1 files changed, 59 insertions, 2 deletions

diff --git a/reftable/basics.h b/reftable/basics.h
index 4c9ef0fe6c..7aa46d7c30 100644
--- a/reftable/basics.h
+++ b/reftable/basics.h
@@ -16,6 +16,64 @@ https://developers.google.com/open-source/licenses/bsd
 #include "system.h"
 #include "reftable-basics.h"
 
+struct reftable_buf {
+	size_t alloc;
+	size_t len;
+	char *buf;
+};
+#define REFTABLE_BUF_INIT { 0 }
+
+/*
+ * Initialize the buffer such that it is ready for use. This is equivalent to
+ * using REFTABLE_BUF_INIT for stack-allocated variables.
+ */
+void reftable_buf_init(struct reftable_buf *buf);
+
+/*
+ * Release memory associated with the buffer. The buffer is reinitialized such
+ * that it can be reused for subsequent operations.
+ */
+void reftable_buf_release(struct reftable_buf *buf);
+
+/*
+ * Reset the buffer such that it is effectively empty, without releasing the
+ * memory that this structure holds on to. This is equivalent to calling
+ * `reftable_buf_setlen(buf, 0)`.
+ */
+void reftable_buf_reset(struct reftable_buf *buf);
+
+/*
+ * Trim the buffer to a shorter length by updating the `len` member and writing
+ * a NUL byte to `buf[len]`. Returns 0 on success, -1 when `len` points outside
+ * of the array.
+ */
+int reftable_buf_setlen(struct reftable_buf *buf, size_t len);
+
+/*
+ * Lexicographically compare the two buffers. Returns 0 when both buffers have
+ * the same contents, -1 when `a` is lexicographically smaller than `b`, and 1
+ * otherwise.
+ */
+int reftable_buf_cmp(const struct reftable_buf *a, const struct reftable_buf *b);
+
+/*
+ * Append `len` bytes from `data` to the buffer. This function works with
+ * arbitrary byte sequences, including ones that contain embedded NUL
+ * characters. As such, we use `void *` as input type. Returns 0 on success,
+ * REFTABLE_OUT_OF_MEMORY_ERROR on allocation failure.
+ */
+int reftable_buf_add(struct reftable_buf *buf, const void *data, size_t len);
+
+/* Equivalent to `reftable_buf_add(buf, s, strlen(s))`. */
+int reftable_buf_addstr(struct reftable_buf *buf, const char *s);
+
+/*
+ * Detach the buffer from the structure such that the underlying memory is now
+ * owned by the caller. The buffer is reinitialized such that it can be reused
+ * for subsequent operations.
+ */
+char *reftable_buf_detach(struct reftable_buf *buf);
+
 /* Bigendian en/decoding of integers */
 
 void put_be24(uint8_t *out, uint32_t i);
@@ -88,8 +146,7 @@ char *reftable_strdup(const char *str);
 #endif
 
 /* Find the longest shared prefix size of `a` and `b` */
-struct strbuf;
-int common_prefix_size(struct strbuf *a, struct strbuf *b);
+int common_prefix_size(struct reftable_buf *a, struct reftable_buf *b);
 
 int hash_size(uint32_t id);