e0dffd814f
The linked list of stack marks may cause problems if the allocation stack is used between an exception and a higher-level popstackmark(), as it may then touch a stack mark that is local to a function which has returned. Also, the adjustment compares to a pointer passed to realloc(), which is undefined behaviour. Instead of adjusting stack marks when reallocating stack blocks, ensure that such an adjustment is never necessary by fixing a small piece of memory in place at a stack mark. This also simplifies the code. To avoid the problems reported in bin/175922, it remains necessary to call setstackmark() after popstackmark() if the stack mark remains in use.
329 lines
7.3 KiB
C
329 lines
7.3 KiB
C
/*-
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* Copyright (c) 1991, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Kenneth Almquist.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#ifndef lint
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#if 0
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static char sccsid[] = "@(#)memalloc.c 8.3 (Berkeley) 5/4/95";
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#endif
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#endif /* not lint */
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/param.h>
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#include "shell.h"
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#include "output.h"
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#include "memalloc.h"
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#include "error.h"
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#include "mystring.h"
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#include "expand.h"
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#include <stdlib.h>
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#include <unistd.h>
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/*
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* Like malloc, but returns an error when out of space.
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*/
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pointer
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ckmalloc(size_t nbytes)
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{
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pointer p;
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INTOFF;
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p = malloc(nbytes);
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INTON;
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if (p == NULL)
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error("Out of space");
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return p;
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}
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/*
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* Same for realloc.
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*/
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pointer
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ckrealloc(pointer p, int nbytes)
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{
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INTOFF;
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p = realloc(p, nbytes);
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INTON;
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if (p == NULL)
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error("Out of space");
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return p;
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}
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void
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ckfree(pointer p)
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{
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INTOFF;
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free(p);
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INTON;
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}
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/*
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* Make a copy of a string in safe storage.
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*/
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char *
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savestr(const char *s)
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{
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char *p;
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p = ckmalloc(strlen(s) + 1);
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scopy(s, p);
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return p;
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}
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/*
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* Parse trees for commands are allocated in lifo order, so we use a stack
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* to make this more efficient, and also to avoid all sorts of exception
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* handling code to handle interrupts in the middle of a parse.
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*
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* The size 496 was chosen because with 16-byte alignment the total size
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* for the allocated block is 512.
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*/
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#define MINSIZE 496 /* minimum size of a block. */
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struct stack_block {
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struct stack_block *prev;
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/* Data follows */
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};
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#define SPACE(sp) ((char*)(sp) + ALIGN(sizeof(struct stack_block)))
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static struct stack_block *stackp;
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char *stacknxt;
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int stacknleft;
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char *sstrend;
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static void
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stnewblock(int nbytes)
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{
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struct stack_block *sp;
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int allocsize;
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if (nbytes < MINSIZE)
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nbytes = MINSIZE;
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allocsize = ALIGN(sizeof(struct stack_block)) + ALIGN(nbytes);
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INTOFF;
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sp = ckmalloc(allocsize);
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sp->prev = stackp;
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stacknxt = SPACE(sp);
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stacknleft = allocsize - (stacknxt - (char*)sp);
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sstrend = stacknxt + stacknleft;
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stackp = sp;
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INTON;
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}
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pointer
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stalloc(int nbytes)
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{
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char *p;
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nbytes = ALIGN(nbytes);
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if (nbytes > stacknleft)
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stnewblock(nbytes);
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p = stacknxt;
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stacknxt += nbytes;
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stacknleft -= nbytes;
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return p;
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}
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void
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stunalloc(pointer p)
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{
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if (p == NULL) { /*DEBUG */
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write(STDERR_FILENO, "stunalloc\n", 10);
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abort();
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}
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stacknleft += stacknxt - (char *)p;
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stacknxt = p;
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}
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void
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setstackmark(struct stackmark *mark)
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{
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mark->stackp = stackp;
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mark->stacknxt = stacknxt;
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mark->stacknleft = stacknleft;
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/* Ensure this block stays in place. */
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if (stackp != NULL && stacknxt == SPACE(stackp))
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stalloc(1);
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}
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void
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popstackmark(struct stackmark *mark)
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{
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struct stack_block *sp;
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INTOFF;
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while (stackp != mark->stackp) {
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sp = stackp;
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stackp = sp->prev;
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ckfree(sp);
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}
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stacknxt = mark->stacknxt;
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stacknleft = mark->stacknleft;
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sstrend = stacknxt + stacknleft;
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INTON;
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}
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/*
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* When the parser reads in a string, it wants to stick the string on the
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* stack and only adjust the stack pointer when it knows how big the
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* string is. Stackblock (defined in stack.h) returns a pointer to a block
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* of space on top of the stack and stackblocklen returns the length of
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* this block. Growstackblock will grow this space by at least one byte,
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* possibly moving it (like realloc). Grabstackblock actually allocates the
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* part of the block that has been used.
