NAME

       icheck - C interface ABI/API checker

SYNOPSIS

       icheck --canonify [[--baseline FILE] ...]  [OPTIONS] [GCC_OPTIONS] [--] files

       icheck --compare [OPTIONS] old_file new_file

DESCRIPTION

       A  tool  for  statically  checking C interfaces for API and ABI changes. All changes to type declarations
       that can cause ABI changes should be detected, along with most API changes.

       icheck is intended for use with libraries, as a method of preventing ABI drift.

COMMANDS

       Reduce a set of source files to a canonical  interface  file  with  --canonify,  then  compare  two  such
       interface  files  with  --compare.  If there are interface changes between them, icheck will describe the
       changes and fail.

       --canonify [[--baseline FILE] ...]  [OPTIONS] [GCC_OPTIONS] [--] files

              Canonify the source code files (typically .h headers) to be compared later with --compare. Usually
              used with the -o option to save the summary to a file.

       --compare [OPTIONS] old_file new_file

              Reads two canonical interface files generated with --canonify and compares the  structure  of  the
              source  code  to  the changes in the Application Public Interface (the developer interface or API)
              and the Application Binary Interface (ABI) used to link against other programs or libraries.

OPTIONS

   ICHECK OPTIONS
       -o, --output FILE

              Emit output to FILE, rather than stdout.

       --debug N

              Dump debugging information.

       --only THING

              Only process the given THING.

       --skip-from FILE

              Skip unnecessary things from FILE.

       --skip-from-re regexp

              Skip unnecessary things from files matching the regular expression.

       --only-from FILE

              Only take things from FILE.

       --only-from-re regexp

              Only take things from files matching the regular expression.

       GCC_OPTIONS

              GCC_OPTIONS are passed through to gcc -E

   HELP OPTIONS
       --help
              Display the help synopsis for icheck.

EXAMPLES

       All source files are preprocessed with gcc, so canonify needs the same include information as the  source
       code  -  follow  the syntax from the Makefile to include -I options to cpp (or gcc) so that all necessary
       headers can be located. icheck will abort if any required headers cannot be found.  The  source  must  be
       compileable;  icheck  cannot  process  files  which  cannot  be directly compiled. If a header is missing
       #include statements, or otherwise requires being used in a  special  way,  then  it  cannot  be  directly
       processed  with icheck. Instead, write a stub C file that sets things up appropriately and then #includes
       the header.

       icheck --canonify -o ~/icheck/oldversion -I/usr/include/foo-2.0 /usr/src/bar/src/foobar.h

       Prepare a text summary of the foobar.h file and all files it includes.  The summary  is  written  out  to
       ~/icheck/oldversion.   Repeat  for  /usr/src/bar1/src/foobar.h  -  the  same  file  in  the  newer source
       directory, outputting to a new file, e.g.  ~/icheck/newversion.

       icheck --compare -o ~/icheck/results.txt ~/icheck/oldversion ~/icheck/newversion

       Writes the report of the comparison of the two summary files. The report indicates all the changes in the
       ABI and/or API found during the comparison.

       icheck     --canonify     -o     debian/icheck.canonical     -Idebian/foo-dev/usr/include     debian/foo-
       dev/usr/include/foobar.h

       icheck --compare debian/icheck.manifest debian/icheck.canonical

       These two statements, included in a debian/rules file, will cause the package build to fail if the API or
       ABI  has  changed in unexpected ways, where icheck.manifest is a copy of the expected interface, included
       in the package.

       Note that  the  arguments  to  --compare  are  themselves  valid  C  files  which  are  preprocessed,  so
       icheck.manifest  can  contain  C  preprocessor logic. This can be useful when a package exports different
       interfaces depending on the host architecture. In this case, you can't replace it  with  a  new  copy  of
       icheck.canonical when the interface changes and you need to update the manifest. Rather than updating the
       entire manifest by hand, put the hand-written interface descriptions in one file (icheck.static-manifest)
       and then use:

       icheck --canonify --baseline debian/icheck.static-manifest -o debian/icheck.dynamic-manifest

       Lastly, create icheck.manifest containing:
       #include "icheck.static-manifest"
       #include "icheck.dynamic-manifest"
       This  allows  you  to update some parts of the manifest by hand, while still automatically generating the
       rest.

OUTPUT

       icheck generates a lengthly description of every possible API or ABI change, based on  type  information.
       It  does not investigate the actual program code, and so it is possible that some type changes it detects
       are not actual ABI or API changes. However,  this  normally  only  happens  when  the  program  code  was
       explicitly written for it. If in doubt, assume it's changed.

       At  the end, icheck provides a summary of the changes. Note that the directions here are dependent on the
       order of the arguments to --compare: the older interface must come first, or the directions will  be  the
       other way around. The meanings of the various terms are as follows:

              ABI    The  ABI  is  compatible  if things compiled against one version of the interface will work
                     when run using the other version.

              API    The API is compatible if things compiled against  one  version  of  the  interface  can  be
                     compiled against the other.

              forwards-compatible
                     An  interface  is  forwards-compatible if things compiled against the old version will work
                     with the new. This is the important feature for soname changes.

              backwards-compatible
                     An interface is backwards-compatible if things compiled against the new version  will  work
                     with  the  old.  This  is  the  important feature for shlibs version changes. If you aren't
                     building Debian packages, you probably don't care about  changes  which  aren't  backwards-
                     compatible.

AUTHOR

       icheck was written by Andrew Suffield <asuffield@debian.org>.

       This   manual   page   was   written   by   Neil  Williams  <linux@codehelp.co.uk>  and  Andrew  Suffield
       <asuffield@debian.org>.

                                                                                                       icheck(1)