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(visited?-proc): Use hashv since we know we're getting

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numbers.  Incorporate stat:dev, since stat:ino is only unique within a
single device.  This fixes a bug where if two files with the same
inode on different devices where seen only the first would be returned
by ftw (and nftw).
This commit is contained in:
Kevin Ryde 2006-10-04 22:12:34 +00:00
parent 22a7ee5876
commit 0b051de863
1 changed files with 25 additions and 6 deletions
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27
ice-9/ftw.scm
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@ -217,13 +217,32 @@
(define (abs? filename)
(char=? #\/ (string-ref filename 0)))
;; `visited?-proc' returns a test procedure VISITED? which when called as
;; (VISITED? stat-obj) returns #f the first time a distinct file is seen,
;; then #t on any subsequent sighting of it.
;;
;; stat:dev and stat:ino together uniquely identify a file (see "Attribute
;; Meanings" in the glibc manual). Often there'll be just one dev, and
;; usually there's just a handful mounted, so the strategy here is a small
;; hash table indexed by dev, containing hash tables indexed by ino.
;;
;; It'd be possible to make a pair (dev . ino) and use that as the key to a
;; single hash table. It'd use an extra pair for every file visited, but
;; might be a little faster if it meant less scheme code.
;;
(define (visited?-proc size)
(let ((visited (make-hash-table size)))
(let ((dev-hash (make-hash-table 7)))
(lambda (s)
(and s (let ((ino (stat:ino s)))
(or (hash-ref visited ino)
(and s
(let ((ino-hash (hashv-ref dev-hash (stat:dev s)))
(ino (stat:ino s)))
(or ino-hash
(begin
(hash-set! visited ino #t)
(set! ino-hash (make-hash-table size))
(hashv-set! dev-hash (stat:dev s) ino-hash)))
(or (hashv-ref ino-hash ino)
(begin
(hashv-set! ino-hash ino #t)
#f)))))))
(define (stat-dir-readable?-proc uid gid)