git_buf_grow_by: increase buf asize incrementally

Introduce `git_buf_grow_by` to incrementally increase the size of a
`git_buf`, performing an overflow calculation on the growth.

1 files changed, 12 insertions, 0 deletions

diff --git a/src/buffer.h b/src/buffer.h
index 8ee4b532c..52342e309 100644
--- a/src/buffer.h
+++ b/src/buffer.h
@@ -37,6 +37,18 @@ GIT_INLINE(bool) git_buf_is_allocated(const git_buf *buf)
 extern void git_buf_init(git_buf *buf, size_t initial_size);
 
 /**
+ * Resize the buffer allocation to make more space.
+ *
+ * This will attempt to grow the buffer to accommodate the additional size.
+ * It is similar to `git_buf_grow`, but performs the new size calculation,
+ * checking for overflow.
+ *
+ * Like `git_buf_grow`, if this is a user-supplied buffer, this will allocate
+ * a new buffer.
+ */
+extern int git_buf_grow_by(git_buf *buffer, size_t additional_size);
+
+/**
  * Attempt to grow the buffer to hold at least `target_size` bytes.
  *
  * If the allocation fails, this will return an error.  If `mark_oom` is true,