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#include "tar.h"
#include <camellia/flags.h>
#include <camellia/fsutil.h>
#include <camellia/syscalls.h>
#include <shared/mem.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <user/lib/compat.h>
#include <user/lib/fs/dir.h>
#define BUF_SIZE 64
static void *tar_open(const char *path, int len, void *base, size_t base_len);
static char tar_type(void *meta);
static void tar_dirbuild(struct dirbuild *db, const char *meta, void *base, size_t base_len);
static void tar_read(struct ufs_request *res, void *base, size_t base_len);
static int tar_size(void *sector);
static int oct_parse(char *str, size_t len);
static const char *root_fakemeta = ""; /* see comment in tar_open */
void tar_driver(void *base) {
static char buf[BUF_SIZE];
struct ufs_request res;
void *ptr;
while (!c0_fs_wait(buf, BUF_SIZE, &res)) {
switch (res.op) {
case VFSOP_OPEN:
ptr = tar_open(buf, res.len, base, ~0);
c0_fs_respond(ptr, ptr ? 0 : -1, 0);
break;
case VFSOP_READ:
tar_read(&res, base, ~0);
break;
case VFSOP_GETSIZE:
if (tar_type(res.id) != '5') {
c0_fs_respond(NULL, tar_size(res.id), 0);
} else {
struct dirbuild db;
dir_start(&db, res.offset, NULL, 0);
tar_dirbuild(&db, res.id, base, ~0);
c0_fs_respond(NULL, dir_finish(&db), 0);
}
break;
default:
c0_fs_respond(NULL, -1, 0); // unsupported
break;
}
}
exit(0);
}
static char tar_type(void *meta) {
if (meta == root_fakemeta) return '5';
return *(char*)(meta + 156);
}
static void *tar_open(const char *path, int len, void *base, size_t base_len) {
if (len <= 0) return NULL;
path += 1; // skip the leading slash
len -= 1;
/* TAR archives don't (seem to) contain an entry for the root dir, so i'm
* returning a fake one. this isn't a full entry because i'm currently too
* lazy to create a full one - thus, it has to be special cased in tar_read */
if (len == 0)
return (void*)root_fakemeta;
return tar_find(path, len, base, base_len);
}
static void tar_dirbuild(struct dirbuild *db, const char *meta, void *base, size_t base_len) {
size_t meta_len = strlen(meta);
for (size_t off = 0; off < base_len;) {
if (0 != memcmp(base + off + 257, "ustar", 5))
break; // not a metadata sector
/* check if prefix matches */
if (0 == memcmp(base + off, meta, meta_len)
&& *(char*)(base + off + meta_len) != '\0') {
char *suffix = base + off + meta_len;
/* check if the path contains any non-trailing slashes */
char *slash = strchr(suffix, '/');
if (!slash || slash[1] == '\0') {
if (dir_append(db, suffix)) break;
}
}
int size = tar_size(base + off);
off += 512; // skip this metadata sector
off += (size + 511) & ~511; // skip the data sectors
}
}
static void tar_read(struct ufs_request *res, void *base, size_t base_len) {
void *meta = (void*)res->id;
static char buf[BUF_SIZE];
// TODO reuse a single buffer for both tar_driver and tar_read
switch (tar_type(meta)) {
case '\0':
case '0': /* normal files */
fs_normslice(&res->offset, &res->len, tar_size(meta), false);
c0_fs_respond(meta + 512 + res->offset, res->len, 0);
break;
case '5': /* directory */
struct dirbuild db;
dir_start(&db, res->offset, buf, sizeof buf);
tar_dirbuild(&db, meta, base, base_len);
c0_fs_respond(buf, dir_finish(&db), 0);
break;
default:
c0_fs_respond(NULL, -1, 0);
break;
}
}
static int tar_size(void *sector) {
return oct_parse(sector + 124, 11);
}
void *tar_find(const char *path, size_t path_len, void *base, size_t base_len) {
int size;
if (path_len > 100) return NULL; // illegal path
for (size_t off = 0; off < base_len;) {
if (0 != memcmp(base + off + 257, "ustar", 5))
break; // not a metadata sector
if (0 == memcmp(base + off, path, path_len) &&
*(char*)(base + off + path_len) == '\0')
return base + off; // file found, quit
size = tar_size(base + off);
off += 512; // skip this metadata sector
off += (size + 511) & ~511; // skip the data sectors
}
return NULL;
}
static int oct_parse(char *str, size_t len) {
int res = 0;
for (size_t i = 0; i < len; i++) {
res *= 8;
res += str[i] - '0'; // no format checking
}
return res;
}
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