d/freebsd-dev
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity
2917ba13f7
freebsd-dev/lib/libc/stdio/vfscanf.c
Tim J. Robbins 4712aa3b59 Implement the %lc, %ls and %[ conversions, which read sequences of wide 
characters, non-whitespace wide character strings and wide character
strings in a scanset.
2002-09-23 11:35:50 +00:00

930 lines
22 KiB
C
Raw Blame History

/*-
* Copyright (c) 1990, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Chris Torek.
*
* 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.
*/
#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)vfscanf.c 8.1 (Berkeley) 6/4/93";
#endif /* LIBC_SCCS and not lint */
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "namespace.h"
#include <ctype.h>
#include <inttypes.h>
#include <stdio.h>
#include <stdlib.h>
#include <stddef.h>
#include <stdarg.h>
#include <string.h>
#include <wchar.h>
#include <wctype.h>
#include "un-namespace.h"
#include "collate.h"
#include "libc_private.h"
#include "local.h"
#define FLOATING_POINT
#ifdef FLOATING_POINT
#include <locale.h>
#include "floatio.h"
#endif
#define BUF 513 /* Maximum length of numeric string. */
/*
* Flags used during conversion.
*/
#define LONG 0x01 /* l: long or double */
#define LONGDBL 0x02 /* L: long double */
#define SHORT 0x04 /* h: short */
#define SUPPRESS 0x08 /* *: suppress assignment */
#define POINTER 0x10 /* p: void * (as hex) */
#define NOSKIP 0x20 /* [ or c: do not skip blanks */
#define LONGLONG 0x400 /* ll: long long (+ deprecated q: quad) */
#define INTMAXT 0x800 /* j: intmax_t */
#define PTRDIFFT 0x1000 /* t: ptrdiff_t */
#define SIZET 0x2000 /* z: size_t */
#define SHORTSHORT 0x4000 /* hh: char */
#define UNSIGNED 0x8000 /* %[oupxX] conversions */
/*
* The following are used in numeric conversions only:
* SIGNOK, NDIGITS, DPTOK, and EXPOK are for floating point;
* SIGNOK, NDIGITS, PFXOK, and NZDIGITS are for integral.
*/
#define SIGNOK 0x40 /* +/- is (still) legal */
#define NDIGITS 0x80 /* no digits detected */
#define DPTOK 0x100 /* (float) decimal point is still legal */
#define EXPOK 0x200 /* (float) exponent (e+3, etc) still legal */
#define PFXOK 0x100 /* 0x prefix is (still) legal */
#define NZDIGITS 0x200 /* no zero digits detected */
/*
* Conversion types.
*/
#define CT_CHAR 0 /* %c conversion */
#define CT_CCL 1 /* %[...] conversion */
#define CT_STRING 2 /* %s conversion */
#define CT_INT 3 /* %[dioupxX] conversion */
#define CT_FLOAT 4 /* %[efgEFG] conversion */
static const u_char *__sccl(char *, const u_char *);
/*
* __vfscanf - MT-safe version
*/
int
__vfscanf(FILE *fp, char const *fmt0, va_list ap)
{
int ret;
FLOCKFILE(fp);
ret = __svfscanf(fp, fmt0, ap);
FUNLOCKFILE(fp);
return (ret);
}
/*
* __svfscanf - non-MT-safe version of __vfscanf
*/
int
__svfscanf(FILE *fp, const char *fmt0, va_list ap)
{
const u_char *fmt = (const u_char *)fmt0;
int c; /* character from format, or conversion */
size_t width; /* field width, or 0 */
char *p; /* points into all kinds of strings */
int n; /* handy integer */
int flags; /* flags as defined above */
char *p0; /* saves original value of p when necessary */
int nassigned; /* number of fields assigned */
int nconversions; /* number of conversions */
int nread; /* number of characters consumed from fp */
int base; /* base argument to conversion function */
char ccltab[256]; /* character class table for %[...] */
char buf[BUF]; /* buffer for numeric and mb conversions */
wchar_t *wcp; /* handy wide character pointer */
wchar_t *wcp0; /* saves original value of wcp */
mbstate_t mbs; /* multibyte conversion state */
size_t nconv; /* length of multibyte sequence converted */
/* `basefix' is used to avoid `if' tests in the integer scanner */
static short basefix[17] =
{ 10, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 };
#ifdef FLOATING_POINT
char decimal_point = localeconv()->decimal_point[0];
#endif
ORIENT(fp, -1);
nassigned = 0;
nconversions = 0;
nread = 0;
for (;;) {
c = *fmt++;
if (c == 0)
return (nassigned);
if (isspace(c)) {
while ((fp->_r > 0 || __srefill(fp) == 0) && isspace(*fp->_p))
nread++, fp->_r--, fp->_p++;
continue;
}
if (c != '%')
goto literal;
width = 0;
flags = 0;
/*
* switch on the format. continue if done;
* break once format type is derived.
