fsplib.c

一个linux下的ftp程序。它是使用文件传输协议的一系列程序的集合。

       /* set entry namelen field */
       if (namelen > 255)
           entry->namlen = 255;
       else
           entry->namlen = namelen;
       /* set record length */	   
       entry->reclen = 10+namelen;

       /* pad to 4 byte boundary */
       while( dir->dirpos & 0x3 )
       {
         dir->dirpos++;
         entry->reclen++;
       }

       /* and return it */
       *result=entry;
       return 0;  
    }
}

struct dirent * fsp_readdir(FSP_DIR *dirp)
{
    static struct dirent entry;
    struct dirent *result;
    
    
    if (dirp == NULL) return NULL;
    if ( fsp_readdir_r(dirp,&entry,&result) )
        return NULL;
    else
        return result;
}

long fsp_telldir(FSP_DIR *dirp)
{
    return dirp->dirpos;
}

void fsp_seekdir(FSP_DIR *dirp, long loc)
{
    dirp->dirpos=loc;
}

void fsp_rewinddir(FSP_DIR *dirp)
{
    dirp->dirpos=0;
}

int fsp_closedir(FSP_DIR *dirp)
{
    if (dirp == NULL) 
        return -1;
    if(dirp->dirname) free(dirp->dirname);
    free(dirp->data);
    free(dirp);
    return 0;
}

/*  ***************** File input/output functions *********  */
FSP_FILE * fsp_fopen(FSP_SESSION *session, const char *path,const char *modeflags)
{
    FSP_FILE   *f;

    if(session == NULL || path == NULL || modeflags == NULL)
    {
	errno = EINVAL;
	return NULL;
    }

    f=calloc(1,sizeof(FSP_FILE));
    if (f == NULL)
    {
	return NULL;
    }

    /* check and parse flags */
    switch (*modeflags++)
    {
	case 'r':
		  break;
        case 'w':
		  f->writing=1;
		  break;
        case 'a':
	          /* not supported */
		  free(f);
		  errno = ENOTSUP;
		  return NULL;
        default:
		  free(f);
		  errno = EINVAL;
		  return NULL;
    }

    if (*modeflags == '+' || ( *modeflags=='b' && modeflags[1]=='+'))
    {
	free(f);
	errno = ENOTSUP;
	return NULL;
    }

    /* build request packet */
    if(f->writing)
    {
	f->out.cmd=FSP_CC_UP_LOAD;
    }
    else
    {
        if(buildfilename(session,&f->out,path))
	{
	    free(f);
            return NULL;
	}
        f->bufpos=FSP_SPACE;
	f->out.cmd=FSP_CC_GET_FILE;
    }
    f->out.xlen=0;

    /* setup control variables */
    f->s=session;
    f->name=strdup(path);
    if(f->name == NULL)
    {
	free(f);
	errno = ENOMEM;
	return NULL;
    }

    return f;
}

size_t fsp_fread(void *dest,size_t size,size_t count,FSP_FILE *file)
{
    size_t total,done,havebytes;
    char *ptr;

    total=count*size;
    done=0;
    ptr=dest;
    
    if(file->eof) return 0;

    while(1)
    {
	/* need more data? */
	if(file->bufpos>=FSP_SPACE)
	{
	    /* fill the buffer */
	    file->out.pos=file->pos;
	    if(fsp_transaction(file->s,&file->out,&file->in))
	    {
	         file->err=1;
		 return done/size;
	    }
	    if(file->in.cmd != FSP_CC_GET_FILE)
	    {
		errno = EIO;
		file->err=1;
		return done/size;
	    }
	    file->bufpos=FSP_SPACE-file->in.len;
	    if(file->bufpos > 0)
	    {
	       memmove(file->in.buf+file->bufpos,file->in.buf,file->in.len);
	    }
	    file->pos+=file->in.len;
	}
	havebytes=FSP_SPACE - file->bufpos;
	if (havebytes == 0 )
	{
	    /* end of file! */
	    file->eof=1;
	    errno = 0;
	    return done/size;
	}
	/* copy ready data to output buffer */
	if(havebytes <= total )
	{
	    /* copy all we have */
	    memcpy(ptr,file->in.buf+file->bufpos,havebytes);
	    ptr+=havebytes;
	    file->bufpos=FSP_SPACE;
	    done+=havebytes;
	    total-=havebytes;
	} else
	{
	    /* copy bytes left */
	    memcpy(ptr,file->in.buf+file->bufpos,total);
	    file->bufpos+=total;
	    errno = 0;
	    return count;
	}
    }
}

