ref: ce1edc34368d192db7d3421673ca98c19cc792b2
dir: /sys/src/ape/cmd/pax/link.c/
/* $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)");
}
}
}
}