git/read-cache.c
David Meybohm 8310c2c0b5 [PATCH] check_file_directory_conflict path fix
check_file_directory_conflict can give the wrong answers. This is
because the wrong length is passed to cache_name_pos. The length
passed should be the length of the whole path from the root, not
the length of each path subcomponent.

	$ git-init-db
	defaulting to local storage area
	$ mkdir path && touch path/file
	$ git-update-cache --add path/file
	$ rm path/file
	$ mkdir path/file && touch path/file/f
	$ git-update-cache --add path/file/f  <-- Conflict ignored
	$

Signed-off-by: David Meybohm <dmeybohmlkml@bellsouth.net>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-05-27 10:34:24 -07:00

460 lines
11 KiB
C

/*
* GIT - The information manager from hell
*
* Copyright (C) Linus Torvalds, 2005
*/
#include "cache.h"
struct cache_entry **active_cache = NULL;
unsigned int active_nr = 0, active_alloc = 0, active_cache_changed = 0;
/*
* This only updates the "non-critical" parts of the directory
* cache, ie the parts that aren't tracked by GIT, and only used
* to validate the cache.
*/
void fill_stat_cache_info(struct cache_entry *ce, struct stat *st)
{
ce->ce_ctime.sec = htonl(st->st_ctime);
ce->ce_mtime.sec = htonl(st->st_mtime);
#ifdef USE_NSEC
ce->ce_ctime.nsec = htonl(st->st_ctim.tv_nsec);
ce->ce_mtime.nsec = htonl(st->st_mtim.tv_nsec);
#endif
ce->ce_dev = htonl(st->st_dev);
ce->ce_ino = htonl(st->st_ino);
ce->ce_uid = htonl(st->st_uid);
ce->ce_gid = htonl(st->st_gid);
ce->ce_size = htonl(st->st_size);
}
int ce_match_stat(struct cache_entry *ce, struct stat *st)
{
unsigned int changed = 0;
switch (ntohl(ce->ce_mode) & S_IFMT) {
case S_IFREG:
changed |= !S_ISREG(st->st_mode) ? TYPE_CHANGED : 0;
/* We consider only the owner x bit to be relevant for "mode changes" */
if (0100 & (ntohl(ce->ce_mode) ^ st->st_mode))
changed |= MODE_CHANGED;
break;
case S_IFLNK:
changed |= !S_ISLNK(st->st_mode) ? TYPE_CHANGED : 0;
break;
default:
die("internal error: ce_mode is %o", ntohl(ce->ce_mode));
}
if (ce->ce_mtime.sec != htonl(st->st_mtime))
changed |= MTIME_CHANGED;
if (ce->ce_ctime.sec != htonl(st->st_ctime))
changed |= CTIME_CHANGED;
#ifdef USE_NSEC
/*
* nsec seems unreliable - not all filesystems support it, so
* as long as it is in the inode cache you get right nsec
* but after it gets flushed, you get zero nsec.
*/
if (ce->ce_mtime.nsec != htonl(st->st_mtim.tv_nsec))
changed |= MTIME_CHANGED;
if (ce->ce_ctime.nsec != htonl(st->st_ctim.tv_nsec))
changed |= CTIME_CHANGED;
#endif
if (ce->ce_uid != htonl(st->st_uid) ||
ce->ce_gid != htonl(st->st_gid))
changed |= OWNER_CHANGED;
if (ce->ce_ino != htonl(st->st_ino))
changed |= INODE_CHANGED;
#ifdef USE_STDEV
/*
* st_dev breaks on network filesystems where different
* clients will have different views of what "device"
* the filesystem is on
*/
if (ce->ce_dev != htonl(st->st_dev))
changed |= INODE_CHANGED;
#endif
if (ce->ce_size != htonl(st->st_size))
changed |= DATA_CHANGED;
return changed;
}
int base_name_compare(const char *name1, int len1, int mode1,
const char *name2, int len2, int mode2)
{
unsigned char c1, c2;
int len = len1 < len2 ? len1 : len2;
int cmp;
cmp = memcmp(name1, name2, len);
if (cmp)
return cmp;
c1 = name1[len];
c2 = name2[len];
if (!c1 && S_ISDIR(mode1))
c1 = '/';
if (!c2 && S_ISDIR(mode2))
c2 = '/';
return (c1 < c2) ? -1 : (c1 > c2) ? 1 : 0;
}
int cache_name_compare(const char *name1, int flags1, const char *name2, int flags2)
{
int len1 = flags1 & CE_NAMEMASK;
int len2 = flags2 & CE_NAMEMASK;
int len = len1 < len2 ? len1 : len2;
int cmp;
cmp = memcmp(name1, name2, len);
if (cmp)
return cmp;
if (len1 < len2)
return -1;
if (len1 > len2)
return 1;
if (flags1 < flags2)
return -1;
if (flags1 > flags2)
return 1;
return 0;
}
int cache_name_pos(const char *name, int namelen)
{
int first, last;
first = 0;
last = active_nr;
while (last > first) {
int next = (last + first) >> 1;
struct cache_entry *ce = active_cache[next];
int cmp = cache_name_compare(name, namelen, ce->name, htons(ce->ce_flags));
if (!cmp)
