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mpir/scanf/doscan.c

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/* __gmp_doscan -- formatted input internals.
THE FUNCTIONS IN THIS FILE ARE FOR INTERNAL USE ONLY. THEY'RE ALMOST
CERTAIN TO BE SUBJECT TO INCOMPATIBLE CHANGES OR DISAPPEAR COMPLETELY IN
FUTURE GNU MP RELEASES.
Copyright 2001, 2002, 2003 Free Software Foundation, Inc.
This file is part of the GNU MP Library.
The GNU MP Library is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or (at your
option) any later version.
The GNU MP Library is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
License for more details.
You should have received a copy of the GNU Lesser General Public License
along with the GNU MP Library; see the file COPYING.LIB. If not, write to
the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
MA 02110-1301, USA. */
#ifndef _GNU_SOURCE
#define _GNU_SOURCE /* for DECIMAL_POINT in langinfo.h */
#endif
#include "config.h"
#if HAVE_STDARG
#include <stdarg.h>
#else
#include <varargs.h>
#endif
#include <ctype.h>
#include <stddef.h> /* for ptrdiff_t */
#include <stdio.h>
#include <stdlib.h> /* for strtol */
#include <string.h>
#if HAVE_LANGINFO_H
#include <langinfo.h> /* for nl_langinfo */
#endif
#if HAVE_LOCALE_H
#include <locale.h> /* for localeconv */
#endif
#if HAVE_INTTYPES_H
# include <inttypes.h> /* for intmax_t */
#else
# if HAVE_STDINT_H
# include <stdint.h>
# endif
#endif
#if HAVE_SYS_TYPES_H
#include <sys/types.h> /* for quad_t */
#endif
#include "mpir.h"
#include "gmp-impl.h"
/* Change this to "#define TRACE(x) x" for some traces. */
#define TRACE(x)
/* General:
It's necessary to parse up the format string to recognise the GMP
extra types F, Q and Z. Other types and conversions are passed
across to the standard sscanf or fscanf via funs->scan, for ease of
implemenation. This is essential in the case of something like glibc
%p where the pointer format isn't actually documented.
Because funs->scan doesn't get the whole input it can't put the right
values in for %n, so that's handled in __gmp_doscan. Neither sscanf
nor fscanf directly indicate how many characters were read, so an
extra %n is appended to each run for that. For fscanf this merely
supports our %n output, but for sscanf it lets funs->step move us
along the input string.
Whitespace and literal matches in the format string, including %%,
are handled directly within __gmp_doscan. This is reasonably
efficient, and avoids some suspicious behaviour observed in various
system libc's. GLIBC 2.2.4 for instance returns 0 on
sscanf(" ", " x")
or
sscanf(" ", " x%d",&n)
whereas we think they should return EOF, since end-of-string is
reached when a match of "x" is required.
For standard % conversions, funs->scan is called once for each
conversion. If we had vfscanf and vsscanf and could rely on their
fixed text matching behaviour then we could call them with multiple
consecutive standard conversions. But plain fscanf and sscanf work
fine, and parsing one field at a time shouldn't be too much of a
slowdown.
gmpscan:
gmpscan reads a gmp type. It's only used from one place, but is a
separate subroutine to avoid a big chunk of complicated code in the
middle of __gmp_doscan. Within gmpscan a couple of loopbacks make it
possible to share code for parsing integers, rationals and floats.
In gmpscan normally one char of lookahead is maintained, but when width
is reached that stops, on the principle that an fgetc/ungetc of a char
past where we're told to stop would be undesirable. "chars" is how many
characters have been read so far, including the current c. When
chars==width and another character is desired then a jump is done to the
"convert" stage. c is invalid and mustn't be unget'ed in this case;
chars is set to width+1 to indicate that.
gmpscan normally returns the number of characters read. -1 means an
invalid field, -2 means EOF reached before any matching characters
were read.
For hex floats, the mantissa part is passed to mpf_set_str, then the
exponent is applied with mpf_mul_exp or mpf_div_2exp. This is easier
than teaching mpf_set_str about an exponent factor (ie. 2) differing
from the mantissa radix point factor (ie. 16). mpf_mul_exp and
mpf_div_2exp will preserve the application requested precision, so
nothing in that respect is lost by making this a two-step process.
