tags.c

专门处理mp3文件的tag信息

/*
 *  MP3Tag - Add ID3 tags to MP3 files based on their filename
 *  Copyright (C)2000 Dave Ewart ([e-mail])
 *
 *  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, write to the Free Software
 *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <stdio.h>
#include <string.h>
#include "defs.h"
#include "const.h"

int WriteTag (struct tagdata sometag, FILE *somefile, int style);
// char *GetArtist (char fname);
int AlreadyGotTag(FILE *somefile);
struct tagdata ReadTag(FILE *somefile);
int DisplayTag(struct tagdata sometag);
struct tagdata CreateTag(char *filename);

int WriteTag (struct tagdata sometag, FILE *somefile, int style) {

   if (style==WRITETAG_REPLACE) {
     if (!fseek(somefile,-128,SEEK_END)) {
       fputs("TAG",somefile);
       fputs(sometag.title,somefile);
       fputs(sometag.artist,somefile);
       fputs(sometag.album,somefile);
       fputs(sometag.year,somefile);
       fputs(sometag.comment,somefile);
       putc(sometag.genre,somefile);
       return (WRITETAG_OK);
     }
     else {
       return(WRITETAG_FAIL);
     };
   }
   else if (style==WRITETAG_NEW) {
     if (!fseek(somefile,0,SEEK_END)) {
       fputs("TAG",somefile);
       fputs(sometag.title,somefile);
       fputs(sometag.artist,somefile);
       fputs(sometag.album,somefile);
       fputs(sometag.year,somefile);
       fputs(sometag.comment,somefile);
       putc(sometag.genre,somefile);
       return (WRITETAG_OK);
     }
     else {
       return(WRITETAG_FAIL);
     };
   }
   else {
     printf("This should never happen!!\n");
     return(WRITETAG_FAIL);
   }
}

/*    Move file pointer to 128 bytes from end of file, to look for tag.
 *    Three characters here should be "TAG".
 */

int AlreadyGotTag(FILE *somefile) {
  int val;
  char tag[4];
  if (!fseek(somefile,-128,SEEK_END)) {
    if (strcmp(fgets(tag,4,somefile),"TAG")==0) {
      return(TAG_FOUND);
    }
    else {
      return (TAG_NOTFOUND);
    }
  }
  else {
    return(TAG_ERROR);
  }
}

struct tagdata ReadTag(FILE *somefile) {
  int val;
  char tag[4];
  char buf[31];
  struct tagdata sometag;

  if (!fseek(somefile,-128,SEEK_END)) {
    if (strcmp(fgets(tag,4,somefile),"TAG")==0) {
      strcpy(sometag.title,fgets(buf,31,somefile));
      strcpy(sometag.artist,fgets(buf,31,somefile));
      strcpy(sometag.album,fgets(buf,31,somefile));
      strcpy(sometag.year,fgets(buf,5,somefile));
      strcpy(sometag.comment,fgets(buf,31,somefile));
      sometag.genre=getc(somefile);
    }
  }
  return(sometag);
}

int DisplayTag(struct tagdata sometag) {
  printf("--- |%s|\n",sometag.title);
  printf("--- |%s|\n",sometag.artist);
  printf("--- |%s|\n",sometag.album);
  printf("--- |%s|\n",sometag.year);
  printf("--- |%s|\n",sometag.comment);
  printf("--- |%d|\n",sometag.genre);
  return(0);
}

struct tagdata CreateTag(char *filename) {
  char *r;
  char *s;
  char tag[4];
  char buf[31];
  struct tagdata sometag;
  int lenart;
  int i;
  char *art;
  char *album;

  // printf("- Creating a tag from filename %s ...\n",filename);
  // Search for " - " in the filename
  r=strstr(filename," - ");
  if (!r) {
    // printf("- Cannot find - in filename.\n");
    strncpy(sometag.title,filename,30);
    sometag.title[30]='\0';
    strncpy(sometag.artist,filename,30);
    sometag.artist[30]='\0';
    strncpy(sometag.album,filename,30);
    sometag.album[30]='\0';
    strncpy(sometag.year,"2000",4);
    sometag.year[4]='\0';
    strncpy(sometag.comment,TAG_COMMENT,30);
    sometag.comment[30]='\0';
    sometag.genre=13;
  }
  else {
    // printf("- Found - processing ...\n");
    lenart=r-filename;
    r+=3;
    strncpy(sometag.title,r,30);
    sometag.title[strlen(sometag.title)-4]='\0';
    if (strlen(sometag.title)<30) {
      for (i=strlen(sometag.title);i<30;i++) {
        sometag.title[i]=' ';
      }
    }
    else {
      sometag.title[30]='\0';
    }
    strncpy(sometag.artist,filename,lenart);
    sometag.artist[lenart]='\0';
    if (strlen(sometag.artist)<30) {
      for (i=strlen(sometag.artist);i<30;i++) {
        sometag.artist[i]=' ';
      }
    }
    else {
      sometag.artist[30]='\0';
    }
    //strncpy(sometag.album,filename,30);
    strcpy(sometag.album,"                              ");
    strncpy(sometag.year,"2000",4);
    sometag.year[4]='\0';
    strncpy(sometag.comment,TAG_COMMENT,30);
    sometag.comment[30]='\0';
    sometag.genre=13;
  }  
  return(sometag);
}