/*-*- mode:c;indent-tabs-mode:t;c-basic-offset:8;tab-width:8;coding:utf-8   -*-â
âvi: set et ft=c ts=8 tw=8 fenc=utf-8                                       :viâ
ââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââ
â                                                                              â
â Copyright (C) Lucent Technologies 1997                                       â
â All Rights Reserved                                                          â
â                                                                              â
â Permission to use, copy, modify, and distribute this software and            â
â its documentation for any purpose and without fee is hereby                  â
â granted, provided that the above copyright notice appear in all              â
â copies and that both that the copyright notice and this                      â
â permission notice and warranty disclaimer appear in supporting               â
â documentation, and that the name Lucent Technologies or any of               â
â its entities not be used in advertising or publicity pertaining              â
â to distribution of the software without specific, written prior              â
â permission.                                                                  â
â                                                                              â
â LUCENT DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,                â
â INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS.             â
â IN NO EVENT SHALL LUCENT OR ANY OF ITS ENTITIES BE LIABLE FOR ANY            â
â SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES                    â
â WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER              â
â IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,               â
â ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF               â
â THIS SOFTWARE.                                                               â
â                                                                              â
ââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââ*/
#define DEBUG
#include "libc/calls/calls.h"
#include "libc/errno.h"
#include "libc/fmt/fmt.h"
#include "libc/limits.h"
#include "libc/math.h"
#include "libc/mem/mem.h"
#include "libc/runtime/runtime.h"
#include "libc/str/str.h"
#include "third_party/awk/awk.h"
#include "third_party/gdtoa/gdtoa.h"
// clang-format off

char	EMPTY[] = { '\0' };
static FILE	*infile	= NULL;
bool	innew;		/* true = infile has not been read by readrec */
char	*file	= EMPTY;
char	*record;
int	recsize	= RECSIZE;
char	*fields;
int	fieldssize = RECSIZE;

Cell	**fldtab;	/* pointers to Cells */
static size_t	len_inputFS = 0;
static char	*inputFS = NULL; /* FS at time of input, for field splitting */

#define	MAXFLD	2
int	nfields	= MAXFLD;	/* last allocated slot for $i */

bool	donefld;	/* true = implies rec broken into fields */
bool	donerec;	/* true = record is valid (no flds have changed) */

int	lastfld	= 0;	/* last used field */
int	argno	= 1;	/* current input argument number */
extern	Awkfloat *ARGC;

static Cell dollar0 = { OCELL, CFLD, NULL, EMPTY, 0.0, REC|STR|DONTFREE, NULL, NULL };
static Cell dollar1 = { OCELL, CFLD, NULL, EMPTY, 0.0, FLD|STR|DONTFREE, NULL, NULL };

void recinit(unsigned int n)
{
	if ( (record = (char *) malloc(n)) == NULL
	  || (fields = (char *) malloc(n+1)) == NULL
	  || (fldtab = (Cell **) calloc(nfields+2, sizeof(*fldtab))) == NULL
	  || (fldtab[0] = (Cell *) malloc(sizeof(**fldtab))) == NULL)
		FATAL("out of space for $0 and fields");
	*record = '\0';
	*fldtab[0] = dollar0;
	fldtab[0]->sval = record;
	fldtab[0]->nval = tostring("0");
	makefields(1, nfields);
}

void makefields(int n1, int n2)		/* create $n1..$n2 inclusive */
{
	char temp[50];
	int i;

	for (i = n1; i <= n2; i++) {
		fldtab[i] = (Cell *) malloc(sizeof(**fldtab));
		if (fldtab[i] == NULL)
			FATAL("out of space in makefields %d", i);
		*fldtab[i] = dollar1;
		snprintf(temp, sizeof(temp), "%d", i);
		fldtab[i]->nval = tostring(temp);
	}
}

void initgetrec(void)
{
	int i;
	char *p;

	for (i = 1; i < *ARGC; i++) {
		p = getargv(i); /* find 1st real filename */
		if (p == NULL || *p == '\0') {  /* deleted or zapped */
			argno++;
			continue;
		}
		if (!isclvar(p)) {
			setsval(lookup("FILENAME", symtab), p);
			return;
		}
		setclvar(p);	/* a commandline assignment before filename */
		argno++;
	}
	infile = stdin;		/* no filenames, so use stdin */
	innew = true;
}

