buffer.c

unix 下tar 执行程序的源代码

				ptr=(char *)malloc(strlen(f_volhdr)+20);
				sprintf(ptr,"%s Volume %d",f_volhdr,volno);
#endif
				if (re_match (label_pattern, head->header.name,
					      strlen (head->header.name),
					      0, 0) < 0) {
					msg("Volume mismatch! %s!=%s",f_volhdr,
					    head->header.name);
					--volno;
					goto try_volume;
				      }
				    
#if 0
 				if(strcmp(ptr,head->header.name)) {
					msg("Volume mismatch! %s!=%s",ptr,head->header.name);
					--volno;
					free(ptr);
					goto try_volume;
				}
				free(ptr);
#endif
			}
			if(f_verbose)
				fprintf(msg_file,"Reading %s",head->header.name);
			head++;
		} else if(f_volhdr) {
			msg("Warning:  No volume header!");
		}

		if(real_s_name[0]) {
			long from_oct();

			if(head->header.linkflag!=LF_MULTIVOL || strcmp(head->header.name,real_s_name)) {
				msg("%s is not continued on this volume!",real_s_name);
				--volno;
				goto try_volume;
			}
			if(real_s_totsize!=from_oct(1+12,head->header.size)+from_oct(1+12,head->header.offset)) {
				msg("%s is the wrong size (%ld!=%ld+%ld)",
				       head->header.name,save_totsize,
				       from_oct(1+12,head->header.size),
				       from_oct(1+12,head->header.offset));
				--volno;
				goto try_volume;
			}
			if(real_s_totsize-real_s_sizeleft!=from_oct(1+12,head->header.offset)) {
				msg("This volume is out of sequence");
				--volno;
				goto try_volume;
			}
			head++;
		}
		ar_record=head;
		return;
	} else if (err < 0) {
		readerror();
		goto error_loop;	/* Try again */
	}

 short_read:
	more = ar_block->charptr + err;
	left = blocksize - err;

again:
	if (0 == (((unsigned)left) % RECORDSIZE)) {
		/* FIXME, for size=0, multi vol support */
		/* On the first block, warn about the problem */
		if (!f_reblock && baserec == 0 && f_verbose && err > 0) {
		/*	msg("Blocksize = %d record%s",
				err / RECORDSIZE, (err > RECORDSIZE)? "s": "");*/
			msg("Blocksize = %d records", err / RECORDSIZE);
		}
		ar_last = ar_block + ((unsigned)(blocksize - left))/RECORDSIZE;
		return;
	}
	if (f_reblock) {
		/*
		 * User warned us about this.  Fix up.
		 */
		if (left > 0) {
error2loop:
			err = rmtread(archive, more, (int)left);
			if (err < 0) {
				readerror();
				goto error2loop;	/* Try again */
			}
			if (err == 0) {
				msg("archive %s EOF not on block boundary",ar_file);
				exit(EX_BADARCH);
			}
			left -= err;
			more += err;
			goto again;
		}
	} else {
		msg("only read %d bytes from archive %s",err,ar_file);
		exit(EX_BADARCH);
	}
}


/*
 * Flush the current buffer to/from the archive.
 */
flush_archive()
{
	int c;

	baserec += ar_last - ar_block;	/* Keep track of block #s */
	ar_record = ar_block;		/* Restore pointer to start */
	ar_last = ar_block + blocking;	/* Restore pointer to end */

	if (ar_reading) {
		if(time_to_start_writing) {
			time_to_start_writing=0;
			ar_reading=0;

			if(file_to_switch_to>=0) {
				if((c=rmtclose(archive))<0)
					msg_perror("Warning: can't close %s(%d,%d)",ar_file,archive,c);

				archive=file_to_switch_to;
			} else
	 			(void)backspace_output();
			fl_write();
		} else
			fl_read();
	} else {
		fl_write();
	}
}

/* Backspace the archive descriptor by one blocks worth.
   If its a tape, MTIOCTOP will work.  If its something else,
   we try to seek on it.  If we can't seek, we lose! */
backspace_output()
{
	long cur;
	/* int er; */
	extern char *output_start;

