scons.0.92 - Implement a --duplicate= option. (Christoph Wiedemann)

2 files changed, 138 insertions, 78 deletions

diff --git a/src/engine/SCons/Node/FS.py b/src/engine/SCons/Node/FS.py
index dbcaf8a..3bf2ee4 100644
--- a/src/engine/SCons/Node/FS.py
+++ b/src/engine/SCons/Node/FS.py
@@ -66,29 +66,77 @@ import SCons.Warnings
 # there should be *no* changes to the external file system(s)...
 #
 
+def _copy_func(src, dest):
+    shutil.copy2(src, dest)
+    st=os.stat(src)
+    os.chmod(dest, stat.S_IMODE(st[stat.ST_MODE]) | stat.S_IWRITE)
+
+Valid_Duplicates = ['hard-soft-copy', 'soft-hard-copy',
+                    'hard-copy', 'soft-copy', 'copy']
+
+Link_Funcs = [] # contains the callables of the specified duplication style
+
+def set_duplicate(duplicate):
+    # Fill in the Link_Funcs list according to the argument
+    # (discarding those not available on the platform).
+
+    # Set up the dictionary that maps the argument names to the
+    # underlying implementations.  We do this inside this function,
+    # not in the top-level module code, so that we can remap os.link
+    # and os.symlink for testing purposes.
+    try:
+        _hardlink_func = os.link
+    except AttributeError:
+        _hardlink_func = None
+
+    try:
+        _softlink_func = os.symlink
+    except AttributeError:
+        _softlink_func = None
+
+    link_dict = {
+        'hard' : _hardlink_func,
+        'soft' : _softlink_func,
+        'copy' : _copy_func
+    }
+
+    if not duplicate in Valid_Duplicates:
+        raise SCons.Errors.InternalError, ("The argument of set_duplicate "
+                                           "should be in Valid_Duplicates")
+    global Link_Funcs
+    Link_Funcs = []
+    for func in string.split(duplicate,'-'):
+        if link_dict[func]:
+            Link_Funcs.append(link_dict[func])
+
 def LinkFunc(target, source, env):
-    t = target[0]
-    dest = t.path
-    fs = t.fs
-    src = source[0].path
+    # Relative paths cause problems with symbolic links, so
+    # we use absolute paths, which may be a problem for people
+    # who want to move their soft-linked src-trees around. Those
+    # people should use the 'hard-copy' mode, softlinks cannot be
+    # used for that; at least I have no idea how ...
+    src = source[0].abspath
+    dest = target[0].abspath
     dir, file = os.path.split(dest)
-    if dir and not fs.isdir(dir):
-        fs.makedirs(dir)
-    # Now actually link the files.  First try to make a hard link.  If that
-    # fails, try a symlink.  If that fails then just copy it.
-    try :
-        fs.link(src, dest)
-    except (AttributeError, OSError):
-        try :
-            fs.symlink(src, dest)
-        except (AttributeError, OSError):
-            fs.copy2(src, dest)
-            st = fs.stat(src)
-            fs.chmod(dest, stat.S_IMODE(st[stat.ST_MODE]) | stat.S_IWRITE)
+    if dir and not os.path.isdir(dir):
+        os.makedirs(dir)
+    if not Link_Funcs:
+        # Set a default order of link functions.
+        set_duplicate('hard-soft-copy')
+    # Now link the files with the previously specified order.
+    for func in Link_Funcs:
+        try:
+            func(src,dest)
+            break
+        except OSError:
+            if func == Link_Funcs[-1]:
+                # exception of the last link method (copy) are fatal
+                raise
+            else:
+                pass
     return 0
 
 Link = SCons.Action.Action(LinkFunc, None)
-
 def LocalString(target, source, env):
     return 'Local copy of %s from %s' % (target[0], source[0])
 
diff --git a/src/engine/SCons/Node/FSTests.py b/src/engine/SCons/Node/FSTests.py
index 85ae4d9..63ac29d 100644
--- a/src/engine/SCons/Node/FSTests.py
+++ b/src/engine/SCons/Node/FSTests.py
@@ -413,15 +413,14 @@ class BuildDirTestCase(unittest.TestCase):
         class LinkSimulator :
             """A class to intercept os.[sym]link() calls and track them."""
 
-            def __init__( self ) :
+            def __init__( self, duplicate ) :
+                self.duplicate = duplicate
                 self._reset()
 
             def _reset( self ) :
                 """Reset the simulator if necessary"""
                 if not self._need_reset() : return # skip if not needed now
-                self.link_called = False
-                self.symlink_called = False
-                self.copy_called = False
+                self.links_to_be_called = self.duplicate
 
             def _need_reset( self ) :
                 """
@@ -430,85 +429,98 @@ class BuildDirTestCase(unittest.TestCase):
                 or if all three methods have been tried already.
                 """
                 return (
-                        ( not hasattr( self , "link_called" ) )
+                        ( not hasattr( self , "links_to_be_called" ) )
                         or
-                        ( self.link_called and
-                          self.symlink_called and
-                          self.copy_called )
+                        (self.links_to_be_called == "")
                        )
 
