ee3b307fc5
PR bin/52302 (core dump with interactive shell, here doc and error on same line) is fixed. (An old bug.) echo "$( echo x; for a in $( seq 1000 ); do printf '%s\n'; done; echo y )" consistently prints 1002 lines (x, 1000 empty ones, then y) as it should (And you don't want to know what it did before, or why.) (Another old one.) (Recently added) Problems with ~ expansion fixed (mem management related). Proper fix for the cwrappers configure problem (which includes the quick fix that was done earlier, but extends upon that to be correct). (This was another newly added problem.) And the really devious (and rare) old bug - if STACKSTRNUL() needs to allocate a new buffer in which to store the \0, calculate the size of the string space remaining correctly, unlike when SPUTC() grows the buffer, there is no actual data being stored in the STACKSTRNUL() case - the string space remaining was calculated as one byte too few. That would be harmless, unless the next buffer also filled, in which case it was assumed that it was really full, not one byte less, meaning one junk char (a nul, or anything) was being copied into the next (even bigger buffer) corrupting the data. Consistent use of stalloc() to allocate a new block of (stack) memory, and grabstackstr() to claim a block of (stack) memory that had already been occupied but not claimed as in use. Since grabstackstr is implemented as just a call to stalloc() this is a no-op change in practice, but makes it much easier to comprehend what is really happening. Previous code sometimes used stalloc() when the use case was really for grabstackstr(). Change grabstackstr() to actually use the arg passed to it, instead of (not much better than) guessing how much space to claim, More care when using unstalloc()/ungrabstackstr() to return space, and in particular when the stack must be returned to its previous state, rather than just returning no-longer needed space, neither of those work. They also don't work properly if there have been (really, even might have been) any stack mem allocations since the last stalloc()/grabstackstr(). (If we know there cannot have been then the alloc/release sequence is kind of pointless.) To work correctly in general we must use setstackmark()/popstackmark() so do that when needed. Have those also save/restore the top of stack string space remaining. [Aside: for those reading this, the "stack" mentioned is not in any way related to the thing used for maintaining the C function call state, ie: the "stack segment" of the program, but the shell's internal memory management strategy.] More comments to better explain what is happening in some cases. Also cleaned up some hopelessly broken DEBUG mode data that were recently added (no effect on anyone but the poor semi-human attempting to make sense of it...). User visible changes: Proper counting of line numbers when a here document is delimited by a multi-line end-delimiter, as in cat << 'REALLY END' here doc line 1 here doc line 2 REALLY END (which is an obscure case, but nothing says should not work.) The \n in the end-delimiter of the here doc (the last one) was not incrementing the line number, which from that point on in the script would be 1 too low (or more, for end-delimiters with more than one \n in them.) With tilde expansion: unset HOME; echo ~ changed to return getpwuid(getuid())->pw_home instead of failing (returning ~) POSIX says this is unspecified, which makes it difficult for a script to compensate for being run without HOME set (as in env -i sh script), so while not able to be used portably, this seems like a useful extension (and is implemented the same way by some other shells). Further, with HOME=; printf %s ~ we now write nothing (which is required by POSIX - which requires ~ to expand to the value of $HOME if it is set) previously if $HOME (in this case) or a user's directory in the passwd file (for ~user) were a null STRING, We failed the ~ expansion and left behind '~' or '~user'.
325 lines
8.0 KiB
C
325 lines
8.0 KiB
C
/* $NetBSD: memalloc.c,v 1.30 2017/06/17 07:22:12 kre Exp $ */
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/*-
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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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* 3. 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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#include <sys/cdefs.h>
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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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#else
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__RCSID("$NetBSD: memalloc.c,v 1.30 2017/06/17 07:22:12 kre Exp $");
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#endif
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#endif /* not lint */
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#include <stdlib.h>
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#include <unistd.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 "machdep.h"
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#include "mystring.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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p = malloc(nbytes);
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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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p = realloc(p, nbytes);
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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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* 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 504 was chosen because the Ultrix malloc handles that size
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* well.
