hardenedbsd/HardenedBSD
1
0
Fork 0
mirror of https://git.hardenedbsd.org/hardenedbsd/HardenedBSD.git synced 2024-12-22 08:53:41 +01:00
Code Issues Actions Packages Projects Releases Wiki Activity
a829865d8e
HardenedBSD/bin/csh/dol.c
David Greenman 89730b290a Added $Id$
1994-09-24 02:59:15 +00:00

988 lines
20 KiB
C
Raw Blame History

/*-
* Copyright (c) 1980, 1991, 1993
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $Id$
*/
#ifndef lint
static char sccsid[] = "@(#)dol.c 8.1 (Berkeley) 5/31/93";
#endif /* not lint */
#include <sys/types.h>
#include <fcntl.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#if __STDC__
# include <stdarg.h>
#else
# include <varargs.h>
#endif
#include "csh.h"
#include "extern.h"
/*
* These routines perform variable substitution and quoting via ' and ".
* To this point these constructs have been preserved in the divided
* input words. Here we expand variables and turn quoting via ' and " into
* QUOTE bits on characters (which prevent further interpretation).
* If the `:q' modifier was applied during history expansion, then
* some QUOTEing may have occurred already, so we dont "trim()" here.
*/
static int Dpeekc, Dpeekrd; /* Peeks for DgetC and Dreadc */
static Char *Dcp, **Dvp; /* Input vector for Dreadc */
#define DEOF -1
#define unDgetC(c) Dpeekc = c
#define QUOTES (_QF|_QB|_ESC) /* \ ' " ` */
/*
* The following variables give the information about the current
* $ expansion, recording the current word position, the remaining
* words within this expansion, the count of remaining words, and the
* information about any : modifier which is being applied.
*/
#define MAXWLEN (BUFSIZ - 4)
#define MAXMOD MAXWLEN /* This cannot overflow */
static Char *dolp; /* Remaining chars from this word */
static Char **dolnxt; /* Further words */
static int dolcnt; /* Count of further words */
static Char dolmod[MAXMOD]; /* : modifier character */
static int dolnmod; /* Number of modifiers */
static int dolmcnt; /* :gx -> 10000, else 1 */
static int dolwcnt; /* :wx -> 10000, else 1 */
static void Dfix2 __P((Char **));
static Char *Dpack __P((Char *, Char *));
static int Dword __P((void));
static void dolerror __P((Char *));
static int DgetC __P((int));
static void Dgetdol __P((void));
static void fixDolMod __P((void));
static void setDolp __P((Char *));
static void unDredc __P((int));
static int Dredc __P((void));
static void Dtestq __P((int));
/*
* Fix up the $ expansions and quotations in the
* argument list to command t.
*/
void
Dfix(t)
register struct command *t;
{
register Char **pp;
register Char *p;
if (noexec)
return;
/* Note that t_dcom isn't trimmed thus !...:q's aren't lost */
for (pp = t->t_dcom; (p = *pp++) != NULL;)
for (; *p; p++) {
if (cmap(*p, _DOL | QUOTES)) { /* $, \, ', ", ` */
Dfix2(t->t_dcom); /* found one */
blkfree(t->t_dcom);
t->t_dcom = gargv;
gargv = 0;
return;
}
}
}
/*
* $ substitute one word, for i/o redirection
*/
Char *
Dfix1(cp)
register Char *cp;
{
Char *Dv[2];
if (noexec)
return (0);
Dv[0] = cp;
Dv[1] = NULL;
Dfix2(Dv);
if (gargc != 1) {
setname(vis_str(cp));
stderror(ERR_NAME | ERR_AMBIG);
}
cp = Strsave(gargv[0]);
blkfree(gargv), gargv = 0;
return (cp);
}
/*
* Subroutine to do actual fixing after state initialization.
