input.c

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/*-
 * Copyright (c) 1991 The Regents of the University of California.
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Kenneth Almquist.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#ifndef lint
static char sccsid[] = "@(#)input.c     5.4 (Berkeley) 7/1/91";
#endif /* not lint */

/*
 * This file implements the input routines used by the parser.
 */

#include <sys/types.h>
#include <stdio.h>      /* defines BUFSIZ */
#include "shell.h"
#include <fcntl.h>
#include <errno.h>
#include "syntax.h"
#include "input.h"
#include "output.h"
#include "memalloc.h"
#include "error.h"

#define EOF_NLEFT -99           /* value of parsenleft when EOF pushed back */


/*
 * The parsefile structure pointed to by the global variable parsefile
 * contains information about the current file being read.
 */

MKINIT
struct parsefile {
        int linno;              /* current line */
        int fd;                 /* file descriptor (or -1 if string) */
        int nleft;              /* number of chars left in buffer */
        char *nextc;            /* next char in buffer */
        struct parsefile *prev; /* preceding file on stack */
        char *buf;              /* input buffer */
};


int plinno = 1;                 /* input line number */
MKINIT int parsenleft;          /* copy of parsefile->nleft */
char *parsenextc;               /* copy of parsefile->nextc */
MKINIT struct parsefile basepf; /* top level input file */
char basebuf[BUFSIZ];           /* buffer for top level input file */
struct parsefile *parsefile = &basepf;  /* current input file */
char *pushedstring;             /* copy of parsenextc when text pushed back */
int pushednleft;                /* copy of parsenleft when text pushed back */

#if READLINE
char *readline __P((const char *prompt));
char *r_use_prompt = NULL;      /* the prompt to use with readline */
#endif

#ifdef __STDC__
STATIC void pushfile(void);
#else
STATIC void pushfile();
#endif



#ifdef mkinit
INCLUDE "input.h"
INCLUDE "error.h"

INIT {
        extern char basebuf[];

        basepf.nextc = basepf.buf = basebuf;
}

RESET {
        if (exception != EXSHELLPROC)
                parsenleft = 0;            /* clear input buffer */
        popallfiles();
}

SHELLPROC {
        popallfiles();
}
#endif


/*
 * Read a line from the script.
 */

char *
pfgets(line, len)
        char *line;
        {
        register char *p = line;
        int nleft = len;
        int c;

        while (--nleft > 0) {
                c = pgetc_macro();
                if (c == PEOF) {
                        if (p == line)
                                return NULL;
                        break;
                }
                *p++ = c;
                if (c == '\n')
                        break;
        }
        *p = '\0';
        return line;
}



/*
 * Read a character from the script, returning PEOF on end of file.
 * Nul characters in the input are silently discarded.
 */

int
pgetc() {
        return pgetc_macro();
}


/*
 * Refill the input buffer and return the next input character:
 *
 * 1) If a string was pushed back on the input, switch back to the regular
 *    buffer.
 * 2) If an EOF was pushed back (parsenleft == EOF_NLEFT) or we are reading
 *    from a string so we can't refill the buffer, return EOF.
 * 3) Call read to read in the characters.
 * 4) Delete all nul characters from the buffer.
 */

int
preadbuffer() {
        register char *p, *q;
        register int i;

        if (pushedstring) {
                parsenextc = pushedstring;
                pushedstring = NULL;
                parsenleft = pushednleft;
                if (--parsenleft >= 0)
                        return *parsenextc++;
        }
        if (parsenleft == EOF_NLEFT || parsefile->buf == NULL)
                return PEOF;
        flushout(&output);
        flushout(&errout);
#if READLINE
    /* Use the readline() call if a prompt is to be printed (interactive). */
    if (r_use_prompt != NULL) {
        char *prompt;
        char *line;

        p = parsenextc = parsefile->buf;

        prompt = r_use_prompt;
        r_use_prompt = NULL;

        if ((line = readline(prompt)) == NULL) {
                parsenleft = EOF_NLEFT;
                return PEOF;
        }
        strcpy(p, line);
        free(line);
        i = strlen(p);
        p[i++] = '\n';
    } else {
#endif
retry:
        p = parsenextc = parsefile->buf;
        i = read(parsefile->fd, p, BUFSIZ);
        if (i <= 0) {
                if (i < 0) {
                        if (errno == EINTR)
                                goto retry;
#ifdef EWOULDBLOCK
                        if (parsefile->fd == 0 && errno == EWOULDBLOCK) {
                                int flags = fcntl(0, F_GETFL, 0);
                                if (flags >= 0 && flags & O_NONBLOCK) {
                                        flags &=~ O_NONBLOCK;
                                        if (fcntl(0, F_SETFL, flags) >= 0) {
                                                out2str("sh: turning off NDELAY mode\n");
                                                goto retry;
                                        }
                                }
                        }
#endif
                }
                parsenleft = EOF_NLEFT;
                return PEOF;
        }
#if READLINE
    }
#endif
        parsenleft = i - 1;

