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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;
+}