*/
again: c = *fmt++;
switch (c) {
case '%':
literal:
if (fp->_r <= 0 && __srefill(fp))
goto input_failure;
if (*fp->_p != c)
goto match_failure;
fp->_r--, fp->_p++;
nread++;
continue;
case '*':
flags |= SUPPRESS;
goto again;
case 'j':
flags |= INTMAXT;
goto again;
case 'l':
if (flags & LONG) {
flags &= ~LONG;
flags |= LONGLONG;
} else
flags |= LONG;
goto again;
case 'q':
flags |= LONGLONG; /* not quite */
goto again;
case 't':
flags |= PTRDIFFT;
goto again;
case 'z':
flags |= SIZET;
goto again;
case 'L':
flags |= LONGDBL;
goto again;
case 'h':
if (flags & SHORT) {
flags &= ~SHORT;
flags |= SHORTSHORT;
} else
flags |= SHORT;
goto again;
case '0': case '1': case '2': case '3': case '4':
case '5': case '6': case '7': case '8': case '9':
width = width * 10 + c - '0';
goto again;
/*
* Conversions.
*/
case 'd':
c = CT_INT;
base = 10;
break;
case 'i':
c = CT_INT;
base = 0;
break;
case 'o':
c = CT_INT;
flags |= UNSIGNED;
base = 8;
break;
case 'u':
c = CT_INT;
flags |= UNSIGNED;
base = 10;
break;
case 'X':
case 'x':
flags |= PFXOK; /* enable 0x prefixing */
c = CT_INT;
flags |= UNSIGNED;
base = 16;
break;
#ifdef FLOATING_POINT
case 'E': case 'F': case 'G':
case 'e': case 'f': case 'g':
c = CT_FLOAT;
break;
#endif
case 'S':
flags |= LONG;
/* FALLTHROUGH */
case 's':
c = CT_STRING;
break;
case '[':
fmt = __sccl(ccltab, fmt);
flags |= NOSKIP;
c = CT_CCL;
break;
case 'C':
flags |= LONG;
/* FALLTHROUGH */
case 'c':
flags |= NOSKIP;
c = CT_CHAR;
break;
case 'p': /* pointer format is like hex */
flags |= POINTER | PFXOK;
c = CT_INT; /* assumes sizeof(uintmax_t) */
flags |= UNSIGNED; /* >= sizeof(uintptr_t) */
base = 16;
break;
case 'n':
nconversions++;
if (flags & SUPPRESS) /* ??? */
continue;
if (flags & SHORTSHORT)
*va_arg(ap, char *) = nread;
else if (flags & SHORT)
*va_arg(ap, short *) = nread;
else if (flags & LONG)
*va_arg(ap, long *) = nread;
else if (flags & LONGLONG)
*va_arg(ap, long long *) = nread;
else if (flags & INTMAXT)
*va_arg(ap, intmax_t *) = nread;
else if (flags & SIZET)
*va_arg(ap, size_t *) = nread;
else if (flags & PTRDIFFT)
*va_arg(ap, ptrdiff_t *) = nread;
else
*va_arg(ap, int *) = nread;
continue;
default:
goto match_failure;
/*
* Disgusting backwards compatibility hack. XXX
*/
case '\0': /* compat */
return (EOF);
}
/*
* We have a conversion that requires input.
