com32/menu/refstr.c

   1 /* ----------------------------------------------------------------------- *
   2  *
   3  *   Copyright 2008 H. Peter Anvin - All Rights Reserved
   4  *
   5  *   This program is free software; you can redistribute it and/or modify
   6  *   it under the terms of the GNU General Public License as published by
   7  *   the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
   8  *   Boston MA 02110-1301, USA; either version 2 of the License, or
   9  *   (at your option) any later version; incorporated herein by reference.
  10  *
  11  * ----------------------------------------------------------------------- */
  12
  13 /*
  14  * refstr.c
  15  *
  16  * Simple reference-counted strings
  17  */
  18
  19 #include <stdlib.h>
  20 #include <string.h>
  21 #include <stdio.h>
  22 #include "refstr.h"
  23
  24 /* Allocate space for a refstring of len bytes, plus final null */
  25 /* The final null is inserted in the string; the rest is uninitialized. */
  26 char *refstr_alloc(size_t len)
  27 {
  28     char *r = malloc(sizeof(unsigned int) + len + 1);
  29     if (!r)
  30         return NULL;
  31     *(unsigned int *)r = 1;
  32     r += sizeof(unsigned int);
  33     r[len] = '\0';
  34     return r;
  35 }
  36
  37 const char *refstrndup(const char *str, size_t len)
  38 {
  39     char *r;
  40
  41     if (!str)
  42         return NULL;
  43
  44     len = strnlen(str, len);
  45     r = refstr_alloc(len);
  46     if (r)
  47         memcpy(r, str, len);
  48     return r;
  49 }
  50
  51 const char *refstrdup(const char *str)
  52 {
  53     char *r;
  54     size_t len;
  55
  56     if (!str)
  57         return NULL;
  58
  59     len = strlen(str);
  60     r = refstr_alloc(len);
  61     if (r)
  62         memcpy(r, str, len);
  63     return r;
  64 }
  65
  66 int vrsprintf(const char **bufp, const char *fmt, va_list ap)
  67 {
  68     va_list ap1;
  69     int len;
  70     char *p;
  71
  72     va_copy(ap1, ap);
  73     len = vsnprintf(NULL, 0, fmt, ap1);
  74     va_end(ap1);
  75
  76     *bufp = p = refstr_alloc(len);
  77     if (!p)
  78         return -1;
  79
  80     return vsnprintf(p, len + 1, fmt, ap);
  81 }
  82
  83 int rsprintf(const char **bufp, const char *fmt, ...)
  84 {
  85     int rv;
  86     va_list ap;
  87
  88     va_start(ap, fmt);
  89     rv = vrsprintf(bufp, fmt, ap);
  90     va_end(ap);
  91
  92     return rv;
  93 }
  94
  95 void refstr_put(const char *r)
  96 {
  97     unsigned int *ref;
  98
  99     if (r) {
 100         ref = (unsigned int *)r - 1;
 101
 102         if (!--*ref)
 103             free(ref);
 104     }
 105 }