*/
static void
Dfix2(v)
Char **v;
{
ginit(); /* Initialize glob's area pointers */
Dvp = v;
Dcp = STRNULL; /* Setup input vector for Dreadc */
unDgetC(0);
unDredc(0); /* Clear out any old peeks (at error) */
dolp = 0;
dolcnt = 0; /* Clear out residual $ expands (...) */
while (Dword())
continue;
}
/*
* Pack up more characters in this word
*/
static Char *
Dpack(wbuf, wp)
Char *wbuf, *wp;
{
register int c;
register int i = MAXWLEN - (wp - wbuf);
for (;;) {
c = DgetC(DODOL);
if (c == '\\') {
c = DgetC(0);
if (c == DEOF) {
unDredc(c);
*wp = 0;
Gcat(STRNULL, wbuf);
return (NULL);
}
if (c == '\n')
c = ' ';
else
c |= QUOTE;
}
if (c == DEOF) {
unDredc(c);
*wp = 0;
Gcat(STRNULL, wbuf);
return (NULL);
}
if (cmap(c, _SP | _NL | _QF | _QB)) { /* sp \t\n'"` */
unDgetC(c);
if (cmap(c, QUOTES))
return (wp);
*wp++ = 0;
Gcat(STRNULL, wbuf);
return (NULL);
}
if (--i <= 0)
stderror(ERR_WTOOLONG);
*wp++ = c;
}
}
/*
* Get a word. This routine is analogous to the routine
* word() in sh.lex.c for the main lexical input. One difference
* here is that we don't get a newline to terminate our expansion.
* Rather, DgetC will return a DEOF when we hit the end-of-input.
*/
static int
Dword()
{
register int c, c1;
Char wbuf[BUFSIZ];
register Char *wp = wbuf;
register int i = MAXWLEN;
register bool dolflg;
bool sofar = 0, done = 0;
while (!done) {
done = 1;
c = DgetC(DODOL);
switch (c) {
case DEOF:
if (sofar == 0)
return (0);
/* finish this word and catch the code above the next time */
unDredc(c);
/* fall into ... */
case '\n':
*wp = 0;
Gcat(STRNULL, wbuf);
return (1);
case ' ':
case '\t':
done = 0;
break;
case '`':
/* We preserve ` quotations which are done yet later */
*wp++ = c, --i;
case '\'':
case '"':
/*
* Note that DgetC never returns a QUOTES character from an
* expansion, so only true input quotes will get us here or out.
*/
c1 = c;
dolflg = c1 == '"' ? DODOL : 0;
for (;;) {
c = DgetC(dolflg);
if (c == c1)
break;
if (c == '\n' || c == DEOF)
stderror(ERR_UNMATCHED, c1);
if ((c & (QUOTE | TRIM)) == ('\n' | QUOTE))
--wp, ++i;
if (--i <= 0)
stderror(ERR_WTOOLONG);
switch (c1) {
case '"':
/*
* Leave any `s alone for later. Other chars are all
* quoted, thus `...` can tell it was within "...".
*/
*wp++ = c == '`' ? '`' : c | QUOTE;
break;
case '\'':
/* Prevent all further interpretation */
*wp++ = c | QUOTE;
break;
case '`':
/* Leave all text alone for later */
*wp++ = c;
break;
default:
break;
}
}
if (c1 == '`')
*wp++ = '`' /* i--; eliminated */;
sofar = 1;
if ((wp = Dpack(wbuf, wp)) == NULL)
return (1);
else {
i = MAXWLEN - (wp - wbuf);
done = 0;
}
break;
case '\\':
c = DgetC(0); /* No $ subst! */
if (c == '\n' || c == DEOF) {
done = 0;
break;
}
c |= QUOTE;
break;
default:
break;
}
if (done) {
unDgetC(c);
sofar = 1;
if ((wp = Dpack(wbuf, wp)) == NULL)
return (1);
else {
i = MAXWLEN - (wp - wbuf);
done = 0;
}
}
}
/* Really NOTREACHED */
return (0);
}
/*
* Get a character, performing $ substitution unless flag is 0.
