bin/sh/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  * 3. All advertising materials mentioning features or use of this software
  17  *    must display the following acknowledgement:
  18  *      This product includes software developed by the University of
  19  *      California, Berkeley and its contributors.
  20  * 4. Neither the name of the University nor the names of its contributors
  21  *    may be used to endorse or promote products derived from this software
  22  *    without specific prior written permission.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  34  * SUCH DAMAGE.
  35  *
  36  * @(#)memalloc.c       8.3 (Berkeley) 5/4/95
  37  * $FreeBSD: src/bin/sh/memalloc.c,v 1.27 2005/10/28 10:45:19 stefanf Exp $
  38  * $DragonFly: src/bin/sh/memalloc.c,v 1.5 2007/01/14 03:59:57 pavalos Exp $
  39  */
  40
  41 #include <sys/param.h>
  42 #include "shell.h"
  43 #include "output.h"
  44 #include "memalloc.h"
  45 #include "error.h"
  46 #include "mystring.h"
  47 #include "expand.h"
  48 #include <stdlib.h>
  49 #include <unistd.h>
  50
  51 /*
  52  * Like malloc, but returns an error when out of space.
  53  */
  54
  55 pointer
  56 ckmalloc(int nbytes)
  57 {
  58         pointer p;
  59
  60         INTOFF;
  61         p = malloc(nbytes);
  62         INTON;
  63         if (p == NULL)
  64                 error("Out of space");
  65         return p;
  66 }
  67
  68
  69 /*
  70  * Same for realloc.
  71  */
  72
  73 pointer
  74 ckrealloc(pointer p, int nbytes)
  75 {
  76         INTOFF;
  77         p = realloc(p, nbytes);
  78         INTON;
  79         if (p == NULL)
  80                 error("Out of space");
  81         return p;
  82 }
  83
  84 void
  85 ckfree(pointer p)
  86 {
  87         INTOFF;
  88         free(p);
  89         INTON;
  90 }
  91
  92
  93 /*
  94  * Make a copy of a string in safe storage.
  95  */
  96
  97 char *
  98 savestr(const char *s)
  99 {
 100         char *p;
 101
 102         p = ckmalloc(strlen(s) + 1);
 103         scopy(s, p);
 104         return p;
 105 }
 106
 107
 108 /*
 109  * Parse trees for commands are allocated in lifo order, so we use a stack
 110  * to make this more efficient, and also to avoid all sorts of exception
 111  * handling code to handle interrupts in the middle of a parse.
 112  *
 113  * The size 496 was chosen because with 16-byte alignment the total size
 114  * for the allocated block is 512.
 115  */
 116
 117 #define MINSIZE 496             /* minimum size of a block. */
 118
 119
 120 struct stack_block {
 121         struct stack_block *prev;
 122         /* Data follows */
 123 };
 124 #define SPACE(sp)       ((char*)(sp) + ALIGN(sizeof(struct stack_block)))
 125
 126 STATIC struct stack_block *stackp;
 127 STATIC struct stackmark *markp;
 128 char *stacknxt;
 129 int stacknleft;
 130 int sstrnleft;
 131 int herefd = -1;
 132
 133
 134 static void
 135 stnewblock(int nbytes)
 136 {
 137         struct stack_block *sp;
 138         int allocsize;
 139
 140         if (nbytes < MINSIZE)
 141                 nbytes = MINSIZE;
 142
 143         allocsize = ALIGN(sizeof(struct stack_block)) + ALIGN(nbytes);
 144
 145         INTOFF;
 146         sp = ckmalloc(allocsize);
 147         sp->prev = stackp;
 148         stacknxt = SPACE(sp);
 149         stacknleft = allocsize - (stacknxt - (char*)sp);
 150         stackp = sp;
 151         INTON;
 152 }
 153
 154
 155 pointer
 156 stalloc(int nbytes)
 157 {
 158         char *p;
 159
 160         nbytes = ALIGN(nbytes);
 161         if (nbytes > stacknleft)
 162                 stnewblock(nbytes);
 163         p = stacknxt;
 164         stacknxt += nbytes;
 165         stacknleft -= nbytes;
 166         return p;
 167 }
 168
 169
 170 void
 171 stunalloc(pointer p)
 172 {
 173         if (p == NULL) {                /*DEBUG */
 174                 write(STDERR_FILENO, "stunalloc\n", 10);
 175                 abort();
 176         }
 177         stacknleft += stacknxt - (char *)p;
 178         stacknxt = p;
 179 }
 180
 181
 182
 183 void
 184 setstackmark(struct stackmark *mark)
 185 {
 186         mark->stackp = stackp;
 187         mark->stacknxt = stacknxt;
 188         mark->stacknleft = stacknleft;
 189         mark->marknext = markp;
 190         markp = mark;
 191 }
 192
 193
 194 void
 195 popstackmark(struct stackmark *mark)
 196 {
 197         struct stack_block *sp;
 198
 199         INTOFF;
 200         markp = mark->marknext;
 201         while (stackp != mark->stackp) {
 202                 sp = stackp;
 203                 stackp = sp->prev;
 204                 ckfree(sp);
 205         }
 206         stacknxt = mark->stacknxt;
 207         stacknleft = mark->stacknleft;
 208         INTON;
 209 }
 210
 211
 212 /*
 213  * When the parser reads in a string, it wants to stick the string on the
 214  * stack and only adjust the stack pointer when it knows how big the
 215  * string is.  Stackblock (defined in stack.h) returns a pointer to a block
 216  * of space on top of the stack and stackblocklen returns the length of
 217  * this block.  Growstackblock will grow this space by at least one byte,
 218  * possibly moving it (like realloc).  Grabstackblock actually allocates the
 219  * part of the block that has been used.
