mirror of
https://github.com/ossrs/srs.git
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623 lines
24 KiB
Text
623 lines
24 KiB
Text
Design document for the unified scheme data
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===========================================
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How are things connected?
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-------------------------
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The unified scheme takes all its data from the build.info files seen
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throughout the source tree. These files hold the minimum information
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needed to build end product files from diverse sources. See the
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section on build.info files below.
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From the information in build.info files, Configure builds up an
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information database as a hash table called %unified_info, which is
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stored in configdata.pm, found at the top of the build tree (which may
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or may not be the same as the source tree).
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Configurations/common.tmpl uses the data from %unified_info to
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generate the rules for building end product files as well as
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intermediary files with the help of a few functions found in the
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build-file templates. See the section on build-file templates further
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down for more information.
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build.info files
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----------------
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As mentioned earlier, build.info files are meant to hold the minimum
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information needed to build output files, and therefore only (with a
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few possible exceptions [1]) have information about end products (such
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as scripts, library files and programs) and source files (such as C
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files, C header files, assembler files, etc). Intermediate files such
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as object files are rarely directly referred to in build.info files (and
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when they are, it's always with the file name extension .o), they are
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inferred by Configure. By the same rule of minimalism, end product
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file name extensions (such as .so, .a, .exe, etc) are never mentioned
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in build.info. Their file name extensions will be inferred by the
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build-file templates, adapted for the platform they are meant for (see
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sections on %unified_info and build-file templates further down).
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The variables PROGRAMS, LIBS, ENGINES and SCRIPTS are used to declare
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end products. There are variants for them with '_NO_INST' as suffix
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(PROGRAM_NO_INST etc) to specify end products that shouldn't get
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installed.
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The variables SOURCE, DEPEND and INCLUDE are indexed by a produced
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file, and their values are the source used to produce that particular
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produced file, extra dependencies, and include directories needed.
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All their values in all the build.info throughout the source tree are
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collected together and form a set of programs, libraries, engines and
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scripts to be produced, source files, dependencies, etc etc etc.
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Let's have a pretend example, a very limited contraption of OpenSSL,
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composed of the program 'apps/openssl', the libraries 'libssl' and
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'libcrypto', an engine 'engines/ossltest' and their sources and
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dependencies.
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# build.info
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LIBS=libcrypto libssl
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INCLUDE[libcrypto]=include
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INCLUDE[libssl]=include
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DEPEND[libssl]=libcrypto
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This is the top directory build.info file, and it tells us that two
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libraries are to be built, the include directory 'include/' shall be
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used throughout when building anything that will end up in each
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library, and that the library 'libssl' depend on the library
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'libcrypto' to function properly.
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# apps/build.info
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PROGRAMS=openssl
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SOURCE[openssl]=openssl.c
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INCLUDE[openssl]=.. ../include
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DEPEND[openssl]=../libssl
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This is the build.info file in 'apps/', one may notice that all file
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paths mentioned are relative to the directory the build.info file is
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located in. This one tells us that there's a program to be built
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called 'apps/openssl' (the file name extension will depend on the
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platform and is therefore not mentioned in the build.info file). It's
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built from one source file, 'apps/openssl.c', and building it requires
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the use of '.' and 'include' include directories (both are declared
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from the point of view of the 'apps/' directory), and that the program
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depends on the library 'libssl' to function properly.
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# crypto/build.info
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LIBS=../libcrypto
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SOURCE[../libcrypto]=aes.c evp.c cversion.c
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DEPEND[cversion.o]=buildinf.h
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GENERATE[buildinf.h]=../util/mkbuildinf.pl "$(CC) $(CFLAGS)" "$(PLATFORM)"
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DEPEND[buildinf.h]=../Makefile
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DEPEND[../util/mkbuildinf.pl]=../util/Foo.pm
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This is the build.info file in 'crypto', and it tells us a little more
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about what's needed to produce 'libcrypto'. LIBS is used again to
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declare that 'libcrypto' is to be produced. This declaration is
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really unnecessary as it's already mentioned in the top build.info
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file, but can make the info file easier to understand. This is to
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show that duplicate information isn't an issue.
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This build.info file informs us that 'libcrypto' is built from a few
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source files, 'crypto/aes.c', 'crypto/evp.c' and 'crypto/cversion.c'.
