Merge remote-tracking branch 'origin/master'

15 files changed, 1101 insertions, 16 deletions

diff --git a/COPYING.txt b/COPYING.txt
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--- /dev/null
+++ b/COPYING.txt
@@ -0,0 +1,661 @@
+                    GNU AFFERO GENERAL PUBLIC LICENSE
+                       Version 3, 19 November 2007
+
+ Copyright (C) 2007 Free Software Foundation, Inc. <https://fsf.org/>
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+                            Preamble
+
+  The GNU Affero General Public License is a free, copyleft license for
+software and other kinds of works, specifically designed to ensure
+cooperation with the community in the case of network server software.
+
+  The licenses for most software and other practical works are designed
+to take away your freedom to share and change the works.  By contrast,
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+
+  When we speak of free software, we are referring to freedom, not
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+  Developers that use our General Public Licenses protect your rights
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+  A secondary benefit of defending all users' freedom is that
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+  An older license, called the Affero General Public License and
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+
+  IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
+WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS
+THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY
+GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE
+USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF
+DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD
+PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS),
+EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF
+SUCH DAMAGES.
+
+  17. Interpretation of Sections 15 and 16.
+
+  If the disclaimer of warranty and limitation of liability provided
+above cannot be given local legal effect according to their terms,
+reviewing courts shall apply local law that most closely approximates
+an absolute waiver of all civil liability in connection with the
+Program, unless a warranty or assumption of liability accompanies a
+copy of the Program in return for a fee.
+
+                     END OF TERMS AND CONDITIONS
+
+            How to Apply These Terms to Your New Programs
+
+  If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+  To do so, attach the following notices to the program.  It is safest
+to attach them to the start of each source file to most effectively
+state the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+    <one line to give the program's name and a brief idea of what it does.>
+    Copyright (C) <year>  <name of author>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+Also add information on how to contact you by electronic and paper mail.
+
+  If your software can interact with users remotely through a computer
+network, you should also make sure that it provides a way for users to
+get its source.  For example, if your program is a web application, its
+interface could display a "Source" link that leads users to an archive
+of the code.  There are many ways you could offer source, and different
+solutions will be better for different programs; see section 13 for the
+specific requirements.
+
+  You should also get your employer (if you work as a programmer) or school,
+if any, to sign a "copyright disclaimer" for the program, if necessary.
+For more information on this, and how to apply and follow the GNU AGPL, see
+<https://www.gnu.org/licenses/>.
diff --git a/backend.go b/backend.go
index 668e06e..0486e98 100644
--- a/backend.go
+++ b/backend.go
@@ -1,3 +1,18 @@
+// Copyright (C) 2017-2018  Luke Shumaker <lukeshu@lukeshu.com>
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
 package libfastimport
 
 import (
@@ -9,7 +24,12 @@ import (
 )
 
 // A Backend is something that consumes a fast-import stream; the
-// Backend object provides methods for writing to it.
+// Backend object provides methods for writing to it.  A program that
+// reads from a Backend would itself be a frontend.
+//
+// You may think of a "Backend" object as a "Writer" object, though it was not
+// given that name because the GetMark, CatBlob, and Ls methods
+// actually provide 2-way communication.
 type Backend struct {
 	fastImportClose io.Closer
 	fastImportFlush *bufio.Writer
@@ -22,6 +42,14 @@ type Backend struct {
 	onErr func(error) error
 }
 
+// NewBackend creates a new Backend object that writes to the given
+// io.WriteCloser.
+//
+// Optionally, you may also provide an io.Reader that responses to
+// "cat-blob", "get-mark", and "ls" commands can be read from.
+//
+// Optionally, you may also provide an onErr function that can be used
+// to handle or transform errors when they are encountered.
 func NewBackend(fastImport io.WriteCloser, catBlob io.Reader, onErr func(error) error) *Backend {
 	ret := &Backend{}
 
@@ -52,8 +80,10 @@ func NewBackend(fastImport io.WriteCloser, catBlob io.Reader, onErr func(error)
 	return ret
 }
 
