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.  Other‐
       wise, 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.

            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.

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 2017-09-15.  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

                                Sep 15, 2017                      ABIDIFF(1)