return next;
if (cmp < 0) {
last = next;
continue;
}
first = next+1;
}
return -first-1;
}
/* Remove entry, return true if there are more entries to go.. */
int remove_cache_entry_at(int pos)
{
active_cache_changed = 1;
active_nr--;
if (pos >= active_nr)
return 0;
memmove(active_cache + pos, active_cache + pos + 1, (active_nr - pos) * sizeof(struct cache_entry *));
return 1;
}
int remove_file_from_cache(char *path)
{
int pos = cache_name_pos(path, strlen(path));
if (pos < 0)
pos = -pos-1;
while (pos < active_nr && !strcmp(active_cache[pos]->name, path))
remove_cache_entry_at(pos);
return 0;
}
int ce_same_name(struct cache_entry *a, struct cache_entry *b)
{
int len = ce_namelen(a);
return ce_namelen(b) == len && !memcmp(a->name, b->name, len);
}
/* We may be in a situation where we already have path/file and path
* is being added, or we already have path and path/file is being
* added. Either one would result in a nonsense tree that has path
* twice when git-write-tree tries to write it out. Prevent it.
*
* If ok-to-replace is specified, we remove the conflicting entries
* from the cache so the caller should recompute the insert position.
* When this happens, we return non-zero.
*/
static int check_file_directory_conflict(const struct cache_entry *ce,
int ok_to_replace)
{
int pos, replaced = 0;
const char *path = ce->name;
int namelen = strlen(path);
int stage = ce_stage(ce);
char *pathbuf = xmalloc(namelen + 1);
char *cp;
memcpy(pathbuf, path, namelen + 1);
/*
* We are inserting path/file. Do they have path registered at
* the same stage? We need to do this for all the levels of our
* subpath.
*/
cp = pathbuf;
while (1) {
char *ep = strchr(cp, '/');
int len;
if (!ep)
break;
*ep = 0; /* first cut it at slash */
len = ep - pathbuf;
pos = cache_name_pos(pathbuf,
htons(create_ce_flags(len, stage)));
if (0 <= pos) {
/* Our leading path component is registered as a file,
* and we are trying to make it a directory. This is
* bad.
*/
if (!ok_to_replace) {
free(pathbuf);
return -1;
}
fprintf(stderr, "removing file '%s' to replace it with a directory to create '%s'.\n", pathbuf, path);
remove_cache_entry_at(pos);
replaced = 1;
}
*ep = '/'; /* then restore it and go downwards */
cp = ep + 1;
}
free(pathbuf);
/* Do we have an entry in the cache that makes our path a prefix
* of it? That is, are we creating a file where they already expect
* a directory there?
*/
pos = cache_name_pos(path,
htons(create_ce_flags(namelen, stage)));
/* (0 <= pos) cannot happen because add_cache_entry()
* should have taken care of that case.
*/
pos = -pos-1;
/* pos would point at an existing entry that would come immediately
* after our path. It could be the same as our path in higher stage,
* or different path but in a lower stage.
*
* E.g. when we are inserting path at stage 2,
*
* 1 path
* pos-> 3 path
* 2 path/file1
* 3 path/file1
* 2 path/file2
* 2 patho
*
* We need to examine pos, ignore it because it is at different
* stage, examine next to find the path/file at stage 2, and
* complain. We need to do this until we are not the leading
* path of an existing entry anymore.
*/
while (pos < active_nr) {
struct cache_entry *other = active_cache[pos];
if (strncmp(other->name, path, namelen))
break; /* it is not our "subdirectory" anymore */
if ((ce_stage(other) == stage) &&
other->name[namelen] == '/') {
if (!ok_to_replace)
return -1;
fprintf(stderr, "removing file '%s' under '%s' to be replaced with a file\n", other->name, path);
remove_cache_entry_at(pos);
replaced = 1;
continue; /* cycle without updating pos */
}
pos++;
}
return replaced;
}
int add_cache_entry(struct cache_entry *ce, int option)
{
int pos;
int ok_to_add = option & ADD_CACHE_OK_TO_ADD;
int ok_to_replace = option & ADD_CACHE_OK_TO_REPLACE;
pos = cache_name_pos(ce->name, htons(ce->ce_flags));
/* existing match? Just replace it */
if (pos >= 0) {
active_cache_changed = 1;
active_cache[pos] = ce;
return 0;
}
pos = -pos-1;
/*
* Inserting a merged entry ("stage 0") into the index
* will always replace all non-merged entries..
