1 files changed, 112 insertions, 0 deletions
diff --git a/include/git2/buffer.h b/include/git2/buffer.h
new file mode 100644
index 000000000..36a61e6c9
--- /dev/null
+++ b/include/git2/buffer.h
@@ -0,0 +1,112 @@
+/*
+ * Copyright (C) the libgit2 contributors. All rights reserved.
+ *
+ * This file is part of libgit2, distributed under the GNU GPL v2 with
+ * a Linking Exception. For full terms see the included COPYING file.
+ */
+#ifndef INCLUDE_git_buf_h__
+#define INCLUDE_git_buf_h__
+
+#include "common.h"
+
+/**
+ * @file git2/buffer.h
+ * @brief Buffer export structure
+ *
+ * @ingroup Git
+ * @{
+ */
+GIT_BEGIN_DECL
+
+/**
+ * A data buffer for exporting data from libgit2
+ *
+ * Sometimes libgit2 wants to return an allocated data buffer to the
+ * caller and have the caller take responsibility for freeing that memory.
+ * This can be awkward if the caller does not have easy access to the same
+ * allocation functions that libgit2 is using.  In those cases, libgit2
+ * will fill in a `git_buf` and the caller can use `git_buf_free()` to
+ * release it when they are done.
+ *
+ * A `git_buf` may also be used for the caller to pass in a reference to
+ * a block of memory they hold.  In this case, libgit2 will not resize or
+ * free the memory, but will read from it as needed.
+ *
+ * A `git_buf` is a public structure with three fields:
+ *
+ * - `ptr` points to the start of the allocated memory.  If it is NULL,
+ *   then the `git_buf` is considered empty and libgit2 will feel free
+ *   to overwrite it with new data.
+ *
+ * - `size` holds the size (in bytes) of the data that is actually used.
+ *
+ * - `asize` holds the known total amount of allocated memory if the `ptr`
+ *    was allocated by libgit2.  It may be larger than `size`.  If `ptr`
+ *    was not allocated by libgit2 and should not be resized and/or freed,
+ *    then `asize` will be set to zero.
+ *
+ * Some APIs may occasionally do something slightly unusual with a buffer,
+ * such as setting `ptr` to a value that was passed in by the user.  In
+ * those cases, the behavior will be clearly documented by the API.
+ */
+typedef struct {
+	char   *ptr;
+	size_t asize, size;
+} git_buf;
+
+/**
+ * Static initializer for git_buf from static buffer
+ */
+#define GIT_BUF_INIT_CONST(STR,LEN) { (char *)(STR), 0, (size_t)(LEN) }
+
+/**
+ * Free the memory referred to by the git_buf.
+ *
+ * Note that this does not free the `git_buf` itself, just the memory
+ * pointed to by `buffer->ptr`.  This will not free the memory if it looks
+ * like it was not allocated internally, but it will clear the buffer back
+ * to the empty state.
+ *
+ * @param buffer The buffer to deallocate
+ */
+GIT_EXTERN(void) git_buf_free(git_buf *buffer);
+
+/**
+ * Resize the buffer allocation to make more space.
+ *
+ * This will attempt to grow the buffer to accomodate the target size.
+ *
+ * If the buffer refers to memory that was not allocated by libgit2 (i.e.
+ * the `asize` field is zero), then `ptr` will be replaced with a newly
+ * allocated block of data.  Be careful so that memory allocated by the
+ * caller is not lost.  As a special variant, if you pass `target_size` as
+ * 0 and the memory is not allocated by libgit2, this will allocate a new
+ * buffer of size `size` and copy the external data into it.
+ *
+ * Currently, this will never shrink a buffer, only expand it.
+ *
+ * If the allocation fails, this will return an error and the buffer will be
+ * marked as invalid for future operations, invaliding the contents.
+ *
+ * @param buffer The buffer to be resized; may or may not be allocated yet
+ * @param target_size The desired available size
+ * @return 0 on success, -1 on allocation failure
+ */
+GIT_EXTERN(int) git_buf_grow(git_buf *buffer, size_t target_size);
+
+/**
+ * Set buffer to a copy of some raw data.
+ *
+ * @param buffer The buffer to set
+ * @param data The data to copy into the buffer
+ * @param datalen The length of the data to copy into the buffer
+ * @return 0 on success, -1 on allocation failure
+ */
+GIT_EXTERN(int) git_buf_set(
+	git_buf *buffer, const void *data, size_t datalen);
+
+GIT_END_DECL
+
+/** @} */
+
+#endif