Improve the ODB writing backend

Temporary files when doing streaming writes are now stored inside the
Objects folder, to prevent issues when moving files between
disks/partitions.

Add support for block writes to the ODB again (for those backends that
cannot implement streaming).

include/git2/odb.h

@@ -156,6 +156,26 @@ GIT_EXTERN(int) git_odb_read_header(size_t *len_p, git_otype *type_p, git_odb *d
  */
 GIT_EXTERN(int) git_odb_exists(git_odb *db, const git_oid *id);
 
+/**
+ * Write an object directly into the ODB
+ *
+ * This method writes a full object straight into the ODB.
+ * For most cases, it is preferred to write objects through a write
+ * stream, which is both faster and less memory intensive, specially
+ * for big objects.
+ *
+ * This method is provided for compatibility with custom backends
+ * which are not able to support streaming writes
+ *
+ * @param oid pointer to store the OID result of the write
+ * @param odb object database where to store the object
+ * @param data buffer with the data to storr
+ * @param len size of the buffer
+ * @param type type of the data to store
+ * @return 0 on success; error code otherwise
+ */
+GIT_EXTERN(int) git_odb_write(git_oid *oid, git_odb *odb, const void *data, size_t len, git_otype type);
+
 /**
  * Open a stream to write an object into the ODB
  *

include/git2/odb_backend.h

@@ -55,6 +55,13 @@ struct git_odb_backend {
 			struct git_odb_backend *,
 			const git_oid *);
 
+	int (* write)(
+			git_oid *,
+			struct git_odb_backend *,
+			const void *,
+			size_t,
+			git_otype);
+
 	int (* writestream)(
 			struct git_odb_stream **,
 			struct git_odb_backend *,

src/filebuf.c

@@ -151,8 +151,7 @@ int git_filebuf_open(git_filebuf *file, const char *path, int flags)
 	int error;
 	size_t path_len;
 
-	if (file == NULL)
-		return GIT_ERROR;
+	assert(file && path);
 
 	memset(file, 0x0, sizeof(git_filebuf));
 
@@ -203,7 +202,7 @@ int git_filebuf_open(git_filebuf *file, const char *path, int flags)
 		char tmp_path[GIT_PATH_MAX];
 
 		/* Open the file as temporary for locking */
-		file->fd = gitfo_creat_tmp(tmp_path, "_filebuf_"); 
+		file->fd = gitfo_mktemp(tmp_path, path); 
 		if (file->fd < 0) {
 			error = GIT_EOSERR;
 			goto cleanup;
@@ -218,12 +217,6 @@ int git_filebuf_open(git_filebuf *file, const char *path, int flags)
 			goto cleanup;
 		}
 	} else {
-		/* If the file is not temporary, make sure we have a path */
-		if (path == NULL) {
-			error = GIT_ERROR;
-			goto cleanup;
-		}
-
 		path_len = strlen(path);
 
 		/* Save the original path of the file */

src/fileops.c

@@ -25,11 +25,11 @@ int gitfo_mkdir_2file(const char *file_path)
 	return GIT_SUCCESS;
 }
 
-static int creat_tempfile(char *path_out, const char *tmp_dir, const char *filename)
+int gitfo_mktemp(char *path_out, const char *filename)
 {
 	int fd;
 
-	git__joinpath(path_out, tmp_dir, filename);
+	strcpy(path_out, filename);
 	strcat(path_out, "_git2_XXXXXX");
 
 #if defined(_MSC_VER)
@@ -46,66 +46,6 @@ static int creat_tempfile(char *path_out, const char *tmp_dir, const char *filen
 	return fd >= 0 ? fd : GIT_EOSERR;
 }
 