*/
if (fp->_r <= 0 && __srefill(fp))
goto input_failure;
/*
* Consume leading white space, except for formats
* that suppress this.
*/
if ((flags & NOSKIP) == 0) {
while (isspace(*fp->_p)) {
nread++;
if (--fp->_r > 0)
fp->_p++;
else if (__srefill(fp))
goto input_failure;
}
/*
* Note that there is at least one character in
* the buffer, so conversions that do not set NOSKIP
* ca no longer result in an input failure.
*/
}
/*
* Do the conversion.
*/
switch (c) {
case CT_CHAR:
/* scan arbitrary characters (sets NOSKIP) */
if (width == 0)
width = 1;
if (flags & SUPPRESS) {
size_t sum = 0;
for (;;) {
if ((n = fp->_r) < width) {
sum += n;
width -= n;
fp->_p += n;
if (__srefill(fp)) {
if (sum == 0)
goto input_failure;
break;
}
} else {
sum += width;
fp->_r -= width;
fp->_p += width;
break;
}
}
nread += sum;
} else if (flags & LONG) {
wcp = va_arg(ap, wchar_t *);
n = 0;
while (width != 0) {
if (n == MB_CUR_MAX)
goto input_failure;
buf[n++] = *fp->_p;
fp->_p++;
fp->_r--;
memset(&mbs, 0, sizeof(mbs));
nconv = mbrtowc(wcp, buf, n, &mbs);
if (nconv == 0 || nconv == (size_t)-1)
goto input_failure;
if (nconv != (size_t)-2) {
nread += n;
width--;
wcp++;
n = 0;
}
if (fp->_r <= 0 && __srefill(fp)) {
if (n != 0)
goto input_failure;
break;
}
}
nassigned++;
} else {
size_t r = fread((void *)va_arg(ap, char *), 1,
width, fp);
if (r == 0)
goto input_failure;
nread += r;
nassigned++;
}
nconversions++;
break;
case CT_CCL:
/* scan a (nonempty) character class (sets NOSKIP) */
if (width == 0)
width = (size_t)~0; /* `infinity' */
/* take only those things in the class */
if (flags & SUPPRESS) {
n = 0;
while (ccltab[*fp->_p]) {
n++, fp->_r--, fp->_p++;
if (--width == 0)
break;
if (fp->_r <= 0 && __srefill(fp)) {
if (n == 0)
goto input_failure;
break;
}
}
if (n == 0)
goto match_failure;
} else if (flags & LONG) {
wcp = wcp0 = va_arg(ap, wchar_t *);
n = 0;
while (width != 0) {
if (n == MB_CUR_MAX)
goto input_failure;
buf[n++] = *fp->_p;
fp->_p++;
fp->_r--;
memset(&mbs, 0, sizeof(mbs));
nconv = mbrtowc(wcp, buf, n, &mbs);
if (nconv == 0 || nconv == (size_t)-1)
goto input_failure;
if (nconv != (size_t)-2) {
if (wctob(*wcp) != EOF &&
!ccltab[wctob(*wcp)]) {
while (--n > 0)
__ungetc(buf[n],
fp);
break;
}
nread += n;
width--;
wcp++;
n = 0;
}
if (fp->_r <= 0 && __srefill(fp)) {
if (n != 0)
goto input_failure;
break;
}
}
if (n != 0)
goto input_failure;
n = wcp - wcp0;
if (n == 0)
goto match_failure;
*wcp = L'\0';
nassigned++;
} else {
p0 = p = va_arg(ap, char *);
while (ccltab[*fp->_p]) {
fp->_r--;
*p++ = *fp->_p++;
if (--width == 0)
break;
if (fp->_r <= 0 && __srefill(fp)) {
if (p == p0)
goto input_failure;
break;
}
}
n = p - p0;
if (n == 0)
goto match_failure;
*p = 0;
nassigned++;
}
nread += n;
nconversions++;
break;
case CT_STRING:
/* like CCL, but zero-length string OK, & no NOSKIP */
if (width == 0)
width = (size_t)~0;
if (flags & SUPPRESS) {
n = 0;