-// will panic if Cmd is a type that may only be used in a commit but
-// we aren't in a commit.
+// Do tells the Backend to do the given command.
+//
+// It is an error (panic) if Cmd is a type that may only be used in a
+// commit but we aren't in a commit.
 func (b *Backend) Do(cmd Cmd) error {
 	if b.err != nil {
 		return b.err
@@ -88,6 +118,11 @@ func (b *Backend) Do(cmd Cmd) error {
 	return nil
 }
 
+// GetMark gets the SHA-1 referred to by the given mark from the
+// Backend.
+//
+// It is an error (panic) to call GetMark if NewBackend did not have a
+// cat-blob reader passed to it.
 func (b *Backend) GetMark(cmd CmdGetMark) (sha1 string, err error) {
 	err = b.Do(cmd)
 	if err != nil {
@@ -105,6 +140,11 @@ func (b *Backend) GetMark(cmd CmdGetMark) (sha1 string, err error) {
 	return
 }
 
+// CatBlob gets the SHA-1 and content of the specified blob from the
+// Backend.
+//
+// It is an error (panic) to call CatBlob if NewBackend did not have a
+// cat-blob reader passed to it.
 func (b *Backend) CatBlob(cmd CmdCatBlob) (sha1 string, data string, err error) {
 	err = b.Do(cmd)
 	if err != nil {
@@ -122,6 +162,11 @@ func (b *Backend) CatBlob(cmd CmdCatBlob) (sha1 string, data string, err error)
 	return
 }
 
+// Ls gets information about the file at the specified path from the
+// Backend.
+//
+// It is an error (panic) to call Ls if NewBackend did not have a
+// cat-blob reader passed to it.
 func (b *Backend) Ls(cmd CmdLs) (mode Mode, dataref string, path Path, err error) {
 	err = b.Do(cmd)
 	if err != nil {
diff --git a/cmd.go b/cmd.go
index 4d56ad8..1665081 100644
--- a/cmd.go
+++ b/cmd.go
@@ -1,3 +1,31 @@
+// Copyright (C) 2017-2018  Luke Shumaker <lukeshu@lukeshu.com>
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+// Package libfastimport implements reading and writing of git
+// fast-import streams.
+//
+// The documentation here focuses on use of the package itself; it
+// generally assumes a working understanding of the format.
+// Documentation on the format itself can be found in the
+// git-fast-import(1) man-page.
+//
+// A program can write commands to a backend by wrapping the
+// appropriate io.Writer with a Backend object.
+//
+// A program can read commands from a frontend by wrapping the
+// appropriate io.Reader with a Frontend object.
 package libfastimport
 
 type fiReader interface {
@@ -19,6 +47,7 @@ const (
 	cmdClassComment cmdClass = cmdClassCommand | cmdClassCommit
 )
 
+// Cmd is a command that may be found in a fast-import stream.
 type Cmd interface {
 	fiCmdRead(fiReader) (Cmd, error)
 	fiCmdWrite(fiWriter) error
diff --git a/cmd_command.go b/cmd_command.go
index a6c5ec1..ff74f80 100644
--- a/cmd_command.go
+++ b/cmd_command.go
@@ -1,3 +1,18 @@
+// Copyright (C) 2017-2018  Luke Shumaker <lukeshu@lukeshu.com>
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
 package libfastimport
 
 import (
@@ -9,6 +24,14 @@ import (
 
 // commit //////////////////////////////////////////////////////////////////////
 
+// CmdCommit requests that the Backend creates or updates a branch
+// with a new commit.
+//
+// This command may be followed by zero or more "File" or "Note"
+// commands to set the content of commit's tree.  When reading from a
+// Frontend, that sequence of "File" and "Note" commands will be
+// terminated by a CmdCommitEnd command.  It is not nescessary to
+// manually emit a CmdCommitEnd when writing to a Backend.
 type CmdCommit struct {
 	Ref       string
 	Mark      int // optional; < 1 for non-use
@@ -87,6 +110,13 @@ func (CmdCommit) fiCmdRead(fir fiReader) (cmd Cmd, err error) {
 	return
 }
 
