90 lines
4.1 KiB
Markdown
90 lines
4.1 KiB
Markdown
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# Current implementation details
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The code has been simplified to use Subst expansion do most of the work.
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The following internal env vars have been added which are python functions (note also ldmodule where shlib is below)
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* `_get_shlib_stem` - given a library name `libxyz.so.1.1.0` it will retrievve `xyz`
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* `_get_shlib_dir` - given a library with a path `DEF/a/b/libxyz.so.1.1.0` it will retrieve `DEF`
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* `_SHLIBSOVERSION` - will look for `SOVERSION` and then `SHLIBVERSION` to determine the `SOVERSION` to be used in file naming
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* `_SHLIBSONAME` - will check for and error if both `SONAME` and `SOVERSION` are defined, otherwise will generate the proper filenaming for SONAME
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* `_SHLIBVERSION` - will return `SHLIBVERSION` or "" if SHLIBVERSION is defined
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* `_SHLIBVERSIONFLAGS` - will return proper compiler flags for SHLIBVERSION
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* `__SHLIBVERSIONFLAGS` - compiler defined proper versioned shared library flags
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* `SHLIB_SONAME_SYMLINK` - this is the symlink for SONAME to be used (`libxyz.1.so`)
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* `SHLIB_NOVERSION_SYMLINK` - this is the symlink for non-versioned filename (`libxyz.so`)
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Shared library file nodes will have `node.attributes.shliblinks` which is a tuple of the symlinks to be created
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# Versioned Shared Library and Loadable modules requirements
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The following env variables can affect the command line and created files for these
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* `SHLIBVERSION` - If this is not set, the all of the following will be ignored?
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* `SONAME`
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* `SOVERSION`
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* `APPLELINK_NO_CURRENT_VERSION` (applelink only)
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* `APPLELINK_CURRENT_VERSION` (applelink only)
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* `APPLELINK_COMPATIBILITY_VERSION` (applelink only)
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In most cases the linker will create a file named as
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`${SHLIBPREFIX}lib_name${SHLIBVERSION}${SHLIBSUFFIX}`
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Which will have a soname baked into it as one of the
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* `${SONAME}`
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* `${SHLIBPREFIX}lib_name${SOVERSION}${SHLIBSUFFIX}`
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* `-Wl,-soname=$_SHLIBSONAME` (for gnulink as similar)
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* (for applelink only)
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* `${SHLIBPREFIX}lib_name${major version only from SHLIBVERSION}${SHLIBSUFFIX}`
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* `-Wl,-compatibility_version,%s`
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* `-Wl,-current_version,%s`
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For **applelink** the version has to follow these rules to verify that the version # is valid.
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* For version # = X[.Y[.Z]]
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* where X 0-65535
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* where Y either not specified or 0-255
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* where Z either not specified or 0-255
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For most platforms this will lead to a series of symlinks eventually pointing to the actual shared library (or loadable module file).
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1. `${SHLIBPREFIX}lib_name${SHLIBSUFFIX} -> ${SHLIBPREFIX}lib_name${SHLIBVERSION}${SHLIBSUFFIX}`
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1. `${SHLIBPREFIX}lib_name${SOVERSION}${SHLIBSUFFIX} -> ${SHLIBPREFIX}lib_name${SHLIBVERSION}${SHLIBSUFFIX}`
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These symlinks are stored by the emitter in the following
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`target[0].attributes.shliblinks = symlinks`
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This means that those values are fixed a the time SharedLibrary() is called (generally)
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For **openbsd** the following rules for symlinks apply
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* OpenBSD uses x.y shared library versioning numbering convention and doesn't use symlinks to backwards-compatible libraries
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User can request:
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env.SharedLibrary('a',sources, SHLIBVERSION)
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env.SharedLibrary('liba.so',sources, SHLIBVERSION)
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Ideally we'll keep the 'a' for use in constructing all follow on. To do this we have to do it in the Builder() or at
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least prevent BuilderBase._create_nodes() from discarding this info if it's available.
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Firstly check if [SH|LD]LIBNOVERSIONSYMLINKS defined or if [SH|LD]LIBVERSION is not defined, if so we do nothing special
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The emitter can calculate the filename stem 'a' above and store it on the target node. Then also create the symlinks
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and store those on the node. We should have all the information needed by the time the emitter is called.
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Same should apply for loadable modules..
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This should be vastly simpler.
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Unfortunately we cannot depend on the target having an OverrideEnvironment() which we could populate all the related
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env variables in the emitter...
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Maybe we can force one at that point?
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SOVERSION can be specified, if not, then defaults to major portion of SHLIBVERSION
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SONAME can be specified, if not defaults to ${SHLIBPREFIX}lib_name${SOVERSION}
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NOTE: mongodb uses Append(SHLIBEMITTER=.. ) for their libdeps stuff. (So test
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with that once you have new logic working)
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