/*
 * POSIX specifies that fields are supposed to be evaluated as if they were
 * split using the value of FS at the time that the record's value ($0) was
 * read.
 *
 * Since field-splitting is done lazily, we save the current value of FS
 * whenever a new record is read in (implicitly or via getline), or when
 * a new value is assigned to $0.
 */
void savefs(void)
{
	size_t len;
	if ((len = strlen(getsval(fsloc))) < len_inputFS) {
		strcpy(inputFS, *FS);	/* for subsequent field splitting */
		return;
	}

	len_inputFS = len + 1;
	inputFS = (char *) realloc(inputFS, len_inputFS);
	if (inputFS == NULL)
		FATAL("field separator %.10s... is too long", *FS);
	memcpy(inputFS, *FS, len_inputFS);
}

static bool firsttime = true;

int getrec(char **pbuf, int *pbufsize, bool isrecord)	/* get next input record */
{			/* note: cares whether buf == record */
	int c;
	char *buf = *pbuf;
	uschar saveb0;
	int bufsize = *pbufsize, savebufsize = bufsize;

	if (firsttime) {
		firsttime = false;
		initgetrec();
	}
	DPRINTF("RS=<%s>, FS=<%s>, ARGC=%g, FILENAME=%s\n",
		*RS, *FS, *ARGC, *FILENAME);
	if (isrecord) {
		donefld = false;
		donerec = true;
		savefs();
	}
	saveb0 = buf[0];
	buf[0] = 0;
	while (argno < *ARGC || infile == stdin) {
		DPRINTF("argno=%d, file=|%s|\n", argno, file);
		if (infile == NULL) {	/* have to open a new file */
			file = getargv(argno);
			if (file == NULL || *file == '\0') {	/* deleted or zapped */
				argno++;
				continue;
			}
			if (isclvar(file)) {	/* a var=value arg */
				setclvar(file);
				argno++;
				continue;
			}
			*FILENAME = file;
			DPRINTF("opening file %s\n", file);
			if (*file == '-' && *(file+1) == '\0')
				infile = stdin;
			else if ((infile = fopen(file, "r")) == NULL)
				FATAL("can't open file %s", file);
			innew = true;
			setfval(fnrloc, 0.0);
		}
		c = readrec(&buf, &bufsize, infile, innew);
		if (innew)
			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, & result)) {
					fldtab[0]->fval = result;
					fldtab[0]->tval |= NUM;
				}
			}
			setfval(nrloc, nrloc->fval+1);
			setfval(fnrloc, fnrloc->fval+1);
			*pbuf = buf;
			*pbufsize = bufsize;
			return 1;
		}
		/* EOF arrived on this file; set up next */
		if (infile != stdin)
			fclose(infile);
		infile = NULL;
		argno++;
	}
	buf[0] = saveb0;
	*pbuf = buf;
	*pbufsize = savebufsize;
	return 0;	/* true end of file */
}

void nextfile(void)
{
	if (infile != NULL && infile != stdin)
		fclose(infile);
	infile = NULL;
	argno++;
}

int readrec(char **pbuf, int *pbufsize, FILE *inf, bool newflag)	/* read one record into buf */
{
	int sep, c, isrec;
	char *rr, *buf = *pbuf;
	int bufsize = *pbufsize;
	char *rs = getsval(rsloc);

	if (*rs && rs[1]) {
		bool found;

