[RFC 06/11] Add support for mark references as path names

[Johan Herland <johan@herland.net>]

When using a mark reference as a path name, the mark reference will be
expanded to the 40-byte hex version of the object name associated with the
mark. This is useful e.g. when importing notes objects (where the filenames
in a notes tree are the object names of the annotated objects).

Signed-off-by: Johan Herland <johan@herland.net>
---
 Documentation/git-fast-import.txt |    9 +++++++--
 fast-import.c                     |   11 +++++++++--
 2 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/Documentation/git-fast-import.txt b/Documentation/git-fast-import.txt
index c2f483a..bbc8b78 100644
--- a/Documentation/git-fast-import.txt
+++ b/Documentation/git-fast-import.txt
@@ -487,12 +487,17 @@ in octal.  Git only supports the following modes:
 
 In both formats `<path>` is the complete path of the file to be added
 (if not already existing) or modified (if already existing).
+`<path>` may also be a mark reference (`:<idnum>`) set by a prior
+command, which will expand to a full 40-byte SHA-1 of the Git object
+associated with the mark. This is useful e.g. when importing commit
+notes (the filenames in a notes commit are the object names of the
+annotated commits).
 
 A `<path>` string must use UNIX-style directory separators (forward
 slash `/`), may contain any byte other than `LF`, and must not
-start with double quote (`"`).
+start with double quote (`"`) or colon (`:`).
 
-If an `LF` or double quote must be encoded into `<path>` shell-style
+If an `LF`, double quote or colon must be encoded into `<path>` shell-style
 quoting should be used, e.g. `"path/with\n and \" in it"`.
 
 The value of `<path>` must be in canonical form. That is it must not:
diff --git a/fast-import.c b/fast-import.c
index 8a7cdc1..3edfcf0 100644
--- a/fast-import.c
+++ b/fast-import.c
@@ -85,13 +85,13 @@ Format of STDIN stream:
      # common escapes of 'c' (e..g \n, \t, \\, \") or \nnn where nnn
      # is the signed byte value in octal.  Note that the only
      # characters which must actually be escaped to protect the
-     # stream formatting is: \, " and LF.  Otherwise these values
+     # stream formatting is: \, ", : and LF.  Otherwise these values
      # are UTF8.
      #
   ref_str     ::= ref;
   sha1exp_str ::= sha1exp;
   tag_str     ::= tag;
-  path_str    ::= path    | '"' quoted(path)    '"' ;
+  path_str    ::= path | '"' quoted(path) '"' | idnum;
   mode        ::= '100644' | '644'
                 | '100755' | '755'
                 | '120000'
@@ -1864,6 +1864,13 @@ static const char *get_path_str(
 	if (!unquote_c_style(sb, p, endp)) {
 		/* successfully unquoted C-style quoted name */
 		p = sb->buf;
+	} else if (*p == ':') {
+		/* resolve mark reference */
+		char *x;
+		struct object_entry *pe = find_mark(strtoumax(p + 1, &x, 10));
+		*endp = x;
+		strbuf_add(sb, sha1_to_hex(pe->sha1), 40);
+		p = sb->buf;
 	} else {
 		/* regular path ending at endc */
 		*endp = strchr(p, endc);
-- 
1.6.4.rc3.138.ga6b98.dirty