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*/
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#define MINSIZE 504 /* minimum size of a block */
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struct stack_block {
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struct stack_block *prev;
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char space[MINSIZE];
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};
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struct stack_block stackbase;
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struct stack_block *stackp = &stackbase;
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struct stackmark *markp;
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char *stacknxt = stackbase.space;
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int stacknleft = MINSIZE;
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int sstrnleft;
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int herefd = -1;
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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 = SHELL_ALIGN(nbytes);
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if (nbytes > stacknleft) {
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int blocksize;
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struct stack_block *sp;
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blocksize = nbytes;
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if (blocksize < MINSIZE)
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blocksize = MINSIZE;
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INTOFF;
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sp = ckmalloc(sizeof(struct stack_block) - MINSIZE + blocksize);
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sp->prev = stackp;
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stacknxt = sp->space;
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stacknleft = blocksize;
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stackp = sp;
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INTON;
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}
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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(2, "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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mark->sstrnleft = sstrnleft;
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mark->marknext = markp;
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markp = mark;
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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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markp = mark->marknext;
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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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sstrnleft = mark->sstrnleft;
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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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void
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growstackblock(void)
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{
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int newlen = SHELL_ALIGN(stacknleft * 2 + 100);
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if (stacknxt == stackp->space && stackp != &stackbase) {
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struct stack_block *oldstackp;
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struct stackmark *xmark;
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struct stack_block *sp;
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INTOFF;
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oldstackp = stackp;
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sp = stackp;
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stackp = sp->prev;
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sp = ckrealloc((pointer)sp,
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sizeof(struct stack_block) - MINSIZE + newlen);
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sp->prev = stackp;
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stackp = sp;
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stacknxt = sp->space;
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stacknleft = newlen;
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/*
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* Stack marks pointing to the start of the old block
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* must be relocated to point to the new block
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*/
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xmark = markp;
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while (xmark != NULL && xmark->stackp == oldstackp) {
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xmark->stackp = stackp;
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xmark->stacknxt = stacknxt;
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xmark->stacknleft = stacknleft;
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xmark = xmark->marknext;
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}
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INTON;
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} else {
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char *oldspace = stacknxt;
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int oldlen = stacknleft;
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char *p = stalloc(newlen);
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(void)memcpy(p, oldspace, oldlen);
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stacknxt = p; /* free the space */
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stacknleft += newlen; /* we just allocated */
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}
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}
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void
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grabstackblock(int len)
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{
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len = SHELL_ALIGN(len);
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stacknxt += len;
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stacknleft -= len;
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}
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/*
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* The following routines are somewhat easier to use than 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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char *
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growstackstr(void)
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{
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int len = stackblocksize();
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if (herefd >= 0 && len >= 1024) {
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xwrite(herefd, stackblock(), len);
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sstrnleft = len - 1;
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return stackblock();
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}
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growstackblock();
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sstrnleft = stackblocksize() - len - 1;
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return stackblock() + len;
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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(void)
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{
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int len = stackblocksize() - sstrnleft;
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growstackblock();
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sstrnleft = stackblocksize() - len;
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return stackblock() + len;
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}
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/*
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* Note that this only works to release stack space for reuse
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* if nothing else has allocated space on the stack since the grabstackstr()
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*
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* "s" is the start of the area to be released, and "p" represents the end
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* of the string we have stored beyond there and are now releasing.
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* (ie: "p" should be the same as in the call to grabstackstr()).
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*
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* stunalloc(s) and ungrabstackstr(s, p) are almost interchangable after
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* a grabstackstr(), however the latter also returns string space so we
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* can just continue with STPUTC() etc without needing a new STARTSTACKSTR(s)
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*/
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void
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ungrabstackstr(char *s, char *p)
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{
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#ifdef DEBUG
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if (s < stacknxt || stacknxt + stacknleft < s)
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abort();
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#endif
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stacknleft += stacknxt - s;
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stacknxt = s;
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sstrnleft = stacknleft - (p - s);
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}
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