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authorDavid Craven <david@craven.ch>2017-02-14 16:28:26 +0100
committerDanny Milosavljevic <dannym@scratchpost.org>2017-03-01 17:27:49 +0100
commitb0377e58c30c399f9844a1607d677e525bb1d05f (patch)
tree03795baa753eac0e7265cdb8a678fb61535f6ae8 /gnu
parentbd9f8869b15891863a6c7420d1cfdae309ba8594 (diff)
downloadguix-b0377e58c30c399f9844a1607d677e525bb1d05f.tar
guix-b0377e58c30c399f9844a1607d677e525bb1d05f.tar.gz
file-systems: Add FAT32 support.
* gnu/build/file-systems.scm (%fat32-endianness, fat32-superblock?, read-fat32-superblock, fat32-superblock-uuid, fat32-uuid->string, fat32-superblock-volume-name, check-fat32-file-system): New variables. (%partition-label-readers, %partition-uuid-readers, check-file-system): Add fat support. (latin1->string): New variable. (null-terminated-latin1->string): Use latin1->string.
Diffstat (limited to 'gnu')
-rw-r--r--gnu/build/file-systems.scm66
1 files changed, 59 insertions, 7 deletions
diff --git a/gnu/build/file-systems.scm b/gnu/build/file-systems.scm
index f8ab95370c..fe98df95d5 100644
--- a/gnu/build/file-systems.scm
+++ b/gnu/build/file-systems.scm
@@ -106,15 +106,17 @@ takes a bytevector and returns #t when it's a valid superblock."
(bytevector-copy! bv start result 0 size)
result))
-(define (null-terminated-latin1->string bv)
- "Return the volume name of SBLOCK as a string of at most 256 characters, or
-#f if SBLOCK has no volume name."
- ;; This is a Latin-1, nul-terminated string.
- (let ((bytes (take-while (negate zero?) (bytevector->u8-list bv))))
+(define (latin1->string bv terminator)
+ "Return a string of BV, a latin1 bytevector, or #f. TERMINATOR is a predicate
+that takes a number and returns #t when a termination character is found."
+ (let ((bytes (take-while (negate terminator) (bytevector->u8-list bv))))
(if (null? bytes)
#f
(list->string (map integer->char bytes)))))
+(define null-terminated-latin1->string
+ (cut latin1->string <> zero?))
+
;;;
;;; Ext2 file systems.
@@ -194,6 +196,51 @@ if DEVICE does not contain a btrfs file system."
;;;
+;;; FAT32 file systems.
+;;;
+
+;; <http://www.ecma-international.org/publications/files/ECMA-ST/Ecma-107.pdf>.
+
+(define-syntax %fat32-endianness
+ ;; Endianness of fat file systems.
+ (identifier-syntax (endianness little)))
+
+(define (fat32-superblock? sblock)
+ "Return #t when SBLOCK is a fat32 superblock."
+ (bytevector=? (sub-bytevector sblock 82 8)
+ (string->utf8 "FAT32 ")))
+
+(define (read-fat32-superblock device)
+ "Return the raw contents of DEVICE's fat32 superblock as a bytevector, or
+#f if DEVICE does not contain a fat32 file system."
+ (read-superblock device 0 90 fat32-superblock?))
+
+(define (fat32-superblock-uuid sblock)
+ "Return the Volume ID of a fat superblock SBLOCK as a 4-byte bytevector."
+ (sub-bytevector sblock 67 4))
+
+(define (fat32-uuid->string uuid)
+ "Convert fat32 UUID, a 4-byte bytevector, to its string representation."
+ (let ((high (bytevector-uint-ref uuid 0 %fat32-endianness 2))
+ (low (bytevector-uint-ref uuid 2 %fat32-endianness 2)))
+ (format #f "~:@(~x-~x~)" low high)))
+
+(define (fat32-superblock-volume-name sblock)
+ "Return the volume name of SBLOCK as a string of at most 11 characters, or
+#f if SBLOCK has no volume name. The volume name is a latin1 string.
+Trailing spaces are trimmed."
+ (string-trim-right (latin1->string (sub-bytevector sblock 71 11) (lambda (c) #f)) #\space))
+
+(define (check-fat32-file-system device)
+ "Return the health of a fat file system on DEVICE."
+ (match (status:exit-val
+ (system* "fsck.vfat" "-v" "-a" device))
+ (0 'pass)
+ (1 'errors-corrected)
+ (_ 'fatal-error)))
+
+
+;;;
;;; LUKS encrypted devices.
;;;
@@ -307,13 +354,17 @@ partition field reader that returned a value."
(list (partition-field-reader read-ext2-superblock
ext2-superblock-volume-name)
(partition-field-reader read-btrfs-superblock
- btrfs-superblock-volume-name)))
+ btrfs-superblock-volume-name)
+ (partition-field-reader read-fat32-superblock
+ fat32-superblock-volume-name)))
(define %partition-uuid-readers
(list (partition-field-reader read-ext2-superblock
ext2-superblock-uuid)
(partition-field-reader read-btrfs-superblock
- btrfs-superblock-uuid)))
+ btrfs-superblock-uuid)
+ (partition-field-reader read-fat32-superblock
+ fat32-superblock-uuid)))
(define read-partition-label
(cut read-partition-field <> %partition-label-readers))
@@ -481,6 +532,7 @@ the following:
(cond
((string-prefix? "ext" type) check-ext2-file-system)
((string-prefix? "btrfs" type) check-btrfs-file-system)
+ ((string-suffix? "fat" type) check-fat32-file-system)
(else #f)))
(if check-procedure