tor-browser

The Tor Browser
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cubeb_strings.c (2859B)

      1 /*
      2 * Copyright © 2011 Mozilla Foundation
      3 *
      4 * This program is made available under an ISC-style license.  See the
      5 * accompanying file LICENSE for details.
      6 */
      7 
      8 #include "cubeb_strings.h"
      9 
     10 #include <assert.h>
     11 #include <stdlib.h>
     12 #include <string.h>
     13 
     14 #define CUBEB_STRINGS_INLINE_COUNT 4
     15 
     16 struct cubeb_strings {
     17  uint32_t size;
     18  uint32_t count;
     19  char ** data;
     20  char * small_store[CUBEB_STRINGS_INLINE_COUNT];
     21 };
     22 
     23 int
     24 cubeb_strings_init(cubeb_strings ** strings)
     25 {
     26  cubeb_strings * strs = NULL;
     27 
     28  if (!strings) {
     29    return CUBEB_ERROR;
     30  }
     31 
     32  strs = calloc(1, sizeof(cubeb_strings));
     33  assert(strs);
     34 
     35  if (!strs) {
     36    return CUBEB_ERROR;
     37  }
     38 
     39  strs->size = sizeof(strs->small_store) / sizeof(strs->small_store[0]);
     40  strs->count = 0;
     41  strs->data = strs->small_store;
     42 
     43  *strings = strs;
     44 
     45  return CUBEB_OK;
     46 }
     47 
     48 void
     49 cubeb_strings_destroy(cubeb_strings * strings)
     50 {
     51  char ** sp = NULL;
     52  char ** se = NULL;
     53 
     54  if (!strings) {
     55    return;
     56  }
     57 
     58  sp = strings->data;
     59  se = sp + strings->count;
     60 
     61  for (; sp != se; sp++) {
     62    if (*sp) {
     63      free(*sp);
     64    }
     65  }
     66 
     67  if (strings->data != strings->small_store) {
     68    free(strings->data);
     69  }
     70 
     71  free(strings);
     72 }
     73 
     74 /** Look for string in string storage.
     75    @param strings Opaque pointer to interned string storage.
     76    @param s String to look up.
     77    @retval Read-only string or NULL if not found. */
     78 static char const *
     79 cubeb_strings_lookup(cubeb_strings * strings, char const * s)
     80 {
     81  char ** sp = NULL;
     82  char ** se = NULL;
     83 
     84  if (!strings || !s) {
     85    return NULL;
     86  }
     87 
     88  sp = strings->data;
     89  se = sp + strings->count;
     90 
     91  for (; sp != se; sp++) {
     92    if (*sp && strcmp(*sp, s) == 0) {
     93      return *sp;
     94    }
     95  }
     96 
     97  return NULL;
     98 }
     99 
    100 static char const *
    101 cubeb_strings_push(cubeb_strings * strings, char const * s)
    102 {
    103  char * is = NULL;
    104 
    105  if (strings->count == strings->size) {
    106    char ** new_data;
    107    uint32_t value_size = sizeof(char const *);
    108    uint32_t new_size = strings->size * 2;
    109    if (!new_size || value_size > (uint32_t)-1 / new_size) {
    110      // overflow
    111      return NULL;
    112    }
    113 
    114    if (strings->small_store == strings->data) {
    115      // First time heap allocation.
    116      new_data = malloc(new_size * value_size);
    117      if (new_data) {
    118        memcpy(new_data, strings->small_store, sizeof(strings->small_store));
    119      }
    120    } else {
    121      new_data = realloc(strings->data, new_size * value_size);
    122    }
    123 
    124    if (!new_data) {
    125      // out of memory
    126      return NULL;
    127    }
    128 
    129    strings->size = new_size;
    130    strings->data = new_data;
    131  }
    132 
    133  is = strdup(s);
    134  strings->data[strings->count++] = is;
    135 
    136  return is;
    137 }
    138 
    139 char const *
    140 cubeb_strings_intern(cubeb_strings * strings, char const * s)
    141 {
    142  char const * is = NULL;
    143 
    144  if (!strings || !s) {
    145    return NULL;
    146  }
    147 
    148  is = cubeb_strings_lookup(strings, s);
    149  if (is) {
    150    return is;
    151  }
    152 
    153  return cubeb_strings_push(strings, s);
    154 }