Allow testlib loggers to dynamically allocate storage for strings.

This enables very long failure messages (e.g. including an entire
build log in a failure message).

This change modifies only the plain test logger to use this feature.

Task: 253861

Reviewed-by: Michael Goddard

4 files changed, 88 insertions, 9 deletions

diff --git a/src/testlib/qabstracttestlogger_p.h b/src/testlib/qabstracttestlogger_p.h
index a0e8a1e..588184e 100644
--- a/src/testlib/qabstracttestlogger_p.h
+++ b/src/testlib/qabstracttestlogger_p.h
@@ -99,6 +99,42 @@ public:
     static bool isTtyOutput();
 };
 
+struct QTestCharBuffer
+{
+    inline QTestCharBuffer()
+            : buf(0)
+    {}
+
+    inline ~QTestCharBuffer()
+    {
+        delete[] buf;
+        buf = 0;
+    }
+
+    inline operator void*()
+    {
+        return buf;
+    }
+
+    inline operator char*()
+    {
+        return buf;
+    }
+
+    inline operator char**()
+    {
+        return &buf;
+    }
+
+    inline const char* constData() const
+    {
+        return buf;
+    }
+
+private:
+    char* buf;
+};
+
 QT_END_NAMESPACE
 
 #endif
diff --git a/src/testlib/qplaintestlogger.cpp b/src/testlib/qplaintestlogger.cpp
index 071b55e..7bebaa1 100644
--- a/src/testlib/qplaintestlogger.cpp
+++ b/src/testlib/qplaintestlogger.cpp
@@ -168,7 +168,7 @@ namespace QTest {
         QTEST_ASSERT(type);
         QTEST_ASSERT(msg);
 
-        char buf[1024];
+        QTestCharBuffer buf;
 
         const char *fn = QTestResult::currentTestFunction() ? QTestResult::currentTestFunction()
             : "UnknownTestFunc";
@@ -178,7 +178,7 @@ namespace QTest {
                          : "";
         const char *filler = (tag[0] && gtag[0]) ? ":" : "";
         if (file) {
-            QTest::qt_snprintf(buf, sizeof(buf), "%s: %s::%s(%s%s%s)%s%s\n"
+            QTest::qt_asprintf(buf, "%s: %s::%s(%s%s%s)%s%s\n"
 #ifdef Q_OS_WIN
                           "%s(%d) : failure location\n"
 #else
@@ -187,10 +187,12 @@ namespace QTest {
                           , type, QTestResult::currentTestObjectName(), fn, gtag, filler, tag,
                           msg[0] ? " " : "", msg, file, line);
         } else {
-            QTest::qt_snprintf(buf, sizeof(buf), "%s: %s::%s(%s%s%s)%s%s\n",
+            QTest::qt_asprintf(buf, "%s: %s::%s(%s%s%s)%s%s\n",
                     type, QTestResult::currentTestObjectName(), fn, gtag, filler, tag,
                     msg[0] ? " " : "", msg);
         }
+        // In colored mode, printf above stripped our nonprintable control characters.
+        // Put them back.
         memcpy(buf, type, strlen(type));
         outputMessage(buf);
     }
diff --git a/src/testlib/qtest_global.h b/src/testlib/qtest_global.h
index b5b0fc0..c40f0ad 100644
--- a/src/testlib/qtest_global.h
+++ b/src/testlib/qtest_global.h
@@ -82,6 +82,7 @@ namespace QTest
     enum TestFailMode { Abort = 1, Continue = 2 };
 
     int Q_TESTLIB_EXPORT qt_snprintf(char *str, int size, const char *format, ...);
+    int qt_asprintf(char **str, const char *format, ...);
 }
 
 QT_END_NAMESPACE
diff --git a/src/testlib/qtestcase.cpp b/src/testlib/qtestcase.cpp
index cb05400..e44be9c 100644
--- a/src/testlib/qtestcase.cpp
+++ b/src/testlib/qtestcase.cpp
@@ -808,6 +808,50 @@ namespace QTest
     static int eventDelay = -1;
     static int keyVerbose = -1;
 
+void filter_unprintable(char *str)
+{
+    char *idx = str;
+    while (*idx) {
+        if (((*idx < 0x20 && *idx != '\n' && *idx != '\t') || *idx > 0x7e))
+            *idx = '?';
+        ++idx;
+    }
+}
+
+int qt_asprintf(char **str, const char *format, ...)
+{
+    static const int MAXSIZE = 1024*1024*2;
+
+    int size = 32;
+    delete[] *str;
+    *str = new char[size];
+
+    va_list ap;
+    int res = 0;
+
+    for (;;) {
+        va_start(ap, format);
+        res = qvsnprintf(*str, size, format, ap);
+        va_end(ap);
+        (*str)[size - 1] = '\0';
+        if (res < size) {
+            // We succeeded or fatally failed
+            break;
+        }
+        // buffer wasn't big enough, try again
+        size *= 2;
+        if (size > MAXSIZE) {
+            break;
+        }
+        delete[] *str;
+        *str = new char[size];
+    }
+
+    filter_unprintable(*str);
+
+    return res;
+}
+
 /*! \internal
  */
 int qt_snprintf(char *str, int size, const char *format, ...)
@@ -820,12 +864,8 @@ int qt_snprintf(char *str, int size, const char *format, ...)
     va_end(ap);
     str[size - 1] = '\0';
 
-    char *idx = str;
-    while (*idx) {
-        if (((*idx < 0x20 && *idx != '\n' && *idx != '\t') || *idx > 0x7e))
-            *idx = '?';
-        ++idx;
-    }
+    filter_unprintable(str);
+
     return res;
 }