[Emacs-diffs] master 808699f: bzr-state randomly/unpredictably fails on non-bzr files.

[Eric S. Raymond]

branch: master
commit 808699f13673a881949ab94d3c0e87f5ba9cd4cf
Author: Eric S. Raymond <address@hidden>
Commit: Eric S. Raymond <address@hidden>

    bzr-state randomly/unpredictably fails on non-bzr files.
---
 lisp/vc/vc-bzr.el |  109 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 files changed, 108 insertions(+), 1 deletions(-)

diff --git a/lisp/vc/vc-bzr.el b/lisp/vc/vc-bzr.el
index 34a7c7b..7f30378 100644
--- a/lisp/vc/vc-bzr.el
+++ b/lisp/vc/vc-bzr.el
@@ -178,6 +178,113 @@ in the repository root directory of FILE."
     (insert-file-contents-literally file)
     (sha1 (current-buffer))))
 
+(defun vc-bzr-state-heuristic (file)
+  "Like `vc-bzr-state' but hopefully without running Bzr."
+  ;; `bzr status' could be slow with large histories and pending merges,
+  ;; so this tries to avoid calling it if possible.  bzr status is
+  ;; faster now, so this is not as important as it was.
+  ;;
+  ;; This function tries first to parse Bzr internal file
+  ;; `checkout/dirstate', but it may fail if Bzr internal file format
+  ;; has changed.  As a safeguard, the `checkout/dirstate' file is
+  ;; only parsed if it contains the string `#bazaar dirstate flat
+  ;; format 3' in the first line.
+  ;; If the `checkout/dirstate' file cannot be parsed, fall back to
+  ;; running `vc-bzr-state'."
+  ;;
+  ;; The format of the dirstate file is explained in bzrlib/dirstate.py
+  ;; in the bzr distribution.  Basically:
+  ;; header-line giving the version of the file format in use.
+  ;; a few lines of stuff
+  ;; entries, one per line, with null-separated fields.  Each line:
+  ;; entry_key = dirname (may be empty), basename, file-id
+  ;; current = common ( = kind, fingerprint, size, executable )
+  ;;           + working ( = packed_stat )
+  ;; parent = common ( as above ) + history ( = rev_id )
+  ;; kinds = (r)elocated, (a)bsent, (d)irectory, (f)ile, (l)ink
+  (let* ((root (vc-bzr-root file))
+         (dirstate (expand-file-name vc-bzr-admin-dirstate root)))
+    (when root                          ; Short cut.
+      (condition-case err
+          (with-temp-buffer
+            (insert-file-contents dirstate)
+            (goto-char (point-min))
+            (if (not (looking-at "#bazaar dirstate flat format 3"))
+                (vc-bzr-state file)     ; Some other unknown format?
+              (let* ((relfile (file-relative-name file root))
+                     (reldir (file-name-directory relfile)))
+                (cond
+                 ((not
+                   (re-search-forward
+                    (concat "^\0"
+                            (if reldir (regexp-quote
+                                        (directory-file-name reldir)))
+                            "\0"
+                            (regexp-quote (file-name-nondirectory relfile))
+                            "\0"
+                            "[^\0]*\0"             ;id?
+                            "\\([^\0]*\\)\0"       ;"a/f/d", a=removed?
+                            "\\([^\0]*\\)\0"       ;sha1 (empty if conflicted)?
+                            "\\([^\0]*\\)\0"       ;size?p
+                            ;; y/n.  Whether or not the current copy
+                            ;; was executable the last time bzr checked?
+                            "[^\0]*\0"
+                            "[^\0]*\0"  ;?
+                            ;; Parent information.  Absent in a new repo.
+                            "\\(?:\\([^\0]*\\)\0"  ;"a/f/d" a=added?
+                            "\\([^\0]*\\)\0"       ;sha1 again?
+                            "\\([^\0]*\\)\0"       ;size again?
+                            ;; y/n.  Whether or not the repo thinks
+                            ;; the file should be executable?
+                            "\\([^\0]*\\)\0"
+                            "[^\0]*\0\\)?" ;last revid?
+                            ;; There are more fields when merges are pending.
+                            )
+                    nil t))
+                  'unregistered)
+                 ;; Apparently the second sha1 is the one we want: when
+                 ;; there's a conflict, the first sha1 is absent (and the
+                 ;; first size seems to correspond to the file with
+                 ;; conflict markers).
+                 ((eq (char-after (match-beginning 1)) ?a) 'removed)
+                 ;; If there is no parent, this must be a new repo.
+                 ;; If file is in dirstate, can only be added (b#8025).
+                 ((or (not (match-beginning 4))
+                      (eq (char-after (match-beginning 4)) ?a)) 'added)
+                 ((or (and (eq (string-to-number (match-string 3))
+                               (nth 7 (file-attributes file)))
+                           (equal (match-string 5)
+                                  (save-match-data (vc-bzr-sha1 file)))
+                           ;; For a file, does the executable state match?
+                           ;; (Bug#7544)
+                           (or (not
+                                (eq (char-after (match-beginning 1)) ?f))
+                               (let ((exe
+                                      (memq
+                                       ?x
+                                       (mapcar
+                                        'identity
+                                        (nth 8 (file-attributes file))))))
+                                 (if (eq (char-after (match-beginning 7))
+                                         ?y)
+                                     exe
+                                   (not exe)))))
+                      (and
+                       ;; It looks like for lightweight
+                       ;; checkouts \2 is empty and we need to
+                       ;; look for size in \6.
+                       (eq (match-beginning 2) (match-end 2))
+                       (eq (string-to-number (match-string 6))
+                           (nth 7 (file-attributes file)))
+                       (equal (match-string 5)
+                              (vc-bzr-sha1 file))))
+                  'up-to-date)
+                 (t 'edited)))))
+        ;; The dirstate file can't be read, or some other problem.
+        (error
+         (message "Falling back on \"slow\" status detection (%S)" err)
+         (vc-bzr-state file))))))
+
 ;; This is a cheap approximation that is autoloaded.  If it finds a
 ;; possible match it loads this file and runs the real function.
 ;; It requires vc-bzr-admin-checkout-format-file to be autoloaded too.
@@ -189,7 +296,7 @@ in the repository root directory of FILE."
 
 (defun vc-bzr-registered (file)
   "Return non-nil if FILE is registered with bzr."
-  (let ((state (vc-bzr-state file)))
+  (let ((state (vc-bzr-state-heuristic file)))
     (not (memq state '(nil unregistered ignored)))))
 
 (defconst vc-bzr-state-words