chrome/installer/mini_installer/mini_string.cc

   1 // Copyright (c) 2011 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 #include "chrome/installer/mini_installer/mini_string.h"
   6
   7 #include <windows.h>
   8
   9 namespace {
  10
  11 // Returns true if the given two ASCII characters are same (ignoring case).
  12 bool EqualASCIICharI(wchar_t a, wchar_t b) {
  13   if (a >= L'A' && a <= L'Z')
  14     a += (L'a' - L'A');
  15   if (b >= L'A' && b <= L'Z')
  16     b += (L'a' - L'A');
  17   return (a == b);
  18 }
  19
  20 }  // namespace
  21
  22 namespace mini_installer {
  23
  24 // Formats a sequence of |bytes| as hex.  The |str| buffer must have room for
  25 // at least 2*|size| + 1.
  26 bool HexEncode(const void* bytes, size_t size, wchar_t* str, size_t str_size) {
  27   if (str_size <= (size * 2))
  28     return false;
  29
  30   static const wchar_t kHexChars[] = L"0123456789ABCDEF";
  31
  32   str[size * 2] = L'\0';
  33
  34   for (size_t i = 0; i < size; ++i) {
  35     char b = reinterpret_cast<const char*>(bytes)[i];
  36     str[(i * 2)] = kHexChars[(b >> 4) & 0xf];
  37     str[(i * 2) + 1] = kHexChars[b & 0xf];
  38   }
  39
  40   return true;
  41 }
  42
  43 size_t SafeStrLen(const wchar_t* str, size_t alloc_size) {
  44   if (!str || !alloc_size)
  45     return 0;
  46   size_t len = 0;
  47   while (--alloc_size && str[len] != L'\0')
  48     ++len;
  49   return len;
  50 }
  51
  52 bool SafeStrCopy(wchar_t* dest, size_t dest_size, const wchar_t* src) {
  53   if (!dest || !dest_size)
  54     return false;
  55
  56   wchar_t* write = dest;
  57   for (size_t remaining = dest_size; remaining != 0; --remaining) {
  58     if ((*write++ = *src++) == L'\0')
  59       return true;
  60   }
  61
  62   // If we fail, we do not want to leave the string with partially copied
  63   // contents.  The reason for this is that we use these strings mostly for
  64   // named objects such as files.  If we copy a partial name, then that could
  65   // match with something we do not want it to match with.
  66   // Furthermore, since SafeStrCopy is called from SafeStrCat, we do not
  67   // want to mutate the string in case the caller handles the error of a
  68   // failed concatenation.  For example:
  69   //
  70   // wchar_t buf[5] = {0};
  71   // if (!SafeStrCat(buf, arraysize(buf), kLongName))
  72   //   SafeStrCat(buf, arraysize(buf), kShortName);
  73   //
  74   // If we were to return false in the first call to SafeStrCat but still
  75   // mutate the buffer, the buffer will be in an unexpected state.
  76   *dest = L'\0';
  77   return false;
  78 }
  79
  80 // Safer replacement for lstrcat function.
  81 bool SafeStrCat(wchar_t* dest, size_t dest_size, const wchar_t* src) {
  82   // Use SafeStrLen instead of lstrlen just in case the |dest| buffer isn't
  83   // terminated.
  84   int str_len = SafeStrLen(dest, dest_size);
  85   return SafeStrCopy(dest + str_len, dest_size - str_len, src);
  86 }
  87
  88 bool StrEndsWith(const wchar_t* str, const wchar_t* end_str) {
  89   if (str == NULL || end_str == NULL)
  90     return false;
  91
  92   for (int i = lstrlen(str) - 1, j = lstrlen(end_str) - 1; j >= 0; --i, --j) {
  93     if (i < 0 || !EqualASCIICharI(str[i], end_str[j]))
  94       return false;
  95   }
  96
  97   return true;
  98 }
  99
 100 bool StrStartsWith(const wchar_t* str, const wchar_t* start_str) {
 101   if (str == NULL || start_str == NULL)
 102     return false;
 103
 104   for (int i = 0; start_str[i] != L'\0'; ++i) {
 105     if (!EqualASCIICharI(str[i], start_str[i]))
 106       return false;
 107   }
 108
 109   return true;
 110 }
 111
 112 const wchar_t* SearchStringI(const wchar_t* source, const wchar_t* find) {
 113   if (!find || find[0] == L'\0')
 114     return source;
 115
 116   const wchar_t* scan = source;
 117   while (*scan) {
 118     const wchar_t* s = scan;
 119     const wchar_t* f = find;
 120
 121     while (*s && *f && EqualASCIICharI(*s, *f))
 122       ++s, ++f;
 123
 124     if (!*f)
 125       return scan;
 126
 127     ++scan;
 128   }
 129
 130   return NULL;
 131 }
 132
 133 bool FindTagInStr(const wchar_t* str,
 134                   const wchar_t* tag,
 135                   const wchar_t** position) {
 136   int tag_length = ::lstrlen(tag);
 137   const wchar_t* scan = str;
 138   for (const wchar_t* tag_start = SearchStringI(scan, tag);
 139        tag_start != NULL;
 140        tag_start = SearchStringI(scan, tag)) {
 141     scan = tag_start + tag_length;
 142     if (*scan == L'-' || *scan == L'\0') {
 143       if (position != NULL)
 144         *position = tag_start;
 145       return true;
 146     }
 147   }
 148   return false;
 149 }
 150
 151 wchar_t* GetNameFromPathExt(wchar_t* path, size_t size) {
 152   if (size <= 1)
 153     return NULL;
 154
 155   wchar_t* current = &path[size - 1];
 156   while (current != path && L'\\' != *current)
 157     --current;
 158
 159   return (current == path) ? NULL : (current + 1);
 160 }
 161
 162 }  // namespace mini_installer