Repository navigation
Expand file tree
/
Copy pathfake-rebuild.c
More file actions
122 lines (109 loc) · 3.91 KB
/
Copy pathfake-rebuild.c
File metadata and controls
122 lines (109 loc) · 3.91 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
#include <stdio.h>
#include <string.h>
#include <sys/stat.h>
#include <unistd.h>
#include "fs/sqlutil.h"
#include "fs/fake-db.h"
#include "kernel/errno.h"
#include "util/list.h"
#include "debug.h"
// rebuild process in pseudocode:
//
// table = {}
// for each path, inode:
// real_inode = stat(path).st_ino
// if inode in table:
// unlink(path)
// link(table[inode], path)
// else:
// table[inode] = path
// stat = db['stat ' + inode]
// new_db['inode ' + path] = real_inode
// new_db['stat ' + real_inode] = stat
// ad hoc hashtable
struct entry {
ino_t inode;
char *path;
struct list chain;
};
int fakefs_rebuild(struct fakefs_db *fs, int root_fd) {
sqlite3 *db = fs->db;
int err;
EXEC("begin");
EXEC("create table paths_old (path blob primary key, inode integer)");
EXEC("create table stats_old (inode integer primary key, stat blob)");
EXEC("insert into paths_old select * from paths");
EXEC("insert into stats_old select * from stats");
EXEC("delete from paths");
EXEC("delete from stats");
sqlite3_stmt *get_paths = PREPARE("select path, inode from paths_old");
sqlite3_stmt *read_stat = PREPARE("select stat from stats_old where inode = ?");
sqlite3_stmt *write_path = PREPARE("insert into paths (path, inode) values (?, ?)");
sqlite3_stmt *write_stat = PREPARE("replace into stats (inode, stat) values (?, ?)");
struct list hashtable[2000];
#define HASH_SIZE (sizeof(hashtable)/sizeof(hashtable[0]))
for (unsigned i = 0; i < HASH_SIZE; i++)
list_init(&hashtable[i]);
while (STEP(get_paths)) {
const char *path = (const char *) sqlite3_column_text(get_paths, 0);
ino_t inode = sqlite3_column_int64(get_paths, 1);
// grab real inode
struct stat stat;
int err = fstatat(root_fd, fix_path(path), &stat, 0);
if (err < 0)
continue;
ino_t real_inode = stat.st_ino;
// restore hardlinks
struct list *bucket = &hashtable[inode % HASH_SIZE];
struct entry *entry;
bool found = false;
list_for_each_entry(bucket, entry, chain) {
if (entry->inode == inode) {
unlinkat(root_fd, fix_path(path), 0);
linkat(root_fd, fix_path(entry->path), root_fd, fix_path(path), 0);
found = true;
break;
}
}
if (!found) {
entry = malloc(sizeof(struct entry));
entry->inode = inode;
entry->path = strdup(path);
list_add(bucket, &entry->chain);
}
// extract the stat so we can copy it
err = sqlite3_bind_int64(read_stat, 1, inode); CHECK_ERR();
if (STEP(read_stat) == false) {
RESET(read_stat);
continue;
}
const void *stat_data = sqlite3_column_blob(read_stat, 0);
size_t stat_data_size = sqlite3_column_bytes(read_stat, 0);
// store all the information in the new database
err = sqlite3_bind_int64(write_stat, 1, real_inode); CHECK_ERR();
err = sqlite3_bind_blob(write_stat, 2, stat_data, stat_data_size, SQLITE_TRANSIENT); CHECK_ERR();
STEP(write_stat);
RESET(write_stat);
err = sqlite3_bind_blob(write_path, 1, path, strlen(path), SQLITE_TRANSIENT); CHECK_ERR();
err = sqlite3_bind_int64(write_path, 2, real_inode); CHECK_ERR();
STEP(write_path);
RESET(write_path);
RESET(read_stat);
}
for (unsigned i = 0; i < HASH_SIZE; i++) {
struct entry *entry, *tmp;
list_for_each_entry_safe(&hashtable[i], entry, tmp, chain) {
list_remove(&entry->chain);
free(entry->path);
free(entry);
}
}
EXEC("drop table paths_old");
EXEC("drop table stats_old");
EXEC("commit");
FINALIZE(get_paths);
FINALIZE(read_stat);
FINALIZE(write_path);
FINALIZE(write_stat);
return 0;
}