size_t fsp_fwrite(const void * source, size_t size, size_t count, FSP_FILE * file)
{
    size_t total,done,freebytes;
    const char *ptr;

    if(file->eof || file->err)
	return 0;

    file->out.len=FSP_SPACE;
    total=count*size;
    done=0;
    ptr=source;

    while(1)
    {
	/* need to write some data? */
	if(file->bufpos>=FSP_SPACE)
	{
	    /* fill the buffer */
	    file->out.pos=file->pos;
	    if(fsp_transaction(file->s,&file->out,&file->in))
	    {
	         file->err=1;
		 return done/size;
	    }
	    if(file->in.cmd != FSP_CC_UP_LOAD)
	    {
		errno = EIO;
		file->err=1;
		return done/size;
	    }
	    file->bufpos=0;
	    file->pos+=file->out.len;
	    done+=file->out.len;
	}
	freebytes=FSP_SPACE - file->bufpos;
	/* copy input data to output buffer */
	if(freebytes <= total )
	{
	    /* copy all we have */
	    memcpy(file->out.buf+file->bufpos,ptr,freebytes);
	    ptr+=freebytes;
	    file->bufpos=FSP_SPACE;
	    total-=freebytes;
	} else
	{
	    /* copy bytes left */
	    memcpy(file->out.buf+file->bufpos,ptr,total);
	    file->bufpos+=total;
	    errno = 0;
	    return count;
	}
    }
}

int fsp_fpurge(FSP_FILE *file)
{
    if(file->writing)
    {
	file->bufpos=0;
    }
    else
    {
	file->bufpos=FSP_SPACE;
    }
    errno = 0;
    return 0;
}

int fsp_fflush(FSP_FILE *file)
{
    if(file == NULL)
    {
	errno = ENOTSUP;
	return -1;
    }
    if(!file->writing)
    {
	errno = EBADF;
	return -1;
    }
    if(file->eof || file->bufpos==0)
    {
	errno = 0;
	return 0;
    }

    file->out.pos=file->pos;
    file->out.len=file->bufpos;
    if(fsp_transaction(file->s,&file->out,&file->in))
    {
	 file->err=1;
	 return -1;
    }
    if(file->in.cmd != FSP_CC_UP_LOAD)
    {
	errno = EIO;
	file->err=1;
	return -1;
    }
    file->bufpos=0;
    file->pos+=file->out.len;
    
    errno = 0;
    return 0;
}



int fsp_fclose(FSP_FILE *file)
{
    int rc;

    rc=0;
    errno = 0;
    if(file->writing)
    {
        if(fsp_fflush(file))
	{  
	    rc=-1;
	}
	else if(fsp_install(file->s,file->name,0))
	{
	    rc=-1;
	}
    }
    free(file->name);
    free(file);
    return rc;
}

int fsp_fseek(FSP_FILE *stream, long offset, int whence)
{
    long newoffset;

    switch(whence)
    {
	case SEEK_SET:
	              newoffset = offset;
		      break;
        case SEEK_CUR:
		      newoffset = stream->pos + offset;
		      break;
        case SEEK_END:
	              errno = ENOTSUP;
		      return -1;
	default:
		      errno = EINVAL;
		      return -1;
    }
    if(stream->writing)
    {
	if(fsp_fflush(stream))
	{
	    return -1;
	}
    }
    stream->pos=newoffset;
    stream->eof=0;
    fsp_fpurge(stream);
    return 0;
}

long fsp_ftell(FSP_FILE *f)
{
    return f->pos + f->bufpos;
}

void fsp_rewind(FSP_FILE *f)
{
    if(f->writing)
	fsp_fflush(f);
    f->pos=0;
    f->err=0;
    f->eof=0;
    fsp_fpurge(f);
}

