native_client_sdk/src/libraries/xray/stringpool.c

   1 /* Copyright (c) 2013 The Chromium Authors. All rights reserved.
   2  * Use of this source code is governed by a BSD-style license that can be
   3  * found in the LICENSE file. */
   4
   5
   6 /* XRay string pool */
   7
   8 /* String pool holds a large pile of strings. */
   9 /* It is up to higher level data structures to avoid duplicates. */
  10 /* It is up to higher level data structures to provide fast lookups. */
  11
  12 /* _GNU_SOURCE must be defined prior to the inclusion of string.h
  13  * so that strnlen is available with glibc */
  14 #define _GNU_SOURCE
  15 #include <stdlib.h>
  16 #include <string.h>
  17 #include "xray/xray_priv.h"
  18
  19 #if defined(XRAY)
  20
  21 struct XRayStringPoolNode {
  22   struct XRayStringPoolNode* next;
  23   char strings[XRAY_STRING_POOL_NODE_SIZE];
  24 };
  25
  26
  27 struct XRayStringPool {
  28   struct XRayStringPoolNode* head;
  29   struct XRayStringPoolNode* current;
  30   int index;
  31 };
  32
  33
  34 static struct XRayStringPoolNode* XRayStringPoolAllocNode() {
  35   struct XRayStringPoolNode* s;
  36   s = (struct XRayStringPoolNode *)XRayMalloc(sizeof(*s));
  37   s->next = NULL;
  38   return s;
  39 }
  40
  41
  42 static int XRayStringPoolCurrentNodeSpaceAvail(struct XRayStringPool* pool) {
  43   int i = pool->index;
  44   return (XRAY_STRING_POOL_NODE_SIZE - i) - 1;
  45 }
  46
  47
  48 /* Append a string to the string pool. */
  49 char* XRayStringPoolAppend(struct XRayStringPool* pool, const char* src) {
  50   /* Add +1 to STRING_POOL_NODE_SIZE to detect large strings */
  51   /* Add +1 to strnlen result to account for string termination */
  52   int n = strnlen(src, XRAY_STRING_POOL_NODE_SIZE + 1) + 1;
  53   int a = XRayStringPoolCurrentNodeSpaceAvail(pool);
  54   char* dst;
  55   /* Don't accept strings larger than the pool node. */
  56   if (n >= (XRAY_STRING_POOL_NODE_SIZE - 1))
  57     return NULL;
  58   /* If string doesn't fit, alloc a new node. */
  59   if (n > a) {
  60     pool->current->next = XRayStringPoolAllocNode();
  61     pool->current = pool->current->next;
  62     pool->index = 0;
  63   }
  64   /* Copy string and return a pointer to copy. */
  65   dst = &pool->current->strings[pool->index];
  66   strcpy(dst, src);
  67   pool->index += n;
  68   return dst;
  69 }
  70
  71
  72 /* Create & initialize a string pool instance. */
  73 struct XRayStringPool* XRayStringPoolCreate() {
  74   struct XRayStringPool* pool;
  75   pool = (struct XRayStringPool*)XRayMalloc(sizeof(*pool));
  76   pool->head = XRayStringPoolAllocNode();
  77   pool->current = pool->head;
  78   return pool;
  79 }
  80
  81
  82 /* Free a string pool. */
  83 void XRayStringPoolFree(struct XRayStringPool* pool) {
  84   struct XRayStringPoolNode* n = pool->head;
  85   while (NULL != n) {
  86     struct XRayStringPoolNode* c = n;
  87     n = n->next;
  88     XRayFree(c);
  89   }
  90   XRayFree(pool);
  91 }
  92
  93 #endif  /* XRAY */
  94