Matching and errors:
C99 7.19.6.2 paras 9 and 10 say an input item is read as the longest
string which is a match for the appropriate type, or a prefix of a
match. With that done, if it's only a prefix then the result is a
matching failure, ie. invalid input.
This rule seems fairly clear, but doesn't seem to be universally
applied in system C libraries. Even GLIBC doesn't seem to get it
right, insofar as it seems to accept some apparently invalid forms.
Eg. glibc 2.3.1 accepts "0x" for a "%i", where a reading of the
standard would suggest a non-empty sequence of digits should be
required after an "0x".
A footnote to 7.19.6.2 para 17 notes how this input item reading can
mean inputs acceptable to strtol are not acceptable to fscanf. We
think this confirms our reading of "0x" as invalid.
Clearly gmp_sscanf could backtrack to a longest input which was a
valid match for a given item, but this is not done, since C99 says
sscanf is identical to fscanf, so we make gmp_sscanf identical to
gmp_fscanf.
Types:
C99 says "ll" is for long long, and "L" is for long double floats.
Unfortunately in GMP 4.1.1 we documented the two as equivalent. This
doesn't affect us directly, since both are passed through to plain
scanf. It seems wisest not to try to enforce the C99 rule. This is
consistent with what we said before, though whether it actually
worked was always up to the C library.
Alternatives:
Consideration was given to using separate code for gmp_fscanf and
gmp_sscanf. The sscanf case could zip across a string doing literal
matches or recognising digits in gmpscan, rather than making a
function call fun->get per character. The fscanf could use getc
rather than fgetc too, which might help those systems where getc is a
macro or otherwise inlined. But none of this scanning and converting
will be particularly fast, so the two are done together to keep it a
little simpler for now.
Various multibyte string issues are not addressed, for a start C99
scanf says the format string is multibyte. Since we pass %c, %s and
%[ to the system scanf, they might do multibyte reads already, but
it's another matter whether or not that can be used, since our digit
and whitespace parsing is only unibyte. The plan is to quietly
ignore multibyte locales for now. This is not as bad as it sounds,
since GMP is presumably used mostly on numbers, which can be
perfectly adequately treated in plain ASCII.
*/
struct gmp_doscan_params_t {
int base;
int ignore;
char type;
int width;
};
#define GET(c) \
do { \
ASSERT (chars <= width); \
chars++; \
if (chars > width) \
goto convert; \
(c) = (*funs->get) (data); \
} while (0)
/* store into "s", extending if necessary */
#define STORE(c) \
do { \
ASSERT (s_upto <= s_alloc); \
if (s_upto >= s_alloc) \
{ \
size_t s_alloc_new = s_alloc + S_ALLOC_STEP; \
s = __GMP_REALLOCATE_FUNC_TYPE (s, s_alloc, s_alloc_new, char); \
s_alloc = s_alloc_new; \
} \
s[s_upto++] = c; \
} while (0)
#define S_ALLOC_STEP 512
static int
gmpscan (const struct gmp_doscan_funs_t *funs, void *data,
const struct gmp_doscan_params_t *p, void *dst)
{
int chars, c, base, first, width, seen_point, seen_digit, hexfloat;
size_t s_upto, s_alloc, hexexp;
char *s;
int invalid = 0;
TRACE (printf ("gmpscan\n"));
ASSERT (p->type == 'F' || p->type == 'Q' || p->type == 'Z');
c = (*funs->get) (data);
if (c == EOF)
return -2;