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It also shows us that building the object file inferred from
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'crypto/cversion.c' depends on 'crypto/buildinf.h'. Finally, it
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also shows the possibility to declare how some files are generated
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using some script, in this case a perl script, and how such scripts
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can be declared to depend on other files, in this case a perl module.
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Two things are worth an extra note:
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'DEPEND[cversion.o]' mentions an object file. DEPEND indexes is the
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only location where it's valid to mention them
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Lines in 'BEGINRAW'..'ENDRAW' sections must always mention files as
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seen from the top directory, no exception.
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# ssl/build.info
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LIBS=../libssl
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SOURCE[../libssl]=tls.c
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This is the build.info file in 'ssl/', and it tells us that the
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library 'libssl' is built from the source file 'ssl/tls.c'.
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# engines/build.info
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ENGINES=dasync
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SOURCE[dasync]=e_dasync.c
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DEPEND[dasync]=../libcrypto
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INCLUDE[dasync]=../include
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ENGINES_NO_INST=ossltest
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SOURCE[ossltest]=e_ossltest.c
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DEPEND[ossltest]=../libcrypto.a
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INCLUDE[ossltest]=../include
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This is the build.info file in 'engines/', telling us that two engines
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called 'engines/dasync' and 'engines/ossltest' shall be built, that
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dasync's source is 'engines/e_dasync.c' and ossltest's source is
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'engines/e_ossltest.c' and that the include directory 'include/' may
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be used when building anything that will be part of these engines.
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Also, both engines depend on the library 'libcrypto' to function
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properly. ossltest is explicitly linked with the static variant of
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the library 'libcrypto'. Finally, only dasync is being installed, as
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ossltest is only for internal testing.
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When Configure digests these build.info files, the accumulated
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information comes down to this:
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LIBS=libcrypto libssl
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SOURCE[libcrypto]=crypto/aes.c crypto/evp.c crypto/cversion.c
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DEPEND[crypto/cversion.o]=crypto/buildinf.h
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INCLUDE[libcrypto]=include
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SOURCE[libssl]=ssl/tls.c
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INCLUDE[libssl]=include
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DEPEND[libssl]=libcrypto
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PROGRAMS=apps/openssl
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SOURCE[apps/openssl]=apps/openssl.c
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INCLUDE[apps/openssl]=. include
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DEPEND[apps/openssl]=libssl
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ENGINES=engines/dasync
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SOURCE[engines/dasync]=engines/e_dasync.c
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DEPEND[engines/dasync]=libcrypto
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INCLUDE[engines/dasync]=include
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ENGINES_NO_INST=engines/ossltest
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SOURCE[engines/ossltest]=engines/e_ossltest.c
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DEPEND[engines/ossltest]=libcrypto.a
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INCLUDE[engines/ossltest]=include
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GENERATE[crypto/buildinf.h]=util/mkbuildinf.pl "$(CC) $(CFLAGS)" "$(PLATFORM)"
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DEPEND[crypto/buildinf.h]=Makefile
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DEPEND[util/mkbuildinf.pl]=util/Foo.pm
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A few notes worth mentioning:
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LIBS may be used to declare routine libraries only.
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PROGRAMS may be used to declare programs only.
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ENGINES may be used to declare engines only.
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The indexes for SOURCE must only be end product files, such as
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libraries, programs or engines. The values of SOURCE variables must
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only be source files (possibly generated).
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INCLUDE and DEPEND shows a relationship between different files
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(usually produced files) or between files and directories, such as a
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program depending on a library, or between an object file and some
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extra source file.
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When Configure processes the build.info files, it will take it as
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truth without question, and will therefore perform very few checks.
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If the build tree is separate from the source tree, it will assume
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that all built files and up in the build directory and that all source
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files are to be found in the source tree, if they can be found there.
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Configure will assume that source files that can't be found in the
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source tree (such as 'crypto/bildinf.h' in the example above) are
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generated and will be found in the build tree.
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The %unified_info database
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--------------------------
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The information in all the build.info get digested by Configure and
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collected into the %unified_info database, divided into the following
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indexes:
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depends => a hash table containing 'file' => [ 'dependency' ... ]
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pairs. These are directly inferred from the DEPEND
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variables in build.info files.
