Merge qt_error_string and QSystemError

This removes a lot of duplicated code that existed in both qglobal.cpp
and qsystemerror.cpp, including the hack to get the correct strerror_r
signature.

This removes the incorrect use of EACCES, EMFILE, ENOENT, and ENOSPC
from qt_error_string on Windows. qt_error_string is supposed to be used
only with Win32 error codes from GetLastError(), despite there being a
lot of uses in cross-platform and even Windows-specific code that pass
errno constants.

It may or may not work: that depends on whether the constants happen to
match. ENOENT matches ERROR_FILE_NOT_FOUND and one could argue that
ENOSPC matching ERROR_OUT_OF_PAPER is acceptable, but EMFILE isn't the
same as ERROR_BAD_LENGTH nor is EACCES, ERROR_INVALID_DATA.

Change-Id: I1eba2b016de74620bfc8fffd14cccb7f77f4b510
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>
Reviewed-by: Kai Koehne <kai.koehne@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

2 files changed, 38 insertions, 5 deletions

diff --git a/src/corelib/kernel/qsystemerror.cpp b/src/corelib/kernel/qsystemerror.cpp
index 3899f24d3b..6583838a9f 100644
--- a/src/corelib/kernel/qsystemerror.cpp
+++ b/src/corelib/kernel/qsystemerror.cpp
@@ -101,6 +101,8 @@ static QString windowsErrorString(int errorCode)
 
     if (ret.isEmpty() && errorCode == ERROR_MOD_NOT_FOUND)
         ret = QString::fromLatin1("The specified module could not be found.");
+    if (ret.endsWith(QLatin1String("\r\n")))
+        ret.chop(2);
     return ret;
 }
 #endif
@@ -126,7 +128,7 @@ static QString standardLibraryErrorString(int errorCode)
         break;
     default: {
       #if !defined(QT_NO_THREAD) && defined(_POSIX_THREAD_SAFE_FUNCTIONS) && _POSIX_VERSION >= 200112L && !defined(Q_OS_INTEGRITY) && !defined(Q_OS_QNX)
-            QByteArray buf(1024, '\0');
+            QByteArray buf(1024, Qt::Uninitialized);
             ret = fromstrerror_helper(strerror_r(errorCode, buf.data(), buf.size()), buf);
       #else
             ret = QString::fromLocal8Bit(strerror(errorCode));
@@ -141,7 +143,7 @@ static QString standardLibraryErrorString(int errorCode)
     return ret.trimmed();
 }
 
-QString QSystemError::toString() const
+QString QSystemError::string(ErrorScope errorScope, int errorCode)
 {
     switch(errorScope) {
     case NativeError:
@@ -161,5 +163,26 @@ QString QSystemError::toString() const
     }
 }
 
-QT_END_NAMESPACE
+QString QSystemError::stdString(int errorCode)
+{
+    return standardLibraryErrorString(errorCode == -1 ? errno : errorCode);
+}
+
+#ifdef Q_OS_WIN
+QString QSystemError::windowsString(int errorCode)
+{
+    return windowsErrorString(errorCode == -1 ? GetLastError() : errorCode);
+}
 
+QString qt_error_string(int code)
+{
+    return windowsErrorString(code == -1 ? GetLastError() : code);
+}
+#else
+QString qt_error_string(int code)
+{
+    return standardLibraryErrorString(code == -1 ? errno : code);
+}
+#endif
+
+QT_END_NAMESPACE
diff --git a/src/corelib/kernel/qsystemerror_p.h b/src/corelib/kernel/qsystemerror_p.h
index 440b763149..1d8c253f53 100644
--- a/src/corelib/kernel/qsystemerror_p.h
+++ b/src/corelib/kernel/qsystemerror_p.h
@@ -69,10 +69,16 @@ public:
     inline QSystemError(int error, ErrorScope scope);
     inline QSystemError();
 
-    QString toString() const;
+    inline QString toString() const;
     inline ErrorScope scope() const;
     inline int error() const;
 
+    static QString string(ErrorScope errorScope, int errorCode);
+    static QString stdString(int errorCode = -1);
+#ifdef Q_OS_WIN
+    static QString windowsString(int errorCode = -1);
+#endif
+
     //data members
     int errorCode;
     ErrorScope errorScope;
@@ -90,6 +96,11 @@ QSystemError::QSystemError()
 
 }
 
+QString QSystemError::toString() const
+{
+    return string(errorScope, errorCode);
+}
+
 QSystemError::ErrorScope QSystemError::scope() const
 {
     return errorScope;
@@ -100,7 +111,6 @@ int QSystemError::error() const
     return errorCode;
 }
 
-
 QT_END_NAMESPACE
 
 #endif // QSYSTEMERROR_P_H