X-Git-Url: https://git.exim.org/exim.git/blobdiff_plain/94e1f16d6033683bdebaf5092f64c58bc044dd2d..e34f8ca2022e340d3c0e36260a0232fab306dfcc:/src/src/string.c

diff --git a/src/src/string.c b/src/src/string.c
index cfe801284..50442bced 100644
--- a/src/src/string.c
+++ b/src/src/string.c
@@ -2,7 +2,7 @@
 *     Exim - an Internet mail transport agent    *
 *************************************************/
 
-/* Copyright (c) University of Cambridge 1995 - 2016 */
+/* Copyright (c) University of Cambridge 1995 - 2018 */
 /* See the file NOTICE for conditions of use and distribution. */
 
 /* Miscellaneous string-handling functions. Some are not required for
@@ -1050,12 +1050,40 @@ return list;
 
 
 
+/************************************************/
+/* Create a growable-string with some preassigned space */
+
+gstring *
+string_get(unsigned size)
+{
+gstring * g = store_get(sizeof(gstring) + size);
+g->size = size;
+g->ptr = 0;
+g->s = US(g + 1);
+return g;
+}
+
+/* NUL-terminate the C string in the growable-string, and return it. */
+
+uschar *
+string_from_gstring(gstring * g)
+{
+if (!g) return NULL;
+g->s[g->ptr] = '\0';
+return g->s;
+}
+
 /*************************************************
 *             Add chars to string                *
 *************************************************/
-/* See inline functions in functions.h */
 
-void
+/* Arguments:
+  g		the grawable-string
+  p		current end of data
+  count		amount to grow by
+*/
+
+static void
 gstring_grow(gstring * g, int p, int count)
 {
 int oldsize = g->size;
@@ -1080,13 +1108,62 @@ was the last item on the dynamic memory stack. This is the case if it matches
 store_last_get. */
 
 if (!store_extend(g->s, oldsize, g->size))
+  g->s = store_newblock(g->s, g->size, p);
+}
+
+
+
+/* This function is used when building up strings of unknown length. Room is
+always left for a terminating zero to be added to the string that is being
+built. This function does not require the string that is being added to be NUL
+terminated, because the number of characters to add is given explicitly. It is
+sometimes called to extract parts of other strings.
+
+Arguments:
+  string   points to the start of the string that is being built, or NULL
+             if this is a new string that has no contents yet
+  s        points to characters to add
+  count    count of characters to add; must not exceed the length of s, if s
+             is a C string.
+
+Returns:   pointer to the start of the string, changed if copied for expansion.
+           Note that a NUL is not added, though space is left for one. This is
+           because string_cat() is often called multiple times to build up a
+           string - there's no point adding the NUL till the end.
+
+*/
+/* coverity[+alloc] */
+
+gstring *
+string_catn(gstring * g, const uschar *s, int count)
+{
+int p;
+
+if (!g)
   {
-  BOOL release_ok = store_last_get[store_pool] == g->s;
-  uschar *newstring = store_get(g->size);
-  memcpy(newstring, g->s, p);
-  if (release_ok) store_release(g->s);
-  g->s = newstring;
+  unsigned inc = count < 4096 ? 127 : 1023;
+  unsigned size = ((count + inc) &  ~inc) + 1;
+  g = string_get(size);
   }
+
+p = g->ptr;
+if (p + count >= g->size)
+  gstring_grow(g, p, count);
+
+/* Because we always specify the exact number of characters to copy, we can
+use memcpy(), which is likely to be more efficient than strncopy() because the
+latter has to check for zero bytes. */
+
+memcpy(g->s + p, s, count);
+g->ptr = p + count;
+return g;
+}
+ 
+ 
+gstring *
+string_cat(gstring *string, const uschar *s)
+{
+return string_catn(string, s, Ustrlen(s));
 }
 
 
@@ -1295,10 +1372,20 @@ while (*fp != 0)
     break;
 
     case 'p':
-    if (p >= last - 24) { yield = FALSE; goto END_FORMAT; }
-    strncpy(newformat, item_start, fp - item_start);
-    newformat[fp - item_start] = 0;
-    p += sprintf(CS p, newformat, va_arg(ap, void *));
+      {
+      void * ptr;
+      if (p >= last - 24) { yield = FALSE; goto END_FORMAT; }
+      /* sprintf() saying "(nil)" for a null pointer seems unreliable.
+      Handle it explicitly. */
+      if ((ptr = va_arg(ap, void *)))
+	{
+	strncpy(newformat, item_start, fp - item_start);
+	newformat[fp - item_start] = 0;
+	p += sprintf(CS p, newformat, ptr);
+	}
+      else
+	p += sprintf(CS p, "(nil)");
+      }
     break;
 
     /* %f format is inherently insecure if the numbers that it may be