commands/ash/memalloc.c

   1 /*-
   2  * Copyright (c) 1991, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * This code is derived from software contributed to Berkeley by
   6  * Kenneth Almquist.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 4. Neither the name of the University nor the names of its contributors
  17  *    may be used to endorse or promote products derived from this software
  18  *    without specific prior written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  */
  32
  33 #ifndef lint
  34 #if 0
  35 static char sccsid[] = "@(#)memalloc.c  8.3 (Berkeley) 5/4/95";
  36 #endif
  37 #endif /* not lint */
  38 /*
  39 #include <sys/cdefs.h>
  40 __FBSDID("$FreeBSD: src/bin/sh/memalloc.c,v 1.26 2004/04/06 20:06:51 markm Exp $");
  41 */
  42
  43 #include "shell.h"
  44 #include "output.h"
  45 #include "machdep.h"
  46 #include "memalloc.h"
  47 #include "error.h"
  48 #include "mystring.h"
  49 #include "expand.h"
  50 #include <stdlib.h>
  51 #include <unistd.h>
  52
  53 /*
  54  * Like malloc, but returns an error when out of space.
  55  */
  56
  57 pointer
  58 ckmalloc(int nbytes)
  59 {
  60         pointer p;
  61
  62         if ((p = malloc(nbytes)) == NULL)
  63                 error("Out of space");
  64         return p;
  65 }
  66
  67
  68 /*
  69  * Same for realloc.
  70  */
  71
  72 pointer
  73 ckrealloc(pointer p, int nbytes)
  74 {
  75         if ((p = realloc(p, nbytes)) == NULL)
  76                 error("Out of space");
  77         return p;
  78 }
  79
  80
  81 /*
  82  * Make a copy of a string in safe storage.
  83  */
  84
  85 char *
  86 savestr(const char *s)
  87 {
  88         char *p;
  89
  90         p = ckmalloc(strlen(s) + 1);
  91         scopy(s, p);
  92         return p;
  93 }
  94
  95
  96 /*
  97  * Parse trees for commands are allocated in lifo order, so we use a stack
  98  * to make this more efficient, and also to avoid all sorts of exception
  99  * handling code to handle interrupts in the middle of a parse.
 100  *
 101  * The size 496 was chosen because with 16-byte alignment the total size
 102  * for the allocated block is 512.
 103  */
 104
 105 #define MINSIZE 496             /* minimum size of a block. */
 106
 107
 108 struct stack_block {
 109         struct stack_block *prev;
 110         /* Data follows */
 111 };
 112 #define SPACE(sp)       ((char*)(sp) + ALIGN(sizeof(struct stack_block)))
 113
 114 STATIC struct stack_block *stackp;
 115 STATIC struct stackmark *markp;
 116 char *stacknxt;
 117 int stacknleft;
 118 int sstrnleft;
 119 int herefd = -1;
 120
 121
 122 static void
 123 stnewblock(int nbytes)
 124 {
 125         struct stack_block *sp;
 126         int allocsize;
 127
 128         if (nbytes < MINSIZE)
 129                 nbytes = MINSIZE;
 130
 131         allocsize = ALIGN(sizeof(struct stack_block)) + ALIGN(nbytes);
 132
 133         INTOFF;
 134         sp = ckmalloc(allocsize);
 135         sp->prev = stackp;
 136         stacknxt = SPACE(sp);
 137         stacknleft = allocsize - (stacknxt - (char*)sp);
 138         stackp = sp;
 139         INTON;
 140 }
 141
 142
 143 pointer
 144 stalloc(int nbytes)
 145 {
 146         char *p;
 147
 148         nbytes = ALIGN(nbytes);
 149         if (nbytes > stacknleft)
 150                 stnewblock(nbytes);
 151         p = stacknxt;
 152         stacknxt += nbytes;
 153         stacknleft -= nbytes;
 154         return p;
 155 }
 156
 157
 158 void
 159 stunalloc(pointer p)
 160 {
 161         if (p == NULL) {                /*DEBUG */
 162                 write(STDERR_FILENO, "stunalloc\n", 10);
 163                 abort();
 164         }
 165         stacknleft += stacknxt - (char *)p;
 166         stacknxt = p;
 167 }
 168
 169
 170
 171 void
 172 setstackmark(struct stackmark *mark)
 173 {
 174         mark->stackp = stackp;
 175         mark->stacknxt = stacknxt;
 176         mark->stacknleft = stacknleft;
 177         mark->marknext = markp;
 178         markp = mark;
 179 }
 180
 181
 182 void
 183 popstackmark(struct stackmark *mark)
 184 {
 185         struct stack_block *sp;
 186
 187         INTOFF;
 188         markp = mark->marknext;
 189         while (stackp != mark->stackp) {
 190                 sp = stackp;
 191                 stackp = sp->prev;
 192                 ckfree(sp);
 193         }
 194         stacknxt = mark->stacknxt;
 195         stacknleft = mark->stacknleft;
 196         INTON;
 197 }
 198
 199
 200 /*
 201  * When the parser reads in a string, it wants to stick the string on the
 202  * stack and only adjust the stack pointer when it knows how big the
 203  * string is.  Stackblock (defined in stack.h) returns a pointer to a block
 204  * of space on top of the stack and stackblocklen returns the length of
 205  * this block.  Growstackblock will grow this space by at least one byte,
 206  * possibly moving it (like realloc).  Grabstackblock actually allocates the
 207  * part of the block that has been used.