chars = 1;
first = 1;
seen_point = 0;
width = (p->width == 0 ? INT_MAX-1 : p->width);
base = p->base;
s_alloc = S_ALLOC_STEP;
s = __GMP_ALLOCATE_FUNC_TYPE (s_alloc, char);
s_upto = 0;
hexfloat = 0;
hexexp = 0;
another:
seen_digit = 0;
if (c == '-')
{
STORE (c);
goto get_for_sign;
}
else if (c == '+')
{
/* don't store '+', it's not accepted by mpz_set_str etc */
get_for_sign:
GET (c);
}
if (base == 0)
{
base = 10; /* decimal if no base indicator */
if (c == '0')
{
seen_digit = 1; /* 0 alone is a valid number */
if (p->type != 'F')
base = 8; /* leading 0 is octal, for non-floats */
STORE (c);
GET (c);
if (c == 'x' || c == 'X')
{
base = 16;
seen_digit = 0; /* must have digits after an 0x */
if (p->type == 'F') /* don't pass 'x' to mpf_set_str_point */
hexfloat = 1;
else
STORE (c);
GET (c);
}
}
}
digits:
for (;;)
{
if (base == 16)
{
if (! isxdigit (c))
break;
}
else
{
if (! isdigit (c))
break;
if (base == 8 && (c == '8' || c == '9'))
break;
}
seen_digit = 1;
STORE (c);
GET (c);
}
if (first)
{
/* decimal point */
if (p->type == 'F' && ! seen_point)
{
/* For a multi-character decimal point, if the first character is
present then all of it must be, otherwise the input is
considered invalid. */
const char *point = GMP_DECIMAL_POINT;
int pc = (unsigned char) *point++;
if (c == pc)
{
for (;;)
{
STORE (c);
GET (c);
pc = (unsigned char) *point++;
if (pc == '\0')
break;
if (c != pc)
goto set_invalid;
}
seen_point = 1;
goto digits;
}
}
/* exponent */
if (p->type == 'F')
{
if (hexfloat && (c == 'p' || c == 'P'))
{
hexexp = s_upto; /* exponent location */
base = 10; /* exponent in decimal */
goto exponent;
}
else if (! hexfloat && (c == 'e' || c == 'E'))
{
exponent:
/* must have at least one digit in the mantissa, just an exponent
is not good enough */
if (! seen_digit)
goto set_invalid;
do_second:
first = 0;
STORE (c);
GET (c);
goto another;
}
}
/* denominator */
if (p->type == 'Q' && c == '/')
{
/* must have at least one digit in the numerator */
if (! seen_digit)
goto set_invalid;
/* now look for at least one digit in the denominator */
seen_digit = 0;
/* allow the base to be redetermined for "%i" */
base = p->base;
goto do_second;
}
}
convert:
if (! seen_digit)
{
set_invalid:
invalid = 1;
goto done;
}
if (! p->ignore)
{
STORE ('\0');
TRACE (printf (" convert \"%s\"\n", s));
/* We ought to have parsed out a valid string above, so just test
mpz_set_str etc with an ASSERT. */
switch (p->type) {
case 'F':
{
mpf_ptr f = (mpf_ptr) dst;
if (hexexp != 0)
s[hexexp] = '\0';
ASSERT_NOCARRY (mpf_set_str (f, s, hexfloat ? 16 : 10));
if (hexexp != 0)
{
char *dummy;
long exp;
exp = strtol (s + hexexp + 1, &dummy, 10);
if (exp >= 0)
mpf_mul_2exp (f, f, (mpir_ui) exp);
else
mpf_div_2exp (f, f, - (mpir_ui) exp);
}
}
break;
case 'Q':
ASSERT_NOCARRY (mpq_set_str ((mpq_ptr) dst, s, p->base));
break;
case 'Z':
ASSERT_NOCARRY (mpz_set_str ((mpz_ptr) dst, s, p->base));
break;
default:
ASSERT (0);
/*FALLTHRU*/
break;
}
}
done:
ASSERT (chars <= width+1);
if (chars != width+1)
{
(*funs->unget) (c, data);
TRACE (printf (" ungetc %d, to give %d chars\n", c, chars-1));
}
chars--;
(*__gmp_free_func) (s, s_alloc);
if (invalid)
{
TRACE (printf (" invalid\n"));
return -1;
}
TRACE (printf (" return %d chars (cf width %d)\n", chars, width));
return chars;
}
/* Read and discard whitespace, if any. Return number of chars skipped.