#ifdef MTIOCTOP
	struct mtop t;

	t.mt_op = MTBSR;
	t.mt_count = 1;
	if((rmtioctl(archive,MTIOCTOP,&t))>=0)
		return 1;
	if(errno==EIO && (rmtioctl(archive,MTIOCTOP,&t))>=0)
		return 1;
#endif

		cur=rmtlseek(archive,0L,1);
	cur-=blocksize;
	/* Seek back to the beginning of this block and
	   start writing there. */

	if(rmtlseek(archive,cur,0)!=cur) {
		/* Lseek failed.  Try a different method */
		msg("Couldn't backspace archive file.  It may be unreadable without -i.");
		/* Replace the first part of the block with nulls */
		if(ar_block->charptr!=output_start)
			bzero(ar_block->charptr,output_start-ar_block->charptr);
		return 2;
	}
	return 3;
}


/*
 * Close the archive file.
 */
close_archive()
{
	int child;
	int status;
	int c;

	if (time_to_start_writing || !ar_reading)
		flush_archive();
	if(cmd_mode==CMD_DELETE) {
		long pos;

		pos = rmtlseek(archive,0L,1);
#ifndef MSDOS
		/* FIXME does ftruncate really take an INT?! */
		(void) ftruncate(archive,(int)pos);
#else
		(void)rmtwrite(archive,"",0);
#endif
	}
	if(f_verify)
		verify_volume();

	if((c=rmtclose(archive))<0)
		msg_perror("Warning: can't close %s(%d,%d)",ar_file,archive,c);

#ifndef	MSDOS
	if (childpid) {
		/*
		 * Loop waiting for the right child to die, or for
		 * no more kids.
		 */
		while (((child = wait(&status)) != childpid) && child != -1)
			;

		if (child != -1) {
			switch (TERM_SIGNAL(status)) {
			case 0:
				/* Child voluntarily terminated  -- but why? */
				if (TERM_VALUE(status) == MAGIC_STAT) {
					exit(EX_SYSTEM);/* Child had trouble */
				}
				if (TERM_VALUE(status) == (SIGPIPE + 128)) {
					/*
					 * /bin/sh returns this if its child
					 * dies with SIGPIPE.  'Sok.
					 */
					break;
				} else if (TERM_VALUE(status))
					msg("child returned status %d",
						TERM_VALUE(status));
			case SIGPIPE:
				break;		/* This is OK. */

			default:
				msg("child died with signal %d%s",
				 TERM_SIGNAL(status),
				 TERM_COREDUMP(status)? " (core dumped)": "");
			}
		}
	}
#endif	/* MSDOS */
}


#ifdef DONTDEF
/*
 * Message management.
 *
 * anno writes a message prefix on stream (eg stdout, stderr).
 *
 * The specified prefix is normally output followed by a colon and a space.
 * However, if other command line options are set, more output can come
 * out, such as the record # within the archive.
 *
 * If the specified prefix is NULL, no output is produced unless the
 * command line option(s) are set.
 *
 * If the third argument is 1, the "saved" record # is used; if 0, the
 * "current" record # is used.
 */
void
anno(stream, prefix, savedp)
	FILE	*stream;
	char	*prefix;
	int	savedp;
{
#	define	MAXANNO	50
	char	buffer[MAXANNO];	/* Holds annorecment */
#	define	ANNOWIDTH 13
	int	space;
	long	offset;
	int	save_e;

	save_e=errno;
	/* Make sure previous output gets out in sequence */
	if (stream == stderr)
		fflush(stdout);
	if (f_sayblock) {
		if (prefix) {
			fputs(prefix, stream);
			putc(' ', stream);
		}
		offset = ar_record - ar_block;
		(void) sprintf(buffer, "rec %d: ",
			savedp?	saved_recno:
				baserec + offset);
		fputs(buffer, stream);
		space = ANNOWIDTH - strlen(buffer);
		if (space > 0) {
			fprintf(stream, "%*s", space, "");
		}
	} else if (prefix) {
		fputs(prefix, stream);
		fputs(": ", stream);
	}
	errno=save_e;
}
#endif