-static const char *find_tmpdir(void)
-{
-	static int tmpdir_not_found = 0;
-	static char temp_dir[GIT_PATH_MAX];
-	static const char *env_vars[] = {
-		"TEMP", "TMP", "TMPDIR"
-	};
-
-	unsigned int i, j;
-	char test_file[GIT_PATH_MAX];
-
-	if (tmpdir_not_found)
-		return NULL;
-
-	if (temp_dir[0] != '\0')
-		return temp_dir;
-
-	for (i = 0; i < ARRAY_SIZE(env_vars); ++i) {
-		char *env_path;
-
-		env_path = getenv(env_vars[i]);
-		if (env_path == NULL)
-			continue;
-
-		strcpy(temp_dir, env_path);
-
-		/* Fix backslashes because Windows environment vars
-		 * are probably fucked up */
-		for (j = 0; j < strlen(temp_dir); ++j)
-			if (temp_dir[j] == '\\')
-				temp_dir[j] = '/';
-
-		if (creat_tempfile(test_file, temp_dir, "writetest") >= 0) {
-			gitfo_unlink(test_file);
-			return temp_dir;
-		}
-	}
-
-	/* last resort: current folder. */
-	strcpy(temp_dir, "./");
-	if (creat_tempfile(test_file, temp_dir, "writetest") >= 0) {
-		gitfo_unlink(test_file);
-		return temp_dir;
-	}
-
-	tmpdir_not_found = 1;
-	return NULL;
-}
-
-int gitfo_creat_tmp(char *path_out, const char *filename)
-{
-	const char *tmp_dir;
-
-	tmp_dir = find_tmpdir();
-	if (tmp_dir == NULL)
-		return GIT_EOSERR;
-
-	return creat_tempfile(path_out, tmp_dir, filename);
-}
-
 int gitfo_open(const char *path, int flags)
 {
 	int fd = open(path, flags | O_BINARY);

src/fileops.h

@@ -58,7 +58,7 @@ extern int gitfo_exists(const char *path);
 extern int gitfo_open(const char *path, int flags);
 extern int gitfo_creat(const char *path, int mode);
 extern int gitfo_creat_force(const char *path, int mode);
-extern int gitfo_creat_tmp(char *path_out, const char *filename);
+extern int gitfo_mktemp(char *path_out, const char *filename);
 extern int gitfo_isdir(const char *path);
 extern int gitfo_mkdir_recurs(const char *path, int mode);
 extern int gitfo_mkdir_2file(const char *path);

src/odb.c

@@ -415,6 +415,41 @@ int git_odb_read(git_odb_object **out, git_odb *db, const git_oid *id)
 	return error;
 }
 
+int git_odb_write(git_oid *oid, git_odb *db, const void *data, size_t len, git_otype type)
+{
+	unsigned int i;
+	int error = GIT_ERROR;
+
+	assert(oid && db);
+
+	for (i = 0; i < db->backends.length && error < 0; ++i) {
+		backend_internal *internal = git_vector_get(&db->backends, i);
+		git_odb_backend *b = internal->backend;
+
+		/* we don't write in alternates! */
+		if (internal->is_alternate)
+			continue;
+
+		if (b->write != NULL)
+			error = b->write(oid, b, data, len, type);
+	}
+
+	/* if no backends were able to write the object directly, we try a streaming
+	 * write to the backends; just write the whole object into the stream in one
+	 * push */
+	if (error < GIT_SUCCESS) {
+		git_odb_stream *stream;
+
+		if ((error = git_odb_open_wstream(&stream, db, len, type)) == GIT_SUCCESS) {
+			stream->write(stream, data, len);
+			error = stream->finalize_write(oid, stream);
+			stream->free(stream);
+		}
+	}
+
+	return error;
+}
+
 int git_odb_open_wstream(git_odb_stream **stream, git_odb *db, size_t size, git_otype type)
 {
 	unsigned int i;

src/odb_loose.c

@@ -579,7 +579,7 @@ int loose_backend__stream(git_odb_stream **stream_out, git_odb_backend *_backend
 	loose_backend *backend;
 	loose_writestream *stream;
 
-	char hdr[64];
+	char hdr[64], tmp_path[GIT_PATH_MAX];
 	int  hdrlen;
 	int error;
 
@@ -603,7 +603,9 @@ int loose_backend__stream(git_odb_stream **stream_out, git_odb_backend *_backend
 	stream->stream.free = &loose_backend__stream_free;
 	stream->stream.mode = GIT_STREAM_WRONLY;
 
-	error = git_filebuf_open(&stream->fbuf, NULL,
+	git__joinpath(tmp_path, backend->objects_dir, "tmp_object");
+
+	error = git_filebuf_open(&stream->fbuf, tmp_path,
 		GIT_FILEBUF_HASH_CONTENTS |
 		GIT_FILEBUF_DEFLATE_CONTENTS |
 		GIT_FILEBUF_TEMPORARY);