xpcom/io/nsScriptableInputStream.cpp

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #include "nsScriptableInputStream.h"
   8 #include "nsString.h"
   9
  10 NS_IMPL_ISUPPORTS(nsScriptableInputStream, nsIScriptableInputStream)
  11
  12 // nsIScriptableInputStream methods
  13 NS_IMETHODIMP
  14 nsScriptableInputStream::Close() {
  15   if (!mInputStream) {
  16     return NS_ERROR_NOT_INITIALIZED;
  17   }
  18   return mInputStream->Close();
  19 }
  20
  21 NS_IMETHODIMP
  22 nsScriptableInputStream::Init(nsIInputStream* aInputStream) {
  23   if (!aInputStream) {
  24     return NS_ERROR_NULL_POINTER;
  25   }
  26   mInputStream = aInputStream;
  27   return NS_OK;
  28 }
  29
  30 NS_IMETHODIMP
  31 nsScriptableInputStream::Available(uint64_t* aResult) {
  32   if (!mInputStream) {
  33     return NS_ERROR_NOT_INITIALIZED;
  34   }
  35   return mInputStream->Available(aResult);
  36 }
  37
  38 NS_IMETHODIMP
  39 nsScriptableInputStream::Read(uint32_t aCount, char** aResult) {
  40   nsresult rv = NS_OK;
  41   uint64_t count64 = 0;
  42   char* buffer = nullptr;
  43
  44   if (!mInputStream) {
  45     return NS_ERROR_NOT_INITIALIZED;
  46   }
  47
  48   rv = mInputStream->Available(&count64);
  49   if (NS_FAILED(rv)) {
  50     return rv;
  51   }
  52
  53   // bug716556 - Ensure count+1 doesn't overflow
  54   uint32_t count =
  55       XPCOM_MIN((uint32_t)XPCOM_MIN<uint64_t>(count64, aCount), UINT32_MAX - 1);
  56   buffer = (char*)malloc(count + 1);  // make room for '\0'
  57   if (!buffer) {
  58     return NS_ERROR_OUT_OF_MEMORY;
  59   }
  60
  61   rv = ReadHelper(buffer, count);
  62   if (NS_FAILED(rv)) {
  63     free(buffer);
  64     return rv;
  65   }
  66
  67   buffer[count] = '\0';
  68   *aResult = buffer;
  69   return NS_OK;
  70 }
  71
  72 NS_IMETHODIMP
  73 nsScriptableInputStream::ReadBytes(uint32_t aCount, nsACString& aResult) {
  74   if (!mInputStream) {
  75     return NS_ERROR_NOT_INITIALIZED;
  76   }
  77
  78   if (!aResult.SetLength(aCount, mozilla::fallible)) {
  79     return NS_ERROR_OUT_OF_MEMORY;
  80   }
  81
  82   MOZ_ASSERT(aResult.Length() == aCount);
  83   char* ptr = aResult.BeginWriting();
  84   nsresult rv = ReadHelper(ptr, aCount);
  85   if (NS_FAILED(rv)) {
  86     aResult.Truncate();
  87   }
  88   return rv;
  89 }
  90
  91 nsresult nsScriptableInputStream::ReadHelper(char* aBuffer, uint32_t aCount) {
  92   uint32_t totalBytesRead = 0;
  93   while (1) {
  94     uint32_t bytesRead;
  95     nsresult rv = mInputStream->Read(aBuffer + totalBytesRead,
  96                                      aCount - totalBytesRead, &bytesRead);
  97     if (NS_FAILED(rv)) {
  98       return rv;
  99     }
 100
 101     totalBytesRead += bytesRead;
 102     if (totalBytesRead == aCount) {
 103       break;
 104     }
 105
 106     // If we have read zero bytes, we have hit EOF.
 107     if (bytesRead == 0) {
 108       return NS_ERROR_FAILURE;
 109     }
 110   }
 111   return NS_OK;
 112 }
 113
 114 nsresult nsScriptableInputStream::Create(REFNSIID aIID, void** aResult) {
 115   RefPtr<nsScriptableInputStream> sis = new nsScriptableInputStream();
 116   return sis->QueryInterface(aIID, aResult);
 117 }