1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/xpcom/build/NSPRInterposer.cpp Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,174 @@
1.4 +/* This Source Code Form is subject to the terms of the Mozilla Public
1.5 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.6 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.7 +
1.8 +#include "IOInterposer.h"
1.9 +#include "NSPRInterposer.h"
1.10 +
1.11 +#include "prio.h"
1.12 +#include "private/pprio.h"
1.13 +
1.14 +namespace {
1.15 +
1.16 +using namespace mozilla;
1.17 +
1.18 +/* Original IO methods */
1.19 +PRCloseFN sCloseFn = nullptr;
1.20 +PRReadFN sReadFn = nullptr;
1.21 +PRWriteFN sWriteFn = nullptr;
1.22 +PRFsyncFN sFSyncFn = nullptr;
1.23 +PRFileInfoFN sFileInfoFn = nullptr;
1.24 +PRFileInfo64FN sFileInfo64Fn = nullptr;
1.25 +
1.26 +/**
1.27 + * RAII class for timing the duration of an NSPR I/O call and reporting the
1.28 + * result to the IOInterposeObserver API.
1.29 + */
1.30 +class NSPRIOAutoObservation : public IOInterposeObserver::Observation
1.31 +{
1.32 +public:
1.33 + NSPRIOAutoObservation(IOInterposeObserver::Operation aOp)
1.34 + : IOInterposeObserver::Observation(aOp, "NSPRIOInterposer")
1.35 + {
1.36 + }
1.37 +
1.38 + ~NSPRIOAutoObservation()
1.39 + {
1.40 + Report();
1.41 + }
1.42 +};
1.43 +
1.44 +PRStatus PR_CALLBACK interposedClose(PRFileDesc* aFd)
1.45 +{
1.46 + // If we don't have a valid original function pointer something is very wrong.
1.47 + NS_ASSERTION(sCloseFn, "NSPR IO Interposing: sCloseFn is NULL");
1.48 +
1.49 + NSPRIOAutoObservation timer(IOInterposeObserver::OpClose);
1.50 + return sCloseFn(aFd);
1.51 +}
1.52 +
1.53 +int32_t PR_CALLBACK interposedRead(PRFileDesc* aFd, void* aBuf, int32_t aAmt)
1.54 +{
1.55 + // If we don't have a valid original function pointer something is very wrong.
1.56 + NS_ASSERTION(sReadFn, "NSPR IO Interposing: sReadFn is NULL");
1.57 +
1.58 + NSPRIOAutoObservation timer(IOInterposeObserver::OpRead);
1.59 + return sReadFn(aFd, aBuf, aAmt);
1.60 +}
1.61 +
1.62 +int32_t PR_CALLBACK interposedWrite(PRFileDesc* aFd, const void* aBuf,
1.63 + int32_t aAmt)
1.64 +{
1.65 + // If we don't have a valid original function pointer something is very wrong.
1.66 + NS_ASSERTION(sWriteFn, "NSPR IO Interposing: sWriteFn is NULL");
1.67 +
1.68 + NSPRIOAutoObservation timer(IOInterposeObserver::OpWrite);
1.69 + return sWriteFn(aFd, aBuf, aAmt);
1.70 +}
1.71 +
1.72 +PRStatus PR_CALLBACK interposedFSync(PRFileDesc* aFd)
1.73 +{
1.74 + // If we don't have a valid original function pointer something is very wrong.
1.75 + NS_ASSERTION(sFSyncFn, "NSPR IO Interposing: sFSyncFn is NULL");
1.76 +
1.77 + NSPRIOAutoObservation timer(IOInterposeObserver::OpFSync);
1.78 + return sFSyncFn(aFd);
1.79 +}
1.80 +
1.81 +PRStatus PR_CALLBACK interposedFileInfo(PRFileDesc *aFd, PRFileInfo *aInfo)
1.82 +{
1.83 + // If we don't have a valid original function pointer something is very wrong.
1.84 + NS_ASSERTION(sFileInfoFn, "NSPR IO Interposing: sFileInfoFn is NULL");
1.85 +
1.86 + NSPRIOAutoObservation timer(IOInterposeObserver::OpStat);
1.87 + return sFileInfoFn(aFd, aInfo);
1.88 +}
1.89 +
1.90 +PRStatus PR_CALLBACK interposedFileInfo64(PRFileDesc *aFd, PRFileInfo64 *aInfo)
1.91 +{
1.92 + // If we don't have a valid original function pointer something is very wrong.