while (!isspace(*fp->_p)) {
n++, fp->_r--, fp->_p++;
if (--width == 0)
break;
if (fp->_r <= 0 && __srefill(fp))
break;
}
nread += n;
} else if (flags & LONG) {
wcp = va_arg(ap, wchar_t *);
n = 0;
while (!isspace(*fp->_p) && width != 0) {
if (n == MB_CUR_MAX)
goto input_failure;
buf[n++] = *fp->_p;
fp->_p++;
fp->_r--;
memset(&mbs, 0, sizeof(mbs));
nconv = mbrtowc(wcp, buf, n, &mbs);
if (nconv == 0 || nconv == (size_t)-1)
goto input_failure;
if (nconv != (size_t)-2) {
if (iswspace(*wcp)) {
while (--n > 0)
__ungetc(buf[n],
fp);
break;
}
nread += n;
width--;
wcp++;
n = 0;
}
if (fp->_r <= 0 && __srefill(fp)) {
if (n != 0)
goto input_failure;
break;
}
}
*wcp = L'\0';
nassigned++;
} else {
p0 = p = va_arg(ap, char *);
while (!isspace(*fp->_p)) {
fp->_r--;
*p++ = *fp->_p++;
if (--width == 0)
break;
if (fp->_r <= 0 && __srefill(fp))
break;
}
*p = 0;
nread += p - p0;
nassigned++;
}
nconversions++;
continue;
case CT_INT:
/* scan an integer as if by the conversion function */
#ifdef hardway
if (width == 0 || width > sizeof(buf) - 1)
width = sizeof(buf) - 1;
#else
/* size_t is unsigned, hence this optimisation */
if (--width > sizeof(buf) - 2)
width = sizeof(buf) - 2;
width++;
#endif
flags |= SIGNOK | NDIGITS | NZDIGITS;
for (p = buf; width; width--) {
c = *fp->_p;
/*
* Switch on the character; `goto ok'
* if we accept it as a part of number.
*/
switch (c) {
/*
* The digit 0 is always legal, but is
* special. For %i conversions, if no
* digits (zero or nonzero) have been
* scanned (only signs), we will have
* base==0. In that case, we should set
* it to 8 and enable 0x prefixing.
* Also, if we have not scanned zero digits
* before this, do not turn off prefixing
* (someone else will turn it off if we
* have scanned any nonzero digits).
*/
case '0':
if (base == 0) {
base = 8;
flags |= PFXOK;
}
if (flags & NZDIGITS)
flags &= ~(SIGNOK|NZDIGITS|NDIGITS);
else
flags &= ~(SIGNOK|PFXOK|NDIGITS);
goto ok;
/* 1 through 7 always legal */
case '1': case '2': case '3':
case '4': case '5': case '6': case '7':
base = basefix[base];
flags &= ~(SIGNOK | PFXOK | NDIGITS);
goto ok;
/* digits 8 and 9 ok iff decimal or hex */
case '8': case '9':
base = basefix[base];
if (base <= 8)
break; /* not legal here */
flags &= ~(SIGNOK | PFXOK | NDIGITS);
goto ok;
/* letters ok iff hex */
case 'A': case 'B': case 'C':
case 'D': case 'E': case 'F':
case 'a': case 'b': case 'c':
case 'd': case 'e': case 'f':
/* no need to fix base here */
if (base <= 10)
break; /* not legal here */
flags &= ~(SIGNOK | PFXOK | NDIGITS);
goto ok;
/* sign ok only as first character */
case '+': case '-':
if (flags & SIGNOK) {
flags &= ~SIGNOK;
goto ok;
}
break;
/* x ok iff flag still set & 2nd char */
case 'x': case 'X':
if (flags & PFXOK && p == buf + 1) {
base = 16; /* if %i */
flags &= ~PFXOK;
goto ok;
}
break;
}
/*
* If we got here, c is not a legal character
* for a number. Stop accumulating digits.