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engines => a list of engines. These are directly inferred from
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the ENGINES variable in build.info files.
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generate => a hash table containing 'file' => [ 'generator' ... ]
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pairs. These are directly inferred from the GENERATE
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variables in build.info files.
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includes => a hash table containing 'file' => [ 'include' ... ]
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pairs. These are directly inferred from the INCLUDE
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variables in build.info files.
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install => a hash table containing 'type' => [ 'file' ... ] pairs.
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The types are 'programs', 'libraries', 'engines' and
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'scripts', and the array of files list the files of
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that type that should be installed.
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libraries => a list of libraries. These are directly inferred from
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the LIBS variable in build.info files.
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programs => a list of programs. These are directly inferred from
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the PROGRAMS variable in build.info files.
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rawlines => a list of build-file lines. These are a direct copy of
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the BEGINRAW..ENDRAW lines in build.info files. Note:
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only the BEGINRAW..ENDRAW section for the current
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platform are copied, the rest are ignored.
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scripts => a list of scripts. There are directly inferred from
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the SCRIPTS variable in build.info files.
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sources => a hash table containing 'file' => [ 'sourcefile' ... ]
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pairs. These are indirectly inferred from the SOURCE
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variables in build.info files. Object files are
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mentioned in this hash table, with source files from
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SOURCE variables, and AS source files for programs and
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libraries.
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shared_sources =>
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a hash table just like 'sources', but only as source
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files (object files) for building shared libraries.
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As an example, here is how the build.info files example from the
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section above would be digested into a %unified_info table:
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our %unified_info = (
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"depends" =>
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{
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"apps/openssl" =>
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[
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"libssl",
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],
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"crypto/buildinf.h" =>
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[
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"Makefile",
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],
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"crypto/cversion.o" =>
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[
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"crypto/buildinf.h",
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],
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"engines/dasync" =>
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[
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"libcrypto",
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],
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"engines/ossltest" =>
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[
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"libcrypto.a",
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],
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"libssl" =>
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[
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"libcrypto",
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],
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"util/mkbuildinf.pl" =>
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[
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"util/Foo.pm",
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],
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},
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"engines" =>
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[
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"engines/dasync",
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"engines/ossltest",
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],
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"generate" =>
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{
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"crypto/buildinf.h" =>
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[
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"util/mkbuildinf.pl",
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"\"\$(CC)",
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"\$(CFLAGS)\"",
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"\"$(PLATFORM)\"",
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],
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},
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"includes" =>
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{
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"apps/openssl" =>
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[
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".",
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"include",
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],
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"engines/ossltest" =>
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[
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"include"
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],
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"libcrypto" =>
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[
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"include",
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],
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"libssl" =>
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[
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"include",
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],
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"util/mkbuildinf.pl" =>
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[
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"util",
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],
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}
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"install" =>
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{
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"engines" =>
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[
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"engines/dasync",
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],
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"libraries" =>
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[
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"libcrypto",
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"libssl",
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],
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"programs" =>
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[
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"apps/openssl",
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],
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},
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"libraries" =>
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[
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"libcrypto",
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"libssl",
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],
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"programs" =>
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[
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"apps/openssl",
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],
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"rawlines" =>
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[
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],
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"sources" =>
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{
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"apps/openssl" =>
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[
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"apps/openssl.o",
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],
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"apps/openssl.o" =>
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[
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"apps/openssl.c",
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],
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"crypto/aes.o" =>
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[
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"crypto/aes.c",
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],
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"crypto/cversion.o" =>
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[
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"crypto/cversion.c",
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],
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"crypto/evp.o" =>
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[
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"crypto/evp.c",
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],
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"engines/e_dasync.o" =>
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[
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"engines/e_dasync.c",
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],
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"engines/dasync" =>
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[
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"engines/e_dasync.o",
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],
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"engines/e_ossltest.o" =>
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[
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"engines/e_ossltest.c",
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],
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"engines/ossltest" =>
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[
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"engines/e_ossltest.o",
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],
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"libcrypto" =>
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[
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"crypto/aes.c",
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"crypto/cversion.c",
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"crypto/evp.c",
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],
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"libssl" =>
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[
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"ssl/tls.c",
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],
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"ssl/tls.o" =>
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[
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"ssl/tls.c",
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],
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},
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);
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As can be seen, everything in %unified_info is fairly simple suggest
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of information. Still, it tells us that to build all programs, we
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must build 'apps/openssl', and to build the latter, we will need to
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build all its sources ('apps/openssl.o' in this case) and all the
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other things it depends on (such as 'libssl'). All those dependencies
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need to be built as well, using the same logic, so to build 'libssl',
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we need to build 'ssl/tls.o' as well as 'libcrypto', and to build the
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latter...