*/
if (pos < active_nr && ce_stage(ce) == 0) {
while (ce_same_name(active_cache[pos], ce)) {
ok_to_add = 1;
if (!remove_cache_entry_at(pos))
break;
}
}
if (!ok_to_add)
return -1;
if (check_file_directory_conflict(ce, ok_to_replace)) {
if (!ok_to_replace)
return -1;
pos = cache_name_pos(ce->name, htons(ce->ce_flags));
pos = -pos-1;
}
/* Make sure the array is big enough .. */
if (active_nr == active_alloc) {
active_alloc = alloc_nr(active_alloc);
active_cache = xrealloc(active_cache, active_alloc * sizeof(struct cache_entry *));
}
/* Add it in.. */
active_nr++;
if (active_nr > pos)
memmove(active_cache + pos + 1, active_cache + pos, (active_nr - pos - 1) * sizeof(ce));
active_cache[pos] = ce;
active_cache_changed = 1;
return 0;
}
static int verify_hdr(struct cache_header *hdr, unsigned long size)
{
SHA_CTX c;
unsigned char sha1[20];
if (hdr->hdr_signature != htonl(CACHE_SIGNATURE))
return error("bad signature");
if (hdr->hdr_version != htonl(2))
return error("bad index version");
SHA1_Init(&c);
SHA1_Update(&c, hdr, size - 20);
SHA1_Final(sha1, &c);
if (memcmp(sha1, (void *)hdr + size - 20, 20))
return error("bad index file sha1 signature");
return 0;
}
int read_cache(void)
{
int fd, i;
struct stat st;
unsigned long size, offset;
void *map;
struct cache_header *hdr;
errno = EBUSY;
if (active_cache)
return error("more than one cachefile");
errno = ENOENT;
fd = open(get_index_file(), O_RDONLY);
if (fd < 0)
return (errno == ENOENT) ? 0 : error("open failed");
size = 0; // avoid gcc warning
map = (void *)-1;
if (!fstat(fd, &st)) {
size = st.st_size;
errno = EINVAL;
if (size >= sizeof(struct cache_header) + 20)
map = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
}
close(fd);
if (-1 == (int)(long)map)
return error("mmap failed");
hdr = map;
if (verify_hdr(hdr, size) < 0)
goto unmap;
active_nr = ntohl(hdr->hdr_entries);
active_alloc = alloc_nr(active_nr);
active_cache = calloc(active_alloc, sizeof(struct cache_entry *));
offset = sizeof(*hdr);
for (i = 0; i < active_nr; i++) {
struct cache_entry *ce = map + offset;
offset = offset + ce_size(ce);
active_cache[i] = ce;
}
return active_nr;
unmap:
munmap(map, size);
errno = EINVAL;
return error("verify header failed");
}
#define WRITE_BUFFER_SIZE 8192
static unsigned char write_buffer[WRITE_BUFFER_SIZE];
static unsigned long write_buffer_len;
static int ce_write(SHA_CTX *context, int fd, void *data, unsigned int len)
{
while (len) {
unsigned int buffered = write_buffer_len;
unsigned int partial = WRITE_BUFFER_SIZE - buffered;
if (partial > len)
partial = len;
memcpy(write_buffer + buffered, data, partial);
buffered += partial;
if (buffered == WRITE_BUFFER_SIZE) {
SHA1_Update(context, write_buffer, WRITE_BUFFER_SIZE);
if (write(fd, write_buffer, WRITE_BUFFER_SIZE) != WRITE_BUFFER_SIZE)
return -1;
buffered = 0;
}
write_buffer_len = buffered;
len -= partial;
data += partial;
}
return 0;
}
static int ce_flush(SHA_CTX *context, int fd)
{
unsigned int left = write_buffer_len;
if (left) {
write_buffer_len = 0;
SHA1_Update(context, write_buffer, left);
}
/* Append the SHA1 signature at the end */
SHA1_Final(write_buffer + left, context);
left += 20;
if (write(fd, write_buffer, left) != left)
return -1;
return 0;
}
int write_cache(int newfd, struct cache_entry **cache, int entries)
{
SHA_CTX c;
struct cache_header hdr;
int i;
hdr.hdr_signature = htonl(CACHE_SIGNATURE);
hdr.hdr_version = htonl(2);
hdr.hdr_entries = htonl(entries);
SHA1_Init(&c);
if (ce_write(&c, newfd, &hdr, sizeof(hdr)) < 0)
return -1;
for (i = 0; i < entries; i++) {
struct cache_entry *ce = cache[i];
if (ce_write(&c, newfd, ce, ce_size(ce)) < 0)
return -1;
}
return ce_flush(&c, newfd);
}