Merge pull request #704 from nulltoken/topic/blob_fromchunks

Add the ability to create blob given a provider of chunks of bytes

include/git2/blob.h

@@ -115,6 +115,48 @@ GIT_EXTERN(int) git_blob_create_fromfile(git_oid *oid, git_repository *repo, con
  */
 GIT_EXTERN(int) git_blob_create_fromdisk(git_oid *oid, git_repository *repo, const char *path);
 
+/**
+ * Write a loose blob to the Object Database from a
+ * provider of chunks of data.
+ *
+ * Provided the `hintpath` parameter is filled, its value
+ * will help to determine what git filters should be applied
+ * to the object before it can be placed to the object database.
+ *
+ *
+ * The implementation of the callback has to respect the
+ * following rules:
+ *
+ *  - `content` will have to be filled by the consumer. The maximum number
+ * of bytes that the buffer can accept per call is defined by the
+ * `max_length` parameter. Allocation and freeing of the buffer will be taken
+ * care of by the function.
+ *
+ *  - The callback is expected to return the number of bytes
+ * that `content` have been filled with.
+ *
+ *  - When there is no more data to stream, the callback should
+ * return 0. This will prevent it from being invoked anymore.
+ *
+ *  - When an error occurs, the callback should return -1.
+ *
+ *
+ * @param oid Return the id of the written blob
+ *
+ * @param repo repository where the blob will be written.
+ * This repository can be bare or not.
+ *
+ * @param hintpath if not NULL, will help selecting the filters
+ * to apply onto the content of the blob to be created.
+ *
+ * @return GIT_SUCCESS or an error code
+ */
+GIT_EXTERN(int) git_blob_create_fromchunks(
+	git_oid *oid,
+	git_repository *repo,
+	const char *hintpath,
+	int (*source_cb)(char *content, size_t max_length, void *payload),
+	void *payload);
 
 /**
  * Write an in-memory buffer to the ODB as a blob

src/blob.c

@@ -148,27 +148,31 @@ static int write_symlink(
 	return error;
 }
 
-static int blob_create_internal(git_oid *oid, git_repository *repo, const char *path)
+static int blob_create_internal(git_oid *oid, git_repository *repo, const char *content_path, const char *hint_path, bool try_load_filters)
 {
 	int error;
 	struct stat st;
 	git_odb *odb = NULL;
 	git_off_t size;
 
-	if ((error = git_path_lstat(path, &st)) < 0 || (error = git_repository_odb__weakptr(&odb, repo)) < 0)
+	assert(hint_path || !try_load_filters);
+
+	if ((error = git_path_lstat(content_path, &st)) < 0 || (error = git_repository_odb__weakptr(&odb, repo)) < 0)
 		return error;
 
 	size = st.st_size;
 
 	if (S_ISLNK(st.st_mode)) {
-		error = write_symlink(oid, odb, path, (size_t)size);
+		error = write_symlink(oid, odb, content_path, (size_t)size);
 	} else {
 		git_vector write_filters = GIT_VECTOR_INIT;
-		int filter_count;
+		int filter_count = 0;
 
-		/* Load the filters for writing this file to the ODB */
-		filter_count = git_filters_load(
-			&write_filters, repo, path, GIT_FILTER_TO_ODB);
+		if (try_load_filters) {
+			/* Load the filters for writing this file to the ODB */
+			filter_count = git_filters_load(
+				&write_filters, repo, hint_path, GIT_FILTER_TO_ODB);
+		}
 
 		if (filter_count < 0) {
 			/* Negative value means there was a critical error */
@@ -176,10 +180,10 @@ static int blob_create_internal(git_oid *oid, git_repository *repo, const char *
 		} else if (filter_count == 0) {
 			/* No filters need to be applied to the document: we can stream
 			 * directly from disk */
-			error = write_file_stream(oid, odb, path, size);
+			error = write_file_stream(oid, odb, content_path, size);
 		} else {
 			/* We need to apply one or more filters */
-			error = write_file_filtered(oid, odb, path, &write_filters);
+			error = write_file_filtered(oid, odb, content_path, &write_filters);
 		}
 
 		git_filters_free(&write_filters);
@@ -216,7 +220,7 @@ int git_blob_create_fromfile(git_oid *oid, git_repository *repo, const char *pat
 		return -1;
 	}
 
-	error = blob_create_internal(oid, repo, git_buf_cstr(&full_path));
+	error = blob_create_internal(oid, repo, git_buf_cstr(&full_path), git_buf_cstr(&full_path), true);
 
 	git_buf_free(&full_path);
 	return error;
@@ -232,8 +236,53 @@ int git_blob_create_fromdisk(git_oid *oid, git_repository *repo, const char *pat
 		return error;
 	}
 