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Build-file templates
|
|
--------------------
|
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Build-file templates are essentially build-files (such as Makefile on
|
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Unix) with perl code fragments mixed in. Those perl code fragment
|
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will generate all the configuration dependent data, including all the
|
|
rules needed to build end product files and intermediary files alike.
|
|
At a minimum, there must be a perl code fragment that defines a set of
|
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functions that are used to generates specific build-file rules, to
|
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build static libraries from object files, to build shared libraries
|
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from static libraries, to programs from object files and libraries,
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|
etc.
|
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|
generatesrc - function that produces build file lines to generate
|
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a source file from some input.
|
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It's called like this:
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generatesrc(src => "PATH/TO/tobegenerated",
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generator => [ "generatingfile", ... ]
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generator_incs => [ "INCL/PATH", ... ]
|
|
generator_deps => [ "dep1", ... ]
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|
incs => [ "INCL/PATH", ... ],
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deps => [ "dep1", ... ],
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intent => one of "libs", "dso", "bin" );
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'src' has the name of the file to be generated.
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'generator' is the command or part of command to
|
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generate the file, of which the first item is
|
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expected to be the file to generate from.
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generatesrc() is expected to analyse and figure out
|
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exactly how to apply that file and how to capture
|
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the result. 'generator_incs' and 'generator_deps'
|
|
are include directories and files that the generator
|
|
file itself depends on. 'incs' and 'deps' are
|
|
include directories and files that are used if $(CC)
|
|
is used as an intermediary step when generating the
|
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end product (the file indicated by 'src'). 'intent'
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|
indicates what the generated file is going to be
|
|
used for.
|
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|
src2obj - function that produces build file lines to build an
|
|
object file from source files and associated data.
|
|
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|
It's called like this:
|
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src2obj(obj => "PATH/TO/objectfile",
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srcs => [ "PATH/TO/sourcefile", ... ],
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|
deps => [ "dep1", ... ],
|
|
incs => [ "INCL/PATH", ... ]
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|
intent => one of "lib", "dso", "bin" );
|
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'obj' has the intended object file *without*
|
|
extension, src2obj() is expected to add that.
|
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'srcs' has the list of source files to build the
|
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object file, with the first item being the source
|
|
file that directly corresponds to the object file.
|
|
'deps' is a list of explicit dependencies. 'incs'
|
|
is a list of include file directories. Finally,
|
|
'intent' indicates what this object file is going
|
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to be used for.
|
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|
|
obj2lib - function that produces build file lines to build a
|
|
static library file ("libfoo.a" in Unix terms) from
|
|
object files.
|
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called like this:
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obj2lib(lib => "PATH/TO/libfile",
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objs => [ "PATH/TO/objectfile", ... ]);
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'lib' has the intended library file name *without*
|
|
extension, obj2lib is expected to add that. 'objs'
|
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has the list of object files (also *without*
|
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extension) to build this library.
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libobj2shlib - function that produces build file lines to build a
|
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shareable object library file ("libfoo.so" in Unix
|
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terms) from the corresponding static library file
|
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or object files.
|
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called like this:
|
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libobj2shlib(shlib => "PATH/TO/shlibfile",
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lib => "PATH/TO/libfile",
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objs => [ "PATH/TO/objectfile", ... ],
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deps => [ "PATH/TO/otherlibfile", ... ]);
|
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'lib' has the intended library file name *without*
|
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extension, libobj2shlib is expected to add that.
|
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'shlib' has the corresponding shared library name
|
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*without* extension. 'deps' has the list of other
|
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libraries (also *without* extension) this library
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needs to be linked with. 'objs' has the list of
|
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object files (also *without* extension) to build
|
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this library.
|
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This function has a choice; it can use the
|
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corresponding static library as input to make the
|
|
shared library, or the list of object files.
|
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obj2dynlib - function that produces build file lines to build a
|
|
dynamically loadable library file ("libfoo.so" on
|
|
Unix) from object files.