/* We've hit the end of the old volume.  Close it and open the next one */
/* Values for type:  0: writing  1: reading  2: updating */
new_volume(type)
int	type;
{
	int	c;
	char	inbuf[80];
	char	*p;
	static FILE *read_file = 0;
	extern int now_verifying;
	extern char TTY_NAME[];
	char *getenv();

	if(!read_file && !f_run_script_at_end)
		read_file = (archive==0) ? fopen(TTY_NAME, "r") : stdin;

	if(now_verifying)
		return -1;
	if(f_verify)
		verify_volume();
	if((c=rmtclose(archive))<0)
		msg_perror("Warning: can't close %s(%d,%d)",ar_file,archive,c);

	volno++;
 tryagain:
	if (f_run_script_at_end)
		system(info_script);
	else for(;;) {
		fprintf(msg_file,"\007Prepare volume #%d and hit return: ",volno);
		fflush(msg_file);
		if(fgets(inbuf,sizeof(inbuf),read_file)==0) {
 			fprintf(msg_file,"EOF?  What does that mean?");
			if(cmd_mode!=CMD_EXTRACT && cmd_mode!=CMD_LIST && cmd_mode!=CMD_DIFF)
				msg("Warning:  Archive is INCOMPLETE!");
			exit(EX_BADARCH);
		}
		if(inbuf[0]=='\n' || inbuf[0]=='y' || inbuf[0]=='Y')
			break;

		switch(inbuf[0]) {
		case '?':
		{
			fprintf(msg_file,"\
 n [name]   Give a new filename for the next (and subsequent) volume(s)\n\
 q          Abort tar\n\
 !          Spawn a subshell\n\
 ?          Print this list\n");
		}
			break;

		case 'q':	/* Quit */
			fprintf(msg_file,"No new volume; exiting.\n");
			if(cmd_mode!=CMD_EXTRACT && cmd_mode!=CMD_LIST && cmd_mode!=CMD_DIFF)
				msg("Warning:  Archive is INCOMPLETE!");
			exit(EX_BADARCH);

		case 'n':	/* Get new file name */
		{
			char *q,*r;
			static char *old_name;

			for(q= &inbuf[1];*q==' ' || *q=='\t';q++)
				;
			for(r=q;*r;r++)
				if(*r=='\n')
					*r='\0';
			if(old_name)
				free(old_name);
			old_name=p=(char *)malloc((unsigned)(strlen(q)+2));
			if(p==0) {
				msg("Can't allocate memory for name");
				exit(EX_SYSTEM);
			}
			(void) strcpy(p,q);
			ar_file=p;
		}
			break;

		case '!':
#ifdef MSDOS
			spawnl(P_WAIT,getenv("COMSPEC"),"-",0);
#else
				/* JF this needs work! */
			switch(fork()) {
			case -1:
				msg_perror("can't fork!");
				break;
			case 0:
				p=getenv("SHELL");
				if(p==0) p="/bin/sh";
				execlp(p,"-sh","-i",0);
				msg_perror("can't exec a shell %s",p);
				_exit(55);
			default:
				wait(0);
				break;
			}
#endif
			break;
		}
	}

	if(type==2 || f_verify)
		archive=rmtopen(ar_file,O_RDWR|O_CREAT,0666);
	else if(type==1)
		archive=rmtopen(ar_file,O_RDONLY,0666);
	else if(type==0)
		archive=rmtcreat(ar_file,0666);
	else
		archive= -1;

	if(archive<0) {
		msg_perror("can't open %s",ar_file);
		goto tryagain;
	}
#ifdef MSDOS
	setmode(archive,O_BINARY);
#endif
	return 0;
}

/* this is a useless function that takes a buffer returned by wantbytes
   and does nothing with it.  If the function called by wantbytes returns
   an error indicator (non-zero), this function is called for the rest of
   the file.
 */
int
no_op(size,data)
int size;
char *data;
{
	return 0;
}

/* Some other routine wants SIZE bytes in the archive.  For each chunk of
   the archive, call FUNC with the size of the chunk, and the address of
   the chunk it can work with.
 */
int
wantbytes(size,func)
long size;
int (*func)();
{
	char *data;
	long	data_size;

	while(size) {
		data = findrec()->charptr;
		if (data == NULL) {	/* Check it... */
			msg("Unexpected EOF on archive file");
			return -1;
		}
		data_size = endofrecs()->charptr - data;
		if(data_size>size)
			data_size=size;
		if((*func)(data_size,data))
			func=no_op;
		userec((union record *)(data + data_size - 1));
		size-=data_size;
	}
	return 0;
}