Package: tramp Version: 1:2.0.45-1 Severity: normal File: /usr/share/emacs/site-lisp/tramp/tramp-smb.el
I recently discovered problems with code that used substitute-in-file-name to expand environment variables in file names. It turned out that the name in question was not having its environment variables expanded correctly. Subsequent investigation showed that substitute-in-file-name is fbound to 'identity. Grepping through all my emacs-lisp for code that could change the binding of substitute-in-file-name turned up this snippet in tramp-smb.el: /-------- | ;; Do `PC-do-completion' without substitution | (let* (save) | (fset 'save (symbol-function 'substitute-in-file-name)) | (fset 'substitute-in-file-name (symbol-function 'identity)) | ad-do-it | (fset 'substitute-in-file-name (symbol-function 'save))) \-------- which has no unwind-protect at all to ensure that substitute-in-file-name is restored afterwards, even in the face of errors. Also, it does not do what you think in the recursive case. Creating a dynamic variable with `let' does not affect function lookup using that name: /-------- | (let* (save) | (fset 'save (symbol-function 'identity)) | (let* (save) | (fset 'save (symbol-function 'ignore))) | (save t)) | nil \-------- /-------- | (let* ((save (symbol-function 'identity))) | (let* ((save (symbol-function 'ignore)))) | (funcall save t)) | t \-------- As well as being neater and easier to read, the version that stores the value in a variable slot rather than a function slot actually works correctly in more cases. I don't know if the above is the source of my problem (I didn't knowingly ask for SMB resources), but there is definitely an issue: * Use unwind-protect to restore the binding * Use the variable slot rather than the function slot to save it Untested code: /-------- | ;; Do `PC-do-completion' without substitution | (let (save (symbol-function 'substitute-in-file-name)) | (fset 'substitute-in-file-name (symbol-function 'identity)) | (unwind-protect | ad-do-it | (fset 'substitute-in-file-name save))) \-------- -- -- System Information: Debian Release: 3.1 APT prefers testing APT policy: (990, 'testing'), (300, 'unstable') Architecture: i386 (i686) Kernel: Linux 2.6.8 Locale: LANG=en_GB, LC_CTYPE=en_GB Versions of packages tramp depends on: ii emacs21 [emacsen] 21.3+1-8 The GNU Emacs editor -- no debconf information
