bin/sh/memalloc.c

   1 /*-
   2  * SPDX-License-Identifier: BSD-3-Clause
   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 #ifndef lint
  36 #if 0
  37 static char sccsid[] = "@(#)memalloc.c  8.3 (Berkeley) 5/4/95";
  38 #endif
  39 #endif /* not lint */
  40 #include <sys/cdefs.h>
  41 __FBSDID("$FreeBSD: head/bin/sh/memalloc.c 360452 2020-04-28 20:34:27Z jilles $");
  42
  43 #include <sys/param.h>
  44 #include "shell.h"
  45 #include "output.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 static void
  54 badalloc(const char *message)
  55 {
  56         write(2, message, strlen(message));
  57         abort();
  58 }
  59
  60 /*
  61  * Like malloc, but returns an error when out of space.
  62  */
  63
  64 pointer
  65 ckmalloc(size_t nbytes)
  66 {
  67         pointer p;
  68
  69         if (!is_int_on())
  70                 badalloc("Unsafe ckmalloc() call\n");
  71         p = malloc(nbytes);
  72         if (p == NULL)
  73                 error("Out of space");
  74         return p;
  75 }
  76
  77
  78 /*
  79  * Same for realloc.
  80  */
  81
  82 pointer
  83 ckrealloc(pointer p, int nbytes)
  84 {
  85         if (!is_int_on())
  86                 badalloc("Unsafe ckrealloc() call\n");
  87         p = realloc(p, nbytes);
  88         if (p == NULL)
  89                 error("Out of space");
  90         return p;
  91 }
  92
  93 void
  94 ckfree(pointer p)
  95 {
  96         if (!is_int_on())
  97                 badalloc("Unsafe ckfree() call\n");
  98         free(p);
  99 }
 100
 101
 102 /*
 103  * Make a copy of a string in safe storage.
 104  */
 105
 106 char *
 107 savestr(const char *s)
 108 {
 109         char *p;
 110         size_t len;
 111
 112         len = strlen(s);
 113         p = ckmalloc(len + 1);
 114         memcpy(p, s, len + 1);
 115         return p;
 116 }
 117
 118
 119 /*
 120  * Parse trees for commands are allocated in lifo order, so we use a stack
 121  * to make this more efficient, and also to avoid all sorts of exception
 122  * handling code to handle interrupts in the middle of a parse.
 123  *
 124  * The size 496 was chosen because with 16-byte alignment the total size
 125  * for the allocated block is 512.
 126  */
 127
 128 #define MINSIZE 496             /* minimum size of a block. */
 129
 130
 131 struct stack_block {
 132         struct stack_block *prev;
 133         /* Data follows */
 134 };
 135 #define SPACE(sp)       ((char*)(sp) + ALIGN(sizeof(struct stack_block)))
 136
 137 static struct stack_block *stackp;
 138 char *stacknxt;
 139 int stacknleft;
 140 char *sstrend;
 141
 142
 143 static void
 144 stnewblock(int nbytes)
 145 {
 146         struct stack_block *sp;
 147         int allocsize;
 148
 149         if (nbytes < MINSIZE)
 150                 nbytes = MINSIZE;
 151
 152         allocsize = ALIGN(sizeof(struct stack_block)) + ALIGN(nbytes);
 153
 154         INTOFF;
 155         sp = ckmalloc(allocsize);
 156         sp->prev = stackp;
 157         stacknxt = SPACE(sp);
 158         stacknleft = allocsize - (stacknxt - (char*)sp);
 159         sstrend = stacknxt + stacknleft;
 160         stackp = sp;
 161         INTON;
 162 }
 163
 164
 165 pointer
 166 stalloc(int nbytes)
 167 {
 168         char *p;
 169
 170         nbytes = ALIGN(nbytes);
 171         if (nbytes > stacknleft)
 172                 stnewblock(nbytes);
 173         p = stacknxt;
 174         stacknxt += nbytes;
 175         stacknleft -= nbytes;
 176         return p;
 177 }
 178
 179
 180 void
 181 stunalloc(pointer p)
 182 {
 183         if (p == NULL) {                /*DEBUG */
 184                 write(STDERR_FILENO, "stunalloc\n", 10);
 185                 abort();
 186         }
 187         stacknleft += stacknxt - (char *)p;
 188         stacknxt = p;
 189 }
 190
 191
 192 char *
 193 stsavestr(const char *s)
 194 {
 195         char *p;
 196         size_t len;
 197
 198         len = strlen(s);
 199         p = stalloc(len + 1);
 200         memcpy(p, s, len + 1);
 201         return p;
 202 }
 203
 204
 205 void
 206 setstackmark(struct stackmark *mark)
 207 {
 208         mark->stackp = stackp;
 209         mark->stacknxt = stacknxt;
 210         mark->stacknleft = stacknleft;
 211         /* Ensure this block stays in place. */
 212         if (stackp != NULL && stacknxt == SPACE(stackp))
 213                 stalloc(1);
 214 }
 215
 216
 217 void
 218 popstackmark(struct stackmark *mark)
 219 {
 220         struct stack_block *sp;
 221
 222         INTOFF;
 223         while (stackp != mark->stackp) {
 224                 sp = stackp;
 225                 stackp = sp->prev;
 226                 ckfree(sp);
 227         }
 228         stacknxt = mark->stacknxt;
 229         stacknleft = mark->stacknleft;
 230         sstrend = stacknxt + stacknleft;
 231         INTON;
 232 }
 233
 234
 235 /*
 236  * When the parser reads in a string, it wants to stick the string on the
 237  * stack and only adjust the stack pointer when it knows how big the
 238  * string is.  Stackblock (defined in stack.h) returns a pointer to a block
 239  * of space on top of the stack and stackblocklen returns the length of
 240  * this block.  Growstackblock will grow this space by at least one byte,
 241  * possibly moving it (like realloc).  Grabstackblock actually allocates the
 242  * part of the block that has been used.
