1+ #
2+ # DownloadCacher.cmake
3+ # Copyright 2021-2022 ItJustWorksTM
4+ #
5+ # Licensed under the Apache License, Version 2.0 (the "License");
6+ # you may not use this file except in compliance with the License.
7+ # You may obtain a copy of the License at
8+ #
9+ # http://www.apache.org/licenses/LICENSE-2.0
10+ #
11+ # Unless required by applicable law or agreed to in writing, software
12+ # distributed under the License is distributed on an "AS IS" BASIS,
13+ # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14+ # See the License for the specific language governing permissions and
15+ # limitations under the License.
16+ #
17+
18+ # function for cleaning the cache
19+ function (clear_download_cache)
20+ # delete all contents in the cached folder
21+ file (REMOVE_RECURSE "${SMCE_DIR} /cached_downloads/" )
22+ message (STATUS "Cache cleared" )
23+ endfunction ()
24+
25+ #[================================================================================================================[.rst:
26+ cached_download
27+ --------------------
28+
29+ Function to allow for caching of various downloads.
30+
31+ Usage:
32+ .. code-block:: cmake
33+
34+ cached_download (URL <url> DEST <dest-var> [RESULT_VARIABLE <res-var>] [FORCE_UPDATE])
35+
36+ Where ``<url>`` is the URL to the file to be downloaded, ``<dest-var>`` is the name of the variable to store the absolute
37+ real path to the download location passed to the parent scope by the function, ``<res-var>``
38+ is the name of the variable to store the result of all processes passed to the parent scope by
39+ the function, ``[FORCE_UPDATE]`` will define whether an already cached download should be re-downloaded and cached.
40+
41+
42+ Note:
43+ No additional arguments except for the ones defined are allowed in the function call.
44+ Uses SHA256 to create a uniquely hashed download location for each download.
45+ Download file is locked until the file has been downloaded and cached, this is done in order to avoid
46+ possible race conditions.
47+ #]================================================================================================================]
48+ function (cached_download)
49+ # initialize the cache download directory
50+ file (MAKE_DIRECTORY "${SMCE_DIR} /cached_downloads" )
51+
52+ # parse args
53+ set (options FORCE_UPDATE)
54+ set (oneValueArgs URL RESULT_VARIABLE DEST)
55+ set (multiValueArgs)
56+ cmake_parse_arguments ("ARG" "${options} " "${oneValueArgs} " "${multiValueArgs} " ${ARGN} )
57+
58+ if (${ARG_UNPARSED_ARGUMENTS} )
59+ if (DEFINED ARG_RESULT_VARIABLE)
60+ set ("Function was called with too many arguments" PARENT_SCOPE)
61+ else ()
62+ message (FATAL_ERROR "Function was called with too many arguments" )
63+ endif ()
64+ endif ()
65+
66+ # use SHA256 hash to URL to create unique identifier, lock download location mutex-style
67+ string (SHA256 hashed_dest "${ARG_URL} " )
68+ set (download_path "${SMCE_DIR} /cached_downloads/${hashed_dest} " )
69+ file (TOUCH "${download_path} .lock" )
70+ file (LOCK "${download_path} .lock" )
71+
72+ # check if plugin has already been downloaded and cached before
73+ if (EXISTS "${download_path} " )
74+ set (index 1)
75+ else ()
76+ set (index -1)
77+ endif ()
78+
79+ # if download has been cached previously and is requested a forced re-download, clean previous download and re-cache
80+ if (${index} GREATER -1 AND ${ARG_FORCE_UPDATE} )
81+ file (REMOVE "${download_path} " )
82+ set (${index} -1)
83+ endif ()
84+
85+ # if download has not been cached, download. Otherwise pass.
86+ if (${index} LESS 0)
87+ message (DEBUG "Downloading" )
88+
89+ file (DOWNLOAD "${ARG_URL} " "${download_path} " STATUS dlstatus)
90+ list (GET dlstatus 0 dlstatus_code)
91+ if (dlstatus_code)
92+ list (GET dlstatus 1 dlstatus_message)
93+ file (REMOVE "${download_path} " )
94+ file (REMOVE "${download_path} .lock" )
95+ if (DEFINED ARG_RESULT_VARIABLE)
96+ set ("${ARG_RESULT_VARIABLE} " "${dlstatus} " PARENT_SCOPE)
97+ else ()
98+ message (FATAL_ERROR "Download failed: (${dlstatus_code} ) ${dlstatus_message} " )
99+ endif ()
100+ endif ()
101+ message (DEBUG "Download complete" )
102+ message (DEBUG "Cached!" )
103+ else ()
104+ message (DEBUG "Has already been cached!" )
105+ endif ()
106+
107+ # Unlock file and output absolute real path to download location
108+ file (LOCK "${download_path} .lock" RELEASE)
109+ file (REMOVE "${download_path} .lock" )
110+
111+ if (CMAKE_VERSION VERSION_GREATER_EQUAL "3.19" )
112+ file (REAL_PATH "${download_path} " download_path)
113+ else ()
114+ get_filename_component (download_path "${download_path} " REALPATH)
115+ endif ()
116+
117+ set ("${ARG_DEST} " "${download_path} " PARENT_SCOPE)
118+ endfunction ()
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