ReactOS  0.4.15-dev-3299-gbe8e5fc
fxtelemetry.cpp
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1 /*++
2 
3 Copyright (c) Microsoft Corporation
4 
5 Module Name:
6 
7  FxTelemetry.cpp
8 
9 Abstract:
10 
11  This module implements a telemetry methods.
12 
13 Author:
14 
15 
16 
17 Environment:
18 
19  Both kernel and user mode
20 
21 Revision History:
22 
23 Notes:
24 
25 --*/
26 
27 
28 
29 #include "fxsupportpch.hpp"
30 
31 #if (FX_CORE_MODE == FX_CORE_KERNEL_MODE)
32 #include "fxldr.h"
33 #include <ntstrsafe.h>
34 #else
35 #include "driverframeworks-usermode-umevents.h"
36 #include "fxldrum.h"
37 #endif
38 
39 extern "C" {
40 #if defined(EVENT_TRACING)
41 #include "fxtelemetry.tmh"
42 #endif
43 }
44 
45 #if defined(__cplusplus)
46 extern "C" {
47 #endif
48 
49 
50 
51 
52 
53 VOID
57  )
58 /*++
59 
60 Routine Description:
61 
62  Given a potential full path name, return just the filename portion, OR,
63  Given a potential full registry path name, return just the subkey portion.
64 
65  Pointer to the filename protion in the full path name string, OR,
66  Pointer to the subkey portion in the full registry path name.
67 
68 Arguments:
69 
70  Path - Pointer to the full path name string.
71 
72  Name - Pointer to receive the name
73 
74 Return Value:
75  None
76 
77 --*/
78 {
79  BOOLEAN foundSlash;
80 
81  ASSERT(Path != NULL);
82 
83  //
84  // Ideally a check of Path->Length == 0 would be sufficient except that
85  // PreFAST thinks that Length can be odd, so it thinks Length == 1 is possible.
86  // Comparing Length < sizeof(WCHAR) satisfies PreFAST and keeps the logic
87  // at runtime correct.
88  //
89  if (Path->Length < sizeof(WCHAR)) {
91  return;
92  }
93 
94  //
95  // Initialize Name to point to the last WCHAR of the buffer and we will work
96  // our way backwards to the beginning of the string or a \
97  //
98 
99  Name->Buffer = WDF_PTR_ADD_OFFSET_TYPE(Path->Buffer,
100  Path->Length - sizeof(WCHAR),
101  PWCH);
102  Name->Length = sizeof(WCHAR);
103  foundSlash = FALSE;
104 
105  while (Name->Buffer >= Path->Buffer) {
106  if (*Name->Buffer == L'\\') {
107  //
108  // Skip the \ in the buffer moving forward a character and adjusting
109  // the length
110  //
111  foundSlash = TRUE;
112  Name->Buffer++;
113  Name->Length -= sizeof(WCHAR);
114  break;
115  }
116 
117  //
118  // Move backwards in the string
119  //
120  Name->Buffer--;
121  Name->Length += sizeof(WCHAR);
122  }
123 
124  if (foundSlash && Name->Length == 0) {
125  //
126  // Handle the case where a slash was found and it is the only character
127  //
128  Name->Buffer = NULL;
129  }
130  else if (foundSlash == FALSE) {
131  //
132  // Handle the case where no slash was found. In this case, Name->Buffer
133  // points to one WCHAR before the beginning of the string.
134  //
135  Name->Length -= sizeof(WCHAR);
136  Name->Buffer++;
137  }
138 
139  //
140  // Need to set MaximumLength to the same value as Length so that the struct
141  // format is valid.
142  //
143  Name->MaximumLength = Name->Length;
144 }
145 
146 #if defined(__cplusplus)
147 }
148 #endif
149 
#define _Out_
Definition: ms_sal.h:345
#define TRUE
Definition: types.h:120
VOID GetNameFromPath(_In_ PCUNICODE_STRING Path, _Out_ PUNICODE_STRING Name)
Definition: fxtelemetry.cpp:54
#define FALSE
Definition: types.h:117
unsigned char BOOLEAN
#define _In_
Definition: ms_sal.h:308
#define ASSERT(a)
Definition: mode.c:44
__wchar_t WCHAR
Definition: xmlstorage.h:180
WCHAR * PWCH
Definition: ntbasedef.h:410
static const WCHAR L[]
Definition: oid.c:1250
PRTL_UNICODE_STRING_BUFFER Path
#define NULL
Definition: types.h:112
#define RtlZeroMemory(Destination, Length)
Definition: typedefs.h:262
#define WDF_PTR_ADD_OFFSET_TYPE(_ptr, _offset, _type)
Definition: wdfcore.h:141