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-rw-r--r--cache.h22
1 files changed, 22 insertions, 0 deletions
diff --git a/cache.h b/cache.h
index 3cbad5b..5624e6c 100644
--- a/cache.h
+++ b/cache.h
@@ -636,6 +636,9 @@ int daemonize(void);
* at least 'nr' entries; the number of entries currently allocated
* is 'alloc', using the standard growing factor alloc_nr() macro.
*
+ * Consider using ALLOC_GROW_BY instead of ALLOC_GROW as it has some
+ * added niceties.
+ *
* DO NOT USE any expression with side-effect for 'x', 'nr', or 'alloc'.
*/
#define ALLOC_GROW(x, nr, alloc) \
@@ -649,6 +652,25 @@ int daemonize(void);
} \
} while (0)
+/*
+ * Similar to ALLOC_GROW but handles updating of the nr value and
+ * zeroing the bytes of the newly-grown array elements.
+ *
+ * DO NOT USE any expression with side-effect for any of the
+ * arguments.
+ */
+#define ALLOC_GROW_BY(x, nr, increase, alloc) \
+ do { \
+ if (increase) { \
+ size_t new_nr = nr + (increase); \
+ if (new_nr < nr) \
+ BUG("negative growth in ALLOC_GROW_BY"); \
+ ALLOC_GROW(x, new_nr, alloc); \
+ memset((x) + nr, 0, sizeof(*(x)) * (increase)); \
+ nr = new_nr; \
+ } \
+ } while (0)
+
/* Initialize and use the cache information */
struct lock_file;
void preload_index(struct index_state *index,