1 files changed, 189 insertions, 0 deletions
diff --git a/site_scons/libdeps.py b/site_scons/libdeps.py
new file mode 100644
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+++ b/site_scons/libdeps.py
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+"""Extension to SCons providing advanced static library dependency tracking.
+
+These modifications to a build environment, which can be attached to
+StaticLibrary and Program builders via a call to setup_environment(env),
+cause the build system to track library dependencies through static libraries,
+and to add them to the link command executed when building programs.
+
+For example, consider a program 'try' that depends on a lib 'tc', which in
+turn uses a symbol from a lib 'tb' which in turn uses a library from 'ta'.
+Without this package, the Program declaration for "try" looks like this:
+
+Program('try', ['try.c', 'path/to/${LIBPREFIX}tc${LIBSUFFIX}',
+                'path/to/${LIBPREFIX}tc${LIBSUFFIX}',
+                'path/to/${LIBPREFIX}tc${LIBSUFFIX}',])
+
+With this library, we can instead write the following
+
+Program('try', ['try.c'], LIBDEPS=['path/to/tc'])
+StaticLibrary('tc', ['c.c'], LIBDEPS=['path/to/tb'])
+StaticLibrary('tb', ['b.c'], LIBDEPS=['path/to/ta'])
+StaticLibrary('ta', ['a.c'])
+
+And the build system will figure out that it needs to link libta.a and libtb.a
+when building 'try'.
+"""
+
+# Copyright (c) 2010, Corensic Inc., All Rights Reserved.
+#
+# Permission is hereby granted, free of charge, to any person obtaining
+# a copy of this software and associated documentation files (the
+# "Software"), to deal in the Software without restriction, including
+# without limitation the rights to use, copy, modify, merge, publish,
+# distribute, sublicense, and/or sell copies of the Software, and to
+# permit persons to whom the Software is furnished to do so, subject to
+# the following conditions:
+#
+# The above copyright notice and this permission notice shall be included
+# in all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY
+# KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
+# WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+import os
+
+import SCons.Errors
+import SCons.Scanner
+import SCons.Util
+
+class DependencyCycleError(SCons.Errors.UserError):
+    """Exception representing a cycle discovered in library dependencies."""
+
+    def __init__(self, first_node ):
+        super(DependencyCycleError, self).__init__()
+        self.cycle_nodes = [first_node]
+
+    def __str__(self):
+        return " => ".join(str(n) for n in self.cycle_nodes)
+
+def __get_libdeps(node, env_var):
+    """Given a SCons Node, return its library dependencies.
+
+    Computes the dependencies if they're not already cached.
+    """
+
+    cached_var_name = env_var + '_cached'
+
+    if not hasattr(node.attributes, cached_var_name):
+        setattr(node.attributes, cached_var_name, __compute_libdeps(node, env_var))
+    return getattr(node.attributes, cached_var_name)
+
+def __compute_libdeps(node, env_var):
+    """Recursively identify all library dependencies for a node."""
+
+    if getattr(node.attributes, 'libdeps_exploring', False):
+        raise DependencyCycleError(node)
+
+    env = node.get_env()
+    deps = set()
+    node.attributes.libdeps_exploring = True
+    try:
+        try:
+            for child in env.Flatten(env.get(env_var, [])):
+                if not child:
+                    continue
+                deps.add(child)
+                deps.update(__get_libdeps(child, env_var))
+
+        except DependencyCycleError, e:
+            if len(e.cycle_nodes) == 1 or e.cycle_nodes[0] != e.cycle_nodes[-1]:
+                e.cycle_nodes.append(node)
+                raise
+    finally:
+        node.attributes.libdeps_exploring = False
+
+    return deps
+
+def update_scanner(builder):
+    """Update the scanner for "builder" to also scan library dependencies."""
