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