ref: 0e96bbd073231aba6cc67421b814609b2b5328b5
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 ([email protected]) * * 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)"); } } } }