summaryrefslogtreecommitdiff
path: root/internal/fusefrontend/file_holes.go
diff options
context:
space:
mode:
authorJakob Unterwurzacher2016-10-25 21:19:37 +0200
committerJakob Unterwurzacher2016-10-25 21:19:37 +0200
commit6538dc15afb7a7a159f070a57a1e9073ca076661 (patch)
treea0fc2ae9d4ef863502c3b44f2671265e1369790d /internal/fusefrontend/file_holes.go
parentf41d2e067679c4c6a8b0b5dcb52a113918806e48 (diff)
fusefrontend: rename "createsHole" to clearer "createsCiphertextHole"
...and add comments for what is happening.
Diffstat (limited to 'internal/fusefrontend/file_holes.go')
-rw-r--r--internal/fusefrontend/file_holes.go10
1 files changed, 8 insertions, 2 deletions
diff --git a/internal/fusefrontend/file_holes.go b/internal/fusefrontend/file_holes.go
index 34f702f..ff626d1 100644
--- a/internal/fusefrontend/file_holes.go
+++ b/internal/fusefrontend/file_holes.go
@@ -8,10 +8,16 @@ import (
"github.com/rfjakob/gocryptfs/internal/tlog"
)
-// Will a write to offset "off" create a file hole?
-func (f *file) createsHole(plainSize uint64, off int64) bool {
+// Will a write to plaintext offset "off" create a file hole in the ciphertext?
+func (f *file) createsCiphertextHole(plainSize uint64, off int64) bool {
+ // Appending a single byte to the file (equivalent to writing to
+ // offset=plainSize) would write to "nextBlock".
nextBlock := f.contentEnc.PlainOffToBlockNo(plainSize)
+ // targetBlock is the block the user wants to write to.
targetBlock := f.contentEnc.PlainOffToBlockNo(uint64(off))
+ // If the write goes past the next block, nextBlock will have
+ // to be zero-padded to the block boundary and at least nextBlock+1
+ // becomes a file hole in the ciphertext.
return targetBlock > nextBlock
}