abidiff(1) — Linux manual page

NAME | INVOCATION | ENVIRONMENT | OPTIONS | RETURN VALUES | USAGE EXAMPLES | AUTHOR | COPYRIGHT | COLOPHON

ABIDIFF(1)                     Libabigail                     ABIDIFF(1)

NAME         top

       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.
       Otherwise, only ELF symbols that were added or removed are
       reported.

INVOCATION         top

          abidiff [options] <first-shared-library> <second-shared-library>

ENVIRONMENT         top

       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.

OPTIONS         top

--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.

            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.

          • --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

          • --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.

          • --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.

            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-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.

          • --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,
            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.

          • --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.

          • --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.

          • --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.

          • --show-bytes

            Show sizes and offsets in bytes, not bits.  By default,
            sizes and offsets are shown in bits.

          • --show-bits

            Show sizes and offsets in bits, not bytes.  This option is
            activated by default.

          • --show-hex

            Show sizes and offsets in hexadecimal base.

          • --show-dec

            Show sizes and offsets in decimal base.  This option is
            activated by default.

          • --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.

          • --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.

          • --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.

          • --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.

          • --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.

RETURN VALUES         top

       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.

USAGE EXAMPLES         top

          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}

                 $

AUTHOR         top

       Dodji Seketeli

COPYRIGHT         top

       2014-2016, Red Hat, Inc.

COLOPHON         top

       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 2021-04-01.  (At
       that time, the date of the most recent commit that was found in
       the repository was 2021-03-31.)  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
       man-pages@man7.org

                              Apr 01, 2021                    ABIDIFF(1)