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index: be careful when handling long names

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We currently use lower 12-bit (masked with CE_NAMEMASK) in the
ce_flags field to store the length of the name in cache_entry,
without checking the length parameter given to
create_ce_flags().  This can make us store incorrect length.

Currently we are mostly protected by the fact that many
codepaths first copy the path in a variable of size PATH_MAX,
which typically is 4096 that happens to match the limit, but
that feels like a bug waiting to happen.  Besides, that would
not allow us to shorten the width of CE_NAMEMASK to use the bits
for new flags.

This redefines the meaning of the name length stored in the
cache_entry.  A name that does not fit is represented by storing
CE_NAMEMASK in the field, and the actual length needs to be
computed by actually counting the bytes in the name[] field.
This way, only the unusually long paths need to suffer.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Junio C Hamano
2008-01-18 23:42:00 -08:00
committed by Linus Torvalds
parent 7a51ed66f6
commit 7fec10b7f4
3 changed files with 46 additions and 3 deletions
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17
cache.h
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@ -131,8 +131,21 @@ struct cache_entry {
#define CE_UPDATE (0x10000)
#define CE_REMOVE (0x20000)
#define create_ce_flags(len, stage) ((len) | ((stage) << CE_STAGESHIFT))
#define ce_namelen(ce) (CE_NAMEMASK & (ce)->ce_flags)
static inline unsigned create_ce_flags(size_t len, unsigned stage)
{
if (len >= CE_NAMEMASK)
len = CE_NAMEMASK;
return (len | (stage << CE_STAGESHIFT));
}
static inline size_t ce_namelen(const struct cache_entry *ce)
{
size_t len = ce->ce_flags & CE_NAMEMASK;
if (len < CE_NAMEMASK)
return len;
return strlen(ce->name + CE_NAMEMASK) + CE_NAMEMASK;
}
#define ce_size(ce) cache_entry_size(ce_namelen(ce))
#define ondisk_ce_size(ce) ondisk_cache_entry_size(ce_namelen(ce))
#define ce_stage(ce) ((CE_STAGEMASK & (ce)->ce_flags) >> CE_STAGESHIFT)