ref: cc9e9b68d124c6c7770eb3903329423ff9f17201
parent: e508d2861c26e89e7289a5a33d99df2951498ff4
author: Arnold Robbins <arnold@skeeve.com>
date: Tue Dec 8 03:05:22 EST 2020
Rework floating point conversions. (#98)
--- a/awk.1
+++ b/awk.1
@@ -577,3 +577,56 @@
the syntax is worse.
.PP
Only eight-bit characters sets are handled correctly.
+.SH UNUSUAL FLOATING-POINT VALUES
+.I Awk
+was designed before IEEE 754 arithmetic defined Not-A-Number (NaN)
+and Infinity values, which are supported by all modern floating-point
+hardware.
+.PP
+Because
+.I awk
+uses
+.IR strtod (3)
+and
+.IR atof (3)
+to convert string values to double-precision floating-point values,
+modern C libraries also convert strings starting with
+.B inf
+and
+.B nan
+into infinity and NaN values respectively. This led to strange results,
+with something like this:
+.PP
+.EX
+.nf
+echo nancy | awk '{ print $1 + 0 }'+.fi
+.EE
+.PP
+printing
+.B nan
+instead of zero.
+.PP
+.I Awk
+now follows GNU AWK, and prefilters string values before attempting
+to convert them to numbers, as follows:
+.TP
+.I "Hexadecimal values"
+Hexadecimal values (allowed since C99) convert to zero, as they did
+prior to C99.
+.TP
+.I "NaN values"
+The two strings
+.B +nan
+and
+.B \-nan
+(case independent) convert to NaN. No others do.
+(NaNs can have signs.)
+.TP
+.I "Infinity values"
+The two strings
+.B +inf
+and
+.B \-inf
+(case independent) convert to positive and negative infinity, respectively.
+No others do.
--- a/lex.c
+++ b/lex.c
@@ -191,7 +191,12 @@
return word(buf);
if (isdigit(c)) {char *cp = tostring(buf);
- yylval.cp = setsymtab(buf, cp, atof(buf), CON|NUM, symtab);
+ double result;
+
+ if (is_number(cp, & result))
+ yylval.cp = setsymtab(buf, cp, result, CON|NUM, symtab);
+ else
+ yylval.cp = setsymtab(buf, cp, 0.0, STR, symtab);
free(cp);
/* should this also have STR set? */
RET(NUMBER);
--- a/lib.c
+++ b/lib.c
@@ -30,6 +30,7 @@
#include <stdlib.h>
#include <stdarg.h>
#include <limits.h>
+#include <math.h>
#include "awk.h"
char EMPTY[] = { '\0' };@@ -181,12 +182,14 @@
innew = false;
if (c != 0 || buf[0] != '\0') { /* normal record */ if (isrecord) {+ double result;
+
if (freeable(fldtab[0]))
xfree(fldtab[0]->sval);
fldtab[0]->sval = buf; /* buf == record */
fldtab[0]->tval = REC | STR | DONTFREE;
- if (is_number(fldtab[0]->sval)) {- fldtab[0]->fval = atof(fldtab[0]->sval);
+ if (is_number(fldtab[0]->sval, & result)) {+ fldtab[0]->fval = result;
fldtab[0]->tval |= NUM;
}
}
@@ -293,6 +296,7 @@
{char *p;
Cell *q;
+ double result;
for (p=s; *p != '='; p++)
;
@@ -300,8 +304,8 @@
p = qstring(p, '\0');
q = setsymtab(s, p, 0.0, STR, symtab);
setsval(q, p);
- if (is_number(q->sval)) {- q->fval = atof(q->sval);
+ if (is_number(q->sval, & result)) {+ q->fval = result;
q->tval |= NUM;
}
DPRINTF("command line set %s to |%s|\n", s, p);@@ -402,9 +406,11 @@
lastfld = i;
donefld = true;
for (j = 1; j <= lastfld; j++) {+ double result;
+
p = fldtab[j];
- if(is_number(p->sval)) {- p->fval = atof(p->sval);
+ if(is_number(p->sval, & result)) {+ p->fval = result;
p->tval |= NUM;
}
}
@@ -756,24 +762,67 @@
/* strtod is supposed to be a proper test of what's a valid number */
/* appears to be broken in gcc on linux: thinks 0x123 is a valid FP number */
/* wrong: violates 4.10.1.4 of ansi C standard */
+
/* well, not quite. As of C99, hex floating point is allowed. so this is
- * a bit of a mess.
