Added support for escaping control chars in strings

Initial fix for issue #42

include/xlsxwriter/xmlwriter.h

@@ -162,6 +162,8 @@ void _xml_data_element(FILE * xmlfile,
                        const char *data,
                        struct xml_attribute_list *attributes);
 
+char *_escape_control_characters(const char *string);
+
 /* *INDENT-OFF* */
 #ifdef __cplusplus
 }

src/shared_strings.c

@@ -138,12 +138,25 @@ _write_t(lxw_sst *self, char *string)
 void
 _write_si(lxw_sst *self, char *string)
 {
+    uint8_t escaped_string = LXW_FALSE;
+
     _xml_start_tag(self->file, "si", NULL);
 
+    /* Look for and escape control chars in the string. */
+    if (strpbrk(string, "\x01\x02\x03\x04\x05\x06\x07\x08\x0B\x0C"
+                "\x0D\x0E\x0F\x10\x11\x12\x13\x14\x15\x16"
+                "\x17\x18\x19\x1A\x1B\x1C\x1D\x1E\x1F")) {
+        string = _escape_control_characters(string);
+        escaped_string = LXW_TRUE;
+    }
+
     /* Write the t element. */
     _write_t(self, string);
 
     _xml_end_tag(self->file, "si");
+
+    if (escaped_string)
+        free(string);
 }
 
 /*

src/xmlwriter.c

@@ -96,7 +96,7 @@ _xml_empty_tag(FILE * xmlfile,
 
 /*
  * Write an XML start tag with optional, unencoded, attributes.
- * This is a minor speed optimisation for elements that don't need encoding.
+ * This is a minor speed optimization for elements that don't need encoding.
  */
 void
 _xml_empty_tag_unencoded(FILE * xmlfile,
@@ -212,7 +212,64 @@ _escape_data(const char *data)
     return encoded;
 }
 
-/* TODO */
+/*
+ * Escape control characters in strings with with _xHHHH_.
+ */
+char *
+_escape_control_characters(const char *string)
+{
+    size_t escape_len = sizeof("_xHHHH_") - 1;
+    size_t encoded_len = (strlen(string) * escape_len + 1);
+
+    char *encoded = (char *) calloc(encoded_len, 1);
+    char *p_encoded = encoded;
+
+    while (*string) {
+        switch (*string) {
+            case '\x01':
+            case '\x02':
+            case '\x03':
+            case '\x04':
+            case '\x05':
+            case '\x06':
+            case '\x07':
+            case '\x08':
+            case '\x0B':
+            case '\x0C':
+            case '\x0D':
+            case '\x0E':
+            case '\x0F':
+            case '\x10':
+            case '\x11':
+            case '\x12':
+            case '\x13':
+            case '\x14':
+            case '\x15':
+            case '\x16':
+            case '\x17':
+            case '\x18':
+            case '\x19':
+            case '\x1A':
+            case '\x1B':
+            case '\x1C':
+            case '\x1D':
+            case '\x1E':
+            case '\x1F':
+                lxw_snprintf(p_encoded, escape_len + 1, "_x%04X_", *string);
+                p_encoded += escape_len;
+                break;
+            default:
+                *p_encoded = *string;
+                p_encoded++;
+                break;
+        }
+        string++;
+    }
+
+    return encoded;
+}
+
+/* Write out escaped attributes. */
 void
 _fprint_escaped_attributes(FILE * xmlfile,
                            struct xml_attribute_list *attributes)
@@ -239,7 +296,7 @@ _fprint_escaped_attributes(FILE * xmlfile,
     }
 }
 
-/* TODO */
+/* Write out escaped XML data. */
 void
 _fprint_escaped_data(FILE * xmlfile, const char *data)
 {
@@ -256,7 +313,7 @@ _fprint_escaped_data(FILE * xmlfile, const char *data)
     }
 }
 
-/* TODO */
+/* Create a new string XML attribute. */
 struct xml_attribute *
 _new_attribute_str(const char *key, const char *value)
 {
@@ -268,7 +325,7 @@ _new_attribute_str(const char *key, const char *value)
     return attribute;
 }
 
-/* TODO */
+/* Create a new integer XML attribute. */
 struct xml_attribute *
 _new_attribute_int(const char *key, uint32_t value)
 {
@@ -280,7 +337,7 @@ _new_attribute_int(const char *key, uint32_t value)
     return attribute;
 }
 
-/* TODO */
+/* Create a new double XML attribute. */
 struct xml_attribute *
 _new_attribute_dbl(const char *key, double value)
 {

test/functional/src/test_shared_strings01.c

@@ -0,0 +1,28 @@
+/*****************************************************************************
+ * Test cases for libxlsxwriter.
+ *
+ * Test to compare output against Excel files.
+ *
+ * Copyright 2014-2015, John McNamara, jmcnamara@cpan.org
+ *
+ */
+
+#include "xlsxwriter.h"
+
+int main() {
+
+    lxw_workbook  *workbook  = new_workbook("test_shared_strings01.xlsx");
+    lxw_worksheet *worksheet = workbook_add_worksheet(workbook, NULL);
+    uint8_t i;
+    char c[] = {0x00, 0x00};
+
+    for (i = 1; i < 127; i++) {
+        (*c)++;
+        if (i != 34) {
+            worksheet_write_string(worksheet, i, 0, c, NULL);
+
+        }
+    }
+
+    return workbook_close(workbook);
+}

test/functional/test_misc.py

@@ -23,3 +23,6 @@ def test_firstsheet01(self):
 
     def test_hide01(self):
         self.run_exe_test('test_hide01')
+
+    def test_shared_strings01(self):
+        self.run_exe_test('test_shared_strings01')