lib: data-stack - Rename block_space_used[] to block_space_left[]

This describes its behavior better. Also add a comment explaining what
exactly it is.

diff --git a/src/lib/data-stack.c b/src/lib/data-stack.c
index 14e4022317ffbc4c821d64a7ae8944313e4c8aff..1c8ed4e3a7ab932689e9938f7259407a4a87508d 100644 (file)
--- a/src/lib/data-stack.c
+++ b/src/lib/data-stack.c
@@ -50,7 +50,10 @@ struct stack_frame_block {
        struct stack_frame_block *prev;
 
        struct stack_block *block[BLOCK_FRAME_COUNT];
-       size_t block_space_used[BLOCK_FRAME_COUNT];
+       /* Each frame initializes this to current_block->left, i.e. how much
+          free space is left in the block. So the frame's start position in
+          the block is (block.size - block_space_left) */
+       size_t block_space_left[BLOCK_FRAME_COUNT];
        size_t last_alloc_size[BLOCK_FRAME_COUNT];
        const char *marker[BLOCK_FRAME_COUNT];
 #ifdef DEBUG
@@ -167,7 +170,7 @@ data_stack_frame_t t_push(const char *marker)
 
        /* mark our current position */
        current_frame_block->block[frame_pos] = current_block;
-       current_frame_block->block_space_used[frame_pos] = current_block->left;
+       current_frame_block->block_space_left[frame_pos] = current_block->left;
        current_frame_block->last_alloc_size[frame_pos] = 0;
        current_frame_block->marker[frame_pos] = marker;
 #ifdef DEBUG
@@ -244,7 +247,7 @@ static void t_pop_verify(void)
        size_t pos, max_pos, used_size;
 
        block = current_frame_block->block[frame_pos];
-       pos = block->size - current_frame_block->block_space_used[frame_pos];
+       pos = block->size - current_frame_block->block_space_left[frame_pos];
        while (block != NULL) {
                block_canary_check(block);
                used_size = block->size - block->left;
@@ -292,13 +295,13 @@ void t_pop_last_unsafe(void)
                size_t pos, used_size;
 
                pos = current_block->size -
-                       current_frame_block->block_space_used[frame_pos];
+                       current_frame_block->block_space_left[frame_pos];
                used_size = current_block->size - current_block->lowwater;
                i_assert(used_size >= pos);
                memset(STACK_BLOCK_DATA(current_block) + pos, CLEAR_CHR,
                       used_size - pos);
        }
-       current_block->left = current_frame_block->block_space_used[frame_pos];
+       current_block->left = current_frame_block->block_space_left[frame_pos];
        current_block->lowwater = current_block->left;
 
        if (current_block->next != NULL) {