+
+    old_scanner = builder.target_scanner
+
+    if old_scanner:
+        path_function = old_scanner.path_function
+        def new_scanner(node, env, path=()):
+            result = set(old_scanner.function(node, env, path))
+            result.update(__get_libdeps(node, 'LIBDEPS'))
+            result.update(__get_libdeps(node, 'SYSLIBDEPS'))
+            return sorted(result)
+    else:
+        path_function = None
+        def new_scanner(node, env, path=()):
+            result = set(__get_libdeps(node, 'LIBDEPS'))
+            result.update(__get_libdeps(node, 'SYSLIBDEPS'))
+            return sorted(result)
+
+    builder.target_scanner = SCons.Scanner.Scanner(function=new_scanner,
+                                                    path_function=path_function)
+
+def get_libdeps(source, target, env, for_signature):
+    """Implementation of the special _LIBDEPS environment variable.
+
+    Expands to the library dependencies for a target.
+    """
+
+    if for_signature:
+        return []
+    return list(__get_libdeps(target[0], 'LIBDEPS'))
+
+def get_syslibdeps(source, target, env, for_signature):
+    if for_signature:
+        return[]
+    deps = list(__get_libdeps(target[0], 'SYSLIBDEPS'))
+    return deps
+
+def libdeps_emitter(target, source, env):
+    """SCons emitter that takes values from the LIBDEPS environment variable and
+    converts them to File node objects, binding correct path information into
+    those File objects.
+
+    Emitters run on a particular "target" node during the initial execution of
+    the SConscript file, rather than during the later build phase.  When they
+    run, the "env" environment's working directory information is what you
+    expect it to be -- that is, the working directory is considered to be the
+    one that contains the SConscript file.  This allows specification of
+    relative paths to LIBDEPS elements.
+
+    This emitter also adds LIBSUFFIX and LIBPREFIX appropriately.
+    """
+
+    libdep_files = []
+    lib_suffix = env.subst('$LIBSUFFIX', target=target, source=source)
+    lib_prefix = env.subst('$LIBPREFIX', target=target, source=source)
+    for dep in env.Flatten([env.get('LIBDEPS', [])]):
+        full_path = env.subst(str(dep), target=target, source=source)
+        dir_name = os.path.dirname(full_path)
+        file_name = os.path.basename(full_path)
+        if not file_name.startswith(lib_prefix):
+            file_name = '${LIBPREFIX}' + file_name
+        if not file_name.endswith(lib_suffix):
+            file_name += '${LIBSUFFIX}'
+        libdep_files.append(env.File(os.path.join(dir_name, file_name)))
+
+    env['LIBDEPS'] = libdep_files
+
+    return target, source
+
+def setup_environment(env):
+    """Set up the given build environment to do LIBDEPS tracking."""
+
+    env['_LIBDEPS'] = get_libdeps
+    env['_SYSLIBDEPS'] = ' ${_stripixes(LIBLINKPREFIX, SYSLIBDEPS, LIBLINKSUFFIX, LIBPREFIXES, LIBSUFFIXES, __env__)} '
+    env['_SHLIBDEPS'] = '$SHLIBDEP_GROUP_START ${_concat(SHLIBDEPPREFIX, __env__.subst(_LIBDEPS, target=TARGET, source=SOURCE), SHLIBDEPSUFFIX, __env__, target=TARGET, source=SOURCE)} $SHLIBDEP_GROUP_END'
+
+    env['LIBDEPS'] = SCons.Util.CLVar()
+    env['SYSLIBDEPS'] = SCons.Util.CLVar()
+    env.Append(LIBEMITTER=libdeps_emitter,
+               PROGEMITTER=libdeps_emitter,
+               SHLIBEMITTER=libdeps_emitter)
+    env.Prepend(_LIBFLAGS=' $LINK_LIBGROUP_START $_LIBDEPS $LINK_LIBGROUP_END $_SYSLIBDEPS ')
+    for builder_name in ('Program', 'SharedLibrary', 'LoadableModule'):
+        try:
+            update_scanner(env['BUILDERS'][builder_name])
+        except KeyError:
+            pass