memdump/argv.c

   1 /* ----------------------------------------------------------------------- *
   2  *
   3  *   Copyright 2004-2008 H. Peter Anvin - All Rights Reserved
   4  *
   5  *   Permission is hereby granted, free of charge, to any person
   6  *   obtaining a copy of this software and associated documentation
   7  *   files (the "Software"), to deal in the Software without
   8  *   restriction, including without limitation the rights to use,
   9  *   copy, modify, merge, publish, distribute, sublicense, and/or
  10  *   sell copies of the Software, and to permit persons to whom
  11  *   the Software is furnished to do so, subject to the following
  12  *   conditions:
  13  *
  14  *   The above copyright notice and this permission notice shall
  15  *   be included in all copies or substantial portions of the Software.
  16  *
  17  *   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  18  *   EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
  19  *   OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  20  *   NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
  21  *   HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
  22  *   WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  23  *   FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  24  *   OTHER DEALINGS IN THE SOFTWARE.
  25  *
  26  * ----------------------------------------------------------------------- */
  27
  28 /*
  29  * argv.c
  30  *
  31  * Parse a single C string into argc and argv (argc is return value.)
  32  * memptr points to available memory.
  33  */
  34
  35 #include <stdint.h>
  36 #include <stddef.h>
  37 #include <stdio.h>
  38
  39 #define ALIGN_UP(p,t)       ((t *)(((uintptr_t)(p) + (sizeof(t)-1)) & ~(sizeof(t)-1)))
  40
  41 extern char _end[];             /* Symbol created by linker */
  42 void *__mem_end = &_end;        /* Global variable for use by malloc() */
  43
  44 int __parse_argv(char ***argv, const char *str)
  45 {
  46     char *mem = __mem_end;
  47     const char *p = str;
  48     char *q = mem;
  49     char *r;
  50     char **arg;
  51     int wasspace = 0;
  52     int argc = 1;
  53
  54     /* First copy the string, turning whitespace runs into nulls */
  55     for (p = str;; p++) {
  56         if (*p <= ' ') {
  57             if (!wasspace) {
  58                 wasspace = 1;
  59                 *q++ = '\0';
  60             }
  61         } else {
  62             if (wasspace) {
  63                 argc++;
  64                 wasspace = 0;
  65             }
  66             *q++ = *p;
  67         }
  68
  69         /* This test is AFTER we have processed the null byte;
  70            we treat it as a whitespace character so it terminates
  71            the last argument */
  72         if (!*p)
  73             break;
  74     }
  75
  76     /* Now create argv */
  77     arg = ALIGN_UP(q, char *);
  78     *argv = arg;
  79     *arg++ = mem;               /* argv[0] */
  80
  81     q--;                        /* Point q to final null */
  82     for (r = mem; r < q; r++) {
  83         if (*r == '\0') {
  84             *arg++ = r + 1;
  85         }
  86     }
  87
  88     *arg++ = NULL;              /* Null pointer at the end */
  89     __mem_end = arg;            /* End of memory we used */
  90
  91     return argc;
  92 }