 243  */
 244
 245 static void
 246 growstackblock(int min)
 247 {
 248         char *p;
 249         int newlen;
 250         char *oldspace;
 251         int oldlen;
 252         struct stack_block *sp;
 253         struct stack_block *oldstackp;
 254
 255         if (min < stacknleft)
 256                 min = stacknleft;
 257         if ((unsigned int)min >=
 258             INT_MAX / 2 - ALIGN(sizeof(struct stack_block)))
 259                 error("Out of space");
 260         min += stacknleft;
 261         min += ALIGN(sizeof(struct stack_block));
 262         newlen = 512;
 263         while (newlen < min)
 264                 newlen <<= 1;
 265         oldspace = stacknxt;
 266         oldlen = stacknleft;
 267
 268         if (stackp != NULL && stacknxt == SPACE(stackp)) {
 269                 INTOFF;
 270                 oldstackp = stackp;
 271                 stackp = oldstackp->prev;
 272                 sp = ckrealloc((pointer)oldstackp, newlen);
 273                 sp->prev = stackp;
 274                 stackp = sp;
 275                 stacknxt = SPACE(sp);
 276                 stacknleft = newlen - (stacknxt - (char*)sp);
 277                 sstrend = stacknxt + stacknleft;
 278                 INTON;
 279         } else {
 280                 newlen -= ALIGN(sizeof(struct stack_block));
 281                 p = stalloc(newlen);
 282                 if (oldlen != 0)
 283                         memcpy(p, oldspace, oldlen);
 284                 stunalloc(p);
 285         }
 286 }
 287
 288
 289
 290 /*
 291  * The following routines are somewhat easier to use that the above.
 292  * The user declares a variable of type STACKSTR, which may be declared
 293  * to be a register.  The macro STARTSTACKSTR initializes things.  Then
 294  * the user uses the macro STPUTC to add characters to the string.  In
 295  * effect, STPUTC(c, p) is the same as *p++ = c except that the stack is
 296  * grown as necessary.  When the user is done, she can just leave the
 297  * string there and refer to it using stackblock().  Or she can allocate
 298  * the space for it using grabstackstr().  If it is necessary to allow
 299  * someone else to use the stack temporarily and then continue to grow
 300  * the string, the user should use grabstack to allocate the space, and
 301  * then call ungrabstr(p) to return to the previous mode of operation.
 302  *
 303  * USTPUTC is like STPUTC except that it doesn't check for overflow.
 304  * CHECKSTACKSPACE can be called before USTPUTC to ensure that there
 305  * is space for at least one character.
 306  */
 307
 308 static char *
 309 growstrstackblock(int n, int min)
 310 {
 311         growstackblock(min);
 312         return stackblock() + n;
 313 }
 314
 315 char *
 316 growstackstr(void)
 317 {
 318         int len;
 319
 320         len = stackblocksize();
 321         return (growstrstackblock(len, 0));
 322 }
 323
 324
 325 /*
 326  * Called from CHECKSTRSPACE.
 327  */
 328
 329 char *
 330 makestrspace(int min, char *p)
 331 {
 332         int len;
 333
 334         len = p - stackblock();
 335         return (growstrstackblock(len, min));
 336 }
 337
 338
 339 char *
 340 stputbin(const char *data, size_t len, char *p)
 341 {
 342         CHECKSTRSPACE(len, p);
 343         memcpy(p, data, len);
 344         return (p + len);
 345 }
 346
 347 char *
 348 stputs(const char *data, char *p)
 349 {
 350         return (stputbin(data, strlen(data), p));
 351 }