Whitespace skipping never provokes the EOF return from __gmp_doscan, so
it's not necessary to watch for EOF from funs->get, */
static int
skip_white (const struct gmp_doscan_funs_t *funs, void *data)
{
int c;
int ret = 0;
do
{
c = (funs->get) (data);
ret++;
}
while (isspace (c));
(funs->unget) (c, data);
ret--;
TRACE (printf (" skip white %d\n", ret));
return ret;
}
int
__gmp_doscan (const struct gmp_doscan_funs_t *funs, void *data,
const char *orig_fmt, va_list orig_ap)
{
struct gmp_doscan_params_t param;
va_list ap;
char *alloc_fmt;
const char *fmt, *this_fmt, *end_fmt;
size_t orig_fmt_len, alloc_fmt_size, len;
int new_fields, new_chars;
char fchar;
int fields = 0;
int chars = 0;
TRACE (printf ("__gmp_doscan \"%s\"\n", orig_fmt);
if (funs->scan == (gmp_doscan_scan_t) sscanf)
printf (" s=\"%s\"\n", * (const char **) data));
/* Don't modify orig_ap, if va_list is actually an array and hence call by
reference. It could be argued that it'd be more efficient to leave
callers to make a copy if they care, but doing so here is going to be a
very small part of the total work, and we may as well keep applications
out of trouble. */
va_copy (ap, orig_ap);
/* Parts of the format string are going to be copied so that a " %n" can
be appended. alloc_fmt is some space for that. orig_fmt_len+4 will be
needed if fmt consists of a single "%" specifier, but otherwise is an
overestimate. We're not going to be very fast here, so use
__gmp_allocate_func rather than TMP_ALLOC. */
orig_fmt_len = strlen (orig_fmt);
alloc_fmt_size = orig_fmt_len + 4;
alloc_fmt = __GMP_ALLOCATE_FUNC_TYPE (alloc_fmt_size, char);
fmt = orig_fmt;
end_fmt = orig_fmt + orig_fmt_len;
for (;;)
{
next:
fchar = *fmt++;
if (fchar == '\0')
break;
if (isspace (fchar))
{
chars += skip_white (funs, data);
continue;
}
if (fchar != '%')
{
int c;
literal:
c = (funs->get) (data);
if (c != fchar)
{
(funs->unget) (c, data);
if (c == EOF)
{
eof_no_match:
if (fields == 0)
fields = EOF;
}
goto done;
}
chars++;
continue;
}
param.type = '\0';
param.base = 0; /* for e,f,g,i */
param.ignore = 0;
param.width = 0;
this_fmt = fmt-1;
TRACE (printf (" this_fmt \"%s\"\n", this_fmt));
for (;;)
{
ASSERT (fmt <= end_fmt);
fchar = *fmt++;
switch (fchar) {
case '\0': /* unterminated % sequence */
ASSERT (0);
goto done;
case '%': /* literal % */
goto literal;
case '[': /* character range */
fchar = *fmt++;
if (fchar == '^')
fchar = *fmt++;
/* ']' allowed as the first char (possibly after '^') */
if (fchar == ']')
fchar = *fmt++;
for (;;)
{
ASSERT (fmt <= end_fmt);
if (fchar == '\0')
{
/* unterminated % sequence */
ASSERT (0);
goto done;
}
if (fchar == ']')
break;
fchar = *fmt++;
}
/*FALLTHRU*/
case 'c': /* characters */
case 's': /* string of non-whitespace */
case 'p': /* pointer */
libc_type:
len = fmt - this_fmt;
memcpy (alloc_fmt, this_fmt, len);
alloc_fmt[len++] = '%';
alloc_fmt[len++] = 'n';
alloc_fmt[len] = '\0';
TRACE (printf (" scan \"%s\"\n", alloc_fmt);
if (funs->scan == (gmp_doscan_scan_t) sscanf)
printf (" s=\"%s\"\n", * (const char **) data));
new_chars = -1;
if (param.ignore)
{
new_fields = (*funs->scan) (data, alloc_fmt, &new_chars);
ASSERT (new_fields == 0 || new_fields == EOF);
}
else
{
new_fields = (*funs->scan) (data, alloc_fmt,
va_arg (ap, void *), &new_chars);
ASSERT (new_fields==0 || new_fields==1 || new_fields==EOF);
if (new_fields == 0)
goto done; /* invalid input */
