~q3cpma/mus: mus_player/format_detect.c - sourcehut git


                                                                                
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#include <errno.h>
#include <fcntl.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>

#include "format_detect.h"
#include "log.h"
#include "misc.h"

#define OGG_PAGE_HEADER_SIZE 28           /* cf. rfc3533 */
#define OGG_MAGIC            "OggS"       /* cf. rfc3533 */
#define OGG_VORBIS_IDENT     "\x01vorbis" /* cf. rfc5334 */
#define OGG_OPUS_IDENT       "OpusHead"   /* cf. rfc7845 */
#define OGG_FLAC_IDENT       "\177FLAC"   /* cf. rfc5334 */
#define OGG_IDENT_MAX_SIZE   8
/*cf. https://xiph.org/flac/format.html */
#define FLAC_IDENT           "fLaC"


static inline int memcmp_str(const void *s1, const char *s2)
{
	return memcmp(s1, s2, strlen(s2));
}

Audio_format detect_audio_format(const char *path)
{
	int fd = xopen(path, O_RDONLY);
	static char buf[OGG_PAGE_HEADER_SIZE + OGG_IDENT_MAX_SIZE];
	const char *ext = strrchr(path, '.');

	if (!strcmp(ext, ".ogg"))
	{
		if (!read_full(fd, buf, OGG_PAGE_HEADER_SIZE + OGG_IDENT_MAX_SIZE))
			LOG_DIE("%s: %s", path, strerror(errno));
		if (!memcmp_str(buf, OGG_MAGIC)) /* Try vorbis, opus then flac */
		{
			if (!memcmp_str(buf + OGG_PAGE_HEADER_SIZE, OGG_VORBIS_IDENT))
				return AUDIO_FORMAT_OGG_VORBIS;
			if (!memcmp_str(buf + OGG_PAGE_HEADER_SIZE, OGG_OPUS_IDENT))
				return AUDIO_FORMAT_OGG_OPUS;
			if (!memcmp_str(buf + OGG_PAGE_HEADER_SIZE, OGG_FLAC_IDENT))
				return AUDIO_FORMAT_OGG_FLAC;
			log_append(LOG_ERR, "%s: ogg file with unknown codec", path);
			return AUDIO_FORMAT_UNKNOWN;
		}
		log_append(LOG_ERR, "%s: ogg extension but not an ogg file", path);
		return AUDIO_FORMAT_UNKNOWN;
	}
	if (!strcmp(ext, ".opus"))
	{
		if (!read_full(fd, buf, OGG_PAGE_HEADER_SIZE + OGG_IDENT_MAX_SIZE))
			LOG_DIE("%s: %s", path, strerror(errno));
		if (!memcmp_str(buf, OGG_MAGIC))
		{
			if (!memcmp_str(buf + OGG_PAGE_HEADER_SIZE, OGG_OPUS_IDENT))
				return AUDIO_FORMAT_OGG_OPUS;
			log_append(LOG_ERR, "%s: ogg file with unknown codec", path);
			return AUDIO_FORMAT_UNKNOWN;
		}
		log_append(LOG_ERR, "%s: opus extension but not an ogg file", path);
		return AUDIO_FORMAT_UNKNOWN;
	}
	if (!strcmp(ext, ".flac"))
	{
		if (!read_full(fd, buf, strlen(FLAC_IDENT)))
			LOG_DIE("%s: %s", path, strerror(errno));
		if (!memcmp_str(buf, FLAC_IDENT))
			return AUDIO_FORMAT_FLAC;
		log_append(LOG_ERR, "%s: flac extension but not a flac file", path);
		return AUDIO_FORMAT_UNKNOWN;
	}
	xclose(fd);
	return AUDIO_FORMAT_UNKNOWN;
}