+// CmdCommitEnd indicates the Frontend will be sending no more "File"
+// or "Note" commands that are "part of" the current CmdCommit.
+//
+// This is a synthesized command to simplify reading from a Frontend;
+// it is not really a command in the stream.  It is thus not
+// nescessary to send a CmdCommitEnd command when writing to a
+// Backend.
 type CmdCommitEnd struct{}
 
 func (CmdCommitEnd) fiCmdClass() cmdClass                { return cmdClassCommit }
@@ -95,6 +125,10 @@ func (CmdCommitEnd) fiCmdRead(fir fiReader) (Cmd, error) { panic("not reached")
 
 // tag /////////////////////////////////////////////////////////////////////////
 
+// CmdTag requests that the Backend creates an *annotated* tag
+// referencing a specific commit.
+//
+// Hint: Use CmdReset to create a *lightweight* tag.
 type CmdTag struct {
 	RefName   string
 	CommitIsh string
@@ -144,6 +178,9 @@ func (CmdTag) fiCmdRead(fir fiReader) (cmd Cmd, err error) {
 
 // reset ///////////////////////////////////////////////////////////////////////
 
+// CmdReset requests that the Backend creates (or recreates) the named
+// ref (usually a branch), optionally starting from a specific
+// revision.
 type CmdReset struct {
 	RefName   string
 	CommitIsh string // optional
@@ -179,8 +216,12 @@ func (CmdReset) fiCmdRead(fir fiReader) (cmd Cmd, err error) {
 
 // blob ////////////////////////////////////////////////////////////////////////
 
+// CmdBlob requests that the Backend write file revision.  The blob
+// can be later referred to by the specified Mark (if a Mark > 0 is
+// given), or by pre-calculating the Git SHA-1 (though this is
+// needlessly difficult, just specify a Mark).
 type CmdBlob struct {
-	Mark int
+	Mark int // optional
 	Data string
 }
 
@@ -220,6 +261,7 @@ func (CmdBlob) fiCmdRead(fir fiReader) (cmd Cmd, err error) {
 
 // checkpoint //////////////////////////////////////////////////////////////////
 
+// CmdCheckpoint requests that the Backend flush already-sent data.
 type CmdCheckpoint struct{}
 
 func (c CmdCheckpoint) fiCmdClass() cmdClass { return cmdClassCommand }
@@ -237,6 +279,8 @@ func (CmdCheckpoint) fiCmdRead(fir fiReader) (cmd Cmd, err error) {
 
 // progress ////////////////////////////////////////////////////////////////////
 
+// CmdProgress requests that the Backend print the given string to its
+// standard output channel.
 type CmdProgress struct {
 	Str string
 }
@@ -256,6 +300,8 @@ func (CmdProgress) fiCmdRead(fir fiReader) (cmd Cmd, err error) {
 
 // feature /////////////////////////////////////////////////////////////////////
 
+// CmdFeature requests that the Backend immediately aborts with an
+// error if it does not support the specified feature.
 type CmdFeature struct {
 	Feature  string
 	Argument string
@@ -290,6 +336,7 @@ func (CmdFeature) fiCmdRead(fir fiReader) (cmd Cmd, err error) {
 
 // option //////////////////////////////////////////////////////////////////////
 
+// CmdOption requests that the Backend changes its settings.
 type CmdOption struct {
 	Option string
 }
@@ -310,6 +357,8 @@ func (CmdOption) fiCmdRead(fir fiReader) (cmd Cmd, err error) {
 
 // done ////////////////////////////////////////////////////////////////////////
 
+// CmdDone indicates to the Backend that no more commands will be
+// sent.
 type CmdDone struct{}
 
 func (c CmdDone) fiCmdClass() cmdClass { return cmdClassCommand }
diff --git a/cmd_comment.go b/cmd_comment.go
index b554487..c0325b4 100644
--- a/cmd_comment.go
+++ b/cmd_comment.go
@@ -1,3 +1,18 @@
+// Copyright (C) 2017-2018  Luke Shumaker <lukeshu@lukeshu.com>
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
 package libfastimport
 
 import (
@@ -9,6 +24,7 @@ import (
 
 // comment /////////////////////////////////////////////////////////////////////
 
+// CmdComment is a comment line; not a real command.
 type CmdComment struct {
 	Comment string
 }
@@ -28,6 +44,9 @@ func (CmdComment) fiCmdRead(fir fiReader) (cmd Cmd, err error) {
 
