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    1 Design document for the unified scheme data
    2 ===========================================
    3 
    4 How are things connected?
    5 -------------------------
    6 
    7 The unified scheme takes all its data from the build.info files seen
    8 throughout the source tree.  These files hold the minimum information
    9 needed to build end product files from diverse sources.  See the
   10 section on build.info files below.
   11 
   12 From the information in build.info files, Configure builds up an
   13 information database as a hash table called %unified_info, which is
   14 stored in configdata.pm, found at the top of the build tree (which may
   15 or may not be the same as the source tree).
   16 
   17 Configurations/common.tmpl uses the data from %unified_info to
   18 generate the rules for building end product files as well as
   19 intermediary files with the help of a few functions found in the
   20 build-file templates.  See the section on build-file templates further
   21 down for more information.
   22 
   23 build.info files
   24 ----------------
   25 
   26 As mentioned earlier, build.info files are meant to hold the minimum
   27 information needed to build output files, and therefore only (with a
   28 few possible exceptions [1]) have information about end products (such
   29 as scripts, library files and programs) and source files (such as C
   30 files, C header files, assembler files, etc).  Intermediate files such
   31 as object files are rarely directly referred to in build.info files (and
   32 when they are, it's always with the file name extension .o), they are
   33 inferred by Configure.  By the same rule of minimalism, end product
   34 file name extensions (such as .so, .a, .exe, etc) are never mentioned
   35 in build.info.  Their file name extensions will be inferred by the
   36 build-file templates, adapted for the platform they are meant for (see
   37 sections on %unified_info and build-file templates further down).
   38 
   39 The variables PROGRAMS, LIBS, ENGINES and SCRIPTS are used to declare
   40 end products.  There are variants for them with '_NO_INST' as suffix
   41 (PROGRAM_NO_INST etc) to specify end products that shouldn't get
   42 installed.
   43 
   44 The variables SOURCE, DEPEND and INCLUDE are indexed by a produced
   45 file, and their values are the source used to produce that particular
   46 produced file, extra dependencies, and include directories needed.
   47 
   48 All their values in all the build.info throughout the source tree are
   49 collected together and form a set of programs, libraries, engines and
   50 scripts to be produced, source files, dependencies, etc etc etc.
   51 
   52 Let's have a pretend example, a very limited contraption of OpenSSL,
   53 composed of the program 'apps/openssl', the libraries 'libssl' and
   54 'libcrypto', an engine 'engines/ossltest' and their sources and
   55 dependencies.
   56 
   57     # build.info
   58     LIBS=libcrypto libssl
   59     INCLUDE[libcrypto]=include
   60     INCLUDE[libssl]=include
   61     DEPEND[libssl]=libcrypto
   62 
   63 This is the top directory build.info file, and it tells us that two
   64 libraries are to be built, the include directory 'include/' shall be
   65 used throughout when building anything that will end up in each
   66 library, and that the library 'libssl' depend on the library
   67 'libcrypto' to function properly.
   68 
   69     # apps/build.info
   70     PROGRAMS=openssl
   71     SOURCE[openssl]=openssl.c
   72     INCLUDE[openssl]=.. ../include
   73     DEPEND[openssl]=../libssl
   74 
   75 This is the build.info file in 'apps/', one may notice that all file
   76 paths mentioned are relative to the directory the build.info file is
   77 located in.  This one tells us that there's a program to be built
   78 called 'apps/openssl' (the file name extension will depend on the
   79 platform and is therefore not mentioned in the build.info file).  It's
   80 built from one source file, 'apps/openssl.c', and building it requires
   81 the use of '.' and 'include' include directories (both are declared
   82 from the point of view of the 'apps/' directory), and that the program
   83 depends on the library 'libssl' to function properly.
