SDL_test: add SDLTest_LogEscapedString

include/SDL3/SDL_test_log.h

@@ -51,6 +51,16 @@ extern "C" {
  */
 void SDLCALL SDLTest_Log(SDL_PRINTF_FORMAT_STRING const char *fmt, ...) SDL_PRINTF_VARARG_FUNC(1);
 
+/**
+ * Prints given prefix and buffer.
+ * Non-printible characters in the raw data are substituted by printible alternatives.
+ *
+ * \param prefix Prefix message.
+ * \param buffer Raw data to be escaped.
+ * \param size Number of bytes in buffer.
+ */
+void SDLCALL SDLTest_LogEscapedString(const char *prefix, const void *buffer, size_t size);
+
 /**
  * Prints given message with a timestamp in the TEST category and the ERROR priority.
  *

src/test/SDL_test_log.c

@@ -109,3 +109,103 @@ void SDLTest_LogError(SDL_PRINTF_FORMAT_STRING const char *fmt, ...)
     /* Log with timestamp and newline */
     SDL_LogMessage(SDL_LOG_CATEGORY_TEST, SDL_LOG_PRIORITY_ERROR, "%s: %s", SDLTest_TimestampToString(time(0)), logMessage);
 }
+
+static char nibble_to_char(Uint8 nibble)
+{
+    if (nibble < 0xa) {
+        return '0' + nibble;
+    } else {
+        return 'a' + nibble - 10;
+    }
+}
+
+void SDLTest_LogEscapedString(const char *prefix, const void *buffer, size_t size)
+{
+    const Uint8 *data = buffer;
+    char logMessage[SDLTEST_MAX_LOGMESSAGE_LENGTH];
+
+    if (data) {
+        size_t i;
+        size_t pos = 0;
+        #define NEED_X_CHARS(N) \
+            if (pos + (N) > sizeof(logMessage) - 2) { \
+                break;                                \
+            }
+
+        logMessage[pos++] = '"';
+        for (i = 0; i < size; i++) {
+            Uint8 c = data[i];
+            size_t pos_start = pos;
+            switch (c) {
+            case '\0':
+                NEED_X_CHARS(2);
+                logMessage[pos++] = '\\';
+                logMessage[pos++] = '0';
+                break;
+            case '"':
+                NEED_X_CHARS(2);
+                logMessage[pos++] = '\\';
+                logMessage[pos++] = '"';
+                break;
+            case '\n':
+                NEED_X_CHARS(2);
+                logMessage[pos++] = '\\';
+                logMessage[pos++] = 'n';
+                break;
+            case '\r':
+                NEED_X_CHARS(2);
+                logMessage[pos++] = '\\';
+                logMessage[pos++] = 'r';
+                break;
+            case '\t':
+                NEED_X_CHARS(2);
+                logMessage[pos++] = '\\';
+                logMessage[pos++] = 't';
+                break;
+            case '\f':
+                NEED_X_CHARS(2);
+                logMessage[pos++] = '\\';
+                logMessage[pos++] = 'f';
+                break;
+            case '\b':
+                NEED_X_CHARS(2);
+                logMessage[pos++] = '\\';
+                logMessage[pos++] = 'b';
+                break;
+            case '\\':
+                NEED_X_CHARS(2);
+                logMessage[pos++] = '\\';
+                logMessage[pos++] = '\\';
+                break;
+            default:
+                if (SDL_isprint(c)) {
+                    NEED_X_CHARS(1);
+                    logMessage[pos++] = c;
+                } else {
+                    NEED_X_CHARS(4);
+                    logMessage[pos++] = '\\';
+                    logMessage[pos++] = 'x';
+                    logMessage[pos++] = nibble_to_char(c >> 4);
+                    logMessage[pos++] = nibble_to_char(c & 0xf);
+                }
+                break;
+            }
+            if (pos == pos_start) {
+                break;
+            }
+        }
+        if (i < size) {
+            logMessage[sizeof(logMessage) - 4] = '.';
+            logMessage[sizeof(logMessage) - 3] = '.';
+            logMessage[sizeof(logMessage) - 2] = '.';
+            logMessage[sizeof(logMessage) - 1] = '\0';
+        } else {
+            logMessage[pos++] = '"';
+            logMessage[pos] = '\0';
+        }
+    } else {
+        SDL_strlcpy(logMessage, "(nil)", sizeof(logMessage));
+    }
+
+    SDLTest_Log("%s%s", prefix, logMessage);
+}