Merge topic 'file-install-follow-symlink-chain'

e3ff7ced63 file(INSTALL): Add FOLLOW_SYMLINK_CHAIN argument

Acked-by: Kitware Robot <kwrobot@kitware.com>
Acked-by: Brad King <brad.king@kitware.com>
Merge-request: !3332

Help/command/file.rst

@@ -311,6 +311,7 @@ Create the given directories and their parents as needed.
        [FILE_PERMISSIONS <permissions>...]
        [DIRECTORY_PERMISSIONS <permissions>...]
        [NO_SOURCE_PERMISSIONS] [USE_SOURCE_PERMISSIONS]
+       [FOLLOW_SYMLINK_CHAIN]
        [FILES_MATCHING]
        [[PATTERN <pattern> | REGEX <regex>]
         [EXCLUDE] [PERMISSIONS <permissions>...]] [...])
@@ -324,6 +325,32 @@ at the destination with the same timestamp.  Copying preserves input
 permissions unless explicit permissions or ``NO_SOURCE_PERMISSIONS``
 are given (default is ``USE_SOURCE_PERMISSIONS``).
 
+If ``FOLLOW_SYMLINK_CHAIN`` is specified, ``COPY`` will recursively resolve
+the symlinks at the paths given until a real file is found, and install
+a corresponding symlink in the destination for each symlink encountered. For
+each symlink that is installed, the resolution is stripped of the directory,
+leaving only the filename, meaning that the new symlink points to a file in
+the same directory as the symlink. This feature is useful on some Unix systems,
+where libraries are installed as a chain of symlinks with version numbers, with
+less specific versions pointing to more specific versions.
+``FOLLOW_SYMLINK_CHAIN`` will install all of these symlinks and the library
+itself into the destination directory. For example, if you have the following
+directory structure:
+
+* ``/opt/foo/lib/libfoo.so.1.2.3``
+* ``/opt/foo/lib/libfoo.so.1.2 -> libfoo.so.1.2.3``
+* ``/opt/foo/lib/libfoo.so.1 -> libfoo.so.1.2``
+* ``/opt/foo/lib/libfoo.so -> libfoo.so.1``
+
+and you do:
+
+.. code-block:: cmake
+
+  file(COPY /opt/foo/lib/libfoo.so DESTINATION lib FOLLOW_SYMLINK_CHAIN)
+
+This will install all of the symlinks and ``libfoo.so.1.2.3`` itself into
+``lib``.
+
 See the :command:`install(DIRECTORY)` command for documentation of
 permissions, ``FILES_MATCHING``, ``PATTERN``, ``REGEX``, and
 ``EXCLUDE`` options.  Copying directories preserves the structure

Help/release/dev/file-install-follow-symlink-chain.rst

@@ -0,0 +1,6 @@
+file-install-follow-symlink-chain
+---------------------------------
+
+* The :command:`file(INSTALL)` command learned a new argument,
+  ``FOLLOW_SYMLINK_CHAIN``, which can be used to recursively resolve and
+  install symlinks.