		fa *pfa = makedfa(rs, 1);
		if (newflag)
			found = fnematch(pfa, inf, &buf, &bufsize, recsize);
		else {
			int tempstat = pfa->initstat;
			pfa->initstat = 2;
			found = fnematch(pfa, inf, &buf, &bufsize, recsize);
			pfa->initstat = tempstat;
		}
		if (found)
			setptr(patbeg, '\0');
		isrec = (found == 0 && *buf == '\0') ? false : true;
	} else {
		if ((sep = *rs) == 0) {
			sep = '\n';
			while ((c=getc(inf)) == '\n' && c != EOF)	/* skip leading \n's */
				;
			if (c != EOF)
				ungetc(c, inf);
		}
		for (rr = buf; ; ) {
			for (; (c=getc(inf)) != sep && c != EOF; ) {
				if (rr-buf+1 > bufsize)
					if (!adjbuf(&buf, &bufsize, 1+rr-buf,
					    recsize, &rr, "readrec 1"))
						FATAL("input record `%.30s...' too long", buf);
				*rr++ = c;
			}
			if (*rs == sep || c == EOF)
				break;
			if ((c = getc(inf)) == '\n' || c == EOF)	/* 2 in a row */
				break;
			if (!adjbuf(&buf, &bufsize, 2+rr-buf, recsize, &rr,
			    "readrec 2"))
				FATAL("input record `%.30s...' too long", buf);
			*rr++ = '\n';
			*rr++ = c;
		}
		if (!adjbuf(&buf, &bufsize, 1+rr-buf, recsize, &rr, "readrec 3"))
			FATAL("input record `%.30s...' too long", buf);
		*rr = 0;
		isrec = (c == EOF && rr == buf) ? false : true;
	}
	*pbuf = buf;
	*pbufsize = bufsize;
	DPRINTF("readrec saw <%s>, returns %d\n", buf, isrec);
	return isrec;
}

char *getargv(int n)	/* get ARGV[n] */
{
	Cell *x;
	char *s, temp[50];
	extern Array *ARGVtab;

	snprintf(temp, sizeof(temp), "%d", n);
	if (lookup(temp, ARGVtab) == NULL)
		return NULL;
	x = setsymtab(temp, "", 0.0, STR, ARGVtab);
	s = getsval(x);
	DPRINTF("getargv(%d) returns |%s|\n", n, s);
	return s;
}

void setclvar(char *s)	/* set var=value from s */
{
	char *e, *p;
	Cell *q;
	double result;

	for (p=s; *p != '='; p++)
		;
	e = p;
	*p++ = 0;
	p = qstring(p, '\0');
	q = setsymtab(s, p, 0.0, STR, symtab);
	setsval(q, p);
	if (is_number(q->sval, & result)) {
		q->fval = result;
		q->tval |= NUM;
	}
	DPRINTF("command line set %s to |%s|\n", s, p);
	*e = '=';
}


void fldbld(void)	/* create fields from current record */
{
	/* this relies on having fields[] the same length as $0 */
	/* the fields are all stored in this one array with \0's */
	/* possibly with a final trailing \0 not associated with any field */
	char *r, *fr, sep;
	Cell *p;
	int i, j, n;

	if (donefld)
		return;
	if (!isstr(fldtab[0]))
		getsval(fldtab[0]);
	r = fldtab[0]->sval;
	n = strlen(r);
	if (n > fieldssize) {
		xfree(fields);
		if ((fields = (char *) malloc(n+2)) == NULL) /* possibly 2 final \0s */
			FATAL("out of space for fields in fldbld %d", n);
		fieldssize = n;
	}
	fr = fields;
	i = 0;	/* number of fields accumulated here */
	if (inputFS == NULL)	/* make sure we have a copy of FS */
		savefs();
	if (strlen(inputFS) > 1) {	/* it's a regular expression */
		i = refldbld(r, inputFS);
	} else if ((sep = *inputFS) == ' ') {	/* default whitespace */
		for (i = 0; ; ) {
			while (*r == ' ' || *r == '\t' || *r == '\n')
				r++;
			if (*r == 0)
				break;
			i++;
			if (i > nfields)
				growfldtab(i);
			if (freeable(fldtab[i]))
				xfree(fldtab[i]->sval);
			fldtab[i]->sval = fr;
			fldtab[i]->tval = FLD | STR | DONTFREE;
			do
				*fr++ = *r++;
			while (*r != ' ' && *r != '\t' && *r != '\n' && *r != '\0');
			*fr++ = 0;
		}
		*fr = 0;
	} else if ((sep = *inputFS) == 0) {		/* new: FS="" => 1 char/field */
		for (i = 0; *r != '\0'; r += n) {
			char buf[MB_LEN_MAX + 1];

