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/* $Source: /u/mark/src/pax/RCS/link.c,v $

 *

 * $Revision: 1.2 $

 *

 * link.c - functions for handling multiple file links 

 *

 * DESCRIPTION

 *

 *	These function manage the link chains which are used to keep track

 *	of outstanding links during archive reading and writing.

 *

 * AUTHOR

 *

 *	Mark H. Colburn, NAPS International (mark@jhereg.mn.org)

 *

 * 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:	link.c,v $

 * Revision 1.2  89/02/12  10:04:38  mark

 * 1.2 release fixes

 * 

 * Revision 1.1  88/12/23  18:02:12  mark

 * Initial revision

 * 

 */

#ifndef lint

static char *ident = "$Id: link.c,v 1.2 89/02/12 10:04:38 mark Exp $";

static char *copyright = "Copyright (c) 1989 Mark H. Colburn.\nAll rights reserved.\n";

#endif /* ! lint */

/* Headers */

#include "pax.h"

/* Defines */

/*

 * Address link information base. 

 */

#define	LINKHASH(ino)	(linkbase + (ino) % NEL(linkbase))

/*

 * Number of array elements. 

 */

#define	NEL(a)		(sizeof(a) / sizeof(*(a)))

/* Internal Identifiers */

static Link    *linkbase[256];	/* Unresolved link information */

/* linkfrom - find a file to link from 

 *

 * DESCRIPTION

 *

 *	Linkfrom searches the link chain to see if there is a file in the

 *	link chain which has the same inode number as the file specified

 *	by the stat block pointed at by asb.  If a file is found, the

 *	name is returned to the caller, otherwise a NULL is returned.

 *

 * PARAMETERS

 *

 *	char    *name   - name of the file which we are attempting

 *                        to find a link for

 *	Stat	*asb	- stat structure of file to find a link to

 *

 * RETURNS

 *

 * 	Returns a pointer to a link structure, or NULL if unsuccessful. 

 *

 */

#ifdef __STDC__

Link *linkfrom(char *name, Stat *asb)

#else

Link *linkfrom(name, asb)

char           *name;

Stat           *asb;

#endif

{

    Link           *linkp;

    Link           *linknext;

    Path           *path;

    Path           *pathnext;

    Link          **abase;

    for (linkp = *(abase = LINKHASH(asb->sb_ino)); linkp; linkp = linknext) {

	if (linkp->l_nlink == 0) {

	    if (linkp->l_name) {

		free((char *) linkp->l_name);

	    }

	    if (linknext = linkp->l_forw) {

		linknext->l_back = linkp->l_back;

	    }

	    if (linkp->l_back) {

		linkp->l_back->l_forw = linkp->l_forw;

	    }

	    free((char *) linkp);

	    *abase = (Link *)NULL;

	} else if (linkp->l_ino == asb->sb_ino && linkp->l_dev == asb->sb_dev) {

	    /* 

	     * check to see if a file with the name "name" exists in the 

	     * chain of files which we have for this particular link

	     */

	    for (path = linkp->l_path; path; path = pathnext) {

		if (strcmp(path->p_name, name) == 0) {

		    --linkp->l_nlink;

		    if (path->p_name) {

			free(path->p_name);

		    }

		    if (pathnext = path->p_forw) {

			pathnext->p_back = path->p_back;

		    }

		    if (path->p_back) {

			path->p_back->p_forw = pathnext;

		    }

		    if (linkp->l_path == path) {

			linkp->l_path = pathnext;

		    }

		    free(path);

		    return (linkp);

		}

		pathnext = path->p_forw;

	    }

	    return((Link *)NULL);

	} else {

	    linknext = linkp->l_forw;

	}

    }

    return ((Link *)NULL);

}

/* islink - determine whether a given file really a link

 *

 * DESCRIPTION

 *

 *	Islink searches the link chain to see if there is a file in the

 *	link chain which has the same inode number as the file specified

 *	by the stat block pointed at by asb.  If a file is found, a

 *	non-zero value is returned to the caller, otherwise a 0 is

 *	returned.

 *

 * PARAMETERS

 *

 *	char    *name   - name of file to check to see if it is link.