* Any QUOTES character which is returned from a $ expansion is
* QUOTEd so that it will not be recognized above.
*/
static int
DgetC(flag)
register int flag;
{
register int c;
top:
if ((c = Dpeekc) != '\0') {
Dpeekc = 0;
return (c);
}
if (lap) {
c = *lap++ & (QUOTE | TRIM);
if (c == 0) {
lap = 0;
goto top;
}
quotspec:
if (cmap(c, QUOTES))
return (c | QUOTE);
return (c);
}
if (dolp) {
if ((c = *dolp++ & (QUOTE | TRIM)) != '\0')
goto quotspec;
if (dolcnt > 0) {
setDolp(*dolnxt++);
--dolcnt;
return (' ');
}
dolp = 0;
}
if (dolcnt > 0) {
setDolp(*dolnxt++);
--dolcnt;
goto top;
}
c = Dredc();
if (c == '$' && flag) {
Dgetdol();
goto top;
}
return (c);
}
static Char *nulvec[] = {0};
static struct varent nulargv = {nulvec, STRargv, { NULL, NULL, NULL }, 0};
static void
dolerror(s)
Char *s;
{
setname(vis_str(s));
stderror(ERR_NAME | ERR_RANGE);
}
/*
* Handle the multitudinous $ expansion forms.
* Ugh.
*/
static void
Dgetdol()
{
register Char *np;
register struct varent *vp = NULL;
Char name[4 * MAXVARLEN + 1];
int c, sc;
int subscr = 0, lwb = 1, upb = 0;
bool dimen = 0, bitset = 0;
char tnp;
Char wbuf[BUFSIZ];
static Char *dolbang = NULL;
dolnmod = dolmcnt = dolwcnt = 0;
c = sc = DgetC(0);
if (c == '{')
c = DgetC(0); /* sc is { to take } later */
if ((c & TRIM) == '#')
dimen++, c = DgetC(0); /* $# takes dimension */
else if (c == '?')
bitset++, c = DgetC(0); /* $? tests existence */
switch (c) {
case '!':
if (dimen || bitset)
stderror(ERR_SYNTAX);
if (backpid != 0) {
if (dolbang)
xfree((ptr_t) dolbang);
setDolp(dolbang = putn(backpid));
}
goto eatbrac;
case '$':
if (dimen || bitset)
stderror(ERR_SYNTAX);
setDolp(doldol);
goto eatbrac;
case '<' | QUOTE:
if (bitset)
stderror(ERR_NOTALLOWED, "$?<");
if (dimen)
stderror(ERR_NOTALLOWED, "$?#");
for (np = wbuf; read(OLDSTD, &tnp, 1) == 1; np++) {
*np = (unsigned char) tnp;
if (np >= &wbuf[BUFSIZ - 1])
stderror(ERR_LTOOLONG);
if (tnp == '\n')
break;
}
*np = 0;
/*
* KLUDGE: dolmod is set here because it will cause setDolp to call
* domod and thus to copy wbuf. Otherwise setDolp would use it
* directly. If we saved it ourselves, no one would know when to free
* it. The actual function of the 'q' causes filename expansion not to
* be done on the interpolated value.