+ * a bit of a mess. We work around the mess by checking for a hexadecimal
+ * value and disallowing it. Similarly, we now follow gawk and allow only
+ * +nan, -nan, +inf, and -inf for NaN and infinity values.
*/
-#include <math.h>
-int is_number(const char *s)
+/*
+ * This routine now has a more complicated interface, the main point
+ * being to avoid the double conversion of a string to double, and
+ * also to convey out, if requested, the information that the numeric
+ * value was a leading string or is all of the string. The latter bit
+ * is used in getfval().
+ */
+
+bool is_valid_number(const char *s, bool trailing_stuff_ok,
+ bool *no_trailing, double *result)
{double r;
char *ep;
+ bool retval = false;
+
+ if (no_trailing)
+ *no_trailing = false;
+
+ while (*s == ' ' || *s == '\t' || *s == '\n' || *s == '\r')
+ s++;
+
+ if (s[0] == '0' && tolower(s[1]) == 'x') // no hex floating point, sorry
+ return false;
+
+ // allow +nan, -nan, +inf, -inf, any other letter, no
+ if (s[0] == '+' || s[0] == '-') {+ if (strcasecmp(s+1, "nan") == 0 || strcasecmp(s+1, "inf") == 0)
+ return true;
+ else if (! isdigit(s[1]) && s[1] != '.')
+ return false;
+ }
+ else if (! isdigit(s[0]) && s[0] != '.')
+ return false;
+
errno = 0;
r = strtod(s, &ep);
if (ep == s || r == HUGE_VAL || errno == ERANGE)
- return 0;
- /* allow \r as well. windows files aren't going to go away. */
+ return false;
+
+ if (result != NULL)
+ *result = r;
+
+ /*
+ * check for trailing stuff
+ * allow \r as well. windows files aren't going to go away.
+ */
while (*ep == ' ' || *ep == '\t' || *ep == '\n' || *ep == '\r')
ep++;
- if (*ep == '\0')
- return 1;
- else
- return 0;
+
+ if (no_trailing)
+ *no_trailing = (*ep == '\0');
+
+ // return true if found the end, or trailing stuff is allowed
+ retval = (*ep == '\0') || trailing_stuff_ok;
+
+ return retval;
}
--- a/proto.h
+++ b/proto.h
@@ -146,7 +146,9 @@
extern void bclass(int);
extern double errcheck(double, const char *);
extern int isclvar(const char *);
-extern int is_number(const char *);
+extern bool is_valid_number(const char *s, bool trailing_stuff_ok,
+ bool *no_trailing, double *result);
+#define is_number(s, val) is_valid_number(s, false, NULL, val)
extern int adjbuf(char **pb, int *sz, int min, int q, char **pbp, const char *what);
extern void run(Node *);
--- a/run.c
+++ b/run.c
@@ -407,6 +407,7 @@
int bufsize = recsize;
int mode;
bool newflag;
+ double result;
if ((buf = (char *) malloc(bufsize)) == NULL)
FATAL("out of memory in getline");@@ -429,15 +430,15 @@
} else if (a[0] != NULL) { /* getline var <file */x = execute(a[0]);
setsval(x, buf);
- if (is_number(x->sval)) {- x->fval = atof(x->sval);
+ if (is_number(x->sval, & result)) {+ x->fval = result;
x->tval |= NUM;
}
tempfree(x);
} else { /* getline <file */setsval(fldtab[0], buf);
- if (is_number(fldtab[0]->sval)) {- fldtab[0]->fval = atof(fldtab[0]->sval);
+ if (is_number(fldtab[0]->sval, & result)) {+ fldtab[0]->fval = result;
fldtab[0]->tval |= NUM;
}
}
@@ -448,8 +449,8 @@
n = getrec(&buf, &bufsize, false);
x = execute(a[0]);
setsval(x, buf);
- if (is_number(x->sval)) {- x->fval = atof(x->sval);
+ if (is_number(x->sval, & result)) {+ x->fval = result;
x->tval |= NUM;
}
tempfree(x);
@@ -726,7 +727,7 @@
