Revert "refactor: remove obsolete lightweight build option (#4509)"

This reverts commit 47ebb3f.

CMakeLists.txt

@@ -49,6 +49,9 @@ option(ENABLE_WEB "Build Web client" OFF)
 option(ENABLE_UTILS "Build utils (create, edit, show)" ON)
 option(ENABLE_CLI "Build command-line client" OFF)
 option(ENABLE_TESTS "Build unit tests" ON)
+option(ENABLE_LIGHTWEIGHT
+    "Optimize libtransmission for low-resource systems: smaller cache size, prefer unencrypted peer connections, etc."
+    OFF)
 option(ENABLE_UTP "Build µTP support" ON)
 option(ENABLE_WERROR "Treat warnings as errors" OFF)
 option(ENABLE_NLS "Enable native language support" ON)

docs/Editing-Configuration-Files.md

@@ -69,14 +69,14 @@ Here is a sample of the three basic types: respectively Boolean, Number and Stri
    _Note: When **watch-dir-enabled** is true, only the transmission-daemon, transmission-gtk, and transmission-qt applications will monitor **watch-dir** for new .torrent files and automatically load them._
 
 #### Misc
- * **cache-size-mb:** Size (default = 4), in megabytes, to allocate for Transmission's memory cache. The cache is used to help batch disk IO together, so increasing the cache size can be used to reduce the number of disk reads and writes.
+ * **cache-size-mb:** Size (default = 4), in megabytes, to allocate for Transmission's memory cache. The cache is used to help batch disk IO together, so increasing the cache size can be used to reduce the number of disk reads and writes. Default is 2 if configured with --enable-lightweight.
  * **dht-enabled:** Boolean (default = true) Enable [Distributed Hash Table (DHT)](https://wiki.theory.org/BitTorrentSpecification#Distributed_Hash_Table).
  * **encryption:** Number (0 = Prefer unencrypted connections, 1 = Prefer encrypted connections, 2 = Require encrypted connections; default = 1) [Encryption](https://wiki.vuze.com/w/Message_Stream_Encryption) preference. Encryption may help get around some ISP filtering, but at the cost of slightly higher CPU use.
  * **lazy-bitfield-enabled:** Boolean (default = true) May help get around some ISP filtering. [Vuze specification](https://wiki.vuze.com/w/Commandline_options#Network_Options).
  * **lpd-enabled:** Boolean (default = false) Enable [Local Peer Discovery (LPD)](https://en.wikipedia.org/wiki/Local_Peer_Discovery).
  * **message-level:** Number (0 = None, 1 = Error, 2 = Info, 3 = Debug, default = 2) Set verbosity of transmission messages.
  * **pex-enabled:** Boolean (default =  true) Enable [https://en.wikipedia.org/wiki/Peer_exchange Peer Exchange (PEX)].
- * **prefetch-enabled:** Boolean (default = true). When enabled, Transmission will hint to the OS which piece data it's about to read from disk in order to satisfy requests from peers. On Linux, this is done by passing `POSIX_FADV_WILLNEED` to [posix_fadvise()](https://www.kernel.org/doc/man-pages/online/pages/man2/posix_fadvise.2.html). On macOS, this is done by passing `F_RDADVISE` to [fcntl()](https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/fcntl.2.html).
+ * **prefetch-enabled:** Boolean (default = true). When enabled, Transmission will hint to the OS which piece data it's about to read from disk in order to satisfy requests from peers. On Linux, this is done by passing `POSIX_FADV_WILLNEED` to [posix_fadvise()](https://www.kernel.org/doc/man-pages/online/pages/man2/posix_fadvise.2.html). On macOS, this is done by passing `F_RDADVISE` to [fcntl()](https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/fcntl.2.html). This defaults to false if configured with --enable-lightweight.
  * **scrape-paused-torrents-enabled:** Boolean (default = true)
  * **script-torrent-added-enabled:** Boolean (default = false) Run a script when a torrent is added to Transmission. Environmental variables are passed in as detailed on the [Scripts](./Scripts.md) page
  * **script-torrent-added-filename:** String (default = "") Path to script.

libtransmission/CMakeLists.txt

@@ -227,6 +227,7 @@ target_compile_definitions(${TR_NAME}
         PACKAGE_DATA_DIR="${CMAKE_INSTALL_FULL_DATAROOTDIR}"
         $<$<BOOL:${WITH_INOTIFY}>:WITH_INOTIFY>
         $<$<BOOL:${WITH_KQUEUE}>:WITH_KQUEUE>
+        $<$<BOOL:${ENABLE_LIGHTWEIGHT}>:TR_LIGHTWEIGHT>
         $<$<BOOL:${ENABLE_UTP}>:WITH_UTP>
         $<$<VERSION_LESS:${MINIUPNPC_VERSION},1.7>:MINIUPNPC_API_VERSION=${MINIUPNPC_API_VERSION}> # API version macro was only added in 1.7
         $<$<BOOL:${USE_SYSTEM_B64}>:USE_SYSTEM_B64>

libtransmission/crypto-utils-openssl.cc

@@ -37,7 +37,11 @@ static void log_openssl_error(char const* file, int line)
 
     if (tr_logLevelIsActive(TR_LOG_ERROR))
     {
-        if (static bool strings_loaded = false; !strings_loaded)
+#ifndef TR_LIGHTWEIGHT
+
+        static bool strings_loaded = false;
+
+        if (!strings_loaded)
         {
 #if OPENSSL_VERSION_NUMBER < 0x10100000 || (defined(LIBRESSL_VERSION_NUMBER) && LIBRESSL_VERSION_NUMBER < 0x20700000)
             ERR_load_crypto_strings();
@@ -48,6 +52,8 @@ static void log_openssl_error(char const* file, int line)
             strings_loaded = true;
         }
 
+#endif
+
         auto buf = std::array<char, 512>{};
         ERR_error_string_n(error_code, std::data(buf), std::size(buf));
         tr_logAddMessage(

libtransmission/utils.h

@@ -43,7 +43,7 @@ struct tr_error;
 
 /* #define DISABLE_GETTEXT */
 #ifndef DISABLE_GETTEXT
-#if defined(_WIN32)
+#if defined(_WIN32) || defined(TR_LIGHTWEIGHT)
 #define DISABLE_GETTEXT
 #endif
 #endif