 220  */
 221
 222 void
 223 growstackblock(void)
 224 {
 225         char *p;
 226         int newlen;
 227         char *oldspace;
 228         int oldlen;
 229         struct stack_block *sp;
 230         struct stack_block *oldstackp;
 231         struct stackmark *xmark;
 232
 233         newlen = (stacknleft == 0) ? MINSIZE : stacknleft * 2 + 100;
 234         newlen = ALIGN(newlen);
 235         oldspace = stacknxt;
 236         oldlen = stacknleft;
 237
 238         if (stackp != NULL && stacknxt == SPACE(stackp)) {
 239                 INTOFF;
 240                 oldstackp = stackp;
 241                 stackp = oldstackp->prev;
 242                 sp = ckrealloc((pointer)oldstackp, newlen);
 243                 sp->prev = stackp;
 244                 stackp = sp;
 245                 stacknxt = SPACE(sp);
 246                 stacknleft = newlen - (stacknxt - (char*)sp);
 247
 248                 /*
 249                  * Stack marks pointing to the start of the old block
 250                  * must be relocated to point to the new block
 251                  */
 252                 xmark = markp;
 253                 while (xmark != NULL && xmark->stackp == oldstackp) {
 254                         xmark->stackp = stackp;
 255                         xmark->stacknxt = stacknxt;
 256                         xmark->stacknleft = stacknleft;
 257                         xmark = xmark->marknext;
 258                 }
 259                 INTON;
 260         } else {
 261                 p = stalloc(newlen);
 262                 if (oldlen != 0)
 263                         memcpy(p, oldspace, oldlen);
 264                 stunalloc(p);
 265         }
 266 }
 267
 268
 269
 270 void
 271 grabstackblock(int len)
 272 {
 273         len = ALIGN(len);
 274         stacknxt += len;
 275         stacknleft -= len;
 276 }
 277
 278
 279
 280 /*
 281  * The following routines are somewhat easier to use that the above.
 282  * The user declares a variable of type STACKSTR, which may be declared
 283  * to be a register.  The macro STARTSTACKSTR initializes things.  Then
 284  * the user uses the macro STPUTC to add characters to the string.  In
 285  * effect, STPUTC(c, p) is the same as *p++ = c except that the stack is
 286  * grown as necessary.  When the user is done, she can just leave the
 287  * string there and refer to it using stackblock().  Or she can allocate
 288  * the space for it using grabstackstr().  If it is necessary to allow
 289  * someone else to use the stack temporarily and then continue to grow
 290  * the string, the user should use grabstack to allocate the space, and
 291  * then call ungrabstr(p) to return to the previous mode of operation.
 292  *
 293  * USTPUTC is like STPUTC except that it doesn't check for overflow.
 294  * CHECKSTACKSPACE can be called before USTPUTC to ensure that there
 295  * is space for at least one character.
 296  */
 297
 298
 299 char *
 300 growstackstr(void)
 301 {
 302         int len;
 303
 304         len = stackblocksize();
 305         if (herefd >= 0 && len >= 1024) {
 306                 xwrite(herefd, stackblock(), len);
 307                 sstrnleft = len - 1;
 308                 return stackblock();
 309         }
 310         growstackblock();
 311         sstrnleft = stackblocksize() - len - 1;
 312         return stackblock() + len;
 313 }
 314
 315
 316 /*
 317  * Called from CHECKSTRSPACE.
 318  */
 319
 320 char *
 321 makestrspace(void)
 322 {
 323         int len;
 324
 325         len = stackblocksize() - sstrnleft;
 326         growstackblock();
 327         sstrnleft = stackblocksize() - len;
 328         return stackblock() + len;
 329 }
 330
 331
 332
 333 void
 334 ungrabstackstr(char *s, char *p)
 335 {
 336         stacknleft += stacknxt - s;
 337         stacknxt = s;
 338         sstrnleft = stacknleft - (p - s);
 339 }