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Re: Bug in vfprintf?
I found a problem. My fix was using ndigits instead of
orig_ndigits for the "%g" format. A revised patch is attached.
-- Jeff J.
Jason Tishler wrote:
Jeff,
On Fri, Jan 31, 2003 at 07:56:05PM -0500, J. Johnston wrote:
Ok, another patch for you.
The attached patch fixes my most recently reported problems with "%f"
formatting. However, my previously reported problem with:
"%#.109g", -3333333333333333371313292264111748921061485000000.0
is back.
Unfortunately, I'm having difficulties isolating the problem in C, but
the following simple Python script SEGVs during exit (i.e., during
garbage collection):
s = "%#.109g" % (-1.e+49/3.)
print s
Attached is my C translation of the above. Single stepping in gdb, I
haven't found the overwrite yet. I will try to dig deeper, but I hope
that reporting what I have found will help you see what I'm missing.
Thanks,
Jason
------------------------------------------------------------------------
#include <stdio.h>
int
main(int argc, char* argv[])
{
const char* format = "%#.109g";
double value = -1.e+49/3.;
printf(format, value);
printf("\n");
return 0;
}
Index: ldtoa.c
===================================================================
RCS file: /cvs/src/src/newlib/libc/stdlib/ldtoa.c,v
retrieving revision 1.7
diff -u -r1.7 ldtoa.c
--- ldtoa.c 7 Jan 2003 19:52:27 -0000 1.7
+++ ldtoa.c 3 Feb 2003 17:12:33 -0000
@@ -2707,10 +2707,13 @@
unsigned short e[NI];
char *s, *p;
int i, j, k;
+int orig_ndigits;
LDPARMS rnd;
LDPARMS *ldp = &rnd;
char *outstr;
+char outbuf[NDEC + MAX_EXP_DIGITS + 10];
+orig_ndigits = ndigits;
rnd.rlast = -1;
rnd.rndprc = NBITS;
@@ -2748,22 +2751,13 @@
if( mode == 0 )
ndigits = 20;
-/* reentrancy addition to use mprec storage pool */
-/* we want to have enough space to hold the formatted result */
-i = ndigits + (mode == 3 ? (MAX_EXP_DIGITS + 1) : 1);
-j = sizeof (__ULong);
-for (_REENT_MP_RESULT_K(ptr) = 0; sizeof (_Bigint) - sizeof (__ULong) + j <= i; j <<= 1)
- _REENT_MP_RESULT_K(ptr)++;
-_REENT_MP_RESULT(ptr) = Balloc (ptr, _REENT_MP_RESULT_K(ptr));
-outstr = (char *)_REENT_MP_RESULT(ptr);
-
/* This sanity limit must agree with the corresponding one in etoasc, to
keep straight the returned value of outexpon. */
if( ndigits > NDEC )
ndigits = NDEC;
-etoasc( e, outstr, ndigits, mode, ldp );
-s = outstr;
+etoasc( e, outbuf, ndigits, mode, ldp );
+s = outbuf;
if( eisinf(e) || eisnan(e) )
{
*decpt = 9999;
@@ -2774,7 +2768,7 @@
/* Transform the string returned by etoasc into what the caller wants. */
/* Look for decimal point and delete it from the string. */
-s = outstr;
+s = outbuf;
while( *s != '\0' )
{
if( *s == '.' )
@@ -2795,19 +2789,19 @@
nodecpt:
/* Back up over the exponent field. */
-while( *s != 'E' && s > outstr)
+while( *s != 'E' && s > outbuf)
--s;
*s = '\0';
stripspaces:
/* Strip leading spaces and sign. */
-p = outstr;
+p = outbuf;
while( *p == ' ' || *p == '-')
++p;
/* Find new end of string. */
-s = outstr;
+s = outbuf;
while( (*s++ = *p++) != '\0' )
;
--s;
@@ -2820,20 +2814,38 @@
else
k = ldp->outexpon;
-while( *(s-1) == '0' && ((s - outstr) > k))
+while( *(s-1) == '0' && ((s - outbuf) > k))
*(--s) = '\0';
/* In f format, flush small off-scale values to zero.
Rounding has been taken care of by etoasc. */
if( mode == 3 && ((ndigits + ldp->outexpon) < 0))
{
- s = outstr;
+ s = outbuf;
*s = '\0';
*decpt = 0;
}
+/* reentrancy addition to use mprec storage pool */
+/* we want to have enough space to hold the formatted result */
+
+if (mode == 3) /* f format, account for sign + dec digits + decpt + frac */
+ i = *decpt + orig_ndigits + 3;
+else /* account for sign + max precision digs + E + exp sign + exponent */
+ i = orig_ndigits + MAX_EXP_DIGITS + 4;
+
+j = sizeof (__ULong);
+for (_REENT_MP_RESULT_K(ptr) = 0; sizeof (_Bigint) - sizeof (__ULong) + j <= i; j <<= 1)
+ _REENT_MP_RESULT_K(ptr)++;
+_REENT_MP_RESULT(ptr) = Balloc (ptr, _REENT_MP_RESULT_K(ptr));
+
+/* Copy from internal temporary buffer to permanent buffer. */
+outstr = (char *)_REENT_MP_RESULT(ptr);
+strcpy (outstr, outbuf);
+
if( rve )
- *rve = s;
+ *rve = outstr + (s - outbuf);
+
return outstr;
}