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Cache uid-from-uname and gid-from-gname lookups during extraction.

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This should provide a big performance boost for folks using NIS or LDAP.

MFC after: 3 days
Thanks to: Jun Kuriyama (for reminding me that this was still on my TODO list)
This commit is contained in:
Tim Kientzle 2004-08-27 03:40:48 +00:00
parent 4cef6d5a53
commit db9e0127da
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=134367
1 changed files with 84 additions and 17 deletions
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101
lib/libarchive/archive_read_extract.c
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@ -74,6 +74,12 @@ struct fixup_entry {
#define FIXUP_TIMES 2
#define FIXUP_FFLAGS 4
struct bucket {
char *name;
int hash;
id_t id;
};
struct extract {
mode_t umask;
mode_t default_dir_mode;
@ -81,6 +87,9 @@ struct extract {
struct fixup_entry *fixup_list;
struct fixup_entry *current_fixup;
struct bucket ucache[127];
struct bucket gcache[127];
/*
* Cached stat data from disk for the current entry.
* If this is valid, pst points to st. Otherwise,
@ -113,6 +122,7 @@ static int extract_fifo(struct archive *, struct archive_entry *, int);
static int extract_file(struct archive *, struct archive_entry *, int);
static int extract_hard_link(struct archive *, struct archive_entry *, int);
static int extract_symlink(struct archive *, struct archive_entry *, int);
static unsigned int hash(const char *);
static gid_t lookup_gid(struct archive *, const char *uname, gid_t);
static uid_t lookup_uid(struct archive *, const char *uname, uid_t);
static int create_parent_dir(struct archive *, const char *, int flags);
@ -1193,23 +1203,44 @@ set_acl(struct archive *a, struct archive_entry *entry, acl_type_t acl_type,
#endif
/*
* XXX The following gid/uid lookups can be a performance bottleneck.
* Some form of caching would probably be very effective, though
* I have concerns about staleness.
* The following routines do some basic caching of uname/gname lookups.
* All such lookups go through these routines, including ACL conversions.
*
* TODO: Provide an API for clients to override these routines.
*/
static gid_t
lookup_gid(struct archive *a, const char *gname, gid_t gid)
{
struct group *grent;
struct extract *extract;
int h;
struct bucket *b;
int cache_size;
(void)a; /* UNUSED */
extract = a->extract;
cache_size = sizeof(extract->gcache) / sizeof(extract->gcache[0]);
/* If no gname, just use the gid provided. */
if (gname == NULL || *gname == '\0')
return (gid);
/* Try to find gname in the cache. */
h = hash(gname);
b = &extract->gcache[h % cache_size ];
if (b->name != NULL && b->hash == h && strcmp(gname, b->name) == 0)
return ((gid_t)b->id);
/* Free the cache slot for a new entry. */
if (b->name != NULL)
free(b->name);
b->name = strdup(gname);
/* Note: If strdup fails, that's okay; we just won't cache. */
b->hash = h;
grent = getgrnam(gname);
if (grent != NULL)
gid = grent->gr_gid;
b->id = gid;
/* Look up gid from gname. */
if (gname != NULL && *gname != '\0') {
grent = getgrnam(gname);
if (grent != NULL)
gid = grent->gr_gid;
}
return (gid);
}
@ -1217,18 +1248,54 @@ static uid_t
lookup_uid(struct archive *a, const char *uname, uid_t uid)
{
struct passwd *pwent;
struct extract *extract;
int h;
struct bucket *b;
int cache_size;
(void)a; /* UNUSED */
extract = a->extract;
cache_size = sizeof(extract->ucache) / sizeof(extract->ucache[0]);
/* If no uname, just use the uid provided. */
if (uname == NULL || *uname == '\0')
return (uid);
/* Try to find uname in the cache. */
h = hash(uname);
b = &extract->ucache[h % cache_size ];
if (b->name != NULL && b->hash == h && strcmp(uname, b->name) == 0)
return ((uid_t)b->id);
/* Free the cache slot for a new entry. */
if (b->name != NULL)
free(b->name);
b->name = strdup(uname);
/* Note: If strdup fails, that's okay; we just won't cache. */
b->hash = h;
pwent = getpwnam(uname);
if (pwent != NULL)
uid = pwent->pw_uid;
b->id = uid;
/* Look up uid from uname. */
if (uname != NULL && *uname != '\0') {
pwent = getpwnam(uname);
if (pwent != NULL)
uid = pwent->pw_uid;
}
return (uid);
}
static unsigned int
hash(const char *p)
{
/* A 32-bit version of Peter Weinberger's (PJW) hash algorithm,
as used by ELF for hashing function names. */
unsigned g,h = 0;
while(*p != '\0') {
h = ( h << 4 ) + *p++;
if (( g = h & 0xF0000000 )) {
h ^= g >> 24;
h &= 0x0FFFFFFF;
}
}
return h;
}
void
archive_read_extract_set_progress_callback(struct archive *a,
void (*progress_func)(void *), void *user_data)