memdump/argv.c

   1 /* ----------------------------------------------------------------------- *
   2  *
   3  *   Copyright 2004 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 }