1;;; dwarf-mode.el --- Browser for DWARF information. -*-lexical-binding:t-*-
2
3;; Version: 1.6
4
5;; Copyright (C) 2012-2020 Free Software Foundation, Inc.
6
7;; This file is not part of GNU Emacs, but is distributed under the
8;; same terms:
9
10;; GNU Emacs is free software: you can redistribute it and/or modify
11;; it under the terms of the GNU General Public License as published by
12;; the Free Software Foundation, either version 3 of the License, or
13;; (at your option) any later version.
14
15;; GNU Emacs is distributed in the hope that it will be useful,
16;; but WITHOUT ANY WARRANTY; without even the implied warranty of
17;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
18;; GNU General Public License for more details.
19
20;; You should have received a copy of the GNU General Public License
21;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
22
23;;; Code:
24
25(defvar dwarf-objdump-program "objdump")
26
27(defconst dwarf-font-lock-keywords
28  '(
29    ;; Name and linkage name.
30    ("DW_AT_[a-zA-Z_]*name\\s *:\\(?:\\s *(.*):\\)?\\s *\\(.*\\)\\s *$"
31     (1 font-lock-function-name-face))
32
33    ("Compilation Unit @ offset 0x[0-9a-f]+"
34     (0 font-lock-string-face))
35    ))
36
37(defvar dwarf-file nil
38  "Buffer-local variable holding the file name passed to objdump.")
39
40(defvar dwarf--process nil
41  "Running objdump process, or nil.")
42
43(defvar dwarf--deletion-region nil
44  "Region to delete before inserting text in `dwarf--filter'.")
45
46(defun dwarf--check-running ()
47  "Throw an exception if an objdump process is already running."
48  (when dwarf--process
49    (error "An objdump process is still running in this buffer")))
50
51(defun dwarf--filter (proc string)
52  "Filter function for objdump processes."
53  (when (buffer-live-p (process-buffer proc))
54    (with-current-buffer (process-buffer proc)
55      (save-excursion
56	(let ((inhibit-read-only t))
57	  (when dwarf--deletion-region
58	    (apply #'delete-region dwarf--deletion-region)
59	    (setq dwarf--deletion-region nil))
60          (goto-char (process-mark proc))
61          (insert string)
62          (set-marker (process-mark proc) (point))
63	  (set-buffer-modified-p nil))))))
64
65(defun dwarf--sentinel (_proc _status)
66  (setq mode-line-process nil)
67  (setq dwarf--process nil))
68
69(defun dwarf--invoke (start end &rest command)
70  "Invoke a command and arrange to insert output into the current buffer."
71  (setq mode-line-process "[Running]")
72  (setq dwarf--deletion-region (list start end))
73  (setq dwarf--process (make-process :name "objdump"
74				     :buffer (current-buffer)
75				     :command command
76				     :connection-type 'pipe
77				     :noquery t
78				     :filter #'dwarf--filter
79				     :sentinel #'dwarf--sentinel))
80  (set-marker (process-mark dwarf--process) (point)))
81
82;; Expand a "..." to show all the child DIES.  NEW-DEPTH controls how
83;; deep to display the new dies; `nil' means display all of them.
84(defun dwarf-do-insert-substructure (new-depth die)
85  (dwarf--check-running)
86  (let ((inhibit-read-only t))
87    (beginning-of-line)
88    (apply #'dwarf--invoke
89	   (point) (save-excursion
90		     (end-of-line)
91		     (forward-char)
92		     (point))
93	   dwarf-objdump-program "-Wi" (concat "--dwarf-start=0x" die)
94	   (expand-file-name dwarf-file)
95	   (if new-depth (list (concat "--dwarf-depth="
96				       (int-to-string new-depth)))))
97    (set-buffer-modified-p nil)))
98
99(defun dwarf-insert-substructure-button (die)
100  (beginning-of-line)
101  (unless (looking-at "^ <\\([0-9]+\\)>")
102    (error "Unrecognized line."))
103  (let ((new-depth (1+ (string-to-number (match-string 1)))))
104    (dwarf-do-insert-substructure new-depth die)))
105
106(defun dwarf-insert-substructure (arg)
107  "Expand a `...' to show children of the current DIE.
108By default, expands just one level of children.
109A prefix argument means expand all children."
110  (interactive "P")
111  (beginning-of-line)
112  (unless (looking-at "^ <\\([0-9]+\\)><\\([0-9a-f]+\\)>")
113    (error "Unrecognized line."))
114  (let ((die (match-string 2)))
115    (if arg
116	(dwarf-do-insert-substructure nil die)
117      (dwarf-insert-substructure-button die))))
118
119;; Called when a button is pressed.
120;; Either follows a DIE reference, or expands a "...".
