Intro ===== This directory contains a few sets of files that are used for configuration in diverse ways: *.conf Target platform configurations, please read 'Configurations of OpenSSL target platforms' for more information. *.tmpl Build file templates, please read 'Build-file programming with the "unified" build system' as well as 'Build info files' for more information. *.pm Helper scripts / modules for the main `Configure` script. See 'Configure helper scripts for more information. Configurations of OpenSSL target platforms ========================================== Configuration targets are a collection of facts that we know about different platforms and their capabilities. We organise them in a hash table, where each entry represent a specific target. Note that configuration target names must be unique across all config files. The Configure script does check that a config file doesn't have config targets that shadow config targets from other files. In each table entry, the following keys are significant: inherit_from => Other targets to inherit values from. Explained further below. [1] template => Set to 1 if this isn't really a platform target. Instead, this target is a template upon which other targets can be built. Explained further below. [1] sys_id => System identity for systems where that is difficult to determine automatically. enable => Enable specific configuration features. This MUST be an array of words. disable => Disable specific configuration features. This MUST be an array of words. Note: if the same feature is both enabled and disabled, disable wins. as => The assembler command. This is not always used (for example on Unix, where the C compiler is used instead). asflags => Default assembler command flags [4]. cpp => The C preprocessor command, normally not given, as the build file defaults are usually good enough. cppflags => Default C preprocessor flags [4]. defines => As an alternative, macro definitions may be given here instead of in 'cppflags' [4]. If given here, they MUST be as an array of the string such as "MACRO=value", or just "MACRO" for definitions without value. includes => As an alternative, inclusion directories may be given here instead of in 'cppflags' [4]. If given here, the MUST be an array of strings, one directory specification each. cc => The C compiler command, usually one of "cc", "gcc" or "clang". This command is normally also used to link object files and libraries into the final program. cxx => The C++ compiler command, usually one of "c++", "g++" or "clang++". This command is also used when linking a program where at least one of the object file is made from C++ source. cflags => Defaults C compiler flags [4]. cxxflags => Default C++ compiler flags [4]. If unset, it gets the same value as cflags. (linking is a complex thing, see [3] below) ld => Linker command, usually not defined (meaning the compiler command is used instead). (NOTE: this is here for future use, it's not implemented yet) lflags => Default flags used when linking apps, shared libraries or DSOs [4]. ex_libs => Extra libraries that are needed when linking shared libraries, DSOs or programs. The value is also assigned to Libs.private in $(libdir)/pkgconfig/libcrypto.pc. shared_cppflags => Extra C preprocessor flags used when processing C files for shared libraries. shared_cflag => Extra C compiler flags used when compiling for shared libraries, typically something like "-fPIC". shared_ldflag => Extra linking flags used when linking shared libraries. module_cppflags module_cflags module_ldflags => Has the same function as the corresponding 'shared_' attributes, but for building DSOs. When unset, they get the same values as the corresponding 'shared_' attributes. ar => The library archive command, the default is "ar". (NOTE: this is here for future use, it's not implemented yet) arflags => Flags to be used with the library archive command. On Unix, this includes the command letter, 'r' by default. ranlib => The library archive indexing command, the default is 'ranlib' it it exists. unistd => An alternative header to the typical ''. This is very rarely needed. shared_extension => File name extension used for shared libraries. obj_extension => File name extension used for object files. On unix, this defaults to ".o" (NOTE: this is here for future use, it's not implemented yet) exe_extension => File name extension used for executable files. On unix, this defaults to "" (NOTE: this is here for future use, it's not implemented yet) shlib_variant => A "variant" identifier inserted between the base shared library name and the extension. On "unixy" platforms (BSD, Linux, Solaris, MacOS/X, ...) this supports installation of custom OpenSSL libraries that don't conflict with other builds of OpenSSL installed on the system. The variant identifier becomes part of the SONAME of the library and also any symbol versions (symbol versions are not used or needed with MacOS/X). For example, on a system where a default build would normally create the SSL shared library as 'libssl.so -> libssl.so.1.1' with the value of the symlink as the SONAME, a target definition that sets 'shlib_variant => "-abc"' will create 'libssl.so -> libssl-abc.so.1.1', again with an SONAME equal to the value of the symlink. The symbol versions associated with the variant library would then be 'OPENSSL_ABC_' rather than the default 'OPENSSL_'. The string inserted into symbol versions is obtained by mapping all letters in the "variant" identifier to upper case and all non-alphanumeric characters to '_'. thread_scheme => The type of threads is used on the configured platform. Currently known values are "(unknown)", "pthreads", "uithreads" (a.k.a solaris threads) and "winthreads". Except for "(unknown)", the actual value is currently ignored but may be used in the future. See further notes below [2]. dso_scheme => The type of dynamic shared objects to build for. This mostly comes into play with modules, but can be used for other purposes as well. Valid values are "DLFCN" (dlopen() et al), "DLFCN_NO_H" (for systems that use dlopen() et al but do not have fcntl.h), "DL" (shl_load() et al), "WIN32" and "VMS". asm_arch => The architecture to be used for compiling assembly source. This acts as a selector in build.info files. uplink_arch => The architecture to be used for compiling uplink source. This acts as a selector in build.info files. This is separate from asm_arch because it's compiled even when 'no-asm' is given, even though it contains assembler source. perlasm_scheme => The perlasm method used to create the assembler files used when compiling with assembler implementations. shared_target => The shared library building method used. This serves multiple purposes: - as index for targets found in shared_info.pl. - as linker script generation selector. To serve both purposes, the index for shared_info.pl should end with '-shared', and this suffix will be removed for use as a linker script generation selector. Note that the latter is only used if 'shared_defflag' is defined. build_scheme => The scheme used to build up a Makefile. In its simplest form, the value is a string with the name of the build scheme. The value may also take the form of a list of strings, if the build_scheme is to have some options. In this case, the first string in the list is the name of the build scheme. Currently recognised build scheme is "unified". For the "unified" build scheme, this item *must* be an array with the first being the word "unified" and the second being a word to identify the platform family. multilib => On systems that support having multiple implementations of a library (typically a 32-bit and a 64-bit variant), this is used to have the different variants in different directories. bn_ops => Building options (was just bignum options in the earlier history of this option, hence the name). This is a string of words that describe algorithms' implementation parameters that are optimal for the designated target platform, such as the type of integers used to build up the bignum, different ways to implement certain ciphers and so on. To fully comprehend the meaning, the best is to read the affected source. The valid words are: THIRTY_TWO_BIT bignum limbs are 32 bits, this is default if no option is specified, it works on any supported system [unless "wider" limb size is implied in assembly code]; BN_LLONG bignum limbs are 32 bits, but 64-bit 'unsigned long long' is used internally in calculations; SIXTY_FOUR_BIT_LONG bignum limbs are 64 bits and sizeof(long) is 8; SIXTY_FOUR_BIT bignums limbs are 64 bits, but execution environment is ILP32; RC4_CHAR RC4 key schedule is made up of 'unsigned char's; RC4_INT RC4 key schedule is made up of 'unsigned int's; [1] as part of the target configuration, one can have a key called `inherit_from` that indicates what other configurations to inherit data from. These are resolved recursively. Inheritance works as a set of default values that can be overridden by corresponding key values in the inheriting configuration. Note 1: any configuration table can be used as a template. Note 2: pure templates have the attribute `template => 1` and cannot be used as build targets. If several configurations are given in the `inherit_from` array, the values of same attribute are concatenated with space separation. With this, it's possible to have several smaller templates for different configuration aspects that can be combined into a complete configuration. Instead of a scalar value or an array, a value can be a code block of the form `sub { /* your code here */ }`. This code block will be called with the list of inherited values for that key as arguments. In fact, the concatenation of strings is really done by using `sub { join(" ",@_) }` on the list of inherited values. An example: "foo" => { template => 1, haha => "ha ha", hoho => "ho", ignored => "This should not appear in the end result", }, "bar" => { template => 1, haha => "ah", hoho => "haho", hehe => "hehe" }, "laughter" => { inherit_from => [ "foo", "bar" ], hehe => sub { join(" ",(@_,"!!!")) }, ignored => "", } The entry for "laughter" will become as follows after processing: "laughter" => { haha => "ha ha ah", hoho => "ho haho", hehe => "hehe !!!", ignored => "" } [2] OpenSSL is built with threading capabilities unless the user specifies `no-threads`. The value of the key `thread_scheme` may be `(unknown)`, in which case the user MUST give some compilation flags to `Configure`. [3] OpenSSL has three types of things to link from object files or static libraries: - shared libraries; that would be libcrypto and libssl. - shared objects (sometimes called dynamic libraries); that would be the modules. - applications; those are apps/openssl and all the test apps. Very roughly speaking, linking is done like this (words in braces represent the configuration settings documented at the beginning of this file): shared libraries: {ld} $(CFLAGS) {lflags} {shared_ldflag} -o libfoo.so \ foo/something.o foo/somethingelse.o {ex_libs} shared objects: {ld} $(CFLAGS) {lflags} {module_ldflags} -o libeng.so \ blah1.o blah2.o -lcrypto {ex_libs} applications: {ld} $(CFLAGS) {lflags} -o app \ app1.o utils.o -lssl -lcrypto {ex_libs} [4] There are variants of these attribute, prefixed with `lib_`, `dso_` or `bin_`. Those variants replace the unprefixed attribute when building library, DSO or program modules specifically. Historically, the target configurations came in form of a string with values separated by colons. This use is deprecated. The string form looked like this: "target" => "{cc}:{cflags}:{unistd}:{thread_cflag}:{sys_id}:{lflags}: {bn_ops}:{cpuid_obj}:{bn_obj}:{ec_obj}:{des_obj}:{aes_obj}: {bf_obj}:{md5_obj}:{sha1_obj}:{cast_obj}:{rc4_obj}: {rmd160_obj}:{rc5_obj}:{wp_obj}:{cmll_obj}:{modes_obj}: {padlock_obj}:{perlasm_scheme}:{dso_scheme}:{shared_target}: {shared_cflag}:{shared_ldflag}:{shared_extension}:{ranlib}: {arflags}:{multilib}" Build info files ================ The `build.info` files that are spread over the source tree contain the minimum information needed to build and distribute OpenSSL. It uses a simple and yet fairly powerful language to determine what needs to be built, from what sources, and other relationships between files. For every `build.info` file, all file references are relative to the directory of the `build.info` file for source files, and the corresponding build directory for built files if the build tree differs from the source tree. When processed, every line is processed with the perl module Text::Template, using the delimiters `{-` and `-}`. The hashes `%config` and `%target` are passed to the perl fragments, along with $sourcedir and $builddir, which are the locations of the source directory for the current `build.info` file and the corresponding build directory, all relative to the top of the build tree. `Configure` only knows inherently about the top `build.info` file. For any other directory that has one, further directories to look into must be indicated like this: SUBDIRS=something someelse On to things to be built; they are declared by setting specific variables: PROGRAMS=foo bar LIBS=libsomething MODULES=libeng SCRIPTS=myhack Note that the files mentioned for PROGRAMS, LIBS and MODULES *must* be without extensions. The build file templates will figure them out. For each thing to be built, it is then possible to say what sources they are built from: PROGRAMS=foo bar SOURCE[foo]=foo.c common.c SOURCE[bar]=bar.c extra.c common.c It's also possible to tell some other dependencies: DEPEND[foo]=libsomething DEPEND[libbar]=libsomethingelse (it could be argued that 'libsomething' and 'libsomethingelse' are source as well. However, the files given through SOURCE are expected to be located in the source tree while files given through DEPEND are expected to be located in the build tree) It's also possible to depend on static libraries explicitly: DEPEND[foo]=libsomething.a DEPEND[libbar]=libsomethingelse.a This should be rarely used, and care should be taken to make sure it's only used when supported. For example, native Windows build doesn't support building static libraries and DLLs at the same time, so using static libraries on Windows can only be done when configured `no-shared`. In some cases, it's desirable to include some source files in the shared form of a library only: SHARED_SOURCE[libfoo]=dllmain.c For any file to be built, it's also possible to tell what extra include paths the build of their source files should use: INCLUDE[foo]=include It's also possible to specify C macros that should be defined: DEFINE[foo]=FOO BAR=1 In some cases, one might want to generate some source files from others, that's done as follows: GENERATE[foo.s]=asm/something.pl $(CFLAGS) GENERATE[bar.s]=asm/bar.S The value of each GENERATE line is a command line or part of it. Configure places no rules on the command line, except that the first item must be the generator file. It is, however, entirely up to the build file template to define exactly how those command lines should be handled, how the output is captured and so on. Sometimes, the generator file itself depends on other files, for example if it is a perl script that depends on other perl modules. This can be expressed using DEPEND like this: DEPEND[asm/something.pl]=../perlasm/Foo.pm There may also be cases where the exact file isn't easily specified, but an inclusion directory still needs to be specified. INCLUDE can be used in that case: INCLUDE[asm/something.pl]=../perlasm NOTE: GENERATE lines are limited to one command only per GENERATE. Finally, you can have some simple conditional use of the `build.info` information, looking like this: IF[1] something ELSIF[2] something other ELSE something else ENDIF The expression in square brackets is interpreted as a string in perl, and will be seen as true if perl thinks it is, otherwise false. For example, the above would have "something" used, since 1 is true. Together with the use of Text::Template, this can be used as conditions based on something in the passed variables, for example: IF[{- $disabled{shared} -}] LIBS=libcrypto SOURCE[libcrypto]=... ELSE LIBS=libfoo SOURCE[libfoo]=... ENDIF Build-file programming with the "unified" build system ====================================================== "Build files" are called `Makefile` on Unix-like operating systems, `descrip.mms` for MMS on VMS, `makefile` for `nmake` on Windows, etc. To use the "unified" build system, the target configuration needs to set the three items `build_scheme`, `build_file` and `build_command`. In the