			i++;
			if (i > nfields)
				growfldtab(i);
			if (freeable(fldtab[i]))
				xfree(fldtab[i]->sval);
			n = mblen(r, MB_LEN_MAX);
			if (n < 0)
				n = 1;
			memcpy(buf, r, n);
			buf[n] = '\0';
			fldtab[i]->sval = tostring(buf);
			fldtab[i]->tval = FLD | STR;
		}
		*fr = 0;
	} else if (*r != 0) {	/* if 0, it's a null field */
		/* subtlecase : if length(FS) == 1 && length(RS > 0)
		 * \n is NOT a field separator (cf awk book 61,84).
		 * this variable is tested in the inner while loop.
		 */
		int rtest = '\n';  /* normal case */
		if (strlen(*RS) > 0)
			rtest = '\0';
		for (;;) {
			i++;
			if (i > nfields)
				growfldtab(i);
			if (freeable(fldtab[i]))
				xfree(fldtab[i]->sval);
			fldtab[i]->sval = fr;
			fldtab[i]->tval = FLD | STR | DONTFREE;
			while (*r != sep && *r != rtest && *r != '\0')	/* \n is always a separator */
				*fr++ = *r++;
			*fr++ = 0;
			if (*r++ == 0)
				break;
		}
		*fr = 0;
	}
	if (i > nfields)
		FATAL("record `%.30s...' has too many fields; can't happen", r);
	cleanfld(i+1, lastfld);	/* clean out junk from previous record */
	lastfld = i;
	donefld = true;
	for (j = 1; j <= lastfld; j++) {
		double result;

		p = fldtab[j];
		if(is_number(p->sval, & result)) {
			p->fval = result;
			p->tval |= NUM;
		}
	}
	setfval(nfloc, (Awkfloat) lastfld);
	donerec = true; /* restore */
	if (dbg) {
		for (j = 0; j <= lastfld; j++) {
			p = fldtab[j];
			printf("field %d (%s): |%s|\n", j, p->nval, p->sval);
		}
	}
}

void cleanfld(int n1, int n2)	/* clean out fields n1 .. n2 inclusive */
{				/* nvals remain intact */
	Cell *p;
	int i;

	for (i = n1; i <= n2; i++) {
		p = fldtab[i];
		if (freeable(p))
			xfree(p->sval);
		p->sval = EMPTY,
		p->tval = FLD | STR | DONTFREE;
	}
}

void newfld(int n)	/* add field n after end of existing lastfld */
{
	if (n > nfields)
		growfldtab(n);
	cleanfld(lastfld+1, n);
	lastfld = n;
	setfval(nfloc, (Awkfloat) n);
}

void setlastfld(int n)	/* set lastfld cleaning fldtab cells if necessary */
{
	if (n < 0)
		FATAL("cannot set NF to a negative value");
	if (n > nfields)
		growfldtab(n);

	if (lastfld < n)
	    cleanfld(lastfld+1, n);
	else
	    cleanfld(n+1, lastfld);

	lastfld = n;
}

Cell *fieldadr(int n)	/* get nth field */
{
	if (n < 0)
		FATAL("trying to access out of range field %d", n);
	if (n > nfields)	/* fields after NF are empty */
		growfldtab(n);	/* but does not increase NF */
	return(fldtab[n]);
}

void growfldtab(int n)	/* make new fields up to at least $n */
{
	int nf = 2 * nfields;
	size_t s;

	if (n > nf)
		nf = n;
	s = (nf+1) * (sizeof (struct Cell *));  /* freebsd: how much do we need? */
	if (s / sizeof(struct Cell *) - 1 == (size_t)nf) /* didn't overflow */
		fldtab = (Cell **) realloc(fldtab, s);
	else					/* overflow sizeof int */
		xfree(fldtab);	/* make it null */
	if (fldtab == NULL)
		FATAL("out of space creating %d fields", nf);
	makefields(nfields+1, nf);
	nfields = nf;
}

int refldbld(const char *rec, const char *fs)	/* build fields from reg expr in FS */
{
	/* this relies on having fields[] the same length as $0 */
	/* the fields are all stored in this one array with \0's */
	char *fr;
	int i, tempstat, n;
	fa *pfa;

