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

ABICOMPAT(1)                     Libabigail                     ABICOMPAT(1)

NAME         top

       abicompat - check ABI compatibility

       abicompat  checks  that  an  application  that  links against a given
       shared library is still ABI compatible with a subsequent  version  of
       that  library.   If  the new version of the library introduces an ABI
       incompatibility, then abicompat hints the user at what  exactly  that
       incompatibility is.

INVOCATION         top

          abicompat [options] [<application> <shared-library-first-version> <shared-library-second-version>]

OPTIONS         top

          · --help

            Display a short help about the command and exit.

          · --version | -v

            Display the version of the program and exit.

          · --list-undefined-symbols | -u

            Display the list of undefined symbols of the application and
            exit.

          · --show-base-names | -b

            In the resulting report emitted by the tool, this option makes
            the application and libraries be referred to by their base names
            only; not by a full absolute name.  This can be useful for use
            in scripts that wants to compare names of the application and
            libraries independently of what their directory names are.

          · --app-debug-info-dir | --appd <path-to-app-debug-info-directory>

            Set the path to the directory under which the debug information
            of the application is supposed to be laid out.  This is useful
            for application binaries for which the debug info is in a
            separate set of files.

          · --lib-debug-info-dir1 | --libd1 <path-to-lib1-debug-info>

            Set the path to the directory under which the debug information
            of the first version of the shared library is supposed to be
            laid out.  This is useful for shared library binaries for which
            the debug info is in a separate set of files.

          · --lib-debug-info-dir2 | --libd2 <path-to-lib1-debug-info>

            Set the path to the directory under which the debug information
            of the second version of the shared library is supposed to be
            laid out.  This is useful for shared library binaries for which
            the debug info is in a separate set of 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; all the suppression specification
            files are then taken into account.

          · --no-show-locs
              Do not show information about where in the second shared
              library the respective type was changed.

          · --weak-mode

            This triggers the weak mode of abicompat.  In this mode, only
            one version of the library is required.  That is, abicompat is
            invoked like this:

                abicompat --weak-mode <the-application> <the-library>

            Note that the --weak-mode option can even be omitted if only one
            version of the library is given, along with the application; in
            that case, abicompat automatically switches to operate in weak
            mode:

                abicompat <the-application> <the-library>

            In this weak mode, the types of functions and variables exported
            by the library and consumed by the application (as in, the
            symbols of the these functions and variables are undefined in
            the application and are defined and exported by the library) are
            compared to the version of these types as expected by the
            application.  And if these two versions of types are different,
            abicompat tells the user what the differences are.

            In other words, in this mode, abicompat checks that the types of
            the functions and variables exported by the library mean the
            same thing as what the application expects, as far as the ABI is
            concerned.

            Note that in this mode, abicompat doesn't detect exported
            functions or variables (symbols) that are expected by the
            application but that are removed from the library.  That is why
            it is called weak mode.

RETURN VALUES         top

       The exit code of the abicompat 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.

       The remaining bits are not used for the moment.

USAGE EXAMPLES         top

          · Detecting a possible ABI incompatibility in a new shared library
            version:

                $ cat -n test0.h
                     1  struct foo
                     2  {
                     3    int m0;
                     4
                     5    foo()
                     6      : m0()
                     7    {}
                     8  };
                     9
                    10  foo*
                    11  first_func();
                    12
                    13  void
                    14  second_func(foo&);
                    15
                    16  void
                    17  third_func();
                $

                $ cat -n test-app.cc
                     1  // Compile with:
                     2  //  g++ -g -Wall -o test-app -L. -ltest-0 test-app.cc
                     3
                     4  #include "test0.h"
                     5
                     6  int
                     7  main()
                     8  {
                     9    foo* f = first_func();
                    10    second_func(*f);
                    11    return 0;
                    12  }
                $

                $ cat -n test0.cc
                     1  // Compile this with:
                     2  //  g++ -g -Wall -shared -o libtest-0.so test0.cc
                     3
                     4  #include "test0.h"
                     5
                     6  foo*
                     7  first_func()
                     8  {
                     9    foo* f = new foo();
                    10    return f;
                    11  }
                    12
                    13  void
                    14  second_func(foo&)
                    15  {
                    16  }
                    17
                    18  void
                    19  third_func()
                    20  {
                    21  }
                $

                $ cat -n test1.h
                     1  struct foo
                     2  {
                     3    int  m0;
                     4    char m1; /* <-- a new member got added here! */
                     5
                     6    foo()
                     7    : m0(),
                     8      m1()
                     9    {}
                    10  };
                    11
                    12  foo*
                    13  first_func();
                    14
                    15  void
                    16  second_func(foo&);
                    17
                    18  void
                    19  third_func();
                $

                $ cat -n test1.cc
                     1  // Compile this with:
                     2  //  g++ -g -Wall -shared -o libtest-1.so test1.cc
                     3
                     4  #include "test1.h"
                     5
                     6  foo*
                     7  first_func()
                     8  {
                     9    foo* f = new foo();
                    10    return f;
                    11  }
                    12
                    13  void
                    14  second_func(foo&)
                    15  {
                    16  }
                    17
                    18  /* Let's comment out the definition of third_func()
                    19     void
                    20     third_func()
                    21     {
                    22     }
                    23  */
                $

            · Compile the first and second versions of the libraries:
              libtest-0.so and libtest-1.so:

                  $ g++ -g -Wall -shared -o libtest-0.so test0.cc
                  $ g++ -g -Wall -shared -o libtest-1.so test1.cc

            · Compile the application and link it against the first version
              of the library, creating the test-app binary:

                  $ g++ -g -Wall -o test-app -L. -ltest-0.so test-app.cc

            · Now, use abicompat to see if libtest-1.so is ABI compatible
              with app, with respect to the ABI of libtest-0.so:

                  $ abicompat test-app libtest-0.so libtest-1.so
                  ELF file 'test-app' might not be ABI compatible with 'libtest-1.so' due to differences with 'libtest-0.so' below:
                  Functions changes summary: 0 Removed, 2 Changed, 0 Added functions
                  Variables changes summary: 0 Removed, 0 Changed, 0 Added variable

                  2 functions with some indirect sub-type change:

                    [C]'function foo* first_func()' has some indirect sub-type changes:
                      return type changed:
                        in pointed to type 'struct foo':
                          size changed from 32 to 64 bits
                          1 data member insertion:
                            'char foo::m1', at offset 32 (in bits)
                    [C]'function void second_func(foo&)' has some indirect sub-type changes:
                      parameter 0 of type 'foo&' has sub-type changes:
                        referenced type 'struct foo' changed, as reported earlier

                  $

            · Now use the weak mode of abicompat, that is, providing just
              the application and the new version of the library:

                  $ abicompat --weak-mode test-app libtest-1.so
                  functions defined in library
                      'libtest-1.so'
                  have sub-types that are different from what application
                      'test-app'
                  expects:

                    function foo* first_func():
                      return type changed:
                        in pointed to type 'struct foo':
                          size changed from 32 to 64 bits
                          1 data member insertion:
                            'char foo::m1', at offset 32 (in bits)

                  $

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 2017-07-05.  If you dis‐
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       COLOPHON (which is not part of the original manual page), send a mail
       to man-pages@man7.org

                                Jul 05, 2017                    ABICOMPAT(1)