*/
dolmod[dolnmod++] = 'q';
dolmcnt = 10000;
setDolp(wbuf);
goto eatbrac;
case DEOF:
case '\n':
stderror(ERR_SYNTAX);
/* NOTREACHED */
break;
case '*':
(void) Strcpy(name, STRargv);
vp = adrof(STRargv);
subscr = -1; /* Prevent eating [...] */
break;
default:
np = name;
if (Isdigit(c)) {
if (dimen)
stderror(ERR_NOTALLOWED, "$#<num>");
subscr = 0;
do {
subscr = subscr * 10 + c - '0';
c = DgetC(0);
} while (Isdigit(c));
unDredc(c);
if (subscr < 0) {
dolerror(vp->v_name);
return;
}
if (subscr == 0) {
if (bitset) {
dolp = ffile ? STR1 : STR0;
goto eatbrac;
}
if (ffile == 0)
stderror(ERR_DOLZERO);
fixDolMod();
setDolp(ffile);
goto eatbrac;
}
if (bitset)
stderror(ERR_DOLQUEST);
vp = adrof(STRargv);
if (vp == 0) {
vp = &nulargv;
goto eatmod;
}
break;
}
if (!alnum(c))
stderror(ERR_VARALNUM);
for (;;) {
*np++ = c;
c = DgetC(0);
if (!alnum(c))
break;
if (np >= &name[MAXVARLEN])
stderror(ERR_VARTOOLONG);
}
*np++ = 0;
unDredc(c);
vp = adrof(name);
}
if (bitset) {
dolp = (vp || getenv(short2str(name))) ? STR1 : STR0;
goto eatbrac;
}
if (vp == 0) {
np = str2short(getenv(short2str(name)));
if (np) {
fixDolMod();
setDolp(np);
goto eatbrac;
}
udvar(name);
/* NOTREACHED */
}
c = DgetC(0);
upb = blklen(vp->vec);
if (dimen == 0 && subscr == 0 && c == '[') {
np = name;
for (;;) {
c = DgetC(DODOL); /* Allow $ expand within [ ] */
if (c == ']')
break;
if (c == '\n' || c == DEOF)
stderror(ERR_INCBR);
if (np >= &name[sizeof(name) / sizeof(Char) - 2])
stderror(ERR_VARTOOLONG);
*np++ = c;
}
*np = 0, np = name;
if (dolp || dolcnt) /* $ exp must end before ] */
stderror(ERR_EXPORD);
if (!*np)
stderror(ERR_SYNTAX);
if (Isdigit(*np)) {
int i;
for (i = 0; Isdigit(*np); i = i * 10 + *np++ - '0')
continue;
if ((i < 0 || i > upb) && !any("-*", *np)) {
dolerror(vp->v_name);
return;
}
lwb = i;
if (!*np)
upb = lwb, np = STRstar;
}
if (*np == '*')
np++;
else if (*np != '-')
stderror(ERR_MISSING, '-');
else {
register int i = upb;
np++;
if (Isdigit(*np)) {
i = 0;
while (Isdigit(*np))
i = i * 10 + *np++ - '0';
if (i < 0 || i > upb) {
dolerror(vp->v_name);
return;
}
}
if (i < lwb)
upb = lwb - 1;
else
upb = i;
}
if (lwb == 0) {
if (upb != 0) {
dolerror(vp->v_name);
return;
}
upb = -1;
}
if (*np)
stderror(ERR_SYNTAX);
}
else {
if (subscr > 0)
if (subscr > upb)
lwb = 1, upb = 0;
else
lwb = upb = subscr;
unDredc(c);
}
if (dimen) {
Char *cp = putn(upb - lwb + 1);
addla(cp);
xfree((ptr_t) cp);
}
else {
eatmod:
fixDolMod();
dolnxt = &vp->vec[lwb - 1];
dolcnt = upb - lwb + 1;
}
eatbrac:
if (sc == '{') {
c = Dredc();
if (c != '}')
stderror(ERR_MISSING, '}');
}
}
static void
fixDolMod()
{
register int c;
c = DgetC(0);
if (c == ':') {
do {
c = DgetC(0), dolmcnt = 1, dolwcnt = 1;
if (c == 'g' || c == 'a') {
if (c == 'g')
dolmcnt = 10000;
else
dolwcnt = 10000;