 208  */
 209
 210 void
 211 growstackblock(void)
 212 {
 213         char *p;
 214         int newlen;
 215         char *oldspace;
 216         int oldlen;
 217         struct stack_block *sp;
 218         struct stack_block *oldstackp;
 219         struct stackmark *xmark;
 220
 221         newlen = (stacknleft == 0) ? MINSIZE : stacknleft * 2 + 100;
 222         newlen = ALIGN(newlen);
 223         oldspace = stacknxt;
 224         oldlen = stacknleft;
 225
 226         if (stackp != NULL && stacknxt == SPACE(stackp)) {
 227                 INTOFF;
 228                 oldstackp = stackp;
 229                 stackp = oldstackp->prev;
 230                 sp = ckrealloc((pointer)oldstackp, newlen);
 231                 sp->prev = stackp;
 232                 stackp = sp;
 233                 stacknxt = SPACE(sp);
 234                 stacknleft = newlen - (stacknxt - (char*)sp);
 235
 236                 /*
 237                  * Stack marks pointing to the start of the old block
 238                  * must be relocated to point to the new block
 239                  */
 240                 xmark = markp;
 241                 while (xmark != NULL && xmark->stackp == oldstackp) {
 242                         xmark->stackp = stackp;
 243                         xmark->stacknxt = stacknxt;
 244                         xmark->stacknleft = stacknleft;
 245                         xmark = xmark->marknext;
 246                 }
 247                 INTON;
 248         } else {
 249                 p = stalloc(newlen);
 250                 if (oldlen != 0)
 251                         memcpy(p, oldspace, oldlen);
 252                 stunalloc(p);
 253         }
 254 }
 255
 256
 257
 258 void
 259 grabstackblock(int len)
 260 {
 261         len = ALIGN(len);
 262         stacknxt += len;
 263         stacknleft -= len;
 264 }
 265
 266
 267
 268 /*
 269  * The following routines are somewhat easier to use that the above.
 270  * The user declares a variable of type STACKSTR, which may be declared
 271  * to be a register.  The macro STARTSTACKSTR initializes things.  Then
 272  * the user uses the macro STPUTC to add characters to the string.  In
 273  * effect, STPUTC(c, p) is the same as *p++ = c except that the stack is
 274  * grown as necessary.  When the user is done, she can just leave the
 275  * string there and refer to it using stackblock().  Or she can allocate
 276  * the space for it using grabstackstr().  If it is necessary to allow
 277  * someone else to use the stack temporarily and then continue to grow
 278  * the string, the user should use grabstack to allocate the space, and
 279  * then call ungrabstr(p) to return to the previous mode of operation.
 280  *
 281  * USTPUTC is like STPUTC except that it doesn't check for overflow.
 282  * CHECKSTACKSPACE can be called before USTPUTC to ensure that there
 283  * is space for at least one character.
 284  */
 285
 286
 287 char *
 288 growstackstr(void)
 289 {
 290         int len;
 291
 292         len = stackblocksize();
 293         if (herefd >= 0 && len >= 1024) {
 294                 xwrite(herefd, stackblock(), len);
 295                 sstrnleft = len - 1;
 296                 return stackblock();
 297         }
 298         growstackblock();
 299         sstrnleft = stackblocksize() - len - 1;
 300         return stackblock() + len;
 301 }
 302
 303
 304 /*
 305  * Called from CHECKSTRSPACE.
 306  */
 307
 308 char *
 309 makestrspace(void)
 310 {
 311         int len;
 312
 313         len = stackblocksize() - sstrnleft;
 314         growstackblock();
 315         sstrnleft = stackblocksize() - len;
 316         return stackblock() + len;
 317 }
 318
 319
 320
 321 void
 322 ungrabstackstr(char *s, char *p)
 323 {
 324         stacknleft += stacknxt - s;
 325         stacknxt = s;
 326         sstrnleft = stacknleft - (p - s);
 327 }
 328
 329 /*
 330  * $PchId: memalloc.c,v 1.5 2006/05/22 12:03:26 philip Exp $
 331  */