 *	Stat	*asb	- stat structure of file to find a link to

 *

 * RETURNS

 *

 * 	Returns a pointer to a link structure, or NULL if unsuccessful. 

 *

 */

#ifdef __STDC__

Link *islink(char *name, Stat *asb)

#else

Link *islink(name, asb)

char           *name;

Stat           *asb;

#endif

{

    Link           *linkp;

    Link           *linknext;

    for (linkp = *(LINKHASH(asb->sb_ino)); linkp; linkp = linknext) {

	if (linkp->l_ino == asb->sb_ino && linkp->l_dev == asb->sb_dev) {

	    if (strcmp(name, linkp->l_name) == 0) {

		return ((Link *)NULL);

	    } 

	    return (linkp);

	} else {

	    linknext = linkp->l_forw;

	}

    }

    return ((Link *)NULL);

}

/* linkto  - remember a file with outstanding links 

 *

 * DESCRIPTION

 *

 *	Linkto adds the specified file to the link chain.  Any subsequent

 *	calls to linkfrom which have the same inode will match the file

 *	just entered.  If not enough space is available to make the link

 *	then the item is not added to the link chain, and a NULL is

 *	returned to the calling function.

 *

 * PARAMETERS

 *

 *	char	*name	- name of file to remember

 *	Stat	*asb	- pointer to stat structure of file to remember

 *

 * RETURNS

 *

 * 	Returns a pointer to the associated link structure, or NULL when 

 *	linking is not possible. 

 *

 */

#ifdef __STDC__

Link *linkto(char *name, Stat *asb)

#else

Link *linkto(name, asb)

char           *name;

Stat           *asb;

#endif

{

    Link           *linkp;

    Link           *linknext;

    Path           *path;

    Link          **abase;

    for (linkp = *(LINKHASH(asb->sb_ino)); linkp; linkp = linknext) {

	if (linkp->l_ino == asb->sb_ino && linkp->l_dev == asb->sb_dev) {

	    if ((path = (Path *) mem_get(sizeof(Path))) == (Path *)NULL || 

		(path->p_name = mem_str(name)) == (char *)NULL) {

		return((Link *)NULL);

	    }

	    if (path->p_forw = linkp->l_path) {

		if (linkp->l_path->p_forw) {

		    linkp->l_path->p_forw->p_back = path;

		}

	    } else {

		linkp->l_path = path;

	    }

	    path->p_back = (Path *)NULL;

	    return(linkp);

	} else {

	    linknext = linkp->l_forw;

	}

    }

    /*

     * This is a brand new link, for which there is no other information

     */

    if ((asb->sb_mode & S_IFMT) == S_IFDIR

	|| (linkp = (Link *) mem_get(sizeof(Link))) == (Link *)NULL

	|| (linkp->l_name = mem_str(name)) == (char *)NULL) {

	return ((Link *)NULL);

    }

    linkp->l_dev = asb->sb_dev;

    linkp->l_ino = asb->sb_ino;

    linkp->l_nlink = asb->sb_nlink - 1;

    linkp->l_size = asb->sb_size;

    linkp->l_path = (Path *)NULL;

    if (linkp->l_forw = *(abase = LINKHASH(asb->sb_ino))) {

	linkp->l_forw->l_back = linkp;

    } else {

	*abase = linkp;

    }

    linkp->l_back = (Link *)NULL;

    return (linkp);

}

/* linkleft - complain about files with unseen links 

 *

 * DESCRIPTION

 *

 *	Linksleft scans through the link chain to see if there were any

 *	files which have outstanding links that were not processed by the

 *	archive.  For each file in the link chain for which there was not

 *	a file,  and error message is printed.

 */

#ifdef __STDC__

void linkleft(void)

#else

void linkleft()

#endif

{

    Link           *lp;

    Link          **base;

    for (base = linkbase; base < linkbase + NEL(linkbase); ++base) {

	for (lp = *base; lp; lp = lp->l_forw) {

	    if (lp->l_nlink) {

		warn(lp->l_path->p_name, "Unseen link(s)");

	    }

	}

    }

}