rest of this section, we will assume that `build_scheme` is set to "unified" (see the configurations documentation above for the details). For any name given by `build_file`, the "unified" system expects a template file in `Configurations/` named like the build file, with `.tmpl` appended, or in case of possible ambiguity, a combination of the second `build_scheme` list item and the `build_file` name. For example, if `build_file` is set to `Makefile`, the template could be `Configurations/Makefile.tmpl` or `Configurations/unix-Makefile.tmpl`. In case both `Configurations/unix-Makefile.tmpl` and `Configurations/Makefile.tmpl` are present, the former takes precedence. The build-file template is processed with the perl module Text::Template, using `{-` and `-}` as delimiters that enclose the perl code fragments that generate configuration-dependent content. Those perl fragments have access to all the hash variables from configdata.pem. The build-file template is expected to define at least the following perl functions in a perl code fragment enclosed with `{-` and `-}`. They are all expected to return a string with the lines they produce. generatesrc - function that produces build file lines to generate a source file from some input. It's called like this: generatesrc(src => "PATH/TO/tobegenerated", generator => [ "generatingfile", ... ] generator_incs => [ "INCL/PATH", ... ] generator_deps => [ "dep1", ... ] generator => [ "generatingfile", ... ] incs => [ "INCL/PATH", ... ], deps => [ "dep1", ... ], intent => one of "libs", "dso", "bin" ); 'src' has the name of the file to be generated. 'generator' is the command or part of command to generate the file, of which the first item is expected to be the file to generate from. generatesrc() is expected to analyse and figure out exactly how to apply that file and how to capture 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 end product (the file indicated by 'src'). 'intent' indicates what the generated file is going to be used for. src2obj - function that produces build file lines to build an object file from source files and associated data. It's called like this: src2obj(obj => "PATH/TO/objectfile", srcs => [ "PATH/TO/sourcefile", ... ], deps => [ "dep1", ... ], incs => [ "INCL/PATH", ... ] intent => one of "lib", "dso", "bin" ); 'obj' has the intended object file with '.o' extension, src2obj() is expected to change it to something more suitable for the platform. 'srcs' has the list of source files to build the 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 to be used for. obj2lib - function that produces build file lines to build a static library file ("libfoo.a" in Unix terms) from object files. called like this: obj2lib(lib => "PATH/TO/libfile", objs => [ "PATH/TO/objectfile", ... ]); 'lib' has the intended library file name *without* extension, obj2lib is expected to add that. 'objs' has the list of object files to build this library. libobj2shlib - backward compatibility function that's used the same way as obj2shlib (described next), and was expected to build the shared library from the corresponding static library when that was suitable. NOTE: building a shared library from a static library is now DEPRECATED, as they no longer share object files. Attempting to do this will fail. obj2shlib - function that produces build file lines to build a shareable object library file ("libfoo.so" in Unix terms) from the corresponding object files. called like this: obj2shlib(shlib => "PATH/TO/shlibfile", lib => "PATH/TO/libfile", objs => [ "PATH/TO/objectfile", ... ], deps => [ "PATH/TO/otherlibfile", ... ]); 'lib' has the base (static) library ffile name *without* extension. This is useful in case supporting files are needed (such as import libraries on Windows). 'shlib' has the corresponding shared library name *without* extension. 'deps' has the list of other libraries (also *without* extension) this library needs to be linked with. 'objs' has the list of object files to build this library. obj2dso - function that produces build file lines to build a dynamic shared object file from object files. called like this: obj2dso(lib => "PATH/TO/libfile", objs => [ "PATH/TO/objectfile", ... ], deps => [ "PATH/TO/otherlibfile", ... ]); This is almost the same as obj2shlib, but the intent is to build a shareable library that can be loaded in runtime (a "plugin"...). 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 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. In all cases, file file paths are relative to the build tree top, and the build file actions run with the build tree top as current working directory. Make sure to end the section with these functions with a string that you thing is appropriate for the resulting build file. If nothing else, end it like this: ""; # Make sure no lingering values end up in the Makefile -} Configure helper scripts ======================== Configure uses helper scripts in this directory: Checker scripts --------------- These scripts are per platform family, to check the integrity of the tools used for configuration and building. The checker script used is either `{build_platform}-{build_file}-checker.pm` or `{build_platform}-checker.pm`, where `{build_platform}` is the second `build_scheme` list element from the configuration target data, and `{build_file}` is `build_file` from the same target data. If the check succeeds, the script is expected to end with a non-zero expression. If the check fails, the script can end with a zero, or with a `die`.