-	error = blob_create_internal(oid, repo, git_buf_cstr(&full_path));
+	error = blob_create_internal(oid, repo, git_buf_cstr(&full_path), git_buf_cstr(&full_path), true);
 
 	git_buf_free(&full_path);
 	return error;
 }
+
+#define BUFFER_SIZE 4096
+
+int git_blob_create_fromchunks(
+	git_oid *oid,
+	git_repository *repo,
+	const char *hintpath,
+	int (*source_cb)(char *content, size_t max_length, void *payload),
+	void *payload)
+{
+	int error = -1, read_bytes;
+	char *content = NULL;
+	git_filebuf file = GIT_FILEBUF_INIT;
+
+	content = git__malloc(BUFFER_SIZE);
+	GITERR_CHECK_ALLOC(content);
+
+	if (git_filebuf_open(&file, hintpath == NULL ? "streamed" : hintpath, GIT_FILEBUF_TEMPORARY) < 0)
+		goto cleanup;
+
+	while (1) {
+		read_bytes = source_cb(content, BUFFER_SIZE, payload);
+
+		assert(read_bytes <= BUFFER_SIZE);
+
+		if (read_bytes <= 0)
+			break;
+
+		if (git_filebuf_write(&file, content, read_bytes) < 0)
+			goto cleanup;
+	}
+
+	if (read_bytes < 0)
+		goto cleanup;
+
+	if (git_filebuf_flush(&file) < 0)
+		goto cleanup;
+
+	error = blob_create_internal(oid, repo, file.path_lock, hintpath, hintpath != NULL);
+
+cleanup:
+	git_filebuf_cleanup(&file);
+	git__free(content);
+	return error;
+}

src/filebuf.c

@@ -130,6 +130,11 @@ GIT_INLINE(int) flush_buffer(git_filebuf *file)
 	return result;
 }
 
+int git_filebuf_flush(git_filebuf *file)
+{
+	return flush_buffer(file);
+}
+
 static int write_normal(git_filebuf *file, void *source, size_t len)
 {
 	if (len > 0) {

src/filebuf.h

@@ -81,5 +81,6 @@ int git_filebuf_commit(git_filebuf *lock, mode_t mode);
 int git_filebuf_commit_at(git_filebuf *lock, const char *path, mode_t mode);
 void git_filebuf_cleanup(git_filebuf *lock);
 int git_filebuf_hash(git_oid *oid, git_filebuf *file);
+int git_filebuf_flush(git_filebuf *file);
 
 #endif

tests-clar/object/blob/fromchunks.c

+#include "clar_libgit2.h"
+#include "buffer.h"
+#include "posix.h"
+#include "path.h"
+#include "fileops.h"
+
+static git_repository *repo;
+static char textual_content[] = "libgit2\n\r\n\0";
+
+void test_object_blob_fromchunks__initialize(void)
+{
+	repo = cl_git_sandbox_init("testrepo.git");
+}
+
+void test_object_blob_fromchunks__cleanup(void)
+{
+	cl_git_sandbox_cleanup();
+}
+
+static int text_chunked_source_cb(char *content, size_t max_length, void *payload)
+{
+	int *count;
+
+	GIT_UNUSED(max_length);
+
+	count = (int *)payload;
+	(*count)--;
+
+	if (*count == 0)
+		return 0;
+
+	strcpy(content, textual_content);
+	return strlen(textual_content);
+}
+
+void test_object_blob_fromchunks__can_create_a_blob_from_a_in_memory_chunk_provider(void)
+{
+	git_oid expected_oid, oid;
+	git_object *blob;
+	int howmany = 7;
+
+	cl_git_pass(git_oid_fromstr(&expected_oid, "321cbdf08803c744082332332838df6bd160f8f9"));
+
+	cl_git_fail(git_object_lookup(&blob, repo, &expected_oid, GIT_OBJ_ANY));
+
+	cl_git_pass(git_blob_create_fromchunks(&oid, repo, NULL, text_chunked_source_cb, &howmany));
+
+	cl_git_pass(git_object_lookup(&blob, repo, &expected_oid, GIT_OBJ_ANY));
+	git_object_free(blob);
+}
+
+#define GITATTR "* text=auto\n" \
+	"*.txt text\n" \
+	"*.data binary\n"
+
+static void write_attributes(git_repository *repo)
+{
+	git_buf buf = GIT_BUF_INIT;
+
+	cl_git_pass(git_buf_joinpath(&buf, git_repository_path(repo), "info"));
+	cl_git_pass(git_buf_joinpath(&buf, git_buf_cstr(&buf), "attributes"));
+
+	cl_git_pass(git_futils_mkpath2file(git_buf_cstr(&buf), 0777));
+	cl_git_rewritefile(git_buf_cstr(&buf), GITATTR);
+
+	git_buf_free(&buf);
+}
+
+static void assert_named_chunked_blob(const char *expected_sha, const char *fake_name)
+{
+	git_oid expected_oid, oid;
+	int howmany = 7;
+
+	cl_git_pass(git_oid_fromstr(&expected_oid, expected_sha));
+
+	cl_git_pass(git_blob_create_fromchunks(&oid, repo, fake_name, text_chunked_source_cb, &howmany));
+	cl_assert(git_oid_cmp(&expected_oid, &oid) == 0);
+}
+
+void test_object_blob_fromchunks__creating_a_blob_from_chunks_honors_the_attributes_directives(void)
+{
+	write_attributes(repo);
+
+	assert_named_chunked_blob("321cbdf08803c744082332332838df6bd160f8f9", "dummy.data");
+	assert_named_chunked_blob("e9671e138a780833cb689753570fd10a55be84fb", "dummy.txt");
+	assert_named_chunked_blob("e9671e138a780833cb689753570fd10a55be84fb", "dummy.dunno");
+}