mirror of
https://github.com/CloverHackyColor/CloverBootloader.git
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605 lines
24 KiB
Markdown
605 lines
24 KiB
Markdown
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`](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`, `MODULES` 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 installed.
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The variables `SOURCE`, `DEPEND`, `INCLUDE` and `DEFINE` are indexed by a
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produced file, and their values are the source used to produce that
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particular produced file, extra dependencies, include directories
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needed, or C macros to be defined.
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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, modules 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 module `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/openss` (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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# 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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MODULES=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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MODULES_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 modules
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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 modules.
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Also, both modules 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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MODULES=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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MODULES_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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`MODULES` may be used to declare modules only.
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The indexes for `SOURCE` must only be end product files, such as
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libraries, programs or modules. 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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modules => a list of modules. These are directly inferred from
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the MODULES 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', 'modules' 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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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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"modules" =>
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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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"modules" =>
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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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"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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--------------------
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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
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rules needed to build end product files and intermediary files alike.
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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", ... ]
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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'
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are include directories and files that the generator
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file itself depends on. 'incs' and 'deps' are
|
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include directories and files that are used if $(CC)
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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
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used for.
|
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src2obj - function that produces build file lines to build an
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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", ... ],
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incs => [ "INCL/PATH", ... ]
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intent => one of "lib", "dso", "bin" );
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'obj' has the intended object file with `.o`
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extension, src2obj() is expected to change it to
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something more suitable for the platform.
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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
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file that directly corresponds to the object file.
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'deps' is a list of explicit dependencies. 'incs'
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is a list of include file directories. Finally,
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'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
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static library file ("libfoo.a" in Unix terms) from
|
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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*
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extension, obj2lib is expected to add that. 'objs'
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has the list of object files to build this library.
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libobj2shlib - backward compatibility function that's used the
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same way as obj2shlib (described next), and was
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expected to build the shared library from the
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corresponding static library when that was suitable.
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NOTE: building a shared library from a static
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library is now DEPRECATED, as they no longer share
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object files. Attempting to do this will fail.
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obj2shlib - 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 object files.
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called like this:
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obj2shlib(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 base (static) library file name
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*without* extension. This is useful in case
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supporting files are needed (such as import
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libraries on Windows).
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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 to build this library.
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obj2dso - function that produces build file lines to build a
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dynamic shared object file from object files.
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called like this:
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obj2dso(lib => "PATH/TO/libfile",
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objs => [ "PATH/TO/objectfile", ... ],
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deps => [ "PATH/TO/otherlibfile",
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... ]);
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This is almost the same as obj2shlib, but the
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intent is to build a shareable library that can be
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loaded in runtime (a "plugin"...).
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obj2bin - function that produces build file lines to build an
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executable file from object files.
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called like this:
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obj2bin(bin => "PATH/TO/binfile",
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objs => [ "PATH/TO/objectfile", ... ],
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deps => [ "PATH/TO/libfile", ... ]);
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'bin' has the intended executable file name
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*without* extension, obj2bin is expected to add
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that. 'objs' has the list of object files to build
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this library. 'deps' has the list of library files
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(also *without* extension) that the programs needs
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to be linked with.
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in2script - function that produces build file lines to build a
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script file from some input.
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called like this:
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in2script(script => "PATH/TO/scriptfile",
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sources => [ "PATH/TO/infile", ... ]);
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'script' has the intended script file name.
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'sources' has the list of source files to build the
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resulting script from.
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Along with the build-file templates is the driving template
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[`Configurations/common.tmpl`](common.tmpl), which looks through all the
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information in `%unified_info` and generates all the rulesets to build libraries,
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programs and all intermediate files, using the rule generating
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functions defined in the build-file template.
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As an example with the smaller `build.info` set we've seen as an
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example, producing the rules to build `libcrypto` would result in the
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following calls:
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# Note: obj2shlib will only be called if shared libraries are
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# to be produced.
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# Note 2: obj2shlib must convert the '.o' extension to whatever
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# is suitable on the local platform.
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obj2shlib(shlib => "libcrypto",
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objs => [ "crypto/aes.o", "crypto/evp.o", "crypto/cversion.o" ],
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deps => [ ]);
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obj2lib(lib => "libcrypto"
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objs => [ "crypto/aes.o", "crypto/evp.o", "crypto/cversion.o" ]);
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src2obj(obj => "crypto/aes.o"
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srcs => [ "crypto/aes.c" ],
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deps => [ ],
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incs => [ "include" ],
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intent => "lib");
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src2obj(obj => "crypto/evp.o"
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srcs => [ "crypto/evp.c" ],
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deps => [ ],
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incs => [ "include" ],
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intent => "lib");
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src2obj(obj => "crypto/cversion.o"
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srcs => [ "crypto/cversion.c" ],
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deps => [ "crypto/buildinf.h" ],
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incs => [ "include" ],
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intent => "lib");
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generatesrc(src => "crypto/buildinf.h",
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generator => [ "util/mkbuildinf.pl", "\"$(CC)",
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"$(CFLAGS)\"", "\"$(PLATFORM)\"" ],
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generator_incs => [ "util" ],
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generator_deps => [ "util/Foo.pm" ],
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incs => [ ],
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deps => [ ],
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intent => "lib");
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The returned strings from all those calls are then concatenated
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together and written to the resulting build-file.
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