   84 
   85     # crypto/build.info
   86     LIBS=../libcrypto
   87     SOURCE[../libcrypto]=aes.c evp.c cversion.c
   88     DEPEND[cversion.o]=buildinf.h
   89 
   90     GENERATE[buildinf.h]=../util/mkbuildinf.pl "$(CC) $(CFLAGS)" "$(PLATFORM)"
   91     DEPEND[buildinf.h]=../Makefile
   92     DEPEND[../util/mkbuildinf.pl]=../util/Foo.pm
   93 
   94 This is the build.info file in 'crypto', and it tells us a little more
   95 about what's needed to produce 'libcrypto'.  LIBS is used again to
   96 declare that 'libcrypto' is to be produced.  This declaration is
   97 really unnecessary as it's already mentioned in the top build.info
   98 file, but can make the info file easier to understand.  This is to
   99 show that duplicate information isn't an issue.
  100 
  101 This build.info file informs us that 'libcrypto' is built from a few
  102 source files, 'crypto/aes.c', 'crypto/evp.c' and 'crypto/cversion.c'.
  103 It also shows us that building the object file inferred from
  104 'crypto/cversion.c' depends on 'crypto/buildinf.h'.  Finally, it
  105 also shows the possibility to declare how some files are generated
  106 using some script, in this case a perl script, and how such scripts
  107 can be declared to depend on other files, in this case a perl module.
  108 
  109 Two things are worth an extra note:
  110 
  111 'DEPEND[cversion.o]' mentions an object file.  DEPEND indexes is the
  112 only location where it's valid to mention them
  113 
  114 Lines in 'BEGINRAW'..'ENDRAW' sections must always mention files as
  115 seen from the top directory, no exception.
  116 
  117     # ssl/build.info
  118     LIBS=../libssl
  119     SOURCE[../libssl]=tls.c
  120 
  121 This is the build.info file in 'ssl/', and it tells us that the
  122 library 'libssl' is built from the source file 'ssl/tls.c'.
  123 
  124     # engines/build.info
  125     ENGINES=dasync
  126     SOURCE[dasync]=e_dasync.c
  127     DEPEND[dasync]=../libcrypto
  128     INCLUDE[dasync]=../include
  129 
  130     ENGINES_NO_INST=ossltest
  131     SOURCE[ossltest]=e_ossltest.c
  132     DEPEND[ossltest]=../libcrypto.a
  133     INCLUDE[ossltest]=../include
  134 
  135 This is the build.info file in 'engines/', telling us that two engines
  136 called 'engines/dasync' and 'engines/ossltest' shall be built, that
  137 dasync's source is 'engines/e_dasync.c' and ossltest's source is
  138 'engines/e_ossltest.c' and that the include directory 'include/' may
  139 be used when building anything that will be part of these engines.
  140 Also, both engines depend on the library 'libcrypto' to function
  141 properly.  ossltest is explicitly linked with the static variant of
  142 the library 'libcrypto'.  Finally, only dasync is being installed, as
  143 ossltest is only for internal testing.
  144 
  145 When Configure digests these build.info files, the accumulated
  146 information comes down to this:
  147 
  148     LIBS=libcrypto libssl
  149     SOURCE[libcrypto]=crypto/aes.c crypto/evp.c crypto/cversion.c
  150     DEPEND[crypto/cversion.o]=crypto/buildinf.h
  151     INCLUDE[libcrypto]=include
  152     SOURCE[libssl]=ssl/tls.c
  153     INCLUDE[libssl]=include
  154     DEPEND[libssl]=libcrypto
  155 
  156     PROGRAMS=apps/openssl
  157     SOURCE[apps/openssl]=apps/openssl.c
  158     INCLUDE[apps/openssl]=. include
  159     DEPEND[apps/openssl]=libssl
  160 
  161     ENGINES=engines/dasync
  162     SOURCE[engines/dasync]=engines/e_dasync.c
  163     DEPEND[engines/dasync]=libcrypto
  164     INCLUDE[engines/dasync]=include
  165 
  166     ENGINES_NO_INST=engines/ossltest
  167     SOURCE[engines/ossltest]=engines/e_ossltest.c
  168     DEPEND[engines/ossltest]=libcrypto.a
  169     INCLUDE[engines/ossltest]=include
  170 
  171     GENERATE[crypto/buildinf.h]=util/mkbuildinf.pl "$(CC) $(CFLAGS)" "$(PLATFORM)"
  172     DEPEND[crypto/buildinf.h]=Makefile
  173     DEPEND[util/mkbuildinf.pl]=util/Foo.pm
  174 
  175 
  176 A few notes worth mentioning:
  177 
  178 LIBS may be used to declare routine libraries only.
  179 
  180 PROGRAMS may be used to declare programs only.
  181 
  182 ENGINES may be used to declare engines only.
  183 
  184 The indexes for SOURCE must only be end product files, such as
  185 libraries, programs or engines.  The values of SOURCE variables must
  186 only be source files (possibly generated).
