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>

3 files changed, 38 insertions, 97 deletions

diff --git a/src/corelib/global/qglobal.cpp b/src/corelib/global/qglobal.cpp
index 9b76c72c0d..4223d2a3e1 100644
--- a/src/corelib/global/qglobal.cpp
+++ b/src/corelib/global/qglobal.cpp
@@ -3102,98 +3102,6 @@ Q_CORE_EXPORT unsigned int qt_int_sqrt(unsigned int n)
 void *qMemCopy(void *dest, const void *src, size_t n) { return memcpy(dest, src, n); }
 void *qMemSet(void *dest, int c, size_t n) { return memset(dest, c, n); }
 
-#if !defined(Q_OS_WIN) && !defined(QT_NO_THREAD) && !defined(Q_OS_INTEGRITY) && !defined(Q_OS_QNX) && \
-    defined(_POSIX_THREAD_SAFE_FUNCTIONS) && _POSIX_VERSION >= 200112L
-namespace {
-    // There are two incompatible versions of strerror_r:
-    // a) the XSI/POSIX.1 version, which returns an int,
-    //    indicating success or not
-    // b) the GNU version, which returns a char*, which may or may not
-    //    be the beginning of the buffer we used
-    // The GNU libc manpage for strerror_r says you should use the XSI
-    // version in portable code. However, it's impossible to do that if
-    // _GNU_SOURCE is defined so we use C++ overloading to decide what to do
-    // depending on the return type
-    static inline Q_DECL_UNUSED QString fromstrerror_helper(int, const QByteArray &buf)
-    {
-        return QString::fromLocal8Bit(buf.constData());
-    }
-    static inline Q_DECL_UNUSED QString fromstrerror_helper(const char *str, const QByteArray &)
-    {
-        return QString::fromLocal8Bit(str);
-    }
-}
-#endif
-
-QString qt_error_string(int errorCode)
-{
-    const char *s = 0;
-    QString ret;
-    if (errorCode == -1) {
-#if defined(Q_OS_WIN)
-        errorCode = GetLastError();
-#else
-        errorCode = errno;
-#endif
-    }
-    switch (errorCode) {
-    case 0:
-        break;
-    case EACCES:
-        s = QT_TRANSLATE_NOOP("QIODevice", "Permission denied");
-        break;
-    case EMFILE:
-        s = QT_TRANSLATE_NOOP("QIODevice", "Too many open files");
-        break;
-    case ENOENT:
-        s = QT_TRANSLATE_NOOP("QIODevice", "No such file or directory");
-        break;
-    case ENOSPC:
-        s = QT_TRANSLATE_NOOP("QIODevice", "No space left on device");
-        break;
-    default: {
-#if defined(Q_OS_WIN)
-        // Retrieve the system error message for the last-error code.
-#  ifndef Q_OS_WINRT
-        wchar_t *string = 0;
-        FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS | FORMAT_MESSAGE_ALLOCATE_BUFFER,
-                      NULL,
-                      errorCode,
-                      MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
-                      (LPWSTR)&string,
-                      0,
-                      NULL);
-        ret = QString::fromWCharArray(string);
-        LocalFree((HLOCAL)string);
-#  else // !Q_OS_WINRT
-        __declspec(thread) static wchar_t errorString[4096];
-        FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
-                      NULL,
-                      errorCode,
-                      MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
-                      errorString,
-                      ARRAYSIZE(errorString),
-                      NULL);
-        ret = QString::fromWCharArray(errorString);
-#  endif // Q_OS_WINRT
-
-        if (ret.isEmpty() && errorCode == ERROR_MOD_NOT_FOUND)
-            ret = QString::fromLatin1("The specified module could not be found.");
-#elif !defined(QT_NO_THREAD) && defined(_POSIX_THREAD_SAFE_FUNCTIONS) && _POSIX_VERSION >= 200112L && !defined(Q_OS_INTEGRITY) && !defined(Q_OS_QNX)
-        QByteArray buf(1024, '\0');
-        ret = fromstrerror_helper(strerror_r(errorCode, buf.data(), buf.size()), buf);
-#else
-        ret = QString::fromLocal8Bit(strerror(errorCode));
-#endif
-    break; }
-    }
-    if (s)
-        // ######## this breaks moc build currently
-//         ret = QCoreApplication::translate("QIODevice", s);
-        ret = QString::fromLatin1(s);
-    return ret.trimmed();
-}
-
 // In the C runtime on all platforms access to the environment is not thread-safe. We
 // add thread-safety for the Qt wrappers.
 static QBasicMutex environmentMutex;
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