 2025-08-11. (At that
time, the date of the most recent commit that was found in the
repository was 2025-07-28.) If you discover 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
[email protected]
Aug 11, 2025 ABIDIFF(1)
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