Ensure that string field lengths are properly aligned

Integers should always be aligned. For some platforms (ARM, SPARC) this
is more important than for others. This changeset ensures that the
string field string lengths are aligned on *all* platforms, not just on
the SPARC for which there was a workaround. It also fixes that the
length integer can be resized to 32 bits without problems if needed.

(closes issue ASTERISK-17310)
Reported by: radael, S Adrian
Reviewed by: Tzafrir Cohen, Terry Wilson
Tested by: S Adrian

Review: https://reviewboard.asterisk.org/r/1549
........

Merged revisions 343157 from http://svn.asterisk.org/svn/asterisk/branches/1.8
........

Merged revisions 343158 from http://svn.asterisk.org/svn/asterisk/branches/10


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@343163 65c4cc65-6c06-0410-ace0-fbb531ad65f3

1 files changed, 16 insertions, 19 deletions

diff --git a/main/utils.c b/main/utils.c
index 8ff6b5215..219d60023 100644
--- a/main/utils.c
+++ b/main/utils.c
@@ -1652,10 +1652,13 @@ ast_string_field __ast_string_field_alloc_space(struct ast_string_field_mgr *mgr
 {
 	char *result = NULL;
 	size_t space = (*pool_head)->size - (*pool_head)->used;
-	size_t to_alloc = needed + sizeof(ast_string_field_allocation);
+	size_t to_alloc;
 
-	/* This +1 accounts for alignment on SPARC */
-	if (__builtin_expect(to_alloc + 1 > space, 0)) {
+	/* Make room for ast_string_field_allocation and make it a multiple of that. */
+	to_alloc = ast_add_and_make_multiple_of(needed, sizeof(ast_string_field_allocation));
+	ast_assert(to_alloc % sizeof(ast_string_field_allocation) == 0);
+
+	if (__builtin_expect(to_alloc > space, 0)) {
 		size_t new_size = (*pool_head)->size;
 
 		while (new_size < to_alloc) {
@@ -1671,14 +1674,11 @@ ast_string_field __ast_string_field_alloc_space(struct ast_string_field_mgr *mgr
 #endif
 	}
 
+	/* pool->base is always aligned (gcc aligned attribute). We ensure that
+	 * to_alloc is also a multiple of sizeof(ast_string_field_allocation)
+	 * causing result to always be aligned as well; which in turn fixes that
+	 * AST_STRING_FIELD_ALLOCATION(result) is aligned. */
 	result = (*pool_head)->base + (*pool_head)->used;
-#ifdef __sparc__
-	/* SPARC requires that the allocation field be aligned. */
-	if ((long) result % sizeof(ast_string_field_allocation)) {
-		result++;
-		(*pool_head)->used++;
-	}
-#endif
 	(*pool_head)->used += to_alloc;
 	(*pool_head)->active += needed;
 	result += sizeof(ast_string_field_allocation);
@@ -1753,13 +1753,10 @@ void __ast_string_field_ptr_build_va(struct ast_string_field_mgr *mgr,
 			available += space;
 		}
 	} else {
+		/* pool->used is always a multiple of sizeof(ast_string_field_allocation)
+		 * so we don't need to re-align anything here.
+		 */
 		target = (*pool_head)->base + (*pool_head)->used + sizeof(ast_string_field_allocation);
-#ifdef __sparc__
-		if ((long) target % sizeof(ast_string_field_allocation)) {
-			target++;
-			space--;
-		}
-#endif
 		available = space - sizeof(ast_string_field_allocation);
 	}
 
@@ -1786,15 +1783,15 @@ void __ast_string_field_ptr_build_va(struct ast_string_field_mgr *mgr,
 		__ast_string_field_release_active(*pool_head, *ptr);
 		mgr->last_alloc = *ptr = target;
 		AST_STRING_FIELD_ALLOCATION(target) = needed;
-		(*pool_head)->used += needed + sizeof(ast_string_field_allocation);
+		(*pool_head)->used += ast_add_and_make_multiple_of(needed, sizeof(ast_string_field_allocation));
 		(*pool_head)->active += needed;
 	} else if ((grow = (needed - AST_STRING_FIELD_ALLOCATION(*ptr))) > 0) {
 		/* the allocation was satisfied by using available space in the pool *and*
 		   the field was the last allocated field from the pool, so it grew
 		*/
-		(*pool_head)->used += grow;
-		(*pool_head)->active += grow;
 		AST_STRING_FIELD_ALLOCATION(*ptr) += grow;
+		(*pool_head)->used += ast_make_multiple_of(grow, sizeof(ast_string_field_allocation));
+		(*pool_head)->active += grow;
 	}
 }