if (new_fields == 1)
ASSERT (new_chars != -1);
}
TRACE (printf (" new_fields %d new_chars %d\n",
new_fields, new_chars));
if (new_fields == -1)
goto eof_no_match; /* EOF before anything matched */
/* Wnder param.ignore, when new_fields==0 we don't know if
it's a successful match or an invalid field. new_chars
won't have been assigned if it was an invalid field. */
if (new_chars == -1)
goto done; /* invalid input */
chars += new_chars;
(*funs->step) (data, new_chars);
increment_fields:
if (! param.ignore)
fields++;
goto next;
case 'd': /* decimal */
case 'u': /* decimal */
param.base = 10;
goto numeric;
case 'e': /* float */
case 'E': /* float */
case 'f': /* float */
case 'g': /* float */
case 'G': /* float */
case 'i': /* integer with base marker */
numeric:
if (param.type != 'F' && param.type != 'Q' && param.type != 'Z')
goto libc_type;
chars += skip_white (funs, data);
new_chars = gmpscan (funs, data, &param,
param.ignore ? NULL : va_arg (ap, void*));
if (new_chars == -2)
goto eof_no_match;
if (new_chars == -1)
goto done;
ASSERT (new_chars >= 0);
chars += new_chars;
goto increment_fields;
case 'a': /* glibc allocate string */
case '\'': /* glibc digit groupings */
break;
case 'F': /* mpf_t */
case 'j': /* intmax_t */
case 'L': /* long long */
case 'q': /* quad_t */
case 'Q': /* mpq_t */
case 't': /* ptrdiff_t */
case 'z': /* size_t */
case 'Z': /* mpz_t */
set_type:
param.type = fchar;
break;
case 'h': /* short or char */
if (param.type != 'h')
goto set_type;
param.type = 'H'; /* internal code for "hh" */
break;
goto numeric;
case 'l': /* long, long long, double or long double */
if (param.type != 'l')
goto set_type;
param.type = 'L'; /* "ll" means "L" */
break;
case 'n':
if (! param.ignore)
{
void *p;
p = va_arg (ap, void *);
TRACE (printf (" store %%n to %p\n", p));
switch (param.type) {
case '\0': * (int *) p = chars; break;
case 'F': mpf_set_si ((mpf_ptr) p, (long) chars); break;
case 'H': * (char *) p = chars; break;
case 'h': * (short *) p = chars; break;
#if HAVE_INTMAX_T
case 'j': * (intmax_t *) p = chars; break;
#else
case 'j': ASSERT_FAIL (intmax_t not available); break;
#endif
case 'l': * (long *) p = chars; break;
#if HAVE_QUAD_T && HAVE_LONG_LONG
case 'q':
ASSERT_ALWAYS (sizeof (quad_t) == sizeof (long long));
/*FALLTHRU*/
#else
case 'q': ASSERT_FAIL (quad_t not available); break;
#endif
#if HAVE_LONG_LONG
case 'L': * (long long *) p = chars; break;
#else
case 'L': ASSERT_FAIL (long long not available); break;
#endif
case 'Q': mpq_set_si ((mpq_ptr) p, (long) chars, 1L); break;
#if HAVE_PTRDIFF_T
case 't': * (ptrdiff_t *) p = chars; break;
#else
case 't': ASSERT_FAIL (ptrdiff_t not available); break;
#endif
case 'z': * (size_t *) p = chars; break;
case 'Z': mpz_set_si ((mpz_ptr) p, (long) chars); break;
default: ASSERT (0); break;
}
}
goto next;
case 'o':
param.base = 8;
goto numeric;
case 'x':
case 'X':
param.base = 16;
goto numeric;
case '0': case '1': case '2': case '3': case '4':
case '5': case '6': case '7': case '8': case '9':
param.width = 0;
do {
param.width = param.width * 10 + (fchar-'0');
fchar = *fmt++;
} while (isdigit (fchar));
fmt--; /* unget the non-digit */
break;
case '*':
param.ignore = 1;
break;
default:
/* something invalid in a % sequence */
ASSERT (0);
goto next;
}
}
}
done:
(*__gmp_free_func) (alloc_fmt, alloc_fmt_size);
return fields;
}
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