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ape.c
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/*
* Copyright 2008-2013 Various Authors
* Copyright 2006 Chun-Yu Shei <cshei AT cs.indiana.edu>
*
* Cleaned up by Timo Hirvonen <tihirvon@gmail.com>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see <http://www.gnu.org/licenses/>.
*/
#include "ape.h"
#include "file.h"
#include "xmalloc.h"
#include "utils.h"
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <strings.h>
/* http://www.personal.uni-jena.de/~pfk/mpp/sv8/apetag.html */
#define PREAMBLE_SIZE (8)
static const char preamble[PREAMBLE_SIZE] = { 'A', 'P', 'E', 'T', 'A', 'G', 'E', 'X' };
/* NOTE: not sizeof(struct ape_header)! */
#define HEADER_SIZE (32)
/* returns position of APE header or -1 if not found */
static int find_ape_tag_slow(int fd)
{
char buf[4096];
int match = 0;
int pos = 0;
/* seek to start of file */
if (lseek(fd, pos, SEEK_SET) == -1)
return -1;
while (1) {
int i, got = read(fd, buf, sizeof(buf));
if (got == -1) {
if (errno == EAGAIN || errno == EINTR)
continue;
break;
}
if (got == 0)
break;
for (i = 0; i < got; i++) {
if (buf[i] != preamble[match]) {
match = 0;
continue;
}
match++;
if (match == PREAMBLE_SIZE)
return pos + i + 1 - PREAMBLE_SIZE;
}
pos += got;
}
return -1;
}
static int ape_parse_header(const char *buf, struct ape_header *h)
{
if (memcmp(buf, preamble, PREAMBLE_SIZE))
return 0;
h->version = read_le32(buf + 8);
h->size = read_le32(buf + 12);
h->count = read_le32(buf + 16);
h->flags = read_le32(buf + 20);
return 1;
}
static int read_header(int fd, struct ape_header *h)
{
char buf[HEADER_SIZE];
if (read_all(fd, buf, sizeof(buf)) != sizeof(buf))
return 0;
return ape_parse_header(buf, h);
}
/* sets fd right after the header and returns 1 if found,
* otherwise returns 0
*/
static int find_ape_tag(int fd, struct ape_header *h, int slow)
{
int pos;
if (lseek(fd, -HEADER_SIZE, SEEK_END) == -1)
return 0;
if (read_header(fd, h))
return 1;
/* try to skip ID3v1 tag at the end of the file */
if (lseek(fd, -(HEADER_SIZE + 128), SEEK_END) == -1)
return 0;
if (read_header(fd, h))
return 1;
if (!slow)
return 0;
pos = find_ape_tag_slow(fd);
if (pos == -1)
return 0;
if (lseek(fd, pos, SEEK_SET) == -1)
return 0;
return read_header(fd, h);
}
/*
* All keys are ASCII and length is 2..255
*
* UTF-8: Artist, Album, Title, Genre
* Integer: Track (N or N/M)
* Date: Year (release), "Record Date"
*
* UTF-8 strings are NOT zero terminated.
*
* Also support "discnumber" (vorbis) and "disc" (non-standard)
*/
static int ape_parse_one(const char *buf, int size, char **keyp, char **valp)
{
int pos = 0;
while (size - pos > 8) {
uint32_t val_len, flags;
char *key, *val;
int64_t max_key_len, key_len;
val_len = read_le32(buf + pos); pos += 4;
flags = read_le32(buf + pos); pos += 4;
max_key_len = size - pos - (int64_t)val_len - 1;
if (max_key_len < 0) {
/* corrupt */
break;
}
for (key_len = 0; key_len < max_key_len && buf[pos + key_len]; key_len++)
; /* nothing */
if (buf[pos + key_len]) {
/* corrupt */
break;
}
if (!AF_IS_UTF8(flags)) {
/* ignore binary data */
pos += key_len + 1 + val_len;
continue;
}
key = xstrdup(buf + pos);
pos += key_len + 1;
/* should not be NUL-terminated */
val = xstrndup(buf + pos, val_len);
pos += val_len;
/* could be moved to comment.c but I don't think anyone else would use it */
if (!strcasecmp(key, "record date") || !strcasecmp(key, "year")) {
free(key);
key = xstrdup("date");
}
if (!strcasecmp(key, "date")) {
/* Date format
*
* 1999-08-11 12:34:56
* 1999-08-11 12:34
* 1999-08-11
* 1999-08
* 1999
* 1999-W34 (week 34, totally crazy)
*
* convert to year, pl.c supports only years anyways
*
* FIXME: which one is the most common tag (year or record date)?
*/
if (strlen(val) > 4)
val[4] = 0;
}
*keyp = key;
*valp = val;
return pos;
}
return -1;
}
/* return the number of comments, or -1 */
int ape_read_tags(struct apetag *ape, int fd, int slow)
{
struct ape_header *h = &ape->header;
int rc = -1;
off_t old_pos;
/* save position */
old_pos = lseek(fd, 0, SEEK_CUR);
if (!find_ape_tag(fd, h, slow))
goto fail;
if (AF_IS_FOOTER(h->flags)) {
/* seek back right after the header */
if (lseek(fd, -((int)h->size), SEEK_CUR) == -1)
goto fail;
}
/* ignore insane tags */
if (h->size > 1024 * 1024)
goto fail;
ape->buf = xnew(char, h->size);
if (read_all(fd, ape->buf, h->size) != h->size)
goto fail;
rc = h->count;
fail:
lseek(fd, old_pos, SEEK_SET);
return rc;
}
/* returned key-name must be free'd */
char *ape_get_comment(struct apetag *ape, char **val)
{
struct ape_header *h = &ape->header;
char *key;
int rc;
if (ape->pos >= h->size)
return NULL;
rc = ape_parse_one(ape->buf + ape->pos, h->size - ape->pos, &key, val);
if (rc < 0)
return NULL;
ape->pos += rc;
return key;
}