  187 
  188 INCLUDE and DEPEND shows a relationship between different files
  189 (usually produced files) or between files and directories, such as a
  190 program depending on a library, or between an object file and some
  191 extra source file.
  192 
  193 When Configure processes the build.info files, it will take it as
  194 truth without question, and will therefore perform very few checks.
  195 If the build tree is separate from the source tree, it will assume
  196 that all built files and up in the build directory and that all source
  197 files are to be found in the source tree, if they can be found there.
  198 Configure will assume that source files that can't be found in the
  199 source tree (such as 'crypto/bildinf.h' in the example above) are
  200 generated and will be found in the build tree.
  201 
  202 
  203 The %unified_info database
  204 --------------------------
  205 
  206 The information in all the build.info get digested by Configure and
  207 collected into the %unified_info database, divided into the following
  208 indexes:
  209 
  210   depends   => a hash table containing 'file' => [ 'dependency' ... ]
  211                pairs.  These are directly inferred from the DEPEND
  212                variables in build.info files.
  213 
  214   engines   => a list of engines.  These are directly inferred from
  215                the ENGINES variable in build.info files.
  216 
  217   generate  => a hash table containing 'file' => [ 'generator' ... ]
  218                pairs.  These are directly inferred from the GENERATE
  219                variables in build.info files.
  220 
  221   includes  => a hash table containing 'file' => [ 'include' ... ]
  222                pairs.  These are directly inferred from the INCLUDE
  223                variables in build.info files.
  224 
  225   install   => a hash table containing 'type' => [ 'file' ... ] pairs.
  226                The types are 'programs', 'libraries', 'engines' and
  227                'scripts', and the array of files list the files of
  228                that type that should be installed.
  229 
  230   libraries => a list of libraries.  These are directly inferred from
  231                the LIBS variable in build.info files.
  232 
  233   programs  => a list of programs.  These are directly inferred from
  234                the PROGRAMS variable in build.info files.
  235 
  236   rawlines  => a list of build-file lines.  These are a direct copy of
  237                the BEGINRAW..ENDRAW lines in build.info files.  Note:
  238                only the BEGINRAW..ENDRAW section for the current
  239                platform are copied, the rest are ignored.
  240 
  241   scripts   => a list of scripts.  There are directly inferred from
  242                the SCRIPTS variable in build.info files.
  243 
  244   sources   => a hash table containing 'file' => [ 'sourcefile' ... ]
  245                pairs.  These are indirectly inferred from the SOURCE
  246                variables in build.info files.  Object files are
  247                mentioned in this hash table, with source files from
  248                SOURCE variables, and AS source files for programs and
  249                libraries.
  250 
  251   shared_sources =>
  252                a hash table just like 'sources', but only as source
  253                files (object files) for building shared libraries.
