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memalloc.c

/*-
 * Copyright (c) 1991, 1993
 *    The Regents of the University of California.  All rights reserved.
 * Copyright (c) 1997-2005
 *    Herbert Xu <herbert@gondor.apana.org.au>.  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. 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.
 */

#include <stdlib.h>
#include <unistd.h>

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

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

pointer
ckmalloc(size_t nbytes)
{
      pointer p;

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


/*
 * Same for realloc.
 */

pointer
ckrealloc(pointer p, size_t nbytes)
{
      p = realloc(p, nbytes);
      if (p == NULL)
            sh_error("Out of space");
      return p;
}


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

char *
savestr(const char *s)
{
      char *p = strdup(s);
      if (!p)
            sh_error("Out of space");
      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.
 */

/* minimum size of a block */
#define MINSIZE SHELL_ALIGN(504)

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

struct stack_block stackbase;
struct stack_block *stackp = &stackbase;
struct stackmark *markp;
char *stacknxt = stackbase.space;
size_t stacknleft = MINSIZE;
char *sstrend = stackbase.space + MINSIZE;
int herefd = -1;

pointer
stalloc(size_t nbytes)
{
      char *p;
      size_t aligned;

      aligned = SHELL_ALIGN(nbytes);
      if (aligned > stacknleft) {
            size_t len;
            size_t blocksize;
            struct stack_block *sp;

            blocksize = aligned;
            if (blocksize < MINSIZE)
                  blocksize = MINSIZE;
            len = sizeof(struct stack_block) - MINSIZE + blocksize;
            if (len < blocksize)
                  sh_error("Out of space");
            INTOFF;
            sp = ckmalloc(len);
            sp->prev = stackp;
            stacknxt = sp->space;
            stacknleft = blocksize;
            sstrend = stacknxt + blocksize;
            stackp = sp;
            INTON;
      }
      p = stacknxt;
      stacknxt += aligned;
      stacknleft -= aligned;
      return p;
}


void
stunalloc(pointer p)
{
#ifdef DEBUG
      if (!p || (stacknxt < (char *)p) || ((char *)p < stackp->space)) {
            write(2, "stunalloc\n", 10);
            abort();
      }
#endif
      stacknleft += stacknxt - (char *)p;
      stacknxt = p;
}



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


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

      INTOFF;
      markp = mark->marknext;
      while (stackp != mark->stackp) {
            sp = stackp;
            stackp = sp->prev;
            ckfree(sp);
      }
      stacknxt = mark->stacknxt;
      stacknleft = mark->stacknleft;
      sstrend = mark->stacknxt + 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(void)
{
      size_t newlen;

      newlen = stacknleft * 2;
      if (newlen < stacknleft)
            sh_error("Out of space");
      if (newlen < 128)
            newlen += 128;

      if (stacknxt == stackp->space && stackp != &stackbase) {
            struct stack_block *oldstackp;
            struct stackmark *xmark;
            struct stack_block *sp;
            struct stack_block *prevstackp;
            size_t grosslen;

            INTOFF;
            oldstackp = stackp;
            sp = stackp;
            prevstackp = sp->prev;
            grosslen = newlen + sizeof(struct stack_block) - MINSIZE;
            sp = ckrealloc((pointer)sp, grosslen);
            sp->prev = prevstackp;
            stackp = sp;
            stacknxt = sp->space;
            stacknleft = newlen;
            sstrend = sp->space + newlen;

            /*
             * Stack marks pointing to the start of the old block
             * must be relocated to point to the new block 
             */
            xmark = markp;
            while (xmark != NULL && xmark->stackp == oldstackp) {
                  xmark->stackp = stackp;
                  xmark->stacknxt = stacknxt;
                  xmark->stacknleft = stacknleft;
                  xmark = xmark->marknext;
            }
            INTON;
      } else {
            char *oldspace = stacknxt;
            int oldlen = stacknleft;
            char *p = stalloc(newlen);

            /* free the space we just allocated */
            stacknxt = memcpy(p, oldspace, oldlen);
            stacknleft += newlen;
      }
}

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

/*
 * The following routines are somewhat easier to use than 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.
 */

void *
growstackstr(void)
{
      size_t len = stackblocksize();
      if (herefd >= 0 && len >= 1024) {
            xwrite(herefd, stackblock(), len);
            return stackblock();
      }
      growstackblock();
      return stackblock() + len;
}

/*
 * Called from CHECKSTRSPACE.
 */

char *
makestrspace(size_t newlen, char *p)
{
      size_t len = p - stacknxt;
      size_t size = stackblocksize();

      for (;;) {
            size_t nleft;

            size = stackblocksize();
            nleft = size - len;
            if (nleft >= newlen)
                  break;
            growstackblock();
      }
      return stackblock() + len;
}

char *
stnputs(const char *s, size_t n, char *p)
{
      p = makestrspace(n, p);
      p = mempcpy(p, s, n);
      return p;
}

char *
stputs(const char *s, char *p)
{
      return stnputs(s, strlen(s), p);
}

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