/*  **************** Utility functions ****************** */

/* return 0 if user has enough privs for uploading the file */
int fsp_canupload(FSP_SESSION *s,const char *fname)
{
  char *dir;
  unsigned char dirpro;
  int rc;
  struct stat sb;

  dir=directoryfromfilename(fname);
  if(dir == NULL)
  {
      errno = ENOMEM;
      return -1;
  }
  
  rc=fsp_getpro(s,dir,&dirpro);
  free(dir);

  if(rc)
  {
      return -1;
  }
  
  if(dirpro & FSP_DIR_OWNER) 
      return 0;
  
  if( ! (dirpro & FSP_DIR_ADD))
      return -1;
      
  if (dirpro & FSP_DIR_DEL)
     return 0;
     
  /* we need to check file existence, because we can not overwrite files */
  
  rc = fsp_stat(s,fname,&sb);
  
  if (rc == 0)
      return -1;
  else
      return 0;
}

/* install file opened for writing */
int fsp_install(FSP_SESSION *s,const char *fname,time_t timestamp)
{
    int rc;
    FSP_PKT in,out;

    /* and install a new file */
    out.cmd=FSP_CC_INSTALL;
    out.xlen=0;
    out.pos=0;
    rc=0;
    if( buildfilename(s,&out,fname) )
	rc=-1;
    else
	{
	    if (timestamp != 0)
	    {
		/* add timestamp extra data */
		*(uint32_t *)(out.buf+out.len)=htonl(timestamp);
		out.xlen=4;
		out.pos=4;
	    }
	    if(fsp_transaction(s,&out,&in))
	    {
		rc=-1;
	    } else
	    {
		if(in.cmd != FSP_CC_INSTALL)
		{
		    rc=-1;
		    errno = EPERM;
		}
	    }
	}

    return rc;
}
/* Get protection byte from the directory */
int fsp_getpro(FSP_SESSION *s,const char *directory,unsigned char *result)
{
   FSP_PKT in,out;
   
   if(buildfilename(s,&out,directory))
       return -1;
   out.cmd=FSP_CC_GET_PRO;
   out.xlen=0;
   out.pos=0;

   if(fsp_transaction(s,&out,&in))
       return -1;

   if(in.cmd != FSP_CC_GET_PRO || in.pos != FSP_PRO_BYTES)
   {
       errno = ENOMSG;
       return -1;
   }

   if(result)
      *result=in.buf[in.len];
   errno = 0;
   return  0;
}

int fsp_stat(FSP_SESSION *s,const char *path,struct stat *sb)
{
   FSP_PKT in,out;
   unsigned char ftype;
   
   if(buildfilename(s,&out,path))
       return -1;
   out.cmd=FSP_CC_STAT;
   out.xlen=0;
   out.pos=0;

   if(fsp_transaction(s,&out,&in))
       return -1;

   if(in.cmd != FSP_CC_STAT)
   {
       errno = ENOTSUP;
       return -1;
   }
   /* parse results */
   ftype=in.buf[8];
   if(ftype == 0)
   {
       errno = ENOENT;
       return -1;
   }
   sb->st_uid=sb->st_gid=0;
   sb->st_mtime=sb->st_ctime=sb->st_atime=ntohl( *(const uint32_t *)( in.buf ));
   sb->st_size=ntohl( *(const uint32_t *)(in.buf + 4 ));
   sb->st_blocks=(sb->st_size+511)/512;
   if (ftype==FSP_RDTYPE_DIR)
   {
       sb->st_mode=S_IFDIR | 0755;
       sb->st_nlink=2;
   }
   else
   {
       sb->st_mode=S_IFREG | 0644;
       sb->st_nlink=1;
   }