1.93 + NS_ASSERTION(sFileInfo64Fn, "NSPR IO Interposing: sFileInfo64Fn is NULL");
1.94 +
1.95 + NSPRIOAutoObservation timer(IOInterposeObserver::OpStat);
1.96 + return sFileInfo64Fn(aFd, aInfo);
1.97 +}
1.98 +
1.99 +} // anonymous namespace
1.100 +
1.101 +namespace mozilla {
1.102 +
1.103 +void InitNSPRIOInterposing()
1.104 +{
1.105 + // Check that we have not interposed any of the IO methods before
1.106 + MOZ_ASSERT(!sCloseFn && !sReadFn && !sWriteFn && !sFSyncFn && !sFileInfoFn &&
1.107 + !sFileInfo64Fn);
1.108 +
1.109 + // We can't actually use this assertion because we initialize this code
1.110 + // before XPCOM is initialized, so NS_IsMainThread() always returns false.
1.111 + // MOZ_ASSERT(NS_IsMainThread());
1.112 +
1.113 + // Get IO methods from NSPR and const cast the structure so we can modify it.
1.114 + PRIOMethods* methods = const_cast<PRIOMethods*>(PR_GetFileMethods());
1.115 +
1.116 + // Something is badly wrong if we don't get IO methods... However, we don't
1.117 + // want to crash over that in non-debug builds. This is unlikely to happen
1.118 + // so an assert is enough, no need to report it to the caller.
1.119 + MOZ_ASSERT(methods);
1.120 + if (!methods) {
1.121 + return;
1.122 + }
1.123 +
1.124 + // Store original functions
1.125 + sCloseFn = methods->close;
1.126 + sReadFn = methods->read;
1.127 + sWriteFn = methods->write;
1.128 + sFSyncFn = methods->fsync;
1.129 + sFileInfoFn = methods->fileInfo;
1.130 + sFileInfo64Fn = methods->fileInfo64;
1.131 +
1.132 + // Overwrite with our interposed functions
1.133 + methods->close = &interposedClose;
1.134 + methods->read = &interposedRead;
1.135 + methods->write = &interposedWrite;
1.136 + methods->fsync = &interposedFSync;
1.137 + methods->fileInfo = &interposedFileInfo;
1.138 + methods->fileInfo64 = &interposedFileInfo64;
1.139 +}
1.140 +
1.141 +void ClearNSPRIOInterposing()
1.142 +{
1.143 + // If we have already cleared IO interposing, or not initialized it this is
1.144 + // actually bad.
1.145 + MOZ_ASSERT(sCloseFn && sReadFn && sWriteFn && sFSyncFn && sFileInfoFn &&
1.146 + sFileInfo64Fn);
1.147 +
1.148 + // Get IO methods from NSPR and const cast the structure so we can modify it.
1.149 + PRIOMethods* methods = const_cast<PRIOMethods*>(PR_GetFileMethods());
1.150 +
1.151 + // Something is badly wrong if we don't get IO methods... However, we don't
1.152 + // want to crash over that in non-debug builds. This is unlikely to happen
1.153 + // so an assert is enough, no need to report it to the caller.
1.154 + MOZ_ASSERT(methods);
1.155 + if (!methods) {
1.156 + return;
1.157 + }
1.158 +
1.159 + // Restore original functions
1.160 + methods->close = sCloseFn;
1.161 + methods->read = sReadFn;
1.162 + methods->write = sWriteFn;
1.163 + methods->fsync = sFSyncFn;
1.164 + methods->fileInfo = sFileInfoFn;
1.165 + methods->fileInfo64 = sFileInfo64Fn;
1.166 +
1.167 + // Forget about original functions
1.168 + sCloseFn = nullptr;
1.169 + sReadFn = nullptr;
1.170 + sWriteFn = nullptr;
1.171 + sFSyncFn = nullptr;
1.172 + sFileInfoFn = nullptr;
1.173 + sFileInfo64Fn = nullptr;
1.174 +}
1.175 +
1.176 +} // namespace mozilla
1.177 +
