shell_cmds/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 326025 2017-11-20 19:49:47Z pfg $");
  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 /*
  54  * Like malloc, but returns an error when out of space.
  55  */
  56
  57 pointer
  58 ckmalloc(size_t nbytes)
  59 {
  60         pointer p;
  61
  62         INTOFF;
  63         p = malloc(nbytes);
  64         INTON;
  65         if (p == NULL)
  66                 error("Out of space");
  67         return p;
  68 }
  69
  70
  71 /*
  72  * Same for realloc.
  73  */
  74
  75 pointer
  76 ckrealloc(pointer p, int nbytes)
  77 {
  78         INTOFF;
  79         p = realloc(p, nbytes);
  80         INTON;
  81         if (p == NULL)
  82                 error("Out of space");
  83         return p;
  84 }
  85
  86 void
  87 ckfree(pointer p)
  88 {
  89         INTOFF;
  90         free(p);
  91         INTON;
  92 }
  93
  94
  95 /*
  96  * Make a copy of a string in safe storage.
  97  */
  98
  99 char *
 100 savestr(const char *s)
 101 {
 102         char *p;
 103         size_t len;
 104
 105         len = strlen(s);
 106         p = ckmalloc(len + 1);
 107         memcpy(p, s, len + 1);
 108         return p;
 109 }
 110
 111
 112 /*
 113  * Parse trees for commands are allocated in lifo order, so we use a stack
 114  * to make this more efficient, and also to avoid all sorts of exception
 115  * handling code to handle interrupts in the middle of a parse.
 116  *
 117  * The size 496 was chosen because with 16-byte alignment the total size
 118  * for the allocated block is 512.
 119  */
 120
 121 #define MINSIZE 496             /* minimum size of a block. */
 122
 123
 124 struct stack_block {
 125         struct stack_block *prev;
 126         /* Data follows */
 127 };
 128 #define SPACE(sp)       ((char*)(sp) + ALIGN(sizeof(struct stack_block)))
 129
 130 static struct stack_block *stackp;
 131 char *stacknxt;
 132 int stacknleft;
 133 char *sstrend;
 134
 135
 136 static void
 137 stnewblock(int nbytes)
 138 {
 139         struct stack_block *sp;
 140         int allocsize;
 141
 142         if (nbytes < MINSIZE)
 143                 nbytes = MINSIZE;
 144
 145         allocsize = ALIGN(sizeof(struct stack_block)) + ALIGN(nbytes);
 146
 147         INTOFF;
 148         sp = ckmalloc(allocsize);
 149         sp->prev = stackp;
 150         stacknxt = SPACE(sp);
 151         stacknleft = allocsize - (stacknxt - (char*)sp);
 152         sstrend = stacknxt + stacknleft;
 153         stackp = sp;
 154         INTON;
 155 }
 156
 157
 158 pointer
 159 stalloc(int nbytes)
 160 {
 161         char *p;
 162
 163         nbytes = ALIGN(nbytes);
 164         if (nbytes > stacknleft)
 165                 stnewblock(nbytes);
 166         p = stacknxt;
 167         stacknxt += nbytes;
 168         stacknleft -= nbytes;
 169         return p;
 170 }
 171
 172
 173 void
 174 stunalloc(pointer p)
 175 {
 176         if (p == NULL) {                /*DEBUG */
 177                 write(STDERR_FILENO, "stunalloc\n", 10);
 178                 abort();
 179         }
 180         stacknleft += stacknxt - (char *)p;
 181         stacknxt = p;
 182 }
 183
 184
 185 char *
 186 stsavestr(const char *s)
 187 {
 188         char *p;
 189         size_t len;
 190
 191         len = strlen(s);
 192         p = stalloc(len + 1);
 193         memcpy(p, s, len + 1);
 194         return p;
 195 }
 196
 197
 198 void
 199 setstackmark(struct stackmark *mark)
 200 {
 201         mark->stackp = stackp;
 202         mark->stacknxt = stacknxt;
 203         mark->stacknleft = stacknleft;
 204         /* Ensure this block stays in place. */
 205         if (stackp != NULL && stacknxt == SPACE(stackp))
 206                 stalloc(1);
 207 }
 208
 209
 210 void
 211 popstackmark(struct stackmark *mark)
 212 {
 213         struct stack_block *sp;
 214
 215         INTOFF;
 216         while (stackp != mark->stackp) {
 217                 sp = stackp;
 218                 stackp = sp->prev;
 219                 ckfree(sp);
 220         }
 221         stacknxt = mark->stacknxt;
 222         stacknleft = mark->stacknleft;
 223         sstrend = stacknxt + stacknleft;
 224         INTON;
 225 }
 226
 227
 228 /*
 229  * When the parser reads in a string, it wants to stick the string on the
 230  * stack and only adjust the stack pointer when it knows how big the
 231  * string is.  Stackblock (defined in stack.h) returns a pointer to a block
 232  * of space on top of the stack and stackblocklen returns the length of
 233  * this block.  Growstackblock will grow this space by at least one byte,
 234  * possibly moving it (like realloc).  Grabstackblock actually allocates the
 235  * part of the block that has been used.
