util: Replace non-threadsafe strerror

Some uses of non-threadsafe `strerror` have snuck into the code since
they were removed in #4152. Add a wrapper `SysErrorString` for
thread-safe strerror alternatives and replace all uses of `strerror`
with this.

src/Makefile.am

@@ -271,6 +271,7 @@ BITCOIN_CORE_H = \
   util/spanparsing.h \
   util/string.h \
   util/syscall_sandbox.h \
+  util/syserror.h \
   util/system.h \
   util/thread.h \
   util/threadnames.h \
@@ -631,6 +632,7 @@ libbitcoin_util_a_SOURCES = \
   util/getuniquepath.cpp \
   util/hasher.cpp \
   util/sock.cpp \
+  util/syserror.cpp \
   util/system.cpp \
   util/message.cpp \
   util/moneystr.cpp \
@@ -853,6 +855,7 @@ bitcoin_chainstate_SOURCES = \
   util/settings.cpp \
   util/strencodings.cpp \
   util/syscall_sandbox.cpp \
+  util/syserror.cpp \
   util/system.cpp \
   util/thread.cpp \
   util/threadnames.cpp \

src/bitcoind.cpp

@@ -20,6 +20,7 @@
 #include <util/check.h>
 #include <util/strencodings.h>
 #include <util/syscall_sandbox.h>
+#include <util/syserror.h>
 #include <util/system.h>
 #include <util/threadnames.h>
 #include <util/tokenpipe.h>
@@ -206,7 +207,7 @@ static bool AppInit(NodeContext& node, int argc, char* argv[])
                 }
                 break;
             case -1: // Error happened.
-                return InitError(Untranslated(strprintf("fork_daemon() failed: %s\n", strerror(errno))));
+                return InitError(Untranslated(strprintf("fork_daemon() failed: %s\n", SysErrorString(errno))));
             default: { // Parent: wait and exit.
                 int token = daemon_ep.TokenRead();
                 if (token) { // Success

src/fs.cpp

@@ -3,6 +3,7 @@
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include <fs.h>
+#include <util/syserror.h>
 
 #ifndef WIN32
 #include <cstring>
@@ -44,7 +45,7 @@ fs::path AbsPathJoin(const fs::path& base, const fs::path& path)
 
 static std::string GetErrorReason()
 {
-    return std::strerror(errno);
+    return SysErrorString(errno);
 }
 
 FileLock::FileLock(const fs::path& file)

src/init.cpp

@@ -65,6 +65,7 @@
 #include <util/strencodings.h>
 #include <util/string.h>
 #include <util/syscall_sandbox.h>
+#include <util/syserror.h>
 #include <util/system.h>
 #include <util/thread.h>
 #include <util/threadnames.h>
@@ -149,7 +150,7 @@ static fs::path GetPidFile(const ArgsManager& args)
 #endif
         return true;
     } else {
-        return InitError(strprintf(_("Unable to create the PID file '%s': %s"), fs::PathToString(GetPidFile(args)), std::strerror(errno)));
+        return InitError(strprintf(_("Unable to create the PID file '%s': %s"), fs::PathToString(GetPidFile(args)), SysErrorString(errno)));
     }
 }
 

src/util/sock.cpp

@@ -7,6 +7,7 @@
 #include <threadinterrupt.h>
 #include <tinyformat.h>
 #include <util/sock.h>
+#include <util/syserror.h>
 #include <util/system.h>
 #include <util/time.h>
 
@@ -344,19 +345,8 @@ std::string NetworkErrorString(int err)
 #else
 std::string NetworkErrorString(int err)
 {
-    char buf[256];
-    buf[0] = 0;
-    /* Too bad there are two incompatible implementations of the
-     * thread-safe strerror. */
-    const char *s;
-#ifdef STRERROR_R_CHAR_P /* GNU variant can return a pointer outside the passed buffer */
-    s = strerror_r(err, buf, sizeof(buf));
-#else /* POSIX variant always returns message in buffer */
-    s = buf;
-    if (strerror_r(err, buf, sizeof(buf)))
-        buf[0] = 0;
-#endif
-    return strprintf("%s (%d)", s, err);
+    // On BSD sockets implementations, NetworkErrorString is the same as SysErrorString.
+    return SysErrorString(err);
 }
 #endif
 

src/util/syserror.cpp

@@ -0,0 +1,29 @@
+// Copyright (c) 2020-2022 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#if defined(HAVE_CONFIG_H)
+#include <config/bitcoin-config.h>
+#endif
+
+#include <tinyformat.h>
+#include <util/syserror.h>
+
+#include <cstring>
+
+std::string SysErrorString(int err)
+{
+    char buf[256];
+    buf[0] = 0;
+    /* Too bad there are two incompatible implementations of the
+     * thread-safe strerror. */
+    const char *s;
+#ifdef STRERROR_R_CHAR_P /* GNU variant can return a pointer outside the passed buffer */
+    s = strerror_r(err, buf, sizeof(buf));
+#else /* POSIX variant always returns message in buffer */
+    s = buf;
+    if (strerror_r(err, buf, sizeof(buf)))
+        buf[0] = 0;
+#endif
+    return strprintf("%s (%d)", s, err);
+}

src/util/syserror.h

@@ -0,0 +1,16 @@
+// Copyright (c) 2010-2022 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef BITCOIN_UTIL_SYSERROR_H
+#define BITCOIN_UTIL_SYSERROR_H
+
+#include <string>
+
+/** Return system error string from errno value. Use this instead of
+ * std::strerror, which is not thread-safe. For network errors use
+ * NetworkErrorString from sock.h instead.
+ */
+std::string SysErrorString(int err);
+
+#endif // BITCOIN_UTIL_SYSERROR_H

src/util/system.cpp

@@ -25,6 +25,7 @@
 #include <util/getuniquepath.h>
 #include <util/strencodings.h>
 #include <util/string.h>
+#include <util/syserror.h>
 #include <util/translation.h>
 
 
@@ -1374,7 +1375,7 @@ void ScheduleBatchPriority()
     const static sched_param param{};
     const int rc = pthread_setschedparam(pthread_self(), SCHED_BATCH, &param);
     if (rc != 0) {
-        LogPrintf("Failed to pthread_setschedparam: %s\n", strerror(rc));
+        LogPrintf("Failed to pthread_setschedparam: %s\n", SysErrorString(rc));
     }
 #endif
 }