*/
break;
ok:
/*
* c is legal: store it and look at the next.
*/
*p++ = c;
if (--fp->_r > 0)
fp->_p++;
else if (__srefill(fp))
break; /* EOF */
}
/*
* If we had only a sign, it is no good; push
* back the sign. If the number ends in `x',
* it was [sign] '0' 'x', so push back the x
* and treat it as [sign] '0'.
*/
if (flags & NDIGITS) {
if (p > buf)
(void) __ungetc(*(u_char *)--p, fp);
goto match_failure;
}
c = ((u_char *)p)[-1];
if (c == 'x' || c == 'X') {
--p;
(void) __ungetc(c, fp);
}
if ((flags & SUPPRESS) == 0) {
uintmax_t res;
*p = 0;
if ((flags & UNSIGNED) == 0)
res = strtoimax(buf, (char **)NULL, base);
else
res = strtoumax(buf, (char **)NULL, base);
if (flags & POINTER)
*va_arg(ap, void **) =
(void *)(uintptr_t)res;
else if (flags & SHORTSHORT)
*va_arg(ap, char *) = res;
else if (flags & SHORT)
*va_arg(ap, short *) = res;
else if (flags & LONG)
*va_arg(ap, long *) = res;
else if (flags & LONGLONG)
*va_arg(ap, long long *) = res;
else if (flags & INTMAXT)
*va_arg(ap, intmax_t *) = res;
else if (flags & PTRDIFFT)
*va_arg(ap, ptrdiff_t *) = res;
else if (flags & SIZET)
*va_arg(ap, size_t *) = res;
else
*va_arg(ap, int *) = res;
nassigned++;
}
nread += p - buf;
nconversions++;
break;
#ifdef FLOATING_POINT
case CT_FLOAT:
/* scan a floating point number as if by strtod */
#ifdef hardway
if (width == 0 || width > sizeof(buf) - 1)
width = sizeof(buf) - 1;
#else
/* size_t is unsigned, hence this optimisation */
if (--width > sizeof(buf) - 2)
width = sizeof(buf) - 2;
width++;
#endif
flags |= SIGNOK | NDIGITS | DPTOK | EXPOK;
for (p = buf; width; width--) {
c = *fp->_p;
/*
* This code mimicks the integer conversion
* code, but is much simpler.
*/
switch (c) {
case '0': case '1': case '2': case '3':
case '4': case '5': case '6': case '7':
case '8': case '9':
flags &= ~(SIGNOK | NDIGITS);
goto fok;
case '+': case '-':
if (flags & SIGNOK) {
flags &= ~SIGNOK;
goto fok;
}
break;
case 'e': case 'E':
/* no exponent without some digits */
if ((flags&(NDIGITS|EXPOK)) == EXPOK) {
flags =
(flags & ~(EXPOK|DPTOK)) |
SIGNOK | NDIGITS;
goto fok;
}
break;
default:
if ((char)c == decimal_point &&
(flags & DPTOK)) {
flags &= ~(SIGNOK | DPTOK);
goto fok;
}
break;
}
break;
fok:
*p++ = c;
if (--fp->_r > 0)
fp->_p++;
else if (__srefill(fp))
break; /* EOF */
}
/*
* If no digits, might be missing exponent digits
* (just give back the exponent) or might be missing
* regular digits, but had sign and/or decimal point.
