lib.c

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

	}
}

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);
}

Cell *fieldadr(int n)	/* get nth field */
{
	if (n < 0)
		FATAL("trying to access 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;

	if (n > nf)
		nf = n;
	fldtab = (Cell **) realloc(fldtab, (nf+1) * (sizeof (struct Cell *)));
	if (fldtab == NULL)
		FATAL("out of space creating %d fields", nf);
	makefields(nfields+1, nf);
	nfields = nf;
}

int refldbld(char *rec, 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;
	void *p;
	int i, tempstat, n;

	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;
	p = compre(fs);
	   dprintf( ("into refldbld, rec = <%s>, pat = <%s>\n", rec, fs) );
	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(p, rec, rec)) {
			   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);
			break;
		}
	}
	return i;		
}

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

	if (donerec == 1)
		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(*OFS)+r-record, recsize, &r, "recbld 2"))
				FATAL("created $0 `%.30s...' too long", record);
			for (p = *OFS; (*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, 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, fldtab[0]) );
	   dprintf( ("recbld = |%s|\n", record) );
	donerec = 1;
}

int	errorflag	= 0;

void yyerror(char *s)
{
	SYNTAX(s);
}

void SYNTAX(char *fmt, ...)
{
	extern char *cmdname, *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);
	if(compile_time == 1 && cursource() != NULL)
		fprintf(stderr, " at %s:%d", cursource(), lineno);
	else
		fprintf(stderr, " at line %d", lineno);
	if (curfname != NULL)
		fprintf(stderr, " in function %s", curfname);
	fprintf(stderr, "\n");
	errorflag = 2;
	eprint();
}

void fpecatch(int n)
{
	FATAL("floating point exception %d", n);
}

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(char *fmt, ...)
{
	extern char *cmdname;
	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(char *fmt, ...)
{
	extern char *cmdname;
	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;
	int line;

	fprintf(stderr, "\n");
	if (compile_time != 2 && NR && *NR > 0) {
		if (strcmp(*FILENAME, "-") != 0)
			fprintf(stderr, " input record %s:%d", *FILENAME, (int) (*FNR));
		else
			fprintf(stderr, " input record number %d", (int) (*FNR));
		fprintf(stderr, "\n");
	}
	if (compile_time != 2 && curnode)
		line = curnode->lineno;
	else if (compile_time != 2 && lineno)
		line = lineno;
	else
		line = -1;
	if (compile_time == 1 && cursource() != NULL){
		if(line >= 0)
			fprintf(stderr, " source %s:%d", cursource(), line);
		else
			fprintf(stderr, " source file %s", cursource());
	}else if(line >= 0)
		fprintf(stderr, " source line %d", line);
	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 == 2 || compile_time == 0 || been_here++ > 0)
		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, 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(char *s)	/* is s of form var=something ? */
{
	char *os = s;

	if (!isalpha(*s) && *s != '_')
		return 0;
	for ( ; *s; s++)
		if (!(isalnum(*s) || *s == '_'))
			break;
	return *s == '=' && s > os && *(s+1) != '=';
}

/* strtod is supposed to be a proper test of what's a valid number */

#include <math.h>
int is_number(char *s)
{
	double r;
	char *ep;

	/*
	 * fast could-it-be-a-number check before calling strtod,
	 * which takes a surprisingly long time to reject non-numbers.
	 */
	switch (*s) {
	case '0': case '1': case '2': case '3': case '4':
	case '5': case '6': case '7': case '8': case '9':
	case '\t':
	case '\n':
	case '\v':
	case '\f':
	case '\r':
	case ' ':
	case '-':
	case '+':
	case '.':
	case 'n':		/* nans */
	case 'N':
	case 'i':		/* infs */
	case 'I':
		break;
	default:
		return 0;	/* can't be a number */
	}

	errno = 0;
	r = strtod(s, &ep);
	if (ep == s || r == HUGE_VAL || errno == ERANGE)
		return 0;
	while (*ep == ' ' || *ep == '\t' || *ep == '\n')
		ep++;
	if (*ep == '\0')
		return 1;
	else
		return 0;
}