Merge bitcoin#15278: Improve PID file error handling

3782075 Move all PID file stuff to init.cpp (Hennadii Stepanov)
561e375 Make PID file creating errors fatal (Hennadii Stepanov)
745a2ac Improve PID file removing errors logging (Hennadii Stepanov)

Pull request description:

  Digging into bitcoin#15240 the lack of the proper logging has been discovered.
  Fixed by this PR.

  UPDATE (inspired by @laanwj's [comment](bitcoin#15278 (comment))):
  Not being able to create the PID file is fatal now.

  Output of `bitcoind`:

  ```
  $ src/bitcoind -pid=/run/bitcoind/bitcoind.pid
  2019-02-01T23:20:10Z Bitcoin Core version v0.17.99.0-561e375c7 (release build)
  2019-02-01T23:20:10Z Assuming ancestors of block 0000000000000037a8cd3e06cd5edbfe9dd1dbcc5dacab279376ef7cfc2b4c75 have valid signatures.
  2019-02-01T23:20:10Z Setting nMinimumChainWork=00000000000000000000000000000000000000000000007dbe94253893cbd463
  2019-02-01T23:20:10Z Using the 'sse4(1way),sse41(4way),avx2(8way)' SHA256 implementation
  2019-02-01T23:20:10Z Using RdRand as an additional entropy source
  2019-02-01T23:20:11Z Error: Unable to create the PID file '/run/bitcoind/bitcoind.pid': No such file or directory
  Error: Unable to create the PID file '/run/bitcoind/bitcoind.pid': No such file or directory
  2019-02-01T23:20:11Z Shutdown: In progress...
  2019-02-01T23:20:11Z Shutdown: Unable to remove PID file: File does not exist
  2019-02-01T23:20:11Z Shutdown: done
  ```

  Output of `bitcoin-qt`:
  ![screenshot from 2019-02-02 01-19-05](https://user-images.githubusercontent.com/32963518/52154886-9349b600-2688-11e9-8128-470f16790305.png)

  **Notes for reviewers**
  1. `CreatePidFile()` has been moved from `util/system.cpp` to `init.cpp` for the following reasons:
  - to get the ability to use `InitError()`
  - now `init.cpp` contains code of both creating PID file and removing it

  2. Regarding 0.18 release process: this PR modifies 1 string and introduces 2 new ones.

Tree-SHA512: ac07d0f800e61ec759e427d0afc0ca43d67f232e977662253963afdd0a220d34b871050f58149fc9fabd427bfc8e0d3f6a6032f2a38f30ad366fc0d074b0f2b3

src/init.cpp

@@ -53,6 +53,8 @@
 #include <stdio.h>
 
 #ifndef WIN32
+#include <attributes.h>
+#include <cerrno>
 #include <signal.h>
 #include <sys/stat.h>
 #endif
@@ -92,6 +94,30 @@ std::unique_ptr<BanMan> g_banman;
 
 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()
+{
+    return AbsPathForConfigVal(fs::path(gArgs.GetArg("-pid", BITCOIN_PID_FILENAME)));
+}
+
+NODISCARD static bool CreatePidFile()
+{
+    FILE* file = fsbridge::fopen(GetPidFile(), "w");
+    if (file) {
+        fprintf(file, "%d\n", getpid());
+        fclose(file);
+        return true;
+    } else {
+        return InitError(strprintf(_("Unable to create the PID file '%s': %s"), GetPidFile().string(), std::strerror(errno)));
+    }
+}
+#endif
+
 //////////////////////////////////////////////////////////////////////////////
 //
 // Shutdown
@@ -262,9 +288,11 @@ void Shutdown(InitInterfaces& interfaces)
 
 #ifndef WIN32
     try {
-        fs::remove(GetPidFile());
+        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 pidfile: %s\n", __func__, e.what());
+        LogPrintf("%s: Unable to remove PID file: %s\n", __func__, e.what());
     }
 #endif
     interfaces.chain_clients.clear();
@@ -1201,7 +1229,10 @@ bool AppInitMain(InitInterfaces& interfaces)
     const CChainParams& chainparams = Params();
     // ********************************************************* Step 4a: application initialization
 #ifndef WIN32
-    CreatePidFile(GetPidFile(), getpid());
+    if (!CreatePidFile()) {
+        // Detailed error printed inside CreatePidFile().
+        return false;
+    }
 #endif
     if (LogInstance().m_print_to_file) {
         if (gArgs.GetBoolArg("-shrinkdebugfile", LogInstance().DefaultShrinkDebugFile())) {

src/util/system.cpp

@@ -74,7 +74,6 @@
 const int64_t nStartupTime = GetTime();
 
 const char * const BITCOIN_CONF_FILENAME = "bitcoin.conf";
-const char * const BITCOIN_PID_FILENAME = "bitcoind.pid";
 
 ArgsManager gArgs;
 
@@ -965,23 +964,6 @@ std::string ArgsManager::GetChainName() const
     return CBaseChainParams::MAIN;
 }
 
-#ifndef WIN32
-fs::path GetPidFile()
-{
-    return AbsPathForConfigVal(fs::path(gArgs.GetArg("-pid", BITCOIN_PID_FILENAME)));
-}
-
-void CreatePidFile(const fs::path &path, pid_t pid)
-{
-    FILE* file = fsbridge::fopen(path, "w");
-    if (file)
-    {
-        fprintf(file, "%d\n", pid);
-        fclose(file);
-    }
-}
-#endif
-
 bool RenameOver(fs::path src, fs::path dest)
 {
 #ifdef WIN32

src/util/system.h

@@ -40,7 +40,6 @@
 int64_t GetStartupTime();
 
 extern const char * const BITCOIN_CONF_FILENAME;
-extern const char * const BITCOIN_PID_FILENAME;
 
 /** Translate a message to the native language of the user. */
 const extern std::function<std::string(const char*)> G_TRANSLATION_FUN;
@@ -86,10 +85,6 @@ const fs::path &GetBlocksDir();
 const fs::path &GetDataDir(bool fNetSpecific = true);
 void ClearDatadirCache();
 fs::path GetConfigFile(const std::string& confPath);
-#ifndef WIN32
-fs::path GetPidFile();
-void CreatePidFile(const fs::path &path, pid_t pid);
-#endif
 #ifdef WIN32
 fs::path GetSpecialFolderPath(int nFolder, bool fCreate = true);
 #endif

test/lint/lint-locale-dependence.sh

@@ -8,6 +8,7 @@ KNOWN_VIOLATIONS=(
     "src/dbwrapper.cpp:.*vsnprintf"
     "src/httprpc.cpp.*trim"
     "src/init.cpp:.*atoi"
+    "src/init.cpp:.*fprintf"
     "src/qt/rpcconsole.cpp:.*atoi"
     "src/rest.cpp:.*strtol"
     "src/test/dbwrapper_tests.cpp:.*snprintf"
@@ -18,7 +19,6 @@ KNOWN_VIOLATIONS=(
     "src/util/strencodings.cpp:.*strtoul"
     "src/util/strencodings.h:.*atoi"
     "src/util/system.cpp:.*atoi"
-    "src/util/system.cpp:.*fprintf"
 )
 
 REGEXP_IGNORE_EXTERNAL_DEPENDENCIES="^src/(crypto/ctaes/|leveldb/|secp256k1/|tinyformat.h|univalue/)"