Configurations/README.design

   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 with '.o'
 475                   extension, src2obj() is expected to change it to
 476                   something more suitable for the platform.
 477                   'srcs' has the list of source files to build the
 478                   object file, with the first item being the source
 479                   file that directly corresponds to the object file.
 480                   'deps' is a list of explicit dependencies.  'incs'
 481                   is a list of include file directories.  Finally,
 482                   'intent' indicates what this object file is going
 483                   to be used for.
 484
 485     obj2lib     - function that produces build file lines to build a
 486                   static library file ("libfoo.a" in Unix terms) from
 487                   object files.
 488
 489                   called like this:
 490
 491                         obj2lib(lib => "PATH/TO/libfile",
 492                                 objs => [ "PATH/TO/objectfile", ... ]);
 493
 494                   'lib' has the intended library file name *without*
 495                   extension, obj2lib is expected to add that.  'objs'
 496                   has the list of object files to build this library.
 497
 498     libobj2shlib - backward compatibility function that's used the
 499                   same way as obj2shlib (described next), and was
 500                   expected to build the shared library from the
 501                   corresponding static library when that was suitable.
 502                   NOTE: building a shared library from a static
 503                   library is now DEPRECATED, as they no longer share
 504                   object files.  Attempting to do this will fail.
 505
 506     obj2shlib   - function that produces build file lines to build a
 507                   shareable object library file ("libfoo.so" in Unix
 508                   terms) from the corresponding object files.
 509
 510                   called like this:
 511
 512                         obj2shlib(shlib => "PATH/TO/shlibfile",
 513                                   lib => "PATH/TO/libfile",
 514                                   objs => [ "PATH/TO/objectfile", ... ],
 515                                   deps => [ "PATH/TO/otherlibfile", ... ]);
 516
 517                   'lib' has the base (static) library file name
 518                   *without* extension.  This is useful in case
 519                   supporting files are needed (such as import
 520                   libraries on Windows).
 521                   'shlib' has the corresponding shared library name
 522                   *without* extension.  'deps' has the list of other
 523                   libraries (also *without* extension) this library
 524                   needs to be linked with.  'objs' has the list of
 525                   object files to build this library.
 526
 527     obj2dso     - function that produces build file lines to build a
 528                   dynamic shared object file from object files.
 529
 530                   called like this:
 531
 532                         obj2dso(lib => "PATH/TO/libfile",
 533                                 objs => [ "PATH/TO/objectfile", ... ],
 534                                 deps => [ "PATH/TO/otherlibfile",
 535                                 ... ]);
 536
 537                   This is almost the same as obj2shlib, but the
 538                   intent is to build a shareable library that can be
 539                   loaded in runtime (a "plugin"...).
 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 to build
 553                   this library.  'deps' has the list of library files
 554                   (also *without* extension) that the programs needs
 555                   to be linked with.
 556
 557     in2script   - function that produces build file lines to build a
 558                   script file from some input.
 559
 560                   called like this:
 561
 562                         in2script(script => "PATH/TO/scriptfile",
 563                                   sources => [ "PATH/TO/infile", ... ]);
 564
 565                   'script' has the intended script file name.
 566                   'sources' has the list of source files to build the
 567                   resulting script from.
 568
 569 Along with the build-file templates is the driving engine
 570 Configurations/common.tmpl, which looks through all the information in
 571 %unified_info and generates all the rulesets to build libraries,
 572 programs and all intermediate files, using the rule generating
 573 functions defined in the build-file template.
 574
 575 As an example with the smaller build.info set we've seen as an
 576 example, producing the rules to build 'libcrypto' would result in the
 577 following calls:
 578
 579     # Note: obj2shlib will only be called if shared libraries are
 580     # to be produced.
 581     # Note 2: obj2shlib must convert the '.o' extension to whatever
 582     # is suitable on the local platform.
 583     obj2shlib(shlib => "libcrypto",
 584               objs => [ "crypto/aes.o", "crypto/evp.o", "crypto/cversion.o" ],
 585               deps => [  ]);
 586
 587     obj2lib(lib => "libcrypto"
 588             objs => [ "crypto/aes.o", "crypto/evp.o", "crypto/cversion.o" ]);
 589
 590     src2obj(obj => "crypto/aes.o"
 591             srcs => [ "crypto/aes.c" ],
 592             deps => [ ],
 593             incs => [ "include" ],
 594             intent => "lib");
 595
 596     src2obj(obj => "crypto/evp.o"
 597             srcs => [ "crypto/evp.c" ],
 598             deps => [ ],
 599             incs => [ "include" ],
 600             intent => "lib");
 601
 602     src2obj(obj => "crypto/cversion.o"
 603             srcs => [ "crypto/cversion.c" ],
 604             deps => [ "crypto/buildinf.h" ],
 605             incs => [ "include" ],
 606             intent => "lib");
 607
 608     generatesrc(src => "crypto/buildinf.h",
 609                 generator => [ "util/mkbuildinf.pl", "\"$(CC)",
 610                                "$(CFLAGS)\"", "\"$(PLATFORM)\"" ],
 611                 generator_incs => [ "util" ],
 612                 generator_deps => [ "util/Foo.pm" ],
 613                 incs => [ ],
 614                 deps => [ ],
 615                 intent => "lib");
 616
 617 The returned strings from all those calls are then concatenated
 618 together and written to the resulting build-file.