c = DgetC(0);
}
if ((c == 'g' && dolmcnt != 10000) ||
(c == 'a' && dolwcnt != 10000)) {
if (c == 'g')
dolmcnt = 10000;
else
dolwcnt = 10000;
c = DgetC(0);
}
if (c == 's') { /* [eichin:19910926.0755EST] */
int delimcnt = 2;
int delim = DgetC(0);
dolmod[dolnmod++] = c;
dolmod[dolnmod++] = delim;
if (!delim || letter(delim)
|| Isdigit(delim) || any(" \t\n", delim)) {
seterror(ERR_BADSUBST);
break;
}
while ((c = DgetC(0)) != (-1)) {
dolmod[dolnmod++] = c;
if(c == delim) delimcnt--;
if(!delimcnt) break;
}
if(delimcnt) {
seterror(ERR_BADSUBST);
break;
}
continue;
}
if (!any("htrqxes", c))
stderror(ERR_BADMOD, c);
dolmod[dolnmod++] = c;
if (c == 'q')
dolmcnt = 10000;
}
while ((c = DgetC(0)) == ':');
unDredc(c);
}
else
unDredc(c);
}
static void
setDolp(cp)
register Char *cp;
{
register Char *dp;
int i;
if (dolnmod == 0 || dolmcnt == 0) {
dolp = cp;
return;
}
dp = cp = Strsave(cp);
for (i = 0; i < dolnmod; i++) {
/* handle s// [eichin:19910926.0510EST] */
if(dolmod[i] == 's') {
int delim;
Char *lhsub, *rhsub, *np;
size_t lhlen = 0, rhlen = 0;
int didmod = 0;
delim = dolmod[++i];
if (!delim || letter(delim)
|| Isdigit(delim) || any(" \t\n", delim)) {
seterror(ERR_BADSUBST);
break;
}
lhsub = &dolmod[++i];
while(dolmod[i] != delim && dolmod[++i]) {
lhlen++;
}
dolmod[i] = 0;
rhsub = &dolmod[++i];
while(dolmod[i] != delim && dolmod[++i]) {
rhlen++;
}
dolmod[i] = 0;
do {
dp = Strstr(cp, lhsub);
if (dp) {
np = (Char *) xmalloc((size_t)
((Strlen(cp) + 1 - lhlen + rhlen) *
sizeof(Char)));
(void) Strncpy(np, cp, dp - cp);
(void) Strcpy(np + (dp - cp), rhsub);
(void) Strcpy(np + (dp - cp) + rhlen, dp + lhlen);
xfree((ptr_t) cp);
dp = cp = np;
didmod = 1;
} else {
/* should this do a seterror? */
break;
}
}
while (dolwcnt == 10000);
/*
* restore dolmod for additional words
*/
dolmod[i] = rhsub[-1] = delim;
if (didmod)
dolmcnt--;
else
break;
} else {
int didmod = 0;
do {
if ((dp = domod(cp, dolmod[i]))) {
didmod = 1;
if (Strcmp(cp, dp) == 0) {
xfree((ptr_t) cp);
cp = dp;
break;
}
else {
xfree((ptr_t) cp);
cp = dp;
}
}
else
break;
}
while (dolwcnt == 10000);
dp = cp;
if (didmod)
dolmcnt--;
else
break;
}
}
if (dp) {
addla(dp);
xfree((ptr_t) dp);
}
else
addla(cp);
dolp = STRNULL;
if (seterr)
stderror(ERR_OLD);
}
static void
unDredc(c)
int c;
{
Dpeekrd = c;
}
static int
Dredc()
{
register int c;
if ((c = Dpeekrd) != '\0') {
Dpeekrd = 0;
return (c);
}
if (Dcp && (c = *Dcp++))
return (c & (QUOTE | TRIM));
if (*Dvp == 0) {
Dcp = 0;
return (DEOF);
}
Dcp = *Dvp++;
return (' ');
}
static void
Dtestq(c)
register int c;
{
if (cmap(c, QUOTES))
gflag = 1;
}
/*
* Form a shell temporary file (in unit 0) from the words
* of the shell input up to EOF or a line the same as "term".
* Unit 0 should have been closed before this call.
