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authorDanny Milosavljevic <dannym@scratchpost.org>2020-05-03 17:29:39 +0200
committerDanny Milosavljevic <dannym@scratchpost.org>2020-05-03 20:35:50 +0200
commitf73f4b3a2d7a313a6cb1667bd69205ea4b09f57c (patch)
treee04fb8946662f0f8c6c2bca50f91e59206c63dbd
parentf8a0065ae391bc9f717033e612f342741c66d946 (diff)
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guix-f73f4b3a2d7a313a6cb1667bd69205ea4b09f57c.tar.gz
file-systems: Fix F2FS volume name accessor.
Follow-up to 23b37c3d40d497cc6f07437ab26ab10e60fb6e09. * gnu/build/file-systems.scm (bytevector-utf16-length): New procedure. (null-terminated-utf16->string): New procedure. (f2fs-superblock-volume-name): Use it.
-rw-r--r--gnu/build/file-systems.scm20
1 files changed, 19 insertions, 1 deletions
diff --git a/gnu/build/file-systems.scm b/gnu/build/file-systems.scm
index bbea4c766e..4ac672d96f 100644
--- a/gnu/build/file-systems.scm
+++ b/gnu/build/file-systems.scm
@@ -98,6 +98,22 @@ 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 (null-terminated-utf16->string bv endianness)
+ (utf16->string (sub-bytevector bv 0 (bytevector-utf16-length bv))
+ endianness))
+
;;;
;;; Ext2 file systems.
@@ -377,7 +393,9 @@ 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."