*/
if (flags & NDIGITS) {
if (flags & EXPOK) {
/* no digits at all */
while (p > buf)
__ungetc(*(u_char *)--p, fp);
goto match_failure;
}
/* just a bad exponent (e and maybe sign) */
c = *(u_char *)--p;
if (c != 'e' && c != 'E') {
(void) __ungetc(c, fp);/* sign */
c = *(u_char *)--p;
}
(void) __ungetc(c, fp);
}
if ((flags & SUPPRESS) == 0) {
double res;
*p = 0;
/* XXX this loses precision for long doubles. */
res = strtod(buf, (char **) NULL);
if (flags & LONGDBL)
*va_arg(ap, long double *) = res;
else if (flags & LONG)
*va_arg(ap, double *) = res;
else
*va_arg(ap, float *) = res;
nassigned++;
}
nread += p - buf;
nconversions++;
break;
#endif /* FLOATING_POINT */
}
}
input_failure:
return (nconversions != 0 ? nassigned : EOF);
match_failure:
return (nassigned);
}
/*
* Fill in the given table from the scanset at the given format
* (just after `['). Return a pointer to the character past the
* closing `]'. The table has a 1 wherever characters should be
* considered part of the scanset.
*/
static const u_char *
__sccl(tab, fmt)
char *tab;
const u_char *fmt;
{
int c, n, v, i;
/* first `clear' the whole table */
c = *fmt++; /* first char hat => negated scanset */
if (c == '^') {
v = 1; /* default => accept */
c = *fmt++; /* get new first char */
} else
v = 0; /* default => reject */
/* XXX: Will not work if sizeof(tab*) > sizeof(char) */
(void) memset(tab, v, 256);
if (c == 0)
return (fmt - 1);/* format ended before closing ] */
/*
* Now set the entries corresponding to the actual scanset
* to the opposite of the above.
*
* The first character may be ']' (or '-') without being special;
* the last character may be '-'.
*/
v = 1 - v;
for (;;) {
tab[c] = v; /* take character c */
doswitch:
n = *fmt++; /* and examine the next */
switch (n) {
case 0: /* format ended too soon */
return (fmt - 1);
case '-':
/*
* A scanset of the form
* [01+-]
* is defined as `the digit 0, the digit 1,
* the character +, the character -', but
* the effect of a scanset such as
* [a-zA-Z0-9]
* is implementation defined. The V7 Unix
* scanf treats `a-z' as `the letters a through
* z', but treats `a-a' as `the letter a, the
* character -, and the letter a'.
*
* For compatibility, the `-' is not considerd
* to define a range if the character following
* it is either a close bracket (required by ANSI)
* or is not numerically greater than the character
* we just stored in the table (c).
*/
n = *fmt;
if (n == ']'
|| (__collate_load_error ? n < c :
__collate_range_cmp (n, c) < 0
)
) {
c = '-';
break; /* resume the for(;;) */
}
fmt++;
/* fill in the range */
if (__collate_load_error) {
do {
tab[++c] = v;
} while (c < n);
} else {
for (i = 0; i < 256; i ++)
if ( __collate_range_cmp (c, i) < 0
&& __collate_range_cmp (i, n) <= 0
)
tab[i] = v;
}
#if 1 /* XXX another disgusting compatibility hack */
c = n;
/*
* Alas, the V7 Unix scanf also treats formats
* such as [a-c-e] as `the letters a through e'.
* This too is permitted by the standard....
*/
goto doswitch;
#else
c = *fmt++;
if (c == 0)
return (fmt - 1);
if (c == ']')
return (fmt);
#endif
break;
case ']': /* end of scanset */
return (fmt);
default: /* just another character */
c = n;
break;
}
}
/* NOTREACHED */
}
Reference in New Issue View Git Blame Copy Permalink