	n = strlen(rec);
	if (n > fieldssize) {
		xfree(fields);
		if ((fields = (char *) malloc(n+1)) == NULL)
			FATAL("out of space for fields in refldbld %d", n);
		fieldssize = n;
	}
	fr = fields;
	*fr = '\0';
	if (*rec == '\0')
		return 0;
	pfa = makedfa(fs, 1);
	DPRINTF("into refldbld, rec = <%s>, pat = <%s>\n", rec, fs);
	tempstat = pfa->initstat;
	for (i = 1; ; i++) {
		if (i > nfields)
			growfldtab(i);
		if (freeable(fldtab[i]))
			xfree(fldtab[i]->sval);
		fldtab[i]->tval = FLD | STR | DONTFREE;
		fldtab[i]->sval = fr;
		DPRINTF("refldbld: i=%d\n", i);
		if (nematch(pfa, rec)) {
			pfa->initstat = 2;	/* horrible coupling to b.c */
			DPRINTF("match %s (%d chars)\n", patbeg, patlen);
			strncpy(fr, rec, patbeg-rec);
			fr += patbeg - rec + 1;
			*(fr-1) = '\0';
			rec = patbeg + patlen;
		} else {
			DPRINTF("no match %s\n", rec);
			strcpy(fr, rec);
			pfa->initstat = tempstat;
			break;
		}
	}
	return i;
}

void recbld(void)	/* create $0 from $1..$NF if necessary */
{
	int i;
	char *r, *p;
	char *sep = getsval(ofsloc);

	if (donerec)
		return;
	r = record;
	for (i = 1; i <= *NF; i++) {
		p = getsval(fldtab[i]);
		if (!adjbuf(&record, &recsize, 1+strlen(p)+r-record, recsize, &r, "recbld 1"))
			FATAL("created $0 `%.30s...' too long", record);
		while ((*r = *p++) != 0)
			r++;
		if (i < *NF) {
			if (!adjbuf(&record, &recsize, 2+strlen(sep)+r-record, recsize, &r, "recbld 2"))
				FATAL("created $0 `%.30s...' too long", record);
			for (p = sep; (*r = *p++) != 0; )
				r++;
		}
	}
	if (!adjbuf(&record, &recsize, 2+r-record, recsize, &r, "recbld 3"))
		FATAL("built giant record `%.30s...'", record);
	*r = '\0';
	DPRINTF("in recbld inputFS=%s, fldtab[0]=%p\n", inputFS, (void*)fldtab[0]);

	if (freeable(fldtab[0]))
		xfree(fldtab[0]->sval);
	fldtab[0]->tval = REC | STR | DONTFREE;
	fldtab[0]->sval = record;

	DPRINTF("in recbld inputFS=%s, fldtab[0]=%p\n", inputFS, (void*)fldtab[0]);
	DPRINTF("recbld = |%s|\n", record);
	donerec = true;
}

int	errorflag	= 0;

void yyerror(const char *s)
{
	SYNTAX("%s", s);
}

extern char *cmdname;

void SYNTAX(const char *fmt, ...)
{
	extern char *curfname;
	static int been_here = 0;
	va_list varg;

	if (been_here++ > 2)
		return;
	fprintf(stderr, "%s: ", cmdname);
	va_start(varg, fmt);
	vfprintf(stderr, fmt, varg);
	va_end(varg);
	fprintf(stderr, " at source line %d", lineno);
	if (curfname != NULL)
		fprintf(stderr, " in function %s", curfname);
	if (compile_time == COMPILING && cursource() != NULL)
		fprintf(stderr, " source file %s", cursource());
	fprintf(stderr, "\n");
	errorflag = 2;
	eprint();
}

extern int bracecnt, brackcnt, parencnt;

void bracecheck(void)
{
	int c;
	static int beenhere = 0;

	if (beenhere++)
		return;
	while ((c = input()) != EOF && c != '\0')
		bclass(c);
	bcheck2(bracecnt, '{', '}');
	bcheck2(brackcnt, '[', ']');
	bcheck2(parencnt, '(', ')');
}

void bcheck2(int n, int c1, int c2)
{
	if (n == 1)
		fprintf(stderr, "\tmissing %c\n", c2);
	else if (n > 1)
		fprintf(stderr, "\t%d missing %c's\n", n, c2);
	else if (n == -1)
		fprintf(stderr, "\textra %c\n", c2);
	else if (n < -1)
		fprintf(stderr, "\t%d extra %c's\n", -n, c2);
}

void FATAL(const char *fmt, ...)
{
	va_list varg;

	fflush(stdout);
	fprintf(stderr, "%s: ", cmdname);
	va_start(varg, fmt);
	vfprintf(stderr, fmt, varg);
	va_end(varg);
	error();
	if (dbg > 1)		/* core dump if serious debugging on */
		abort();
	exit(2);
}

void WARNING(const char *fmt, ...)
{
	va_list varg;

