list.c

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

/* $Source: /u/mark/src/pax/RCS/list.c,v $
 *
 * $Revision: 1.2 $
 *
 * list.c - List all files on an archive
 *
 * DESCRIPTION
 *
 *	These function are needed to support archive table of contents and
 *	verbose mode during extraction and creation of achives.
 *
 * AUTHOR
 *
 *	Mark H. Colburn, NAPS International ([e-mail])
 *
 * Sponsored by The USENIX Association for public distribution. 
 *
 * Copyright (c) 1989 Mark H. Colburn.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that the above copyright notice is duplicated in all such 
 * forms and that any documentation, advertising materials, and other 
 * materials related to such distribution and use acknowledge that the 
 * software was developed * by Mark H. Colburn and sponsored by The 
 * USENIX Association. 
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 *
 * $Log:	list.c,v $
 * Revision 1.2  89/02/12  10:04:43  mark
 * 1.2 release fixes
 * 
 * Revision 1.1  88/12/23  18:02:14  mark
 * Initial revision
 * 
 */

#ifndef lint
static char *ident = "$Id: list.c,v 1.2 89/02/12 10:04:43 mark Exp $";
static char *copyright = "Copyright (c) 1989 Mark H. Colburn.\nAll rights reserved.\n";
#endif /* ! lint */


/* Headers */

#include "pax.h"


/* Defines */

/*
 * isodigit returns non zero iff argument is an octal digit, zero otherwise
 */
#define	ISODIGIT(c)	(((c) >= '0') && ((c) <= '7'))


/* Function Prototypes */

#ifdef __STDC__

static void cpio_entry(char *, Stat *);
static void tar_entry(char *, Stat *);
static void pax_entry(char *, Stat *);
static void print_mode(ushort);
static long from_oct(int digs, char *where);

#else /* !__STDC__ */

static void cpio_entry();
static void tar_entry();
static void pax_entry();
static void print_mode();
static long from_oct();

#endif /* __STDC__ */


/* Internal Identifiers */

static char       *monnames[] = {
    "Jan", "Feb", "Mar", "Apr", "May", "Jun",
    "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
};


/* read_header - read a header record
 *
 * DESCRIPTION
 *
 * 	Read a record that's supposed to be a header record. Return its 
 *	address in "head", and if it is good, the file's size in 
 *	asb->sb_size.  Decode things from a file header record into a "Stat". 
 *	Also set "head_standard" to !=0 or ==0 depending whether header record 
 *	is "Unix Standard" tar format or regular old tar format. 
 *
 * PARAMETERS
 *
 *	char   *name		- pointer which will contain name of file
 *	Stat   *asb		- pointer which will contain stat info
 *
 * RETURNS
 *
 * 	Return 1 for success, 0 if the checksum is bad, EOF on eof, 2 for a 
 * 	record full of zeros (EOF marker). 
 */

#ifdef __STDC__

int read_header(char *name, Stat *asb)

#else
    
int read_header(name, asb)
char           *name;
Stat           *asb;

#endif
{
    int             i;
    long            sum;
    long	    recsum;
    Link           *link;
    char           *p;
    char            hdrbuf[BLOCKSIZE];

    memset((char *)asb, 0, sizeof(Stat));
    /* read the header from the buffer */
    if (buf_read(hdrbuf, BLOCKSIZE) != 0) {
	return (EOF);
    }

    strcpy(name, hdrbuf);

    recsum = from_oct(8, &hdrbuf[148]);
    sum = 0;
    p = hdrbuf;
    for (i = 0 ; i < 500; i++) {

	/*
	 * We can't use unsigned char here because of old compilers, e.g. V7. 
	 */
	sum += 0xFF & *p++;
    }

    /* Adjust checksum to count the "chksum" field as blanks. */
    for (i = 0; i < 8; i++) {
	sum -= 0xFF & hdrbuf[148 + i];
    }
    sum += ' ' * 8;

    if (sum == 8 * ' ') {

	/*
	 * This is a zeroed record...whole record is 0's except for the 8
	 * blanks we faked for the checksum field. 
	 */
	return (2);
    }
    if (sum == recsum) {
	/*
	 * Good record.  Decode file size and return. 
	 */
	if (hdrbuf[156] != LNKTYPE) {
	    asb->sb_size = from_oct(1 + 12, &hdrbuf[124]);
	}
	asb->sb_mtime = from_oct(1 + 12, &hdrbuf[136]);
	asb->sb_mode = from_oct(8, &hdrbuf[100]);

