source: trunk/minix/commands/ash/memalloc.c@ 22

/*-
 * 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[] = "@(#)memalloc.c  5.2 (Berkeley) 3/13/91";
#endif /* not lint */

#include "shell.h"
#include "output.h"
#include "memalloc.h"
#include "error.h"
#include "machdep.h"
#include "mystring.h"

/*
 * Like malloc, but returns an error when out of space.
 */

pointer
ckmalloc(nbytes) {
        register pointer p;
        pointer malloc();

        if ((p = malloc(nbytes)) == NULL)
                error("Out of space");
        return p;
}


/*
 * Same for realloc.
 */

pointer
ckrealloc(p, nbytes)
        register pointer p;
        {
        pointer realloc();

        if ((p = realloc(p, nbytes)) == NULL)
                error("Out of space");
        return p;
}


/*
 * Make a copy of a string in safe storage.
 */

char *
savestr(s)
        char *s;
        {
        register char *p;

        p = ckmalloc(strlen(s) + 1);
        scopy(s, p);
        return p;
}


/*
 * Parse trees for commands are allocated in lifo order, so we use a stack
 * to make this more efficient, and also to avoid all sorts of exception
 * handling code to handle interrupts in the middle of a parse.
 *
 * The size 504 was chosen because the Ultrix malloc handles that size
 * well.
 */

#define MINSIZE 504             /* minimum size of a block */


struct stack_block {
        struct stack_block *prev;
        char space[MINSIZE];
};

struct stack_block stackbase;
struct stack_block *stackp = &stackbase;
char *stacknxt = stackbase.space;
int stacknleft = MINSIZE;
int sstrnleft;
int herefd = -1;



pointer
stalloc(nbytes) {
        register char *p;

        nbytes = ALIGN(nbytes);
        if (nbytes > stacknleft) {
                int blocksize;
                struct stack_block *sp;

                blocksize = nbytes;
                if (blocksize < MINSIZE)
                        blocksize = MINSIZE;
                INTOFF;
                sp = ckmalloc(sizeof(struct stack_block) - MINSIZE + blocksize);
                sp->prev = stackp;
                stacknxt = sp->space;
                stacknleft = blocksize;
                stackp = sp;
                INTON;
        }
        p = stacknxt;
        stacknxt += nbytes;
        stacknleft -= nbytes;
        return p;
}


void
stunalloc(p)
        pointer p;
        {
        if (p == NULL) {                /*DEBUG */
                write(2, "stunalloc\n", 10);
                abort();
        }
        stacknleft += stacknxt - (char *)p;
        stacknxt = p;
}



void
setstackmark(mark)
        struct stackmark *mark;
        {
        mark->stackp = stackp;
        mark->stacknxt = stacknxt;
        mark->stacknleft = stacknleft;
}


void
popstackmark(mark)
        struct stackmark *mark;
        {
        struct stack_block *sp;

        INTOFF;
        while (stackp != mark->stackp) {
                sp = stackp;
                stackp = sp->prev;
                ckfree(sp);
        }
        stacknxt = mark->stacknxt;
        stacknleft = mark->stacknleft;
        INTON;
}


/*
 * When the parser reads in a string, it wants to stick the string on the
 * stack and only adjust the stack pointer when it knows how big the
 * string is.  Stackblock (defined in stack.h) returns a pointer to a block
 * of space on top of the stack and stackblocklen returns the length of
 * this block.  Growstackblock will grow this space by at least one byte,
 * possibly moving it (like realloc).  Grabstackblock actually allocates the
 * part of the block that has been used.
 */

void
growstackblock() {
        char *p;
        int newlen = stacknleft * 2 + 100;
        char *oldspace = stacknxt;
        int oldlen = stacknleft;
        struct stack_block *sp;

        if (stacknxt == stackp->space && stackp != &stackbase) {
                INTOFF;
                sp = stackp;
                stackp = sp->prev;
                sp = ckrealloc((pointer)sp, sizeof(struct stack_block) - MINSIZE + newlen);
                sp->prev = stackp;
                stackp = sp;
                stacknxt = sp->space;
                stacknleft = newlen;
                INTON;
        } else {
                p = stalloc(newlen);
                bcopy(oldspace, p, oldlen);
                stacknxt = p;                   /* free the space */
                stacknleft += newlen;           /* we just allocated */
        }
}



void
grabstackblock(len) {
        len = ALIGN(len);
        stacknxt += len;
        stacknleft -= len;
}



/*
 * The following routines are somewhat easier to use that the above.
 * The user declares a variable of type STACKSTR, which may be declared
 * to be a register.  The macro STARTSTACKSTR initializes things.  Then
 * the user uses the macro STPUTC to add characters to the string.  In
 * effect, STPUTC(c, p) is the same as *p++ = c except that the stack is
 * grown as necessary.  When the user is done, she can just leave the
 * string there and refer to it using stackblock().  Or she can allocate
 * the space for it using grabstackstr().  If it is necessary to allow
 * someone else to use the stack temporarily and then continue to grow
 * the string, the user should use grabstack to allocate the space, and
 * then call ungrabstr(p) to return to the previous mode of operation.
 *
 * USTPUTC is like STPUTC except that it doesn't check for overflow.
 * CHECKSTACKSPACE can be called before USTPUTC to ensure that there
 * is space for at least one character.
 */


char *
growstackstr() {
        int len = stackblocksize();
        if (herefd >= 0 && len >= 1024) {
                xwrite(herefd, stackblock(), len);
                sstrnleft = len - 1;
                return stackblock();
        }
        growstackblock();
        sstrnleft = stackblocksize() - len - 1;
        return stackblock() + len;
}


/*
 * Called from CHECKSTRSPACE.
 */

char *
makestrspace() {
        int len = stackblocksize() - sstrnleft;
        growstackblock();
        sstrnleft = stackblocksize() - len;
        return stackblock() + len;
}



void
ungrabstackstr(s, p)
        char *s;
        char *p;
        {
        stacknleft += stacknxt - s;
        stacknxt = s;
        sstrnleft = stacknleft - (p - s);
}