 // get-mark ////////////////////////////////////////////////////////////////////
 
+// CmdGetMark requests that the Backend to report back (over the
+// auxiliary cat-blob stream) with the SHA-1 corresponding to the
+// given Mark.
 type CmdGetMark struct {
 	Mark int
 }
@@ -52,6 +71,10 @@ func (CmdGetMark) fiCmdRead(fir fiReader) (cmd Cmd, err error) {
 
 // cat-blob ////////////////////////////////////////////////////////////////////
 
+// CmdCatBlob requests that the Backend to report back (over the
+// auxiliary cat-blob stream) with the SHA-1 and content of the
+// requested blob.  The blob can be specified either by a mark
+// reference (":<idnum>") or by a full 40-byte SHA-1.
 type CmdCatBlob struct {
 	DataRef string
 }
@@ -71,6 +94,12 @@ func (CmdCatBlob) fiCmdRead(fir fiReader) (cmd Cmd, err error) {
 
 // ls //////////////////////////////////////////////////////////////////////////
 
+// CmdLs requests that the Backend to report back (over the auxiliary
+// cat-blob stream) with information about the object at a path in the
+// specified commit.  If inside of a commit, specifying the commit is
+// optional, and the ongoing commit is used.  The commit can be
+// specified either by a mark reference (":<idnum>") or by a full
+// 40-byte SHA-1.
 type CmdLs struct {
 	DataRef string // optional if inside of a commit
 	Path    Path
diff --git a/cmd_commit.go b/cmd_commit.go
index db22642..170c511 100644
--- a/cmd_commit.go
+++ b/cmd_commit.go
@@ -1,3 +1,18 @@
+// Copyright (C) 2017-2018  Luke Shumaker <lukeshu@lukeshu.com>
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
 package libfastimport
 
 import (
@@ -9,6 +24,13 @@ import (
 
 // M ///////////////////////////////////////////////////////////////////////////
 
+// FileModify appears after a CmdCommit (and before a CmdCommitEnd),
+// and causes the CmdCommit to add a new file or change the content of
+// an existing file.  The content of the file is specified by giving
+// either a mark reference (":<idnum>") or by a full 40-byte SHA-1.
+//
+// To specify the full content of the file inline, use
+// FileModifyInline instead.
 type FileModify struct {
 	Mode    Mode
 	Path    Path
@@ -63,6 +85,13 @@ func (FileModify) fiCmdRead(fir fiReader) (cmd Cmd, err error) {
 	}
 }
 
+// FileModifyInline appears after a CmdCommit (and before a
+// CmdCommitEnd), and causes the CmdCommit to add a new file or change
+// the content of an existing file.  The full content of the file are
+// specified directly
+//
+// To instead specify the content with a mark reference (":<idnum>")
+// or with a full 40-byte SHA-1, use FileModify instead.
 type FileModifyInline struct {
 	Mode Mode
 	Path Path
@@ -80,6 +109,8 @@ func (FileModifyInline) fiCmdRead(fiReader) (Cmd, error) { panic("not reached")
 
 // D ///////////////////////////////////////////////////////////////////////////
 
+// FileDelete appears after a CmdCommit (and before a CmdCommitEnd),
+// and causes the CmdCommit to recursively remove a file or directory.
 type FileDelete struct {
 	Path Path
 }
@@ -99,6 +130,9 @@ func (FileDelete) fiCmdRead(fir fiReader) (cmd Cmd, err error) {
 
