bin/sh/memalloc.c

   1 /*      $NetBSD: memalloc.c,v 1.29 2008/02/15 17:26:06 matt Exp $       */
   2
   3 /*-
   4  * Copyright (c) 1991, 1993
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * This code is derived from software contributed to Berkeley by
   8  * Kenneth Almquist.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  * 3. Neither the name of the University nor the names of its contributors
  19  *    may be used to endorse or promote products derived from this software
  20  *    without specific prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  */
  34
  35 #include <sys/cdefs.h>
  36 #ifndef lint
  37 #if 0
  38 static char sccsid[] = "@(#)memalloc.c  8.3 (Berkeley) 5/4/95";
  39 #else
  40 __RCSID("$NetBSD: memalloc.c,v 1.29 2008/02/15 17:26:06 matt Exp $");
  41 #endif
  42 #endif /* not lint */
  43
  44 #include <stdlib.h>
  45 #include <unistd.h>
  46
  47 #include "shell.h"
  48 #include "output.h"
  49 #include "memalloc.h"
  50 #include "error.h"
  51 #include "machdep.h"
  52 #include "mystring.h"
  53
  54 /*
  55  * Like malloc, but returns an error when out of space.
  56  */
  57
  58 pointer
  59 ckmalloc(size_t nbytes)
  60 {
  61         pointer p;
  62
  63         p = malloc(nbytes);
  64         if (p == NULL)
  65                 error("Out of space");
  66         return p;
  67 }
  68
  69
  70 /*
  71  * Same for realloc.
  72  */
  73
  74 pointer
  75 ckrealloc(pointer p, int nbytes)
  76 {
  77         p = realloc(p, nbytes);
  78         if (p == NULL)
  79                 error("Out of space");
  80         return p;
  81 }
  82
  83
  84 /*
  85  * Make a copy of a string in safe storage.
  86  */
  87
  88 char *
  89 savestr(const char *s)
  90 {
  91         char *p;
  92
  93         p = ckmalloc(strlen(s) + 1);
  94         scopy(s, p);
  95         return p;
  96 }
  97
  98
  99 /*
 100  * Parse trees for commands are allocated in lifo order, so we use a stack
 101  * to make this more efficient, and also to avoid all sorts of exception
 102  * handling code to handle interrupts in the middle of a parse.
 103  *
 104  * The size 504 was chosen because the Ultrix malloc handles that size
 105  * well.
 106  */
 107
 108 #define MINSIZE 504             /* minimum size of a block */
 109
 110 struct stack_block {
 111         struct stack_block *prev;
 112         char space[MINSIZE];
 113 };
 114
 115 struct stack_block stackbase;
 116 struct stack_block *stackp = &stackbase;
 117 struct stackmark *markp;
 118 char *stacknxt = stackbase.space;
 119 int stacknleft = MINSIZE;
 120 int sstrnleft;
 121 int herefd = -1;
 122
 123 pointer
 124 stalloc(int nbytes)
 125 {
 126         char *p;
 127
 128         nbytes = SHELL_ALIGN(nbytes);
 129         if (nbytes > stacknleft) {
 130                 int blocksize;
 131                 struct stack_block *sp;
 132
 133                 blocksize = nbytes;
 134                 if (blocksize < MINSIZE)
 135                         blocksize = MINSIZE;
 136                 INTOFF;
 137                 sp = ckmalloc(sizeof(struct stack_block) - MINSIZE + blocksize);
 138                 sp->prev = stackp;
 139                 stacknxt = sp->space;
 140                 stacknleft = blocksize;
 141                 stackp = sp;
 142                 INTON;
 143         }
 144         p = stacknxt;
 145         stacknxt += nbytes;
 146         stacknleft -= nbytes;
 147         return p;
 148 }
 149
 150
 151 void
 152 stunalloc(pointer p)
 153 {
 154         if (p == NULL) {                /*DEBUG */
 155                 write(2, "stunalloc\n", 10);
 156                 abort();
 157         }
 158         stacknleft += stacknxt - (char *)p;
 159         stacknxt = p;
 160 }
 161
 162
 163
 164 void
 165 setstackmark(struct stackmark *mark)
 166 {
 167         mark->stackp = stackp;
 168         mark->stacknxt = stacknxt;
 169         mark->stacknleft = stacknleft;
 170         mark->marknext = markp;
 171         markp = mark;
 172 }
 173
 174
 175 void
 176 popstackmark(struct stackmark *mark)
 177 {
 178         struct stack_block *sp;
 179
 180         INTOFF;
 181         markp = mark->marknext;
 182         while (stackp != mark->stackp) {
 183                 sp = stackp;
 184                 stackp = sp->prev;
 185                 ckfree(sp);
 186         }
 187         stacknxt = mark->stacknxt;
 188         stacknleft = mark->stacknleft;
 189         INTON;
 190 }
 191
 192
 193 /*
 194  * When the parser reads in a string, it wants to stick the string on the
 195  * stack and only adjust the stack pointer when it knows how big the
 196  * string is.  Stackblock (defined in stack.h) returns a pointer to a block
 197  * of space on top of the stack and stackblocklen returns the length of
 198  * this block.  Growstackblock will grow this space by at least one byte,
 199  * possibly moving it (like realloc).  Grabstackblock actually allocates the
 200  * part of the block that has been used.