 236  */
 237
 238 static void
 239 growstackblock(int min)
 240 {
 241         char *p;
 242         int newlen;
 243         char *oldspace;
 244         int oldlen;
 245         struct stack_block *sp;
 246         struct stack_block *oldstackp;
 247
 248         if (min < stacknleft)
 249                 min = stacknleft;
 250         if ((unsigned int)min >=
 251             INT_MAX / 2 - ALIGN(sizeof(struct stack_block)))
 252                 error("Out of space");
 253         min += stacknleft;
 254         min += ALIGN(sizeof(struct stack_block));
 255         newlen = 512;
 256         while (newlen < min)
 257                 newlen <<= 1;
 258         oldspace = stacknxt;
 259         oldlen = stacknleft;
 260
 261         if (stackp != NULL && stacknxt == SPACE(stackp)) {
 262                 INTOFF;
 263                 oldstackp = stackp;
 264                 stackp = oldstackp->prev;
 265                 sp = ckrealloc((pointer)oldstackp, newlen);
 266                 sp->prev = stackp;
 267                 stackp = sp;
 268                 stacknxt = SPACE(sp);
 269                 stacknleft = newlen - (stacknxt - (char*)sp);
 270                 sstrend = stacknxt + stacknleft;
 271                 INTON;
 272         } else {
 273                 newlen -= ALIGN(sizeof(struct stack_block));
 274                 p = stalloc(newlen);
 275                 if (oldlen != 0)
 276                         memcpy(p, oldspace, oldlen);
 277                 stunalloc(p);
 278         }
 279 }
 280
 281
 282
 283 /*
 284  * The following routines are somewhat easier to use that the above.
 285  * The user declares a variable of type STACKSTR, which may be declared
 286  * to be a register.  The macro STARTSTACKSTR initializes things.  Then
 287  * the user uses the macro STPUTC to add characters to the string.  In
 288  * effect, STPUTC(c, p) is the same as *p++ = c except that the stack is
 289  * grown as necessary.  When the user is done, she can just leave the
 290  * string there and refer to it using stackblock().  Or she can allocate
 291  * the space for it using grabstackstr().  If it is necessary to allow
 292  * someone else to use the stack temporarily and then continue to grow
 293  * the string, the user should use grabstack to allocate the space, and
 294  * then call ungrabstr(p) to return to the previous mode of operation.
 295  *
 296  * USTPUTC is like STPUTC except that it doesn't check for overflow.
 297  * CHECKSTACKSPACE can be called before USTPUTC to ensure that there
 298  * is space for at least one character.
 299  */
 300
 301 static char *
 302 growstrstackblock(int n, int min)
 303 {
 304         growstackblock(min);
 305         return stackblock() + n;
 306 }
 307
 308 char *
 309 growstackstr(void)
 310 {
 311         int len;
 312
 313         len = stackblocksize();
 314         return (growstrstackblock(len, 0));
 315 }
 316
 317
 318 /*
 319  * Called from CHECKSTRSPACE.
 320  */
 321
 322 char *
 323 makestrspace(int min, char *p)
 324 {
 325         int len;
 326
 327         len = p - stackblock();
 328         return (growstrstackblock(len, min));
 329 }
 330
 331
 332 char *
 333 stputbin(const char *data, size_t len, char *p)
 334 {
 335         CHECKSTRSPACE(len, p);
 336         memcpy(p, data, len);
 337         return (p + len);
 338 }
 339
 340 char *
 341 stputs(const char *data, char *p)
 342 {
 343         return (stputbin(data, strlen(data), p));
 344 }