  254 
  255 As an example, here is how the build.info files example from the
  256 section above would be digested into a %unified_info table:
  257 
  258     our %unified_info = (
  259         "depends" =>
  260             {
  261                 "apps/openssl" =>
  262                     [
  263                         "libssl",
  264                     ],
  265                 "crypto/buildinf.h" =>
  266                     [
  267                         "Makefile",
  268                     ],
  269                 "crypto/cversion.o" =>
  270                     [
  271                         "crypto/buildinf.h",
  272                     ],
  273                 "engines/dasync" =>
  274                     [
  275                         "libcrypto",
  276                     ],
  277                 "engines/ossltest" =>
  278                     [
  279                         "libcrypto.a",
  280                     ],
  281                 "libssl" =>
  282                     [
  283                         "libcrypto",
  284                     ],
  285                 "util/mkbuildinf.pl" =>
  286                     [
  287                         "util/Foo.pm",
  288                     ],
  289             },
  290         "engines" =>
  291             [
  292                 "engines/dasync",
  293                 "engines/ossltest",
  294             ],
  295         "generate" =>
  296             {
  297                 "crypto/buildinf.h" =>
  298                     [
  299                         "util/mkbuildinf.pl",
  300                         "\"\$(CC)",
  301                         "\$(CFLAGS)\"",
  302                         "\"$(PLATFORM)\"",
  303                     ],
  304             },
  305         "includes" =>
  306             {
  307                 "apps/openssl" =>
  308                     [
  309                         ".",
  310                         "include",
  311                     ],
  312                 "engines/ossltest" =>
  313                     [
  314                         "include"
  315                     ],
  316                 "libcrypto" =>
  317                     [
  318                         "include",
  319                     ],
  320                 "libssl" =>
  321                     [
  322                         "include",
  323                     ],
  324                 "util/mkbuildinf.pl" =>
  325                     [
  326                         "util",
  327                     ],
  328             }
  329         "install" =>
  330             {
  331                 "engines" =>
  332                     [
  333                         "engines/dasync",
  334                     ],
  335                 "libraries" =>
  336                     [
  337                         "libcrypto",
  338                         "libssl",
  339                     ],
  340                 "programs" =>
  341                     [
  342                         "apps/openssl",
  343                     ],
  344            },
  345         "libraries" =>
  346             [
  347                 "libcrypto",
  348                 "libssl",
  349             ],
  350         "programs" =>
  351             [
  352                 "apps/openssl",
  353             ],
  354         "rawlines" =>
  355             [
  356             ],
  357         "sources" =>
  358             {
  359                 "apps/openssl" =>
  360                     [
  361                         "apps/openssl.o",
  362                     ],
  363                 "apps/openssl.o" =>
  364                     [
  365                         "apps/openssl.c",
  366                     ],
  367                 "crypto/aes.o" =>
  368                     [
  369                         "crypto/aes.c",
  370                     ],
  371                 "crypto/cversion.o" =>
  372                     [
  373                         "crypto/cversion.c",
  374                     ],
  375                 "crypto/evp.o" =>
  376                     [
  377                         "crypto/evp.c",
  378                     ],
  379                 "engines/e_dasync.o" =>
  380                     [
  381                         "engines/e_dasync.c",
  382                     ],
  383                 "engines/dasync" =>
  384                     [
  385                         "engines/e_dasync.o",
  386                     ],
  387                 "engines/e_ossltest.o" =>
  388                     [
  389                         "engines/e_ossltest.c",
  390                     ],
  391                 "engines/ossltest" =>
  392                     [
  393                         "engines/e_ossltest.o",
  394                     ],
  395                 "libcrypto" =>
  396                     [
  397                         "crypto/aes.c",
  398                         "crypto/cversion.c",
  399                         "crypto/evp.c",
  400                     ],
  401                 "libssl" =>
  402                     [
  403                         "ssl/tls.c",
  404                     ],
  405                 "ssl/tls.o" =>
  406                     [
  407                         "ssl/tls.c",
  408                     ],
  409             },
  410     );
  411 
  412 As can be seen, everything in %unified_info is fairly simple suggest
  413 of information.  Still, it tells us that to build all programs, we
  414 must build 'apps/openssl', and to build the latter, we will need to
  415 build all its sources ('apps/openssl.o' in this case) and all the
  416 other things it depends on (such as 'libssl').  All those dependencies
  417 need to be built as well, using the same logic, so to build 'libssl',
  418 we need to build 'ssl/tls.o' as well as 'libcrypto', and to build the
  419 latter...
  420 
  421 
  422 Build-file templates
  423 --------------------
  424 
  425 Build-file templates are essentially build-files (such as Makefile on
  426 Unix) with perl code fragments mixed in.  Those perl code fragment
  427 will generate all the configuration dependent data, including all the
  428 rules needed to build end product files and intermediary files alike.
