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fix some error handling and support for short-lived UTF-32 string encoding

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svn: r5445
This commit is contained in:
Matthew Flatt 2007-01-24 06:53:08 +00:00
parent 272980489c
commit 4511f58d0c
2 changed files with 29 additions and 7 deletions
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7
collects/wxme/doc.txt
View File

@ -60,6 +60,13 @@ an unrecognized snip class is encountered in a WXME stream. When set to
a true value, instances of unrecognized snip classes are simply
omitted from the transformed stream.
> broken-wxme-big-endian?
A parameter. Some old and short-lived WXME formats depended on the
endian order of the machine where the file was saved. Set this
parameter to pick the endian order to use when reading the file; the
default is the current platform's endian order.
> (wxme-read port)
Like `read', but for a stream that starts with WXME-format data. If

29
collects/wxme/wxme.ss
View File

@ -265,7 +265,10 @@
(define (read-a-string who port vers what)
(let ([s (read-raw-string who port vers what)])
(subbytes s 0 (sub1 (bytes-length s)))))
(let ([len (bytes-length s)])
(when (zero? len)
(read-error who "non-empty raw string" what port))
(subbytes s 0 (sub1 len)))))
(define (read-integer who port vers what)
(cond
@ -307,7 +310,7 @@
#t
(if (vers . > . 1)
#t
(system-big-endian?)))]))
(broken-wxme-big-endian?)))]))
(define (read-inexact who port vers what)
(cond
@ -321,12 +324,13 @@
(floating-point-bytes->real (read-bytes 8 port)
(if (vers . > . 1)
#t
(system-big-endian?)))]))
(broken-wxme-big-endian?)))]))
(define (read-error who expected what port)
(error who "WXME format problem while reading for ~a (expected ~a) from port: ~v"
what expected port))
(error who "WXME format problem while reading for ~a (expected ~a) from port: ~e around position: ~a"
what expected port
(file-position port)))
(define (skip-data port vers len)
(if (vers . >= . 8)
@ -369,9 +373,17 @@
(read-error who "size of read byte string is not a multiple of 4" "string-snip content" port))
(let loop ([pos 0][accum null])
(if (= pos (bytes-length s))
(string->bytes/utf-8 (apply string (reverse accum)))
(begin
(string->bytes/utf-8 (apply string (reverse accum))))
(loop (+ pos 4)
(cons (integer-bytes->integer (subbytes s pos (+ pos 4)))
(cons (integer->char
(let ([v (integer-bytes->integer (subbytes s pos (+ pos 4)) #f
(broken-wxme-big-endian?))])
(unless (or (<= 0 v #xD7FF)
(<= #xE000 v #x10FFFF))
(read-error who "UTF-32 character; probably an endian order mismatch"
"string-snip content" port))
v))
accum))))]
[(cvers . > . 2) s])))]
[(equal? name #"wxmedia")
@ -591,6 +603,8 @@
(define unknown-extensions-skip-enabled (make-parameter #f))
(define broken-wxme-big-endian? (make-parameter (system-big-endian?)))
(define (is-wxme-stream? p)
(and (regexp-match-peek #rx#"^(?:#reader[(]lib\"read[.]ss\"\"wxme\"[)])?WXME01[0-9][0-9] ##[ \r\n]" p)
#t))
@ -635,6 +649,7 @@
[register-lib-mapping! (string? string? . -> . void?)])
(provide unknown-extensions-skip-enabled
broken-wxme-big-endian?
snip-reader<%>
readable<%>
wxme-read