 201  */
 202
 203 void
 204 growstackblock(void)
 205 {
 206         int newlen = SHELL_ALIGN(stacknleft * 2 + 100);
 207
 208         if (stacknxt == stackp->space && stackp != &stackbase) {
 209                 struct stack_block *oldstackp;
 210                 struct stackmark *xmark;
 211                 struct stack_block *sp;
 212
 213                 INTOFF;
 214                 oldstackp = stackp;
 215                 sp = stackp;
 216                 stackp = sp->prev;
 217                 sp = ckrealloc((pointer)sp,
 218                     sizeof(struct stack_block) - MINSIZE + newlen);
 219                 sp->prev = stackp;
 220                 stackp = sp;
 221                 stacknxt = sp->space;
 222                 stacknleft = newlen;
 223
 224                 /*
 225                  * Stack marks pointing to the start of the old block
 226                  * must be relocated to point to the new block
 227                  */
 228                 xmark = markp;
 229                 while (xmark != NULL && xmark->stackp == oldstackp) {
 230                         xmark->stackp = stackp;
 231                         xmark->stacknxt = stacknxt;
 232                         xmark->stacknleft = stacknleft;
 233                         xmark = xmark->marknext;
 234                 }
 235                 INTON;
 236         } else {
 237                 char *oldspace = stacknxt;
 238                 int oldlen = stacknleft;
 239                 char *p = stalloc(newlen);
 240
 241                 (void)memcpy(p, oldspace, oldlen);
 242                 stacknxt = p;                   /* free the space */
 243                 stacknleft += newlen;           /* we just allocated */
 244         }
 245 }
 246
 247 void
 248 grabstackblock(int len)
 249 {
 250         len = SHELL_ALIGN(len);
 251         stacknxt += len;
 252         stacknleft -= len;
 253 }
 254
 255 /*
 256  * The following routines are somewhat easier to use than the above.
 257  * The user declares a variable of type STACKSTR, which may be declared
 258  * to be a register.  The macro STARTSTACKSTR initializes things.  Then
 259  * the user uses the macro STPUTC to add characters to the string.  In
 260  * effect, STPUTC(c, p) is the same as *p++ = c except that the stack is
 261  * grown as necessary.  When the user is done, she can just leave the
 262  * string there and refer to it using stackblock().  Or she can allocate
 263  * the space for it using grabstackstr().  If it is necessary to allow
 264  * someone else to use the stack temporarily and then continue to grow
 265  * the string, the user should use grabstack to allocate the space, and
 266  * then call ungrabstr(p) to return to the previous mode of operation.
 267  *
 268  * USTPUTC is like STPUTC except that it doesn't check for overflow.
 269  * CHECKSTACKSPACE can be called before USTPUTC to ensure that there
 270  * is space for at least one character.
 271  */
 272
 273 char *
 274 growstackstr(void)
 275 {
 276         int len = stackblocksize();
 277         if (herefd >= 0 && len >= 1024) {
 278                 xwrite(herefd, stackblock(), len);
 279                 sstrnleft = len - 1;
 280                 return stackblock();
 281         }
 282         growstackblock();
 283         sstrnleft = stackblocksize() - len - 1;
 284         return stackblock() + len;
 285 }
 286
 287 /*
 288  * Called from CHECKSTRSPACE.
 289  */
 290
 291 char *
 292 makestrspace(void)
 293 {
 294         int len = stackblocksize() - sstrnleft;
 295         growstackblock();
 296         sstrnleft = stackblocksize() - len;
 297         return stackblock() + len;
 298 }
 299
 300 void
 301 ungrabstackstr(char *s, char *p)
 302 {
 303         stacknleft += stacknxt - s;
 304         stacknxt = s;
 305         sstrnleft = stacknleft - (p - s);
 306
 307 }