  429 At a minimum, there must be a perl code fragment that defines a set of
  430 functions that are used to generates specific build-file rules, to
  431 build static libraries from object files, to build shared libraries
  432 from static libraries, to programs from object files and libraries,
  433 etc.
  434 
  435     generatesrc - function that produces build file lines to generate
  436                   a source file from some input.
  437 
  438                   It's called like this:
  439 
  440                         generatesrc(src => "PATH/TO/tobegenerated",
  441                                     generator => [ "generatingfile", ... ]
  442                                     generator_incs => [ "INCL/PATH", ... ]
  443                                     generator_deps => [ "dep1", ... ]
  444                                     incs => [ "INCL/PATH", ... ],
  445                                     deps => [ "dep1", ... ],
  446                                     intent => one of "libs", "dso", "bin" );
  447 
  448                   'src' has the name of the file to be generated.
  449                   'generator' is the command or part of command to
  450                   generate the file, of which the first item is
  451                   expected to be the file to generate from.
  452                   generatesrc() is expected to analyse and figure out
  453                   exactly how to apply that file and how to capture
  454                   the result.  'generator_incs' and 'generator_deps'
  455                   are include directories and files that the generator
  456                   file itself depends on.  'incs' and 'deps' are
  457                   include directories and files that are used if $(CC)
  458                   is used as an intermediary step when generating the
  459                   end product (the file indicated by 'src').  'intent'
  460                   indicates what the generated file is going to be
  461                   used for.
  462 
  463     src2obj     - function that produces build file lines to build an
  464                   object file from source files and associated data.
  465 
  466                   It's called like this:
  467 
  468                         src2obj(obj => "PATH/TO/objectfile",
  469                                 srcs => [ "PATH/TO/sourcefile", ... ],
  470                                 deps => [ "dep1", ... ],
  471                                 incs => [ "INCL/PATH", ... ]
  472                                 intent => one of "lib", "dso", "bin" );
  473 
  474                   'obj' has the intended object file *without*
  475                   extension, src2obj() is expected to add that.
  476                   'srcs' has the list of source files to build the
  477                   object file, with the first item being the source
  478                   file that directly corresponds to the object file.
  479                   'deps' is a list of explicit dependencies.  'incs'
  480                   is a list of include file directories.  Finally,
  481                   'intent' indicates what this object file is going
  482                   to be used for.
  483 
  484     obj2lib     - function that produces build file lines to build a
  485                   static library file ("libfoo.a" in Unix terms) from
  486                   object files.
  487 
  488                   called like this:
  489 
  490                         obj2lib(lib => "PATH/TO/libfile",
  491                                 objs => [ "PATH/TO/objectfile", ... ]);
  492 
  493                   'lib' has the intended library file name *without*
  494                   extension, obj2lib is expected to add that.  'objs'
  495                   has the list of object files (also *without*
  496                   extension) to build this library.
  497 
  498     libobj2shlib - function that produces build file lines to build a
  499                   shareable object library file ("libfoo.so" in Unix
  500                   terms) from the corresponding static library file
  501                   or object files.
  502 
  503                   called like this:
  504 
  505                         libobj2shlib(shlib => "PATH/TO/shlibfile",
  506                                      lib => "PATH/TO/libfile",
  507                                      objs => [ "PATH/TO/objectfile", ... ],
  508                                      deps => [ "PATH/TO/otherlibfile", ... ]);
  509 
  510                   'lib' has the intended library file name *without*
  511                   extension, libobj2shlib is expected to add that.
  512                   'shlib' has the corresponding shared library name
  513                   *without* extension.  'deps' has the list of other
  514                   libraries (also *without* extension) this library
  515                   needs to be linked with.  'objs' has the list of
  516                   object files (also *without* extension) to build
  517                   this library.
  518 
  519                   This function has a choice; it can use the
  520                   corresponding static library as input to make the
  521                   shared library, or the list of object files.
