Consolidate debug string generation

Several QIODevice subclasses use the qt_prettyDebug() function to get
a printable representation of the buffer data for debug output.

Rather than having this feature statically implemented in each
respective file, this patch introduces a generic function in the
QtDebugUtils namespace. Accordingly, some inaccuracies in the
use-cases have been corrected.

Change-Id: I1a8465cab08c8acf5fdcdba5085182511b1cbb7b
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@gmx.de>
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>

4 files changed, 59 insertions, 87 deletions

diff --git a/src/corelib/io/qdebug.cpp b/src/corelib/io/qdebug.cpp
index b1ebf097cf..0a7a847ef6 100644
--- a/src/corelib/io/qdebug.cpp
+++ b/src/corelib/io/qdebug.cpp
@@ -46,15 +46,63 @@
 #endif
 
 #include "qdebug.h"
+#include "private/qdebug_p.h"
 #include "qmetaobject.h"
 #include <private/qtextstream_p.h>
 #include <private/qtools_p.h>
+#include <ctype.h>
 
 QT_BEGIN_NAMESPACE
 
 using QtMiscUtils::toHexUpper;
+using QtMiscUtils::toHexLower;
 using QtMiscUtils::fromHex;
 
+/*
+    Returns a human readable representation of the first \a maxSize
+    characters in \a data.
+*/
+QByteArray QtDebugUtils::toPrintable(const char *data, int len, int maxSize)
+{
+    if (!data)
+        return "(null)";
+
+    QByteArray out;
+    for (int i = 0; i < qMin(len, maxSize); ++i) {
+        char c = data[i];
+        if (isprint(c)) {
+            out += c;
+        } else {
+            switch (c) {
+            case '\n':
+                out += "\\n";
+                break;
+            case '\r':
+                out += "\\r";
+                break;
+            case '\t':
+                out += "\\t";
+                break;
+            default: {
+                const char buf[] = {
+                    '\\',
+                    'x',
+                    toHexLower(uchar(c) / 16),
+                    toHexLower(uchar(c) % 16),
+                    0
+                };
+                out += buf;
+            }
+            }
+        }
+    }
+
+    if (maxSize < len)
+        out += "...";
+
+    return out;
+}
+
 // This file is needed to force compilation of QDebug into the kernel library.
 
 /*!
diff --git a/src/corelib/io/qdebug_p.h b/src/corelib/io/qdebug_p.h
index dcb906d156..1ca632338f 100644
--- a/src/corelib/io/qdebug_p.h
+++ b/src/corelib/io/qdebug_p.h
@@ -55,11 +55,14 @@
 #include "QtCore/qdebug.h"
 #include "QtCore/qmetaobject.h"
 #include "QtCore/qflags.h"
+#include "QtCore/qbytearray.h"
 
 QT_BEGIN_NAMESPACE
 
 namespace QtDebugUtils {
 
+Q_CORE_EXPORT QByteArray toPrintable(const char *data, int len, int maxSize);
+
 // inline helpers for formatting basic classes.
 
 template <class Point>
diff --git a/src/corelib/io/qprocess.cpp b/src/corelib/io/qprocess.cpp
index 745c88e726..16fb2be0ae 100644
--- a/src/corelib/io/qprocess.cpp
+++ b/src/corelib/io/qprocess.cpp
@@ -41,49 +41,12 @@
 //#define QPROCESS_DEBUG
 
 #include <qdebug.h>
+#include <private/qdebug_p.h>
 #include <qdir.h>
 #include <qscopedvaluerollback.h>
 #if defined(Q_OS_WIN)
 #include <qtimer.h>
 #endif
-#if defined QPROCESS_DEBUG
-#include <qstring.h>
-#include <ctype.h>
-
-QT_BEGIN_NAMESPACE
-/*
-    Returns a human readable representation of the first \a len
-    characters in \a data.
-*/
-static QByteArray qt_prettyDebug(const char *data, int len, int maxSize)
-{
-    if (!data) return "(null)";
-    QByteArray out;
-    for (int i = 0; i < len && i < maxSize; ++i) {
-        char c = data[i];
-        if (isprint(c)) {
-            out += c;
-        } else switch (c) {
-        case '\n': out += "\\n"; break;
-        case '\r': out += "\\r"; break;
-        case '\t': out += "\\t"; break;
-        default:
-            char buf[5];
-            qsnprintf(buf, sizeof(buf), "\\%3o", c);
-            buf[4] = '\0';
-            out += QByteArray(buf);
-        }
-    }
-
-    if (len < maxSize)
-        out += "...";
-
-    return out;
-}
-
-QT_END_NAMESPACE
-
-#endif
 
