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-rw-r--r--gnu/build/file-systems.scm45
1 files changed, 44 insertions, 1 deletions
diff --git a/gnu/build/file-systems.scm b/gnu/build/file-systems.scm
index bbea4c766e..b920e8fc62 100644
--- a/gnu/build/file-systems.scm
+++ b/gnu/build/file-systems.scm
@@ -98,6 +98,47 @@ takes a bytevector and returns #t when it's a valid superblock."
(define null-terminated-latin1->string
(cut latin1->string <> zero?))
+(define (bytevector-utf16-length bv)
+ "Given a bytevector BV containing a NUL-terminated UTF16-encoded string,
+determine where the NUL terminator is and return its index. If there's no
+NUL terminator, return the size of the bytevector."
+ (let ((length (bytevector-length bv)))
+ (let loop ((index 0))
+ (if (< index length)
+ (if (zero? (bytevector-u16-ref bv index 'little))
+ index
+ (loop (+ index 2)))
+ length))))
+
+(define* (bytevector->u16-list bv endianness #:optional (index 0))
+ (if (< index (bytevector-length bv))
+ (cons (bytevector-u16-ref bv index endianness)
+ (bytevector->u16-list bv endianness (+ index 2)))
+ '()))
+
+;; The initrd doesn't have iconv data, so do the conversion ourselves.
+(define (utf16->string bv endianness)
+ (list->string
+ (map integer->char
+ (reverse
+ (let loop ((remainder (bytevector->u16-list bv endianness))
+ (result '()))
+ (match remainder
+ (() result)
+ ((a) (cons a result))
+ ((a b x ...)
+ (if (and (>= a #xD800) (< a #xDC00) ; high surrogate
+ (>= b #xDC00) (< b #xE000)) ; low surrogate
+ (loop x (cons (+ #x10000
+ (* #x400 (- a #xD800))
+ (- b #xDC00))
+ result))
+ (loop (cons b x) (cons a result))))))))))
+
+(define (null-terminated-utf16->string bv endianness)
+ (utf16->string (sub-bytevector bv 0 (bytevector-utf16-length bv))
+ endianness))
+
;;;
;;; Ext2 file systems.
@@ -377,7 +418,9 @@ if DEVICE does not contain an F2FS file system."
(define (f2fs-superblock-volume-name sblock)
"Return the volume name of SBLOCK as a string of at most 512 characters, or
#f if SBLOCK has no volume name."
- (utf16->string (sub-bytevector sblock (- (+ #x470 12) #x400) 512) %f2fs-endianness))
+ (null-terminated-utf16->string
+ (sub-bytevector sblock (- (+ #x470 12) #x400) 512)
+ %f2fs-endianness))
(define (check-f2fs-file-system device)
"Return the health of a F2FS file system on DEVICE."