str: Always null-terminate string in str_format_26adic().

[pspp-builds.git] / src / libpspp / str.c

diff --git a/src/libpspp/str.c b/src/libpspp/str.c
index 08a85ad790f20fe625de485b6c22058226910e2e..7e722c17e6b92602798725e3bdd618327a46691f 100644 (file)
--- a/src/libpspp/str.c
+++ b/src/libpspp/str.c
@@ -270,17 +270,22 @@ str_format_26adic (unsigned long int number, char buffer[], size_t size)
   while (number-- > 0)
     {
       if (length >= size)
-        return false;
+        goto overflow;
       buffer[length++] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"[number % 26];
       number /= 26;
     }
 
   if (length >= size)
-    return false;
+    goto overflow;
   buffer[length] = '\0';
 
   buf_reverse (buffer, length);
   return true;
+
+overflow:
+  if (length > 0)
+    buffer[0] = '\0';
+  return false;
 }
 
 /* Sets the SIZE bytes starting at BLOCK to C,
@@ -1455,6 +1460,30 @@ ds_put_uninit (struct string *st, size_t incr)
   return end;
 }
 
+/* Moves the bytes in ST following offset OFS + OLD_LEN in ST to offset OFS +
+   NEW_LEN and returns the byte at offset OFS.  The first min(OLD_LEN, NEW_LEN)
+   bytes at the returned position are unchanged; if NEW_LEN > OLD_LEN then the
+   following NEW_LEN - OLD_LEN bytes are initially indeterminate.
+
+   The intention is that the caller should write NEW_LEN bytes at the returned
+   position, to effectively replace the OLD_LEN bytes previously at that
+   position. */
+char *
+ds_splice_uninit (struct string *st,
+                  size_t ofs, size_t old_len, size_t new_len)
+{
+  if (new_len != old_len)
+    {
+      if (new_len > old_len)
+        ds_extend (st, ds_length (st) + (new_len - old_len));
+      memmove (ds_data (st) + (ofs + new_len),
+               ds_data (st) + (ofs + old_len),
+               ds_length (st) - (ofs + old_len));
+      st->ss.length += new_len - old_len;
+    }
+  return ds_data (st) + ofs;
+}
+
 /* Formats FORMAT as a printf string and appends the result to ST. */
 void
 ds_put_format (struct string *st, const char *format, ...)