	fflush(stdout);
	fprintf(stderr, "%s: ", cmdname);
	va_start(varg, fmt);
	vfprintf(stderr, fmt, varg);
	va_end(varg);
	error();
}

void error()
{
	extern Node *curnode;

	fprintf(stderr, "\n");
	if (compile_time != ERROR_PRINTING) {
		if (NR && *NR > 0) {
			fprintf(stderr, " input record number %d", (int) (*FNR));
			if (strcmp(*FILENAME, "-") != 0)
				fprintf(stderr, ", file %s", *FILENAME);
			fprintf(stderr, "\n");
		}
		if (curnode)
			fprintf(stderr, " source line number %d", curnode->lineno);
		else if (lineno)
			fprintf(stderr, " source line number %d", lineno);
		if (compile_time == COMPILING && cursource() != NULL)
			fprintf(stderr, " source file %s", cursource());
		fprintf(stderr, "\n");
		eprint();
	}
}

void eprint(void)	/* try to print context around error */
{
	char *p, *q;
	int c;
	static int been_here = 0;
	extern char ebuf[], *ep;

	if (compile_time != COMPILING || been_here++ > 0 || ebuf == ep)
		return;
	if (ebuf == ep)
		return;
	p = ep - 1;
	if (p > ebuf && *p == '\n')
		p--;
	for ( ; p > ebuf && *p != '\n' && *p != '\0'; p--)
		;
	while (*p == '\n')
		p++;
	fprintf(stderr, " context is\n\t");
	for (q=ep-1; q>=p && *q!=' ' && *q!='\t' && *q!='\n'; q--)
		;
	for ( ; p < q; p++)
		if (*p)
			putc(*p, stderr);
	fprintf(stderr, " >>> ");
	for ( ; p < ep; p++)
		if (*p)
			putc(*p, stderr);
	fprintf(stderr, " <<< ");
	if (*ep)
		while ((c = input()) != '\n' && c != '\0' && c != EOF) {
			putc(c, stderr);
			bclass(c);
		}
	putc('\n', stderr);
	ep = ebuf;
}

void bclass(int c)
{
	switch (c) {
	case '{': bracecnt++; break;
	case '}': bracecnt--; break;
	case '[': brackcnt++; break;
	case ']': brackcnt--; break;
	case '(': parencnt++; break;
	case ')': parencnt--; break;
	}
}

double errcheck(double x, const char *s)
{

	if (errno == EDOM) {
		errno = 0;
		WARNING("%s argument out of domain", s);
		x = 1;
	} else if (errno == ERANGE) {
		errno = 0;
		WARNING("%s result out of range", s);
		x = 1;
	}
	return x;
}

int isclvar(const char *s)	/* is s of form var=something ? */
{
	const char *os = s;

	if (!isalpha((uschar) *s) && *s != '_')
		return 0;
	for ( ; *s; s++)
		if (!(isalnum((uschar) *s) || *s == '_'))
			break;
	return *s == '=' && s > os;
}

/* 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. 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.
 */

/*
 * 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;
	bool is_nan = false;
	bool is_inf = false;

	if (no_trailing)
		*no_trailing = false;

	while (isspace(*s))
		s++;

	// no hex floating point, sorry
	if (s[0] == '0' && tolower(s[1]) == 'x')
		return false;

	// allow +nan, -nan, +inf, -inf, any other letter, no
	if (s[0] == '+' || s[0] == '-') {
		is_nan = (strncasecmp(s+1, "nan", 3) == 0);
		is_inf = (strncasecmp(s+1, "inf", 3) == 0);
		if ((is_nan || is_inf)
		    && (isspace(s[4]) || s[4] == '\0'))
			goto convert;
		else if (! isdigit(s[1]) && s[1] != '.')
			return false;
	}
	else if (! isdigit(s[0]) && s[0] != '.')
		return false;

convert:
	errno = 0;
	r = strtod(s, &ep);
	if (ep == s || errno == ERANGE)
		return false;

	if (isnan(r) && s[0] == '-' && signbit(r) == 0)
		r = -r;

	if (result != NULL)
		*result = r;

	/*
	 * check for trailing stuff
	 */
	while (isspace(*ep))
		ep++;

	if (no_trailing != NULL)
		*no_trailing = (*ep == '\0');

        // return true if found the end, or trailing stuff is allowed
	retval = *ep == '\0' || trailing_stuff_ok;

	return retval;
}
