From fe50a8b9ba79b4ac14a3a352d8bf84eaee4f2122 Mon Sep 17 00:00:00 2001 From: Philipp Stephani Date: Sun, 13 Dec 2020 17:13:50 +0100 Subject: [PATCH] Byte compilation: handle case where the output file is a mountpoint. See Bug#44631. While testing for a readonly output directory has slightly different semantics, in practice they should cover cases where Emacs is sandboxed and can only write to the destination file, not its directory. * lisp/emacs-lisp/bytecomp.el (byte-compile-file): Handle the case where the output directory is not writable. * test/lisp/emacs-lisp/bytecomp-tests.el (bytecomp-tests--not-writable-directory) (bytecomp-tests--dest-mountpoint): New unit tests. --- lisp/emacs-lisp/bytecomp.el | 14 +++++- test/lisp/emacs-lisp/bytecomp-tests.el | 69 ++++++++++++++++++++++++++ 2 files changed, 82 insertions(+), 1 deletion(-) diff --git a/lisp/emacs-lisp/bytecomp.el b/lisp/emacs-lisp/bytecomp.el index 51accc08654..e23bb9f5e6e 100644 --- a/lisp/emacs-lisp/bytecomp.el +++ b/lisp/emacs-lisp/bytecomp.el @@ -1963,7 +1963,11 @@ See also `emacs-lisp-byte-compile-and-load'." (insert "\n") ; aaah, unix. (cond ((null target-file) nil) ;We only wanted the warnings! - ((file-writable-p target-file) + ((and (file-writable-p target-file) + ;; We attempt to create a temporary file in the + ;; target directory, so the target directory must be + ;; writable. + (file-writable-p (file-name-directory target-file))) ;; We must disable any code conversion here. (let* ((coding-system-for-write 'no-conversion) ;; Write to a tempfile so that if another Emacs @@ -1992,6 +1996,14 @@ See also `emacs-lisp-byte-compile-and-load'." ;; deleting target-file before writing it. (rename-file tempfile target-file t)) (or noninteractive (message "Wrote %s" target-file))) + ((file-writable-p target-file) + ;; In case the target directory isn't writable (see e.g. Bug#44631), + ;; try writing to the output file directly. We must disable any + ;; code conversion here. + (let ((coding-system-for-write 'no-conversion)) + (with-file-modes (logand (default-file-modes) #o666) + (write-region (point-min) (point-max) target-file nil 1))) + (or noninteractive (message "Wrote %s" target-file))) (t ;; This is just to give a better error message than write-region (let ((exists (file-exists-p target-file))) diff --git a/test/lisp/emacs-lisp/bytecomp-tests.el b/test/lisp/emacs-lisp/bytecomp-tests.el index 8fa4d278f11..c2a3e3ba117 100644 --- a/test/lisp/emacs-lisp/bytecomp-tests.el +++ b/test/lisp/emacs-lisp/bytecomp-tests.el @@ -947,6 +947,75 @@ literals (Bug#20852)." '((suspicious set-buffer)) "Warning: Use .with-current-buffer. rather than")) +(ert-deftest bytecomp-tests--not-writable-directory () + "Test that byte compilation works if the output directory isn't +writable (Bug#44631)." + (let ((directory (make-temp-file "bytecomp-tests-" :directory))) + (unwind-protect + (let* ((input-file (expand-file-name "test.el" directory)) + (output-file (expand-file-name "test.elc" directory)) + (byte-compile-dest-file-function + (lambda (_) output-file)) + (byte-compile-error-on-warn t)) + (write-region "" nil input-file nil nil nil 'excl) + (write-region "" nil output-file nil nil nil 'excl) + (set-file-modes input-file #o400) + (set-file-modes output-file #o200) + (set-file-modes directory #o500) + (should (byte-compile-file input-file)) + (should (file-regular-p output-file)) + (should (cl-plusp (file-attribute-size + (file-attributes output-file))))) + (with-demoted-errors "Error cleaning up directory: %s" + (set-file-modes directory #o700) + (delete-directory directory :recursive))))) + +(ert-deftest bytecomp-tests--dest-mountpoint () + "Test that byte compilation works if the destination file is a +mountpoint (Bug#44631)." + (let ((bwrap (executable-find "bwrap")) + (emacs (expand-file-name invocation-name invocation-directory))) + (skip-unless bwrap) + (skip-unless (file-executable-p bwrap)) + (skip-unless (not (file-remote-p bwrap))) + (skip-unless (file-executable-p emacs)) + (skip-unless (not (file-remote-p emacs))) + (let ((directory (make-temp-file "bytecomp-tests-" :directory))) + (unwind-protect + (let* ((input-file (expand-file-name "test.el" directory)) + (output-file (expand-file-name "test.elc" directory)) + (unquoted-file (file-name-unquote output-file)) + (byte-compile-dest-file-function + (lambda (_) output-file)) + (byte-compile-error-on-warn t)) + (should-not (file-remote-p input-file)) + (should-not (file-remote-p output-file)) + (write-region "" nil input-file nil nil nil 'excl) + (write-region "" nil output-file nil nil nil 'excl) + (set-file-modes input-file #o400) + (set-file-modes output-file #o200) + (set-file-modes directory #o500) + (with-temp-buffer + (let ((status (call-process + bwrap nil t nil + "--ro-bind" "/" "/" + "--bind" unquoted-file unquoted-file + emacs "--quick" "--batch" "--load=bytecomp" + (format "--eval=%S" + `(setq byte-compile-dest-file-function + (lambda (_) ,output-file) + byte-compile-error-on-warn t)) + "--funcall=batch-byte-compile" input-file))) + (unless (eql status 0) + (ert-fail `((status . ,status) + (output . ,(buffer-string))))))) + (should (file-regular-p output-file)) + (should (cl-plusp (file-attribute-size + (file-attributes output-file))))) + (with-demoted-errors "Error cleaning up directory: %s" + (set-file-modes directory #o700) + (delete-directory directory :recursive)))))) + ;; Local Variables: ;; no-byte-compile: t ;; End: -- 2.39.2