	if (strcmp(&hdrbuf[257], TMAGIC) == 0) {
	    /* Unix Standard tar archive */
	    head_standard = 1;
#ifdef NONAMES
	    asb->sb_uid = from_oct(8, &hdrbuf[108]);
	    asb->sb_gid = from_oct(8, &hdrbuf[116]);
#else
	    asb->sb_uid = finduid(&hdrbuf[265]);
	    asb->sb_gid = findgid(&hdrbuf[297]);
#endif
	    switch (hdrbuf[156]) {
	    case BLKTYPE:
	    case CHRTYPE:
#ifndef _POSIX_SOURCE
		asb->sb_rdev = makedev(from_oct(8, &hdrbuf[329]),
				      from_oct(8, &hdrbuf[337]));
#endif
		break;
	    default:
		/* do nothing... */
		break;
	    }
	} else {
	    /* Old fashioned tar archive */
	    head_standard = 0;
	    asb->sb_uid = from_oct(8, &hdrbuf[108]);
	    asb->sb_gid = from_oct(8, &hdrbuf[116]);
	}

	switch (hdrbuf[156]) {
	case REGTYPE:
	case AREGTYPE:
	    /*
	     * Berkeley tar stores directories as regular files with a
	     * trailing /
	     */
	    if (name[strlen(name) - 1] == '/') {
		name[strlen(name) - 1] = '\0';
		asb->sb_mode |= S_IFDIR;
	    } else {
		asb->sb_mode |= S_IFREG;
	    }
	    break;
	case LNKTYPE:
	    asb->sb_nlink = 2;
	    linkto(&hdrbuf[157], asb);
	    linkto(name, asb);
	    asb->sb_mode |= S_IFREG;
	    break;
	case BLKTYPE:
	    asb->sb_mode |= S_IFBLK;
	    break;
	case CHRTYPE:
	    asb->sb_mode |= S_IFCHR;
	    break;
	case DIRTYPE:
	    asb->sb_mode |= S_IFDIR;
	    break;
#ifdef S_IFLNK
	case SYMTYPE:
	    asb->sb_mode |= S_IFLNK;
	    strcpy(asb->sb_link, &hdrbuf[157]);
	    break;
#endif
#ifdef S_IFIFO
	case FIFOTYPE:
	    asb->sb_mode |= S_IFIFO;
	    break;
#endif
#ifdef S_IFCTG
	case CONTTYPE:
	    asb->sb_mode |= S_IFCTG;
	    break;
#endif
	}
	return (1);
    }
    return (0);
}


/* print_entry - print a single table-of-contents entry
 *
 * DESCRIPTION
 * 
 *	Print_entry prints a single line of file information.  The format
 *	of the line is the same as that used by the LS command.  For some
 *	archive formats, various fields may not make any sense, such as
 *	the link count on tar archives.  No error checking is done for bad
 *	or invalid data.
 *
 * PARAMETERS
 *
 *	char   *name		- pointer to name to print an entry for
 *	Stat   *asb		- pointer to the stat structure for the file
 */

#ifdef __STDC__

void print_entry(char *name, Stat *asb)

#else
    
void print_entry(name, asb)
char		*name;
Stat	        *asb;

#endif
{
    switch (ar_interface) {
    case TAR:
	tar_entry(name, asb);
	break;
    case CPIO:
	cpio_entry(name, asb);
	break;
    case PAX: pax_entry(name, asb);
	break;
    }
}


/* cpio_entry - print a verbose cpio-style entry
 *
 * DESCRIPTION
 *
 *	Print_entry prints a single line of file information.  The format
 *	of the line is the same as that used by the traditional cpio 
 *	command.  No error checking is done for bad or invalid data.
 *
 * PARAMETERS
 *
 *	char   *name		- pointer to name to print an entry for
 *	Stat   *asb		- pointer to the stat structure for the file
 */

#ifdef __STDC__

static void cpio_entry(char *name, Stat *asb)

#else
    
static void cpio_entry(name, asb)
char	       *name;
Stat	       *asb;

#endif
{
    struct tm	       *atm;
    Link	       *from;
    struct passwd      *pwp;
    struct group       *grp;

    if (f_list && f_verbose) {
	fprintf(msgfile, "%-7o", asb->sb_mode);
	atm = localtime(&asb->sb_mtime);
	if (pwp = getpwuid((int) USH(asb->sb_uid))) {
	    fprintf(msgfile, "%-6s", pwp->pw_name);
	} else {
	    fprintf(msgfile, "%-6u", USH(asb->sb_uid));
	}
	fprintf(msgfile,"%7ld  %3s %2d %02d:%02d:%02d %4d  ",
	               asb->sb_size, monnames[atm->tm_mon], 
		       atm->tm_mday, atm->tm_hour, atm->tm_min, 
		       atm->tm_sec, atm->tm_year + 1900);