             def link_fail( self , src , dest ) :
                 self._reset()
-                assert not self.symlink_called , \
-                        "Wrong link order: symlink tried before hard link."
-                assert not self.copy_called , \
-                        "Wrong link order: copy tried before hard link."
-                self.link_called = True
+                l = string.split(self.links_to_be_called, "-")
+                next_link = l[0]
+                assert  next_link == "hard", \
+                       "Wrong link order: expected %s to be called "\
+                       "instead of hard" % next_link
+                self.links_to_be_called = string.join(l[1:], '-')
                 raise OSError( "Simulating hard link creation error." )
 
             def symlink_fail( self , src , dest ) :
                 self._reset()
-                assert self.link_called , \
-                        "Wrong link order: hard link not tried before symlink."
-                assert not self.copy_called , \
-                        "Wrong link order: copy tried before symlink link."
-                self.symlink_called = True
+                l = string.split(self.links_to_be_called, "-")
+                next_link = l[0]
+                assert  next_link == "soft", \
+                       "Wrong link order: expected %s to be called "\
+                       "instead of soft" % next_link
+                self.links_to_be_called = string.join(l[1:], '-')
                 raise OSError( "Simulating symlink creation error." )
 
             def copy( self , src , dest ) :
                 self._reset()
-                assert self.link_called , \
-                        "Wrong link order: hard link not tried before copy."
-                assert self.symlink_called , \
-                        "Wrong link order: symlink not tried before copy."
-                self.copy_called = True
+                l = string.split(self.links_to_be_called, "-")
+                next_link = l[0]
+                assert  next_link == "copy", \
+                       "Wrong link order: expected %s to be called "\
+                       "instead of copy" % next_link
+                self.links_to_be_called = string.join(l[1:], '-')
                 # copy succeeds, but use the real copy
                 self._real_copy(src, dest)
         # end class LinkSimulator
-        simulator = LinkSimulator()
 
-        # save the real functions for later restoration
-        real_link = None
-        real_symlink = None
         try:
-            real_link = os.link
-        except AttributeError:
-            pass
-        try:
-            real_symlink = os.symlink
-        except AttributeError:
+            SCons.Node.FS.set_duplicate("no-link-order")
+            assert 0, "Expected exception when passing an invalid duplicate to set_duplicate"
+        except SCons.Errors.InternalError:
             pass
-        real_copy = shutil.copy2
-        simulator._real_copy = real_copy # the simulator needs the real one
+            
+        for duplicate in SCons.Node.FS.Valid_Duplicates:
+            simulator = LinkSimulator(duplicate)
 
-        # override the real functions with our simulation
-        os.link = simulator.link_fail
-        os.symlink = simulator.symlink_fail
-        shutil.copy2 = simulator.copy
+            # save the real functions for later restoration
+            real_link = None
+            real_symlink = None
+            try:
+                real_link = os.link
+            except AttributeError:
+                pass
+            try:
+                real_symlink = os.symlink
+            except AttributeError:
+                pass
+            real_copy = shutil.copy2
+            simulator._real_copy = real_copy # the simulator needs the real one
+
+            # override the real functions with our simulation
+            os.link = simulator.link_fail
+            os.symlink = simulator.symlink_fail
+            shutil.copy2 = simulator.copy
+            SCons.Node.FS.set_duplicate(duplicate)
+
+            src_foo = test.workpath('src', 'foo')
+            build_foo = test.workpath('build', 'foo')
 
-        try:
-            test.write('src/foo', 'src/foo\n')
             try:
-                os.chmod(test.workpath('src/foo'), stat.S_IRUSR)
-                SCons.Node.FS.Link(fs.File(test.workpath('build/foo')),
-                                   fs.File(test.workpath('src/foo')),
-                                   None)
-                os.chmod(test.workpath('src/foo'), stat.S_IRUSR | stat.S_IWRITE)
-            finally:
-                test.unlink( "src/foo" )
-                test.unlink( "build/foo" )
+                test.write(src_foo, 'src/foo\n')
+                os.chmod(src_foo, stat.S_IRUSR)
+                try:
+                    SCons.Node.FS.Link(fs.File(build_foo),
+                                       fs.File(src_foo),
+                                       None)
+                finally:
+                    os.chmod(src_foo, stat.S_IRUSR | stat.S_IWRITE)
+                    test.unlink(src_foo)
+                    test.unlink(build_foo)
 
-        finally:
-            # restore the real functions
-            if real_link:
-                os.link = real_link
-            else:
-                delattr(os, 'link')
-            if real_symlink:
-                os.symlink = real_symlink
-            else:
-                delattr(os, 'symlink')
-            shutil.copy2 = real_copy
+            finally:
+                # restore the real functions
+                if real_link:
+                    os.link = real_link
+                else:
+                    delattr(os, 'link')
+                if real_symlink:
+                    os.symlink = real_symlink
+                else:
+                    delattr(os, 'symlink')
+                shutil.copy2 = real_copy
 
 class FSTestCase(unittest.TestCase):
     def runTest(self):