 // C ///////////////////////////////////////////////////////////////////////////
 
+// FileCopy appears after a CmdCommit (and before a CmdCommitEnd),
+// and causes the CmdCommit to recursively copy an existing file or
+// subdirectory to a different location.
 type FileCopy struct {
 	Src Path
 	Dst Path
@@ -116,6 +150,9 @@ func (FileCopy) fiCmdRead(fir fiReader) (cmd Cmd, err error) {
 
 // R ///////////////////////////////////////////////////////////////////////////
 
+// FileRename appears after a CmdCommit (and before a CmdCommitEnd),
+// and causes the CmdCommit to rename an existing file or subdirectory
+// to a different location.
 type FileRename struct {
 	Src string
 	Dst string
@@ -133,6 +170,9 @@ func (FileRename) fiCmdRead(fir fiReader) (cmd Cmd, err error) {
 
 // deleteall ///////////////////////////////////////////////////////////////////
 
+// FileDeleteAll appears after a CmdCommit (and before a
+// CmdCommitEnd), and removes all files and directories from the
+// CmdCommit.
 type FileDeleteAll struct{}
 
 func (o FileDeleteAll) fiCmdClass() cmdClass { return cmdClassCommit }
@@ -150,6 +190,14 @@ func (FileDeleteAll) fiCmdRead(fir fiReader) (cmd Cmd, err error) {
 
 // N ///////////////////////////////////////////////////////////////////////////
 
+// NoteModify appears after a CmdCommit (and before a CmdCommitEnd),
+// and causes the CmdCommit to add a new note describing CommitIsh or
+// change the content of an existing note describing CommitIsh.  The
+// content of the note is specified by giving either a mark reference
+// (":<idnum>") or by a full 40-byte SHA-1.
+//
+// To specify the full content of the note inline, use
+// NoteModifyInline instead.
 type NoteModify struct {
 	CommitIsh string
 	DataRef   string
@@ -196,6 +244,14 @@ func (NoteModify) fiCmdRead(fir fiReader) (cmd Cmd, err error) {
 	}
 }
 
+// NoteModifyInline appears after a CmdCommit (and before a
+// CmdCommitEnd), and causes the CmdCommit to add a new note
+// describing CommitIsh or change the content of an existing note
+// describing CommitIsh.  The full content of the note is specified
+// directly.
+//
+// To instead specify the content with a mark reference (":<idnum>")
+// or with a full 40-byte SHA-1, use NoteModify instead.
 type NoteModifyInline struct {
 	CommitIsh string
 	Data      string
diff --git a/ez.go b/ez.go
index 8fe429d..be57d58 100644
--- a/ez.go
+++ b/ez.go
@@ -1,3 +1,18 @@
+// Copyright (C) 2017  Luke Shumaker <lukeshu@lukeshu.com>
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
 package libfastimport
 
 import (
diff --git a/frontend.go b/frontend.go
index d0c8c10..c069ddf 100644
--- a/frontend.go
+++ b/frontend.go
@@ -1,3 +1,18 @@
+// Copyright (C) 2017-2018  Luke Shumaker <lukeshu@lukeshu.com>
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
 package libfastimport
 
 import (
@@ -15,7 +30,13 @@ func (e UnsupportedCommand) Error() string {
 }
 
 // A Frontend is something that produces a fast-import stream; the
-// Frontend object provides methods for reading from it.
+// Frontend object provides methods for reading from it.  A program
+// that writes to a Frontend would itself be a backend.
+//
+// You may think of a "Frontend" object as a "Reader" object, though
+// it was not given that name because the RespondGetMark,
+// RespondCatBlob, and RespondLs methods actually write information;
+// it isn't a read-only object.
 type Frontend struct {
 	fastImport   *parser
 	catBlobWrite *textproto.CatBlobWriter
@@ -24,6 +45,14 @@ type Frontend struct {
 	onErr func(error) error
 }
 
+// NewFrontend creates a new Frontend object that reads from the given
+// io.Reader.
+//
+// Optionally, you may also provide an io.Writer that responses to
+// "cat-blob", "get-mark", and "ls" commands can be written to.
+//
+// Optionally, you may also provide an onErr function that can bue
+// used to handle or transform errors when they are encountered.
 func NewFrontend(fastImport io.Reader, catBlob io.Writer, onErr func(error) error) *Frontend {
 	ret := &Frontend{}
 
