mergefonts can crash with an all whitespace value

c/mergefonts/source/mergeFonts.c

@@ -1177,21 +1177,21 @@ static void stringStrip(char *str) {
     if (end == 0)
         return;
 
-    while (start < MAX_DICT_ENTRY_LEN) {
-        if ((str[start] == ' ') || (str[start] == '\t') || (str[start] == '(') || (str[start] == '\r') || (str[start] == '\n'))
-            start++;
+    while (end >= 0) {
+        if ((str[end] == ' ') || (str[end] == '\t') || (str[end] == ')') || (str[end] == '\r') || (str[end] == '\n'))
+            end--;
         else
             break;
     }
+    str[end + 1] = 0;
 
-    while (end >= 0) {
-        if ((str[end] == ' ') || (str[end] == '\t') || (str[end] == ')') || (str[end] == '\r') || (str[end] == '\n'))
-            end--;
+    while (start < MAX_DICT_ENTRY_LEN) {
+        if ((str[start] == ' ') || (str[start] == '\t') || (str[start] == '(') || (str[start] == '\r') || (str[start] == '\n'))
+            start++;
         else
             break;
     }
 
-    str[end + 1] = 0;
     if (start > 0)
         memmove(str, &str[start], (end - start) + 2);
     if (strlen(str) == 0) {

tests/mergefonts_data/input/cidwhitespace/cidfontinfo.txt

@@ -0,0 +1,9 @@
+FontName	(  )
+Registry	Adobe
+Ordering	Identity
+Supplement	0
+FSType	4
+Weight	(Regular)
+FamilyName	(Source Sans)
+version	(2.20)
+AdobeCopyright	(Copyright 2010, 2012, 2014 Adobe Systems Incorporated (http://www.adobe.com/), with Reserved Font Name 'Source'.)

tests/mergefonts_test.py

@@ -83,3 +83,21 @@ def test_camel_case():
     expected_path = generate_ps_dump(expected_path)
 
     assert differ([expected_path, actual_path, '-s', r'%ADOt1write:'])
+
+
+def test_cidwhitespace():
+    font1_filename = 'font1.pfa'
+    font2_filename = 'font2.pfa'
+    font3_filename = 'font3.pfa'
+    alias1_filename = 'alias1.txt'
+    alias2_filename = 'alias2.txt'
+    alias3_filename = 'alias3.txt'
+    fontinfo_filename = 'cidwhitespace/cidfontinfo.txt'
+    actual_path = get_temp_file_path()
+
+    # without fix this dies with <Signals.SIGSEGV: 11...>
+    runner(CMD + ['-o', 'cid', '-f', fontinfo_filename, actual_path,
+                  alias1_filename, font1_filename,
+                  alias2_filename, font2_filename,
+                  alias3_filename, font3_filename])
+