r25164: Add talloc_asprintf_append_buffer() and the docs for it.

Jeremy.
(This used to be commit 5bb8613b86a6788efde840d5b50710f9afd22fed)

3 files changed, 82 insertions, 4 deletions

diff --git a/source4/lib/talloc/talloc.c b/source4/lib/talloc/talloc.c
index c3e5d2c076..7920a66d64 100644
--- a/source4/lib/talloc/talloc.c
+++ b/source4/lib/talloc/talloc.c
@@ -1223,7 +1223,8 @@ char *talloc_asprintf(const void *t, const char *fmt, ...)
 /**
  * Realloc @p s to append the formatted result of @p fmt and @p ap,
  * and return @p s, which may have moved.  Good for gradually
- * accumulating output into a string buffer.
+ * accumulating output into a string buffer. Appends at the end
+ * of the string.
  **/
 char *talloc_vasprintf_append(char *s, const char *fmt, va_list ap)
 {
@@ -1245,7 +1246,52 @@ char *talloc_vasprintf_append(char *s, const char *fmt, va_list ap)
 		/* Either the vsnprintf failed or the format resulted in
 		 * no characters being formatted. In the former case, we
 		 * ought to return NULL, in the latter we ought to return
-		 * the original string. Most current callers of this 
+		 * the original string. Most current callers of this
+		 * function expect it to never return NULL.
+		 */
+		return s;
+	}
+
+	s = talloc_realloc(NULL, s, char, s_len + len+1);
+	if (!s) return NULL;
+
+	va_copy(ap2, ap);
+	vsnprintf(s+s_len, len+1, fmt, ap2);
+	va_end(ap2);
+	_talloc_set_name_const(s, s);
+
+	return s;
+}
+
+/**
+ * Realloc @p s to append the formatted result of @p fmt and @p ap,
+ * and return @p s, which may have moved. Always appends at the
+ * end of the talloc'ed buffer, not the end of the string.
+ **/
+char *talloc_vasprintf_append_buffer(char *s, const char *fmt, va_list ap)
+{
+	struct talloc_chunk *tc;
+	int len, s_len;
+	va_list ap2;
+	char c;
+
+	if (s == NULL) {
+		return talloc_vasprintf(NULL, fmt, ap);
+	}
+
+	tc = talloc_chunk_from_ptr(s);
+
+	s_len = tc->size - 1;
+
+	va_copy(ap2, ap);
+	len = vsnprintf(&c, 1, fmt, ap2);
+	va_end(ap2);
+
+	if (len <= 0) {
+		/* Either the vsnprintf failed or the format resulted in
+		 * no characters being formatted. In the former case, we
+		 * ought to return NULL, in the latter we ought to return
+		 * the original string. Most current callers of this
 		 * function expect it to never return NULL.
 		 */
 		return s;
@@ -1278,6 +1324,21 @@ char *talloc_asprintf_append(char *s, const char *fmt, ...)
 }
 
 /*
+  Realloc @p s to append the formatted result of @p fmt and return @p
+  s, which may have moved.  Good for gradually accumulating output
+  into a buffer.
+ */
+char *talloc_asprintf_append_buffer(char *s, const char *fmt, ...)
+{
+	va_list ap;
+
+	va_start(ap, fmt);
+	s = talloc_vasprintf_append_buffer(s, fmt, ap);
+	va_end(ap);
+	return s;
+}
+
+/*
   alloc an array, checking for integer overflow in the array size
 */
 void *_talloc_array(const void *ctx, size_t el_size, unsigned count, const char *name)
diff --git a/source4/lib/talloc/talloc.h b/source4/lib/talloc/talloc.h
index 15130d0d98..95152a1416 100644
--- a/source4/lib/talloc/talloc.h
+++ b/source4/lib/talloc/talloc.h
@@ -157,8 +157,10 @@ char *talloc_strndup(const void *t, const char *p, size_t n);
 char *talloc_append_string(const void *t, char *orig, const char *append);
 char *talloc_vasprintf(const void *t, const char *fmt, va_list ap) PRINTF_ATTRIBUTE(2,0);
 char *talloc_vasprintf_append(char *s, const char *fmt, va_list ap) PRINTF_ATTRIBUTE(2,0);
+char *talloc_vasprintf_append_buffer(char *s, const char *fmt, va_list ap) PRINTF_ATTRIBUTE(2,0);
 char *talloc_asprintf(const void *t, const char *fmt, ...) PRINTF_ATTRIBUTE(2,3);
 char *talloc_asprintf_append(char *s, const char *fmt, ...) PRINTF_ATTRIBUTE(2,3);
+char *talloc_asprintf_append_buffer(char *s, const char *fmt, ...) PRINTF_ATTRIBUTE(2,3);
 void *_talloc_array(const void *ctx, size_t el_size, unsigned count, const char *name);
 void *_talloc_zero_array(const void *ctx, size_t el_size, unsigned count, const char *name);
 void *_talloc_realloc_array(const void *ctx, void *ptr, size_t el_size, unsigned count, const char *name);
diff --git a/source4/lib/talloc/talloc_guide.txt b/source4/lib/talloc/talloc_guide.txt
index c4634ae19a..18663b370d 100644
--- a/source4/lib/talloc/talloc_guide.txt
+++ b/source4/lib/talloc/talloc_guide.txt
@@ -568,8 +568,23 @@ string. This is equivalent to:
 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
 char *talloc_asprintf_append(char *s, const char *fmt, ...);
 
+The talloc_asprintf_append() function appends the given formatted
+string to the given string.
+Use this varient when the string in the current talloc buffer may
+have been truncated in length.
+
+This functions sets the name of the new pointer to the new
+string. This is equivalent to:
+   talloc_set_name_const(ptr, ptr)
+
+
+=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
+char *talloc_asprintf_append_buffer(char *s, const char *fmt, ...);
+
 The talloc_asprintf_append() function appends the given formatted 
-string to the given string. 
+string to the end of the currently allocated talloc buffer.
+Use this varient when the string in the current talloc buffer has
+not been changed.
 
 This functions sets the name of the new pointer to the new
 string. This is equivalent to:
@@ -577,7 +592,7 @@ string. This is equivalent to:
 
 
 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
-(type *)talloc_array(const void *ctx, type, uint_t count);
+((type *)talloc_array(const void *ctx, type, uint_t count);
 
 The talloc_array() macro is equivalent to: