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

/****************************************************************
Copyright (C) Lucent Technologies 1997
All Rights Reserved

Permission to use, copy, modify, and distribute this software and
its documentation for any purpose and without fee is hereby
granted, provided that the above copyright notice appear in all
copies and that both that the copyright notice and this
permission notice and warranty disclaimer appear in supporting
documentation, and that the name Lucent Technologies or any of
its entities not be used in advertising or publicity pertaining
to distribution of the software without specific, written prior
permission.

LUCENT DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS.
IN NO EVENT SHALL LUCENT OR ANY OF ITS ENTITIES BE LIABLE FOR ANY
SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER
IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
THIS SOFTWARE.
****************************************************************/

#define DEBUG
#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include <errno.h>
#include <stdlib.h>
#include <stdarg.h>
#include "awk.h"
#include "y.tab.h"

FILE	*infile	= NULL;
char	*file	= "";
char	*record;
int	recsize	= RECSIZE;
char	*fields;
int	fieldssize = RECSIZE;

Cell	**fldtab;	/* pointers to Cells */
char	inputFS[100] = " ";

#define	MAXFLD	200
int	nfields	= MAXFLD;	/* last allocated slot for $i */

int	donefld;	/* 1 = implies rec broken into fields */
int	donerec;	/* 1 = 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, "", 0.0, REC|STR|DONTFREE };
static Cell dollar1 = { OCELL, CFLD, NULL, "", 0.0, FLD|STR|DONTFREE };

void recinit(unsigned int n)
{
	record = (char *) malloc(n);
	fields = (char *) malloc(n);
	fldtab = (Cell **) malloc((nfields+1) * sizeof(Cell *));
	if (record == NULL || fields == NULL || fldtab == NULL)
		FATAL("out of space for $0 and fields");
	fldtab[0] = (Cell *) malloc(sizeof (Cell));
	*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 (struct Cell));
		if (fldtab[i] == NULL)
			FATAL("out of space in makefields %d", i);
		*fldtab[i] = dollar1;
		sprintf(temp, "%d", i);
		fldtab[i]->nval = tostring(temp);
	}
}

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

	for (i = 1; i < *ARGC; i++) {
		if (!isclvar(p = getargv(i))) {	/* find 1st real filename */
			setsval(lookup("FILENAME", symtab), getargv(i));
			return;
		}
		setclvar(p);	/* a commandline assignment before filename */
		argno++;
	}
	infile = stdin;		/* no filenames, so use stdin */
}

int getrec(char **pbuf, int *pbufsize, int isrecord)	/* get next input record */
{			/* note: cares whether buf == record */
	int c;
	static int firsttime = 1;
	char *buf = *pbuf;
	int bufsize = *pbufsize;

	if (firsttime) {
		firsttime = 0;
		initgetrec();
	}
	   dprintf( ("RS=<%s>, FS=<%s>, ARGC=%g, FILENAME=%s\n",
		*RS, *FS, *ARGC, *FILENAME) );
	if (isrecord) {
		donefld = 0;
		donerec = 1;
	}
	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 == '\0') {	/* it's been 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);
			setfval(fnrloc, 0.0);
		}
		c = readrec(&buf, &bufsize, infile);
		if (c != 0 || buf[0] != '\0') {	/* normal record */
			if (isrecord) {
				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);
					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++;
	}
	*pbuf = buf;
	*pbufsize = bufsize;
	return 0;	/* true end of file */
}

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

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

	if (strlen(*FS) >= sizeof(inputFS))
		FATAL("field separator %.10s... is too long", *FS);
	strcpy(inputFS, *FS);	/* for subsequent field splitting */
	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;
	   dprintf( ("readrec saw <%s>, returns %d\n", buf, c == EOF && rr == buf ? 0 : 1) );
	*pbuf = buf;
	*pbufsize = bufsize;
	return c == EOF && rr == buf ? 0 : 1;
}

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

	sprintf(temp, "%d", n);
	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 *p;
	Cell *q;

	for (p=s; *p != '='; p++)
		;
	*p++ = 0;
	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);
		q->tval |= NUM;
	}
	   dprintf( ("command line set %s to |%s|\n", s, p) );
}


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 */
	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+1)) == NULL)
			FATAL("out of space for fields in fldbld %d", n);
		fieldssize = n;
	}
	fr = fields;
	i = 0;	/* number of fields accumulated here */
	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++) {
			char buf[2];
			i++;
			if (i > nfields)
				growfldtab(i);
			if (freeable(fldtab[i]))
				xfree(fldtab[i]->sval);
			buf[0] = *r;
			buf[1] = 0;
			fldtab[i]->sval = tostring(buf);
			fldtab[i]->tval = FLD | STR;
		}
		*fr = 0;
	} else if (*r != 0) {	/* if 0, it's a null field */
		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 != '\n' && *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 = 1;
	for (j = 1; j <= lastfld; j++) {
		p = fldtab[j];
		if(is_number(p->sval)) {
			p->fval = atof(p->sval);
			p->tval |= NUM;
		}
	}
	setfval(nfloc, (Awkfloat) lastfld);
	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 = "";
		p->tval = FLD | STR | DONTFREE;