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* epg.el (epg--make-temp-file): Avoid permission race conditions

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when creating temporary directories and files on older Emacs.
This commit is contained in:
Paul Eggert 2011-12-29 14:08:29 -08:00
parent a0562b3d54
commit dbf17d8b48
2 changed files with 7 additions and 3 deletions
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7
lisp/epg.el
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@ -1951,14 +1951,16 @@ The returned file name (created by appending some random characters at the end
of PREFIX, and expanding against `temporary-file-directory' if necessary),
is guaranteed to point to a newly created empty file.
You can then use `write-region' to write new data into the file."
(let (tempdir tempfile)
(let (tempdir tempfile orig-modes)
(setq prefix (expand-file-name prefix
(if (featurep 'xemacs)
(temp-directory)
temporary-file-directory)))
(setq orig-modes (default-file-modes))
(unwind-protect
(let (file)
;; First, create a temporary directory.
(set-default-file-modes #o700)
(while (condition-case ()
(progn
(setq tempdir (make-temp-name
@ -1969,14 +1971,12 @@ You can then use `write-region' to write new data into the file."
(make-directory tempdir))
;; let's try again.
(file-already-exists t)))
(set-file-modes tempdir 448)
;; Second, create a temporary file in the tempdir.
;; There *is* a race condition between `make-temp-name'
;; and `write-region', but we don't care it since we are
;; in a private directory now.
(setq tempfile (make-temp-name (concat tempdir "/EMU")))
(write-region "" nil tempfile nil 'silent)
(set-file-modes tempfile 384)
;; Finally, make a hard-link from the tempfile.
(while (condition-case ()
(progn
@ -1986,6 +1986,7 @@ You can then use `write-region' to write new data into the file."
;; let's try again.
(file-already-exists t)))
file)
(set-default-file-modes orig-modes)
;; Cleanup the tempfile.
(and tempfile
(file-exists-p tempfile)