1 ;;;; This software is part of the SBCL system. See the README file for
4 ;;;; This software is derived from the CMU CL system, which was
5 ;;;; written at Carnegie Mellon University and released into the
6 ;;;; public domain. The software is in the public domain and is
7 ;;;; provided with absolutely no warranty. See the COPYING and CREDITS
8 ;;;; files for more information.
10 (in-package "SB!ALIEN")
12 (/show0 "host-c-call.lisp 12")
14 (define-alien-type-class (c-string :include pointer :include-args (to))
15 (external-format :default :type keyword)
16 (element-type 'character :type (member character base-char)))
18 (define-alien-type-translator c-string
19 (&key (external-format :default)
20 (element-type 'character))
21 (make-alien-c-string-type
22 :to (parse-alien-type 'char (sb!kernel:make-null-lexenv))
23 :element-type element-type
24 :external-format external-format))
26 (defun c-string-external-format (type)
27 (let ((external-format (alien-c-string-type-external-format type)))
28 (if (eq external-format :default)
29 (default-c-string-external-format)
32 (define-alien-type-method (c-string :unparse) (type)
34 :external-format (alien-c-string-type-external-format type)
35 :element-type (alien-c-string-type-element-type type)))
37 (define-alien-type-method (c-string :lisp-rep) (type)
38 (declare (ignore type))
39 '(or simple-string null (alien (* char))))
41 (defun c-string-needs-conversion-p (type)
45 (let ((external-format (sb!impl::get-external-format
46 ;; Can't use C-STRING-EXTERNAL-FORMAT here,
47 ;; since the meaning of :DEFAULT can change
48 ;; when *DEFAULT-C-STRING-EXTERNAL-FORMAT*
50 (alien-c-string-type-external-format type))))
51 (not (and external-format
52 (or (eq (caar external-format) :ascii)
53 ;; On non-SB-UNICODE all latin-1 codepoints will fit
54 ;; into a base-char, on SB-UNICODE they won't.
56 (eq (caar external-format) :latin-1))))))
58 (define-alien-type-method (c-string :naturalize-gen) (type alien)
59 `(if (zerop (sap-int ,alien))
61 ;; Check whether we need to do a full external-format
62 ;; conversion, or whether we can just do a cheap byte-by-byte
63 ;; copy of the c-string data.
65 ;; On SB-UNICODE we can never do the cheap copy, even if the
66 ;; external format and element-type are suitable, since
67 ;; simple-base-strings may not contain ISO-8859-1 characters.
68 ;; If we need to check for non-ascii data in the input, we
69 ;; might as well go through the usual external-format machinery
70 ;; instead of rewriting another version of it.
72 #!-sb-unicode (c-string-needs-conversion-p type)
73 `(sb!alien::c-string-to-string ,alien
74 (c-string-external-format ,type)
75 (alien-c-string-type-element-type
77 `(%naturalize-c-string ,alien))))
79 (define-alien-type-method (c-string :deport-gen) (type value)
82 ((alien (* char)) (alien-sap ,value))
83 ;; FIXME: GC safety alert! These SAPs are not safe, since the
84 ;; Lisp string can move. This is not hard to arrange, for example
85 ;; the following will fail very quickly on a SB-UNICODE build:
87 ;; (setf (bytes-consed-between-gcs) 4096)
88 ;; (define-alien-routine "strcmp" int (s1 c-string) (s2 c-string))
91 ;; (let ((string "hello, world"))
92 ;; (assert (zerop (strcmp string string)))))
94 ;; (This will appear to work on post-0.9.8.19 GENCGC, since
95 ;; the GC no longer zeroes memory immediately after releasing
96 ;; it after a minor GC. Either enabling the READ_PROTECT_FREE_PAGES
97 ;; #define in gencgc.c or modifying the example so that a major
98 ;; GC will occasionally be triggered would unmask the bug).
100 ;; The pure VECTOR-SAP branch for the SIMPLE-BASE-STRING case
101 ;; will generally be very hard to trigger on GENCGC (even when
102 ;; threaded) thanks to GC conservativeness. It's mostly a problem
103 ;; on cheneygc. -- JES, 2006-01-13
105 ,(if (c-string-needs-conversion-p type)
106 ;; If the alien type is not ascii-compatible (+SB-UNICODE)
107 ;; or latin-1-compatible (-SB-UNICODE), we need to do
108 ;; external format conversion.
109 `(vector-sap (string-to-c-string ,value
110 (c-string-external-format ,type)))
111 ;; Otherwise we can just pass it uncopied.
112 `(vector-sap ,value)))
113 ;; This case, on the other hand, will cause trouble on GENCGC, since
114 ;; we're taking the SAP of a immediately discarded temporary -> the
115 ;; conservativeness doesn't protect us.
116 ;; -- JES, 2006-01-13
118 (vector-sap (string-to-c-string ,value
119 (c-string-external-format ,type))))))
121 (/show0 "host-c-call.lisp end of file")