if ((Awkfloat)INT_MAX < val)
FATAL("trying to access out of range field %s", x->nval);m = (int) val;
- if (m == 0 && !is_number(s = getsval(x))) /* suspicion! */
+ if (m == 0 && !is_number(s = getsval(x), NULL)) /* suspicion! */
FATAL("illegal field $(%s), name \"%s\"", s, x->nval);/* BUG: can x->nval ever be null??? */
tempfree(x);
@@ -1259,6 +1260,7 @@
int sep;
char temp, num[50];
int n, tempstat, arg3type;
+ double result;
y = execute(a[0]); /* source string */
origs = s = strdup(getsval(y));
@@ -1303,8 +1305,8 @@
snprintf(num, sizeof(num), "%d", n);
temp = *patbeg;
setptr(patbeg, '\0');
- if (is_number(s))
- setsymtab(num, s, atof(s), STR|NUM, (Array *) ap->sval);
+ if (is_number(s, & result))
+ setsymtab(num, s, result, STR|NUM, (Array *) ap->sval);
else
setsymtab(num, s, 0.0, STR, (Array *) ap->sval);
setptr(patbeg, temp);
@@ -1322,8 +1324,8 @@
}
n++;
snprintf(num, sizeof(num), "%d", n);
- if (is_number(s))
- setsymtab(num, s, atof(s), STR|NUM, (Array *) ap->sval);
+ if (is_number(s, & result))
+ setsymtab(num, s, result, STR|NUM, (Array *) ap->sval);
else
setsymtab(num, s, 0.0, STR, (Array *) ap->sval);
spdone:
@@ -1343,8 +1345,8 @@
temp = *s;
setptr(s, '\0');
snprintf(num, sizeof(num), "%d", n);
- if (is_number(t))
- setsymtab(num, t, atof(t), STR|NUM, (Array *) ap->sval);
+ if (is_number(t, & result))
+ setsymtab(num, t, result, STR|NUM, (Array *) ap->sval);
else
setsymtab(num, t, 0.0, STR, (Array *) ap->sval);
setptr(s, temp);
@@ -1372,8 +1374,8 @@
temp = *s;
setptr(s, '\0');
snprintf(num, sizeof(num), "%d", n);
- if (is_number(t))
- setsymtab(num, t, atof(t), STR|NUM, (Array *) ap->sval);
+ if (is_number(t, & result))
+ setsymtab(num, t, result, STR|NUM, (Array *) ap->sval);
else
setsymtab(num, t, 0.0, STR, (Array *) ap->sval);
setptr(s, temp);
--- a/tran.c
+++ b/tran.c
@@ -129,9 +129,11 @@
free(cp->sval);
cp->sval = (char *) ARGVtab;
for (i = 0; i < ac; i++) {+ double result;
+
sprintf(temp, "%d", i);
- if (is_number(*av))
- setsymtab(temp, *av, atof(*av), STR|NUM, ARGVtab);
+ if (is_number(*av, & result))
+ setsymtab(temp, *av, result, STR|NUM, ARGVtab);
else
setsymtab(temp, *av, 0.0, STR, ARGVtab);
av++;
@@ -148,13 +150,15 @@
free(cp->sval);
cp->sval = (char *) ENVtab;
for ( ; *envp; envp++) {+ double result;
+
if ((p = strchr(*envp, '=')) == NULL)
continue;
if( p == *envp ) /* no left hand side name in env string */
continue;
*p++ = 0; /* split into two strings at = */
- if (is_number(p))
- setsymtab(*envp, p, atof(p), STR|NUM, ENVtab);
+ if (is_number(p, & result))
+ setsymtab(*envp, p, result, STR|NUM, ENVtab);
else
setsymtab(*envp, p, 0.0, STR, ENVtab);
p[-1] = '='; /* restore in case env is passed down to a shell */
@@ -399,9 +403,15 @@
else if (isrec(vp) && !donerec)
recbld();
if (!isnum(vp)) { /* not a number */- vp->fval = atof(vp->sval); /* best guess */
- if (is_number(vp->sval) && !(vp->tval&CON))
- vp->tval |= NUM; /* make NUM only sparingly */
+ double fval;
+ bool no_trailing;
+
+ if (is_valid_number(vp->sval, true, & no_trailing, & fval)) {+ vp->fval = fval;
+ if (no_trailing && !(vp->tval&CON))
+ vp->tval |= NUM; /* make NUM only sparingly */
+ } else
+ vp->fval = 0.0;
}
DPRINTF("getfval %p: %s = %g, t=%o\n",(void*)vp, NN(vp->nval), vp->fval, vp->tval);
--
⑨