David Howells 5d439467b8 cachefiles: Implement key to filename encoding ... Implement a function to encode a binary cookie key as something that can be used as a filename. Four options are considered: (1) All printable chars with no '/' characters. Prepend a 'D' to indicate the encoding but otherwise use as-is. (2) Appears to be an array of __be32. Encode as 'S' plus a list of hex-encoded 32-bit ints separated by commas. If a number is 0, it is rendered as "" instead of "0". (3) Appears to be an array of __le32. Encoded as (2) but with a 'T' encoding prefix. (4) Encoded as base64 with an 'E' prefix plus a second char indicating how much padding is involved. A non-standard base64 encoding is used because '/' cannot be used in the encoded form. If (1) is not possible, whichever of (2), (3) or (4) produces the shortest string is selected (hex-encoding a number may be less dense than base64 encoding it). Note that the prefix characters have to be selected from the set [DEIJST@] lest cachefilesd remove the files because it recognise the name. Changes ======= ver #2: - Fix a short allocation that didn't allow for a string terminator[1] Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: linux-cachefs@redhat.com Link: https://lore.kernel.org/r/bcefb8f2-576a-b3fc-cc29-89808ebfd7c1@linux.alibaba.com/ [1] Link: https://lore.kernel.org/r/163819640393.215744.15212364106412961104.stgit@warthog.procyon.org.uk/ # v1 Link: https://lore.kernel.org/r/163906940529.143852.17352132319136117053.stgit@warthog.procyon.org.uk/ # v2 Link: https://lore.kernel.org/r/163967149827.1823006.6088580775428487961.stgit@warthog.procyon.org.uk/ # v3 Link: https://lore.kernel.org/r/164021549223.640689.14762875188193982341.stgit@warthog.procyon.org.uk/ # v4		2022-01-07 13:42:16 +00:00
..
cache.c	cachefiles: Implement volume support	2022-01-07 13:41:53 +00:00
daemon.c	cachefiles: Implement volume support	2022-01-07 13:41:53 +00:00
error_inject.c	cachefiles: Add some error injection support	2022-01-07 13:40:56 +00:00
interface.c	cachefiles: Implement object lifecycle funcs	2022-01-07 13:42:08 +00:00
internal.h	cachefiles: Implement key to filename encoding	2022-01-07 13:42:16 +00:00
Kconfig	cachefiles: Add some error injection support	2022-01-07 13:40:56 +00:00
key.c	cachefiles: Implement key to filename encoding	2022-01-07 13:42:16 +00:00
main.c	cachefiles: Implement object lifecycle funcs	2022-01-07 13:42:08 +00:00
Makefile	cachefiles: Implement key to filename encoding	2022-01-07 13:42:16 +00:00
namei.c	cachefiles: Implement a function to get/create a directory in the cache	2022-01-07 13:41:40 +00:00
security.c	cachefiles: Add security derivation	2022-01-07 13:41:14 +00:00
volume.c	cachefiles: Implement volume support	2022-01-07 13:41:53 +00:00