@@ -43,6 +72,7 @@ func NewFrontend(fastImport io.Reader, catBlob io.Writer, onErr func(error) erro
 	return ret
 }
 
+// ReadCmd reads a command from the Frontend.
 func (f *Frontend) ReadCmd() (Cmd, error) {
 	cmd, err := f.fastImport.ReadCmd()
 	if err != nil {
@@ -51,6 +81,11 @@ func (f *Frontend) ReadCmd() (Cmd, error) {
 	return cmd, err
 }
 
+// RespondGetMark sends to the Frontend a response to a "get-mark"
+// command.
+//
+// It is an error (panic) to call RespondGetMark if NewFrontend did
+// not have a cat-blob writer passed to it.
 func (f *Frontend) RespondGetMark(sha1 string) error {
 	err := f.catBlobWrite.WriteLine(sha1)
 	if err != nil {
@@ -59,6 +94,11 @@ func (f *Frontend) RespondGetMark(sha1 string) error {
 	return f.catBlobFlush.Flush()
 }
 
+// RespondCatBlob sends to the Frontend a response to a "cat-blob"
+// command.
+//
+// It is an error (panic) to call RespondCatBlob if NewFrontend did
+// not have a cat-blob writer passed to it.
 func (f *Frontend) RespondCatBlob(sha1 string, data string) error {
 	err := f.catBlobWrite.WriteBlob(sha1, data)
 	if err != nil {
@@ -67,6 +107,10 @@ func (f *Frontend) RespondCatBlob(sha1 string, data string) error {
 	return f.catBlobFlush.Flush()
 }
 
+// RespondLs sends to the Frontend a response to a "ls" command.
+//
+// It is an error (panic) to call RespondLs if NewFrontend did not
+// have a cat-blob writer passed to it.
 func (f *Frontend) RespondLs(mode Mode, dataref string, path Path) error {
 	var err error
 	if mode == 0 {
diff --git a/parse_catblob.go b/parse_catblob.go
index c6f66c8..9f08da8 100644
--- a/parse_catblob.go
+++ b/parse_catblob.go
@@ -1,3 +1,18 @@
+// Copyright (C) 2017  Luke Shumaker <lukeshu@lukeshu.com>
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
 package libfastimport
 
 import (
diff --git a/parse_fastimport.go b/parse_fastimport.go
index 14080b6..b01b251 100644
--- a/parse_fastimport.go
+++ b/parse_fastimport.go
@@ -1,3 +1,18 @@
+// Copyright (C) 2017-2018  Luke Shumaker <lukeshu@lukeshu.com>
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
 package libfastimport
 
 import (
@@ -26,7 +41,8 @@ var parser_comment func(line string) func(fiReader) (Cmd, error)
 
 func parser_compile(cmds map[string]Cmd) func(line string) func(fiReader) (Cmd, error) {
 	// This assumes that 2 characters is enough to uniquely
-	// identify a command, and that "#" is the only one-chara
+	// identify a command, and that "#" is the only one-character
+	// command.
 	ch2map := make(map[string]string, len(cmds))
 	for prefix := range cmds {
 		var ch2 string
diff --git a/textproto/catblob.go b/textproto/catblob.go
index 678b842..6836689 100644
--- a/textproto/catblob.go
+++ b/textproto/catblob.go
@@ -1,3 +1,18 @@
+// Copyright (C) 2017-2018  Luke Shumaker <lukeshu@lukeshu.com>
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
 package textproto
 
 import (
@@ -7,16 +22,22 @@ import (
 	"strconv"
 )
 
+// CatBlobReader is a low-level parser of an fast-import auxiliary
+// "cat-blob" stream.
 type CatBlobReader struct {
 	r *bufio.Reader
 }
 
+// NewCatBlobReader creates a new CatBlobReader parser.
 func NewCatBlobReader(r io.Reader) *CatBlobReader {
 	return &CatBlobReader{
 		r: bufio.NewReader(r),
 	}
 }
 