   errno = 0;
   return  0;
}

int fsp_mkdir(FSP_SESSION *s,const char *directory)
{
   return simplecommand(s,directory,FSP_CC_MAKE_DIR);
}

int fsp_rmdir(FSP_SESSION *s,const char *directory)
{
   return simplecommand(s,directory,FSP_CC_DEL_DIR);
}

int fsp_unlink(FSP_SESSION *s,const char *directory)
{
   return simplecommand(s,directory,FSP_CC_DEL_FILE);
}

int fsp_rename(FSP_SESSION *s,const char *from, const char *to)
{
   FSP_PKT in,out;
   int l;
   
   if(buildfilename(s,&out,from))
       return -1;
   /* append target name */
   l=strlen(to)+1;
   if( l + out.len > FSP_SPACE )
   {
       errno = ENAMETOOLONG;
       return -1;
   }
   memcpy(out.buf+out.len,to,l);
   out.xlen = l;

   if(s->password)
   {
       l=strlen(s->password)+1;
       if(out.len + out.xlen + l > FSP_SPACE)
       {
	   errno = ENAMETOOLONG;
	   return -1;
       }
       out.buf[out.len+out.xlen-1] = '\n';
       memcpy(out.buf+out.len+out.xlen,s->password,l);
       out.xlen += l;
   }

   out.cmd=FSP_CC_RENAME;
   out.pos=out.xlen;
    
   if(fsp_transaction(s,&out,&in))
       return -1;

   if(in.cmd != FSP_CC_RENAME)
   {
       errno = EPERM;
       return -1;
   }

   errno = 0; 
   return 0;
}

int fsp_access(FSP_SESSION *s,const char *path, int mode)
{
    struct stat sb;
    int rc;
    unsigned char dirpro;
    char *dir;

    rc=fsp_stat(s,path,&sb);
    if(rc == -1)
    {
	/* not found */
	/* errno is set by fsp_stat */
	return -1;
    }

    /* just test file existence */
    if(mode == F_OK)
    {
	errno = 0;
	return  0;
    }

    /* deny execute access to file */
    if (mode & X_OK)
    {
	if(S_ISREG(sb.st_mode))
	{
	    errno = EACCES;
	    return -1;
	}
    }
    
    /* Need to get ACL of directory */
    if(S_ISDIR(sb.st_mode))
	dir=NULL;
    else
	dir=directoryfromfilename(path);	
    
    rc=fsp_getpro(s,dir==NULL?path:dir,&dirpro);
    /* get pro failure */
    if(rc)
    {
	if(dir) free(dir);
	errno = EACCES;
	return -1;
    }
    /* owner shortcut */
    if(dirpro & FSP_DIR_OWNER)
    {
	if(dir) free(dir);
	errno = 0;
	return 0;
    }
    /* check read access */
    if(mode & R_OK)
    {
	if(dir)
	{
	    if(! (dirpro & FSP_DIR_GET))
	    {
		free(dir);
		errno = EACCES;
		return -1;
	    }
	} else
	{
	    if(! (dirpro & FSP_DIR_LIST))
	    {
		errno = EACCES;
		return -1;
	    }
	}
    }
    /* check write access */
    if(mode & W_OK)
    {
	if(dir)
	{
	    if( !(dirpro & FSP_DIR_DEL) || !(dirpro & FSP_DIR_ADD))
	    {
		free(dir);
		errno = EACCES;
		return -1;
	    }
	} else
	{
	    /* when checking directory for write access we are cheating
	       by allowing ADD or DEL right */
	    if( !(dirpro & FSP_DIR_DEL) && !(dirpro & FSP_DIR_ADD))
	    {
		errno = EACCES;
		return -1;
	    }
	}
    }

    if(dir) free(dir);
    errno = 0;
    return 0;
}