*/
void
/*ARGSUSED*/
heredoc(term)
Char *term;
{
register int c;
Char *Dv[2];
Char obuf[BUFSIZ], lbuf[BUFSIZ], mbuf[BUFSIZ];
int ocnt, lcnt, mcnt;
register Char *lbp, *obp, *mbp;
Char **vp;
bool quoted;
char *tmp;
if (creat(tmp = short2str(shtemp), 0600) < 0)
stderror(ERR_SYSTEM, tmp, strerror(errno));
(void) close(0);
if (open(tmp, O_RDWR) < 0) {
int oerrno = errno;
(void) unlink(tmp);
errno = oerrno;
stderror(ERR_SYSTEM, tmp, strerror(errno));
}
(void) unlink(tmp); /* 0 0 inode! */
Dv[0] = term;
Dv[1] = NULL;
gflag = 0;
trim(Dv);
rscan(Dv, Dtestq);
quoted = gflag;
ocnt = BUFSIZ;
obp = obuf;
for (;;) {
/*
* Read up a line
*/
lbp = lbuf;
lcnt = BUFSIZ - 4;
for (;;) {
c = readc(1); /* 1 -> Want EOF returns */
if (c < 0 || c == '\n')
break;
if ((c &= TRIM) != '\0') {
*lbp++ = c;
if (--lcnt < 0) {
setname("<<");
stderror(ERR_NAME | ERR_OVERFLOW);
}
}
}
*lbp = 0;
/*
* Check for EOF or compare to terminator -- before expansion
*/
if (c < 0 || eq(lbuf, term)) {
(void) write(0, short2str(obuf), (size_t) (BUFSIZ - ocnt));
(void) lseek(0, 0l, L_SET);
return;
}
/*
* If term was quoted or -n just pass it on
*/
if (quoted || noexec) {
*lbp++ = '\n';
*lbp = 0;
for (lbp = lbuf; (c = *lbp++) != '\0';) {
*obp++ = c;
if (--ocnt == 0) {
(void) write(0, short2str(obuf), BUFSIZ);
obp = obuf;
ocnt = BUFSIZ;
}
}
continue;
}
/*
* Term wasn't quoted so variable and then command expand the input
* line
*/
Dcp = lbuf;
Dvp = Dv + 1;
mbp = mbuf;
mcnt = BUFSIZ - 4;
for (;;) {
c = DgetC(DODOL);
if (c == DEOF)
break;
if ((c &= TRIM) == 0)
continue;
/* \ quotes \ $ ` here */
if (c == '\\') {
c = DgetC(0);
if (!any("$\\`", c))
unDgetC(c | QUOTE), c = '\\';
else
c |= QUOTE;
}
*mbp++ = c;
if (--mcnt == 0) {
setname("<<");
stderror(ERR_NAME | ERR_OVERFLOW);
}
}
*mbp++ = 0;
/*
* If any ` in line do command substitution
*/
mbp = mbuf;
if (any(short2str(mbp), '`')) {
/*
* 1 arg to dobackp causes substitution to be literal. Words are
* broken only at newlines so that all blanks and tabs are
* preserved. Blank lines (null words) are not discarded.
*/
vp = dobackp(mbuf, 1);
}
else
/* Setup trivial vector similar to return of dobackp */
Dv[0] = mbp, Dv[1] = NULL, vp = Dv;
/*
* Resurrect the words from the command substitution each separated by
* a newline. Note that the last newline of a command substitution
* will have been discarded, but we put a newline after the last word
* because this represents the newline after the last input line!
*/
for (; *vp; vp++) {
for (mbp = *vp; *mbp; mbp++) {
*obp++ = *mbp & TRIM;
if (--ocnt == 0) {
(void) write(0, short2str(obuf), BUFSIZ);
obp = obuf;
ocnt = BUFSIZ;
}
}
*obp++ = '\n';
if (--ocnt == 0) {
(void) write(0, short2str(obuf), BUFSIZ);
obp = obuf;
ocnt = BUFSIZ;
}
}
if (pargv)
blkfree(pargv), pargv = 0;
}
}
Reference in New Issue View Git Blame Copy Permalink