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*/
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static void
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growstackblock(int min)
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{
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char *p;
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int newlen;
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char *oldspace;
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int oldlen;
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struct stack_block *sp;
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struct stack_block *oldstackp;
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if (min < stacknleft)
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min = stacknleft;
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if ((unsigned int)min >=
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INT_MAX / 2 - ALIGN(sizeof(struct stack_block)))
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error("Out of space");
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min += stacknleft;
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min += ALIGN(sizeof(struct stack_block));
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newlen = 512;
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while (newlen < min)
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newlen <<= 1;
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oldspace = stacknxt;
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oldlen = stacknleft;
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if (stackp != NULL && stacknxt == SPACE(stackp)) {
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INTOFF;
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oldstackp = stackp;
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stackp = oldstackp->prev;
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sp = ckrealloc((pointer)oldstackp, newlen);
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sp->prev = stackp;
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stackp = sp;
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stacknxt = SPACE(sp);
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stacknleft = newlen - (stacknxt - (char*)sp);
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sstrend = stacknxt + stacknleft;
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INTON;
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} else {
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newlen -= ALIGN(sizeof(struct stack_block));
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p = stalloc(newlen);
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if (oldlen != 0)
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memcpy(p, oldspace, oldlen);
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stunalloc(p);
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}
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}
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/*
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* The following routines are somewhat easier to use that the above.
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* The user declares a variable of type STACKSTR, which may be declared
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* to be a register. The macro STARTSTACKSTR initializes things. Then
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* the user uses the macro STPUTC to add characters to the string. In
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* effect, STPUTC(c, p) is the same as *p++ = c except that the stack is
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* grown as necessary. When the user is done, she can just leave the
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* string there and refer to it using stackblock(). Or she can allocate
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* the space for it using grabstackstr(). If it is necessary to allow
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* someone else to use the stack temporarily and then continue to grow
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* the string, the user should use grabstack to allocate the space, and
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* then call ungrabstr(p) to return to the previous mode of operation.
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*
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* USTPUTC is like STPUTC except that it doesn't check for overflow.
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* CHECKSTACKSPACE can be called before USTPUTC to ensure that there
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* is space for at least one character.
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*/
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static char *
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growstrstackblock(int n, int min)
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{
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growstackblock(min);
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return stackblock() + n;
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}
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char *
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growstackstr(void)
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{
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int len;
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len = stackblocksize();
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return (growstrstackblock(len, 0));
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}
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/*
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* Called from CHECKSTRSPACE.
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*/
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char *
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makestrspace(int min, char *p)
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{
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int len;
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len = p - stackblock();
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return (growstrstackblock(len, min));
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}
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char *
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stputbin(const char *data, size_t len, char *p)
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{
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CHECKSTRSPACE(len, p);
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memcpy(p, data, len);
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return (p + len);
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}
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char *
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stputs(const char *data, char *p)
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{
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return (stputbin(data, strlen(data), p));
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}
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