121(defun dwarf-die-button-action (button)
122  (let* ((die (button-get button 'die))
123	 ;; Note that the first number can only be decimal.  It is
124	 ;; included in this search because otherwise following a ref
125	 ;; might lead to a zero-length boolean attribute in the
126	 ;; previous DIE.
127	 (die-rx (concat "^\\s *<[0-9]+><" die ">:"))
128	 (old (point))
129	 (is-ref (button-get button 'die-ref)))
130    (if is-ref
131	(progn
132	  (goto-char (point-min))
133	  (if (re-search-forward die-rx nil 'move)
134	      (push-mark old)
135	    (goto-char old)
136	    (error "Could not find DIE <0x%s>" die)))
137      (dwarf-insert-substructure-button die))))
138
139;; Button definition.
140(define-button-type 'dwarf-die-button
141  'follow-link t
142  'action #'dwarf-die-button-action)
143
144;; Helper regexp to match a DIE reference.
145(defconst dwarf-die-reference "\\(<0x\\([0-9a-f]+\\)>\\)")
146
147;; Helper regexp to match a `...' indicating that there are hidden
148;; children.
149(defconst dwarf-die-more "^ <[0-9]+><\\([0-9a-z]+\\)>: \\([.][.][.]\\)")
150
151;; jit-lock callback function to fontify a region.  This applies the
152;; buttons, since AFAICT there is no good way to apply buttons via
153;; font-lock.
154(defun dwarf-fontify-region (start end)
155  (save-excursion
156    (let ((beg-line (progn (goto-char start) (line-beginning-position)))
157	  (end-line (progn (goto-char end) (line-end-position))))
158      (goto-char beg-line)
159      (while (re-search-forward dwarf-die-reference end-line 'move)
160	(let ((b-start (match-beginning 1))
161	      (b-end (match-end 1))
162	      (hex (match-string-no-properties 2)))
163	  (make-text-button b-start b-end :type 'dwarf-die-button
164			    'die hex 'die-ref t)))
165      ;; This is a bogus approach.  Why can't we make buttons from the
166      ;; font-lock defaults?
167      (goto-char beg-line)
168      (while (re-search-forward dwarf-die-more end-line 'move)
169	(let ((hex (match-string-no-properties 1))
170	      (b-start (match-beginning 2))
171	      (b-end (match-end 2)))
172	  (make-text-button b-start b-end :type 'dwarf-die-button
173			    'die hex 'die-ref nil))))))
174
175;; Run objdump and insert the contents into the buffer.  The arguments
176;; are the way they are because this is also called as a
177;; revert-buffer-function.
178(defun dwarf-do-refresh (&rest ignore)
179  (dwarf--check-running)
180  (let ((inhibit-read-only t))
181    (dwarf--invoke (point-min) (point-max)
182		   dwarf-objdump-program "-Wi" "--dwarf-depth=1"
183		   (expand-file-name dwarf-file))
184    (set-buffer-modified-p nil)))
185
186(defvar dwarf-mode-syntax-table
187  (let ((table (make-syntax-table)))
188    ;; This at least makes it so mark-sexp on some hex digits inside
189    ;; <...> does not also copy the ">".
190    (modify-syntax-entry ?< "(>" table)
191    (modify-syntax-entry ?> ")<" table)
192    table)
193  "Syntax table for dwarf-mode buffers.")
194
195(defvar dwarf-mode-map
196  (let ((map (make-sparse-keymap)))
197    (set-keymap-parent map special-mode-map)
198    (define-key map [(control ?m)] #'dwarf-insert-substructure)
199    map)
200  "Keymap for dwarf-mode buffers.")
201
202(define-derived-mode dwarf-mode special-mode "DWARF"
203  "Major mode for browsing DWARF output.
204
205\\{dwarf-mode-map}"
206
207  (set (make-local-variable 'font-lock-defaults) '(dwarf-font-lock-keywords))
208  ;; FIXME: we could be smarter and check the file time.
209  (set (make-local-variable 'revert-buffer-function) #'dwarf-do-refresh)
210  (jit-lock-register #'dwarf-fontify-region))
211
212;;;###autoload
213(defun dwarf-browse (file)
214  "Invoke `objdump' and put output into a `dwarf-mode' buffer.
215This is the main interface to `dwarf-mode'."
216  (interactive "fFile name: ")
217  (let* ((base-name (file-name-nondirectory file))
218	 (buffer (generate-new-buffer (concat "*DWARF for " base-name "*"))))
219    (pop-to-buffer buffer)
220    (dwarf-mode)
221    (setq default-directory (file-name-directory file))
222    (set (make-local-variable 'dwarf-file) file)
223    (set (make-local-variable 'dwarf--process) nil)
224    (set (make-local-variable 'dwarf--deletion-region) nil)
225    (dwarf-do-refresh)))
226
227(provide 'dwarf-mode)
228
229;;; dwarf-mode.el ends here
230