 #include "qprocess.h"
 #include "qprocess_p.h"
@@ -1940,8 +1903,8 @@ qint64 QProcess::writeData(const char *data, qint64 len)
 
     if (d->stdinChannel.closed) {
 #if defined QPROCESS_DEBUG
-    qDebug("QProcess::writeData(%p \"%s\", %lld) == 0 (write channel closing)",
-           data, qt_prettyDebug(data, len, 16).constData(), len);
+        qDebug("QProcess::writeData(%p \"%s\", %lld) == 0 (write channel closing)",
+               data, QtDebugUtils::toPrintable(data, len, 16).constData(), len);
 #endif
         return 0;
     }
@@ -1965,7 +1928,7 @@ qint64 QProcess::writeData(const char *data, qint64 len)
 #endif
 #if defined QPROCESS_DEBUG
     qDebug("QProcess::writeData(%p \"%s\", %lld) == %lld (written to buffer)",
-           data, qt_prettyDebug(data, len, 16).constData(), len, len);
+           data, QtDebugUtils::toPrintable(data, len, 16).constData(), len, len);
 #endif
     return len;
 }
diff --git a/src/corelib/io/qprocess_unix.cpp b/src/corelib/io/qprocess_unix.cpp
index 79e0cbd1c0..4fa36238a7 100644
--- a/src/corelib/io/qprocess_unix.cpp
+++ b/src/corelib/io/qprocess_unix.cpp
@@ -41,49 +41,7 @@
 
 //#define QPROCESS_DEBUG
 #include "qdebug.h"
-
-#if QT_CONFIG(process) && defined(QPROCESS_DEBUG)
-#include "private/qtools_p.h"
-#include <ctype.h>
-
-/*
-    Returns a human readable representation of the first \a len
-    characters in \a data.
-*/
-QT_BEGIN_NAMESPACE
-static QByteArray qt_prettyDebug(const char *data, int len, int maxSize)
-{
-    if (!data) return "(null)";
-    QByteArray out;
-    for (int i = 0; i < len; ++i) {
-        char c = data[i];
-        if (isprint(c)) {
-            out += c;
-        } else switch (c) {
-        case '\n': out += "\\n"; break;
-        case '\r': out += "\\r"; break;
-        case '\t': out += "\\t"; break;
-        default: {
-            const char buf[] =  {
-                '\\',
-                QtMiscUtils::toOct(uchar(c) / 64),
-                QtMiscUtils::toOct(uchar(c) % 64 / 8),
-                QtMiscUtils::toOct(uchar(c) % 8),
-                0
-            };
-            out += buf;
-            }
-        }
-    }
-
-    if (len < maxSize)
-        out += "...";
-
-    return out;
-}
-QT_END_NAMESPACE
-#endif
-
+#include <private/qdebug_p.h>
 #include "qplatformdefs.h"
 
 #include "qprocess.h"
@@ -676,7 +634,7 @@ qint64 QProcessPrivate::readFromChannel(const Channel *channel, char *data, qint
     int save_errno = errno;
     qDebug("QProcessPrivate::readFromChannel(%d, %p \"%s\", %lld) == %lld",
            int(channel - &stdinChannel),
-           data, qt_prettyDebug(data, bytesRead, 16).constData(), maxlen, bytesRead);
+           data, QtDebugUtils::toPrintable(data, bytesRead, 16).constData(), maxlen, bytesRead);
     errno = save_errno;
 #endif
     if (bytesRead == -1 && errno == EWOULDBLOCK)
@@ -691,8 +649,8 @@ bool QProcessPrivate::writeToStdin()
 
     qint64 written = qt_safe_write_nosignal(stdinChannel.pipe[1], data, bytesToWrite);
 #if defined QPROCESS_DEBUG
-    qDebug("QProcessPrivate::writeToStdin(), write(%p \"%s\", %lld) == %lld",
-           data, qt_prettyDebug(data, bytesToWrite, 16).constData(), bytesToWrite, written);
+    qDebug("QProcessPrivate::writeToStdin(), write(%p \"%s\", %lld) == %lld", data,
+           QtDebugUtils::toPrintable(data, bytesToWrite, 16).constData(), bytesToWrite, written);
     if (written == -1)
         qDebug("QProcessPrivate::writeToStdin(), failed to write (%ls)", qUtf16Printable(qt_error_string(errno)));
 #endif