odb: Error when streaming in too [few|many] bytes

2 files changed, 16 insertions, 3 deletions

diff --git a/include/git2/odb.h b/include/git2/odb.h
index 3e93a932c..e50a2a1c1 100644
--- a/include/git2/odb.h
+++ b/include/git2/odb.h
@@ -238,6 +238,9 @@ GIT_EXTERN(int) git_odb_open_wstream(git_odb_stream **out, git_odb *db, size_t s
 /**
  * Write to an odb stream
  *
+ * This method will fail as soon as the total number of
+ * received bytes exceeds the size declared with `git_odb_open_wstream()`
+ *
  * @param stream the stream
  * @param buffer the data to write
  * @param len the buffer's length
@@ -251,6 +254,9 @@ GIT_EXTERN(int) git_odb_stream_write(git_odb_stream *stream, const char *buffer,
  * The object will take its final name and will be available to the
  * odb.
  *
+ * This method will fail if the total number of received bytes
+ * differs from the size declared with `git_odb_open_wstream()`
+ *
  * @param out pointer to store the resulting object's id
  * @param stream the stream
  * @return 0 on success; an error code otherwise
diff --git a/include/git2/odb_backend.h b/include/git2/odb_backend.h
index bafeec047..e558bbb1c 100644
--- a/include/git2/odb_backend.h
+++ b/include/git2/odb_backend.h
@@ -78,6 +78,9 @@ struct git_odb_stream {
 	unsigned int mode;
 	void *hash_ctx;
 
+	size_t declared_size;
+	size_t received_bytes;
+
 	/**
 	 * Write at most `len` bytes into `buffer` and advance the
 	 * stream.
@@ -93,9 +96,13 @@ struct git_odb_stream {
 	 * Store the contents of the stream as an object with the id
 	 * specified in `oid`.
 	 *
-	 * This method will *not* be invoked by libgit2 if the object pointed at
-	 * by `oid` already exists in any backend. Libgit2 will however take care
-	 * of properly disposing the stream through a call to `free()`.
+	 * This method will *not* be invoked by libgit2 when:
+	 *  - the object pointed at by `oid` already exists in any backend.
+	 * 	- the total number of received bytes differs from the size declared
+	 *    with `git_odb_open_wstream()`
+	 *
+	 * Libgit2 will however take care of properly disposing the stream through
+	 * a call to `free()`.
 	 */
 	int (*finalize_write)(git_odb_stream *stream, const git_oid *oid);