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|
|
|
called like this:
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|
|
|
obj2dynlib(lib => "PATH/TO/libfile",
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|
objs => [ "PATH/TO/objectfile", ... ],
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|
deps => [ "PATH/TO/otherlibfile",
|
|
... ]);
|
|
|
|
This is almost the same as libobj2shlib, but the
|
|
intent is to build a shareable library that can be
|
|
loaded in runtime (a "plugin"...). The differences
|
|
are subtle, one of the most visible ones is that the
|
|
resulting shareable library is produced from object
|
|
files only.
|
|
|
|
obj2bin - function that produces build file lines to build an
|
|
executable file from object files.
|
|
|
|
called like this:
|
|
|
|
obj2bin(bin => "PATH/TO/binfile",
|
|
objs => [ "PATH/TO/objectfile", ... ],
|
|
deps => [ "PATH/TO/libfile", ... ]);
|
|
|
|
'bin' has the intended executable file name
|
|
*without* extension, obj2bin is expected to add
|
|
that. 'objs' has the list of object files (also
|
|
*without* extension) to build this library. 'deps'
|
|
has the list of library files (also *without*
|
|
extension) that the programs needs to be linked
|
|
with.
|
|
|
|
in2script - function that produces build file lines to build a
|
|
script file from some input.
|
|
|
|
called like this:
|
|
|
|
in2script(script => "PATH/TO/scriptfile",
|
|
sources => [ "PATH/TO/infile", ... ]);
|
|
|
|
'script' has the intended script file name.
|
|
'sources' has the list of source files to build the
|
|
resulting script from.
|
|
|
|
Along with the build-file templates is the driving engine
|
|
Configurations/common.tmpl, which looks through all the information in
|
|
%unified_info and generates all the rulesets to build libraries,
|
|
programs and all intermediate files, using the rule generating
|
|
functions defined in the build-file template.
|
|
|
|
As an example with the smaller build.info set we've seen as an
|
|
example, producing the rules to build 'libcrypto' would result in the
|
|
following calls:
|
|
|
|
# Note: libobj2shlib will only be called if shared libraries are
|
|
# to be produced.
|
|
# Note 2: libobj2shlib gets both the name of the static library
|
|
# and the names of all the object files that go into it. It's up
|
|
# to the implementation to decide which to use as input.
|
|
# Note 3: common.tmpl peals off the ".o" extension from all object
|
|
# files, as the platform at hand may have a different one.
|
|
libobj2shlib(shlib => "libcrypto",
|
|
lib => "libcrypto",
|
|
objs => [ "crypto/aes", "crypto/evp", "crypto/cversion" ],
|
|
deps => [ ]);
|
|
|
|
obj2lib(lib => "libcrypto"
|
|
objs => [ "crypto/aes", "crypto/evp", "crypto/cversion" ]);
|
|
|
|
src2obj(obj => "crypto/aes"
|
|
srcs => [ "crypto/aes.c" ],
|
|
deps => [ ],
|
|
incs => [ "include" ],
|
|
intent => "lib");
|
|
|
|
src2obj(obj => "crypto/evp"
|
|
srcs => [ "crypto/evp.c" ],
|
|
deps => [ ],
|
|
incs => [ "include" ],
|
|
intent => "lib");
|
|
|
|
src2obj(obj => "crypto/cversion"
|
|
srcs => [ "crypto/cversion.c" ],
|
|
deps => [ "crypto/buildinf.h" ],
|
|
incs => [ "include" ],
|
|
intent => "lib");
|
|
|
|
generatesrc(src => "crypto/buildinf.h",
|
|
generator => [ "util/mkbuildinf.pl", "\"$(CC)",
|
|
"$(CFLAGS)\"", "\"$(PLATFORM)\"" ],
|
|
generator_incs => [ "util" ],
|
|
generator_deps => [ "util/Foo.pm" ],
|
|
incs => [ ],
|
|
deps => [ ],
|
|
intent => "lib");
|
|
|
|
The returned strings from all those calls are then concatenated
|
|
together and written to the resulting build-file.
|