+// ReadLine reads a response from the stream; with special handling
+// for responses to "cat-blob" commands, which contain multiple
+// newline characters.
 func (cbr *CatBlobReader) ReadLine() (line string, err error) {
 	for len(line) <= 1 {
 		line, err = cbr.r.ReadString('\n')
@@ -52,21 +73,29 @@ func (cbr *CatBlobReader) ReadLine() (line string, err error) {
 	return
 }
 
+// CatBlobWriter is a low-level marshaller for an auxiliary cat-blob
+// stream.
 type CatBlobWriter struct {
 	w io.Writer
 }
 
+// NewCatBlobWriter creates a new CatBlobWriter marshaller.
 func NewCatBlobWriter(w io.Writer) *CatBlobWriter {
 	return &CatBlobWriter{
 		w: w,
 	}
 }
 
+// WriteLine writes a response (to a command OTHER THAN "cat-blob") to
+// the stream; arguments are handled similarly to fmt.Println.
+//
+// Use WriteBlob instead to write responses to "cat-blob" commands.
 func (cbw *CatBlobWriter) WriteLine(a ...interface{}) error {
 	_, err := fmt.Fprintln(cbw.w, a...)
 	return err
 }
 
+// WriteBlob writes a response to a "cat-blob" command to the stream.
 func (cbw *CatBlobWriter) WriteBlob(sha1 string, data string) error {
 	err := cbw.WriteLine(sha1, "blob", len(data))
 	if err != nil {
diff --git a/textproto/doc.go b/textproto/doc.go
new file mode 100644
index 0000000..82154a1
--- /dev/null
+++ b/textproto/doc.go
@@ -0,0 +1,24 @@
+// Copyright (C) 2017-2018  Luke Shumaker <lukeshu@lukeshu.com>
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+// Package textproto implements low-level details of the fast-import
+// format.
+//
+// This package deals with parsing and marshalling idiosyncratic
+// datatypes used by the format (Ident tuples, 18-bit Mode numbers,
+// oddly-quoted Path strings), and abstracting over special-case
+// commands that break the "line-based" nature of the format (the
+// "data" command, responses to the "cat-blob" command).
+package textproto
diff --git a/textproto/fastimport.go b/textproto/fastimport.go
index c845f7f..b43c378 100644
--- a/textproto/fastimport.go
+++ b/textproto/fastimport.go
@@ -1,3 +1,18 @@
+// Copyright (C) 2017-2018  Luke Shumaker <lukeshu@lukeshu.com>
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
 package textproto
 
 import (
@@ -8,6 +23,7 @@ import (
 	"strings"
 )
 
+// FIReader is a low-level parser of a fast-import stream.
 type FIReader struct {
 	r *bufio.Reader
 
@@ -15,12 +31,16 @@ type FIReader struct {
 	err  error
 }
 
+// NewFIReader creates a new FIReader parser.
 func NewFIReader(r io.Reader) *FIReader {
 	return &FIReader{
 		r: bufio.NewReader(r),
 	}
 }
 
+// ReadLine reads a "line" from the stream; with special handling for
+// the "data" command, which isn't really a single line, but rather
+// contains arbitrary binary data.
 func (fir *FIReader) ReadLine() (line string, err error) {
 	for len(line) <= 1 {
 		line, err = fir.r.ReadString('\n')
@@ -58,21 +78,26 @@ func (fir *FIReader) ReadLine() (line string, err error) {
 	return
 }
 
+// FIWriter is a low-level marshaller of a fast-import stream.
 type FIWriter struct {
 	w io.Writer
 }
 
+// NewFIWriter creates a new FIWriter marshaller.
 func NewFIWriter(w io.Writer) *FIWriter {
 	return &FIWriter{
 		w: w,
 	}
 }
 
+// WriteLine writes an ordinary line to the stream; arguments are
+// handled similarly to fmt.Println.
 func (fiw *FIWriter) WriteLine(a ...interface{}) error {
 	_, err := fmt.Fprintln(fiw.w, a...)
 	return err
 }
 