  522 
  523     obj2dynlib  - function that produces build file lines to build a
  524                   dynamically loadable library file ("libfoo.so" on
  525                   Unix) from object files.
  526 
  527                   called like this:
  528 
  529                         obj2dynlib(lib => "PATH/TO/libfile",
  530                                    objs => [ "PATH/TO/objectfile", ... ],
  531                                    deps => [ "PATH/TO/otherlibfile",
  532                                    ... ]);
  533 
  534                   This is almost the same as libobj2shlib, but the
  535                   intent is to build a shareable library that can be
  536                   loaded in runtime (a "plugin"...).  The differences
  537                   are subtle, one of the most visible ones is that the
  538                   resulting shareable library is produced from object
  539                   files only.
  540 
  541     obj2bin     - function that produces build file lines to build an
  542                   executable file from object files.
  543 
  544                   called like this:
  545 
  546                         obj2bin(bin => "PATH/TO/binfile",
  547                                 objs => [ "PATH/TO/objectfile", ... ],
  548                                 deps => [ "PATH/TO/libfile", ... ]);
  549 
  550                   'bin' has the intended executable file name
  551                   *without* extension, obj2bin is expected to add
  552                   that.  'objs' has the list of object files (also
  553                   *without* extension) to build this library.  'deps'
  554                   has the list of library files (also *without*
  555                   extension) that the programs needs to be linked
  556                   with.
  557 
  558     in2script   - function that produces build file lines to build a
  559                   script file from some input.
  560 
  561                   called like this:
  562 
  563                         in2script(script => "PATH/TO/scriptfile",
  564                                   sources => [ "PATH/TO/infile", ... ]);
  565 
  566                   'script' has the intended script file name.
  567                   'sources' has the list of source files to build the
  568                   resulting script from.
  569 
  570 Along with the build-file templates is the driving engine
  571 Configurations/common.tmpl, which looks through all the information in
  572 %unified_info and generates all the rulesets to build libraries,
  573 programs and all intermediate files, using the rule generating
  574 functions defined in the build-file template.
  575 
  576 As an example with the smaller build.info set we've seen as an
  577 example, producing the rules to build 'libcrypto' would result in the
  578 following calls:
  579 
  580     # Note: libobj2shlib will only be called if shared libraries are
  581     # to be produced.
  582     # Note 2: libobj2shlib gets both the name of the static library
  583     # and the names of all the object files that go into it.  It's up
  584     # to the implementation to decide which to use as input.
  585     # Note 3: common.tmpl peals off the ".o" extension from all object
  586     # files, as the platform at hand may have a different one.
  587     libobj2shlib(shlib => "libcrypto",
  588                  lib => "libcrypto",
  589                  objs => [ "crypto/aes", "crypto/evp", "crypto/cversion" ],
  590                  deps => [  ]);
  591 
  592     obj2lib(lib => "libcrypto"
  593             objs => [ "crypto/aes", "crypto/evp", "crypto/cversion" ]);
  594 
  595     src2obj(obj => "crypto/aes"
  596             srcs => [ "crypto/aes.c" ],
  597             deps => [ ],
  598             incs => [ "include" ],
  599             intent => "lib");
  600 
  601     src2obj(obj => "crypto/evp"
  602             srcs => [ "crypto/evp.c" ],
  603             deps => [ ],
  604             incs => [ "include" ],
  605             intent => "lib");
  606 
  607     src2obj(obj => "crypto/cversion"
  608             srcs => [ "crypto/cversion.c" ],
  609             deps => [ "crypto/buildinf.h" ],
  610             incs => [ "include" ],
  611             intent => "lib");
  612 
  613     generatesrc(src => "crypto/buildinf.h",
  614                 generator => [ "util/mkbuildinf.pl", "\"$(CC)",
  615                                "$(CFLAGS)\"", "\"$(PLATFORM)\"" ],
  616                 generator_incs => [ "util" ],
  617                 generator_deps => [ "util/Foo.pm" ],
  618                 incs => [ ],
  619                 deps => [ ],
  620                 intent => "lib");
  621 
  622 The returned strings from all those calls are then concatenated
  623 together and written to the resulting build-file.