        /* delete nul characters */
        for (;;) {
                if (*p++ == '\0')
                        break;
                if (--i <= 0)
                        return *parsenextc++;           /* no nul characters */
        }
        q = p - 1;
        while (--i > 0) {
                if (*p != '\0')
                        *q++ = *p;
                p++;
        }
        if (q == parsefile->buf)
                goto retry;                     /* buffer contained nothing but nuls */
        parsenleft = q - parsefile->buf - 1;
        return *parsenextc++;
}


/*
 * Undo the last call to pgetc.  Only one character may be pushed back.
 * PEOF may be pushed back.
 */

void
pungetc() {
        parsenleft++;
        parsenextc--;
}


/*
 * Push a string back onto the input.  This code doesn't work if the user
 * tries to push back more than one string at once.
 */

void
ppushback(string, length)
        char *string;
        {
        pushedstring = parsenextc;
        pushednleft = parsenleft;
        parsenextc = string;
        parsenleft = length;
}



/*
 * Set the input to take input from a file.  If push is set, push the
 * old input onto the stack first.
 */

void
setinputfile(fname, push)
        char *fname;
        {
        int fd;
        int fd2;

        INTOFF;
        if ((fd = open(fname, O_RDONLY)) < 0)
                error("Can't open %s", fname);
        if (fd < 10) {
                fd2 = copyfd(fd, 10);
                close(fd);
                if (fd2 < 0)
                        error("Out of file descriptors");
                fd = fd2;
        }
        setinputfd(fd, push);
        INTON;
}


/*
 * Like setinputfile, but takes an open file descriptor.  Call this with
 * interrupts off.
 */

void
setinputfd(fd, push) {
        (void) fcntl(fd, F_SETFD, fcntl(fd, F_GETFD) | FD_CLOEXEC);
        if (push) {
                pushfile();
                parsefile->buf = ckmalloc(BUFSIZ);
        }
        if (parsefile->fd > 0)
                close(parsefile->fd);
        parsefile->fd = fd;
        if (parsefile->buf == NULL)
                parsefile->buf = ckmalloc(BUFSIZ);
        parsenleft = 0;
        plinno = 1;
}


/*
 * Like setinputfile, but takes input from a string.
 */

void
setinputstring(string, push)
        char *string;
        {
        INTOFF;
        if (push)
                pushfile();
        parsenextc = string;
        parsenleft = strlen(string);
        parsefile->buf = NULL;
        plinno = 1;
        INTON;
}



/*
 * To handle the "." command, a stack of input files is used.  Pushfile
 * adds a new entry to the stack and popfile restores the previous level.
 */

STATIC void
pushfile() {
        struct parsefile *pf;

        parsefile->nleft = parsenleft;
        parsefile->nextc = parsenextc;
        parsefile->linno = plinno;
        pf = (struct parsefile *)ckmalloc(sizeof (struct parsefile));
        pf->prev = parsefile;
        pf->fd = -1;
        parsefile = pf;
}


void
popfile() {
        struct parsefile *pf = parsefile;

        INTOFF;
        if (pf->fd >= 0)
                close(pf->fd);
        if (pf->buf)
                ckfree(pf->buf);
        parsefile = pf->prev;
        ckfree(pf);
        parsenleft = parsefile->nleft;
        parsenextc = parsefile->nextc;
        plinno = parsefile->linno;
        INTON;
}


/*
 * Return to top level.
 */

void
popallfiles() {
        while (parsefile != &basepf)
                popfile();
}



/*
 * Close the file(s) that the shell is reading commands from.  Called
 * after a fork is done.
 */

void
closescript() {
        popallfiles();
        if (parsefile->fd > 0) {
                close(parsefile->fd);
                parsefile->fd = 0;
        }
}

---