Merge #15456: Enable PID file creation on WIN

3f5ad622e5fe0781a70bee9e3322b23c2352e956 Enable PID file creation on Windows - Add available WIN PID function - Consider WIN32 in each relevant case - Add new preprocessor definitions to suppress warning - Update error message for generic OS (riordant)

Pull request description:

  # Introduction

  As discussed with @laanwj on IRC:

  - PID file creation was never enabled for Windows, as the `pid_t` filetype is not available for it. However, the WIN32 API contains the header [`Processthreadsapi.h`](https://github.com/CodeShark/x86_64-w64-mingw32/blob/master/include/processthreadsapi.h) which in turn contains the function [`GetCurrentProcessId()`](https://docs.microsoft.com/en-gb/windows/desktop/api/processthreadsapi/nf-processthreadsapi-getcurrentprocessid). ~~This function is called at a higher level by [`_getpid()`](https://docs.microsoft.com/en-us/cpp/c-runtime-library/reference/getpid?view=vs-2017)~~ EDIT: `_getpid()` is not available to the MSVC compiler used in the AppVeyor build. As a result, I have changed the function call to`GetCurrentProcessId()`, which performs the same function and is available to both MinGW & MSVC.
  This allows one to capture the PID in Windows, without any additional includes - the above function is already available.

  - Within this PR, I have added a separate line that calls `GetCurrentProcessId()` in the case of a WIN compilation, and the usual `getpid()` otherwise. All code blocks processing PID file logic that avoid WIN32 have been changed to consider it. I have also updated the preprocessor definitions in `libbitcoin_server.vcxproj.in` to suppress a warning related to `std::strerror` for the MSVC build, that was causing the AppVeyor build to fail (see @fanquake comment below).

  # Rationale
  - Consistency between OS's running Bitcoin
      - Applications which build off of `bitcoind`, such as novel front-end clients, often need access to the PID in order to control the daemon. Instead of designing some alternate way of doing this for one system, it should be consistent between all of them.

  In collaboration with @joernroeder

Tree-SHA512: 22fcbf866e99115d12ed29716e68d200d4c118ae2f7b188b7705dc0cf5f0cd0ce5fb18f772744c6238eecd9e6d0922c615e2f0e12a7fe7c810062a79d97aa6a2

1 files changed, 5 insertions, 11 deletions

diff --git a/src/init.cpp b/src/init.cpp
index 8b831a726f..8876b54fde 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -97,7 +97,6 @@ static const char* FEE_ESTIMATES_FILENAME="fee_estimates.dat";
 /**
  * The PID file facilities.
  */
-#ifndef WIN32
 static const char* BITCOIN_PID_FILENAME = "bitcoind.pid";
 
 static fs::path GetPidFile()
@@ -109,14 +108,17 @@ NODISCARD static bool CreatePidFile()
 {
     FILE* file = fsbridge::fopen(GetPidFile(), "w");
     if (file) {
+#ifdef WIN32
+        fprintf(file, "%d\n", GetCurrentProcessId());
+#else
         fprintf(file, "%d\n", getpid());
+#endif
         fclose(file);
         return true;
     } else {
         return InitError(strprintf(_("Unable to create the PID file '%s': %s"), GetPidFile().string(), std::strerror(errno)));
     }
 }
-#endif
 
 //////////////////////////////////////////////////////////////////////////////
 //
@@ -286,15 +288,13 @@ void Shutdown(InitInterfaces& interfaces)
     }
 #endif
 
-#ifndef WIN32
     try {
         if (!fs::remove(GetPidFile())) {
             LogPrintf("%s: Unable to remove PID file: File does not exist\n", __func__);
         }
     } catch (const fs::filesystem_error& e) {
-        LogPrintf("%s: Unable to remove PID file: %s\n", __func__, e.what());
+        LogPrintf("%s: Unable to remove PID file: %s\n", __func__, fsbridge::get_filesystem_error_message(e));
     }
-#endif
     interfaces.chain_clients.clear();
     UnregisterAllValidationInterfaces();
     GetMainSignals().UnregisterBackgroundSignalScheduler();
@@ -392,11 +392,7 @@ void SetupServerArgs()
     gArgs.AddArg("-par=<n>", strprintf("Set the number of script verification threads (%u to %d, 0 = auto, <0 = leave that many cores free, default: %d)",
         -GetNumCores(), MAX_SCRIPTCHECK_THREADS, DEFAULT_SCRIPTCHECK_THREADS), false, OptionsCategory::OPTIONS);
     gArgs.AddArg("-persistmempool", strprintf("Whether to save the mempool on shutdown and load on restart (default: %u)", DEFAULT_PERSIST_MEMPOOL), false, OptionsCategory::OPTIONS);
-#ifndef WIN32
     gArgs.AddArg("-pid=<file>", strprintf("Specify pid file. Relative paths will be prefixed by a net-specific datadir location. (default: %s)", BITCOIN_PID_FILENAME), false, OptionsCategory::OPTIONS);
-#else
-    hidden_args.emplace_back("-pid");
-#endif
     gArgs.AddArg("-prune=<n>", strprintf("Reduce storage requirements by enabling pruning (deleting) of old blocks. This allows the pruneblockchain RPC to be called to delete specific blocks, and enables automatic pruning of old blocks if a target size in MiB is provided. This mode is incompatible with -txindex and -rescan. "
             "Warning: Reverting this setting requires re-downloading the entire blockchain. "
             "(default: 0 = disable pruning blocks, 1 = allow manual pruning via RPC, >=%u = automatically prune block files to stay under the specified target size in MiB)", MIN_DISK_SPACE_FOR_BLOCK_FILES / 1024 / 1024), false, OptionsCategory::OPTIONS);
@@ -1228,12 +1224,10 @@ bool AppInitMain(InitInterfaces& interfaces)
 {
     const CChainParams& chainparams = Params();
     // ********************************************************* Step 4a: application initialization
-#ifndef WIN32
     if (!CreatePidFile()) {
         // Detailed error printed inside CreatePidFile().
         return false;
     }
-#endif
     if (LogInstance().m_print_to_file) {
         if (gArgs.GetBoolArg("-shrinkdebugfile", LogInstance().DefaultShrinkDebugFile())) {
             // Do this first since it both loads a bunch of debug.log into memory,