+// WriteData writes a 'data' command to the stream.
 func (fiw *FIWriter) WriteData(data string) error {
 	err := fiw.WriteLine("data", len(data))
 	if err != nil {
diff --git a/types.go b/types.go
index 8bb3450..2a89048 100644
--- a/types.go
+++ b/types.go
@@ -1,3 +1,18 @@
+// Copyright (C) 2017-2018  Luke Shumaker <lukeshu@lukeshu.com>
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
 package libfastimport
 
 import (
@@ -9,8 +24,11 @@ import (
 	"github.com/pkg/errors"
 )
 
-// BUG(lukeshu): Only supports the "raw" date format (not "rfc2822" or
-// "now")
+// Ident is a tuple of a commiter's (or author's) name, email, and a
+// timestamp with timezone.
+//
+// BUG(lukeshu): Ident (and ParseIdent) only supports the "raw" date
+// format (not "rfc2822" or "now")
 type Ident struct {
 	Name  string
 	Email string
@@ -33,6 +51,16 @@ func (ut Ident) String() string {
 	}
 }
 
+// ParseIdent parses a string containing an Ident.
+//
+// The format of this string is
+//
+//     <name> SP LT <email> GT SP <time> SP <offutc>
+//
+// Where <name> may contain a space, but not "<" or ">"; <time> is an
+// integer number of seconds since the UNIX epoch (UTC); <offutc> is
+// positive or negative 4-digit offset from UTC (for example, EST
+// would be "-0500").
 func ParseIdent(str string) (Ident, error) {
 	ret := Ident{}
 	lt := strings.IndexAny(str, "<>")
@@ -72,14 +100,15 @@ func ParseIdent(str string) (Ident, error) {
 	return ret, nil
 }
 
+// Mode is a file mode as seen by git.
 type Mode uint32 // 18 bits
 
-var (
-	ModeFil = Mode(0100644)
-	ModeExe = Mode(0100755)
-	ModeSym = Mode(0120000)
-	ModeGit = Mode(0160000)
-	ModeDir = Mode(0040000)
+const (
+	ModeFil = Mode(0100644) // A regular file
+	ModeExe = Mode(0100755) // An executable file
+	ModeSym = Mode(0120000) // A symbolic link
+	ModeGit = Mode(0160000) // A nested git repository (e.g. submodule)
+	ModeDir = Mode(0040000) // A directory
 )
 
 func (m Mode) String() string {
@@ -90,6 +119,10 @@ func (m Mode) GoString() string {
 	return fmt.Sprintf("%07o", m)
 }
 
+// Path is a string storing a git path.
+type Path string
+
+// PathEscape escapes a path in case it contains special characters.
 func PathEscape(path Path) string {
 	if strings.HasPrefix(string(path), "\"") || strings.ContainsRune(string(path), '\n') {
 		return "\"" + strings.Replace(strings.Replace(strings.Replace(string(path), "\\", "\\\\", -1), "\"", "\\\"", -1), "\n", "\\n", -1) + "\""
@@ -98,6 +131,7 @@ func PathEscape(path Path) string {
 	}
 }
 
+// PathUnescape unescapes a quoted path.
 func PathUnescape(epath string) Path {
 	if strings.HasPrefix(epath, "\"") {
 		return Path(strings.Replace(strings.Replace(strings.Replace(epath[1:len(epath)-1], "\\n", "\n", -1), "\\\"", "\"", -1), "\\\\", "\\", -1))
@@ -106,8 +140,7 @@ func PathUnescape(epath string) Path {
 	}
 }
 
-type Path string
-
+// String calls PathEscape on the Path.
 func (p Path) String() string {
 	return PathEscape(p)
 }
diff --git a/util.go b/util.go
index 39bf2bd..4ca60e9 100644
--- a/util.go
+++ b/util.go
@@ -1,3 +1,18 @@
+// Copyright (C) 2017  Luke Shumaker <lukeshu@lukeshu.com>
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
 package libfastimport
 
 import (