fxtelemetry.cpp File Reference

#include "fxsupportpch.hpp"
#include "fxldr.h"
#include <ntstrsafe.h>

Include dependency graph for fxtelemetry.cpp:

Go to the source code of this file.

Functions
VOID	GetNameFromPath (_In_ PCUNICODE_STRING Path, _Out_ PUNICODE_STRING Name)

Function Documentation

GetNameFromPath()

VOID GetNameFromPath	(	_In_ PCUNICODE_STRING	Path,
		_Out_ PUNICODE_STRING	Name
	)

Definition at line 54 of file fxtelemetry.cpp.

{
    BOOLEAN foundSlash;
 
    ASSERT(Path != NULL);
 
    //
    // Ideally a check of Path->Length == 0 would be sufficient except that
    // PreFAST thinks that Length can be odd, so it thinks Length == 1 is possible.
    // Comparing Length < sizeof(WCHAR) satisfies PreFAST and keeps the logic
    // at runtime correct.
    //
    if (Path->Length < sizeof(WCHAR)) {
        RtlZeroMemory(Name, sizeof(UNICODE_STRING));
        return;
    }
 
    //
    // Initialize Name to point to the last WCHAR of the buffer and we will work
    // our way backwards to the beginning of the string or a '\'
    //
 
    Name->Buffer = WDF_PTR_ADD_OFFSET_TYPE(Path->Buffer,
                                           Path->Length - sizeof(WCHAR),
                                           PWCH);
    Name->Length = sizeof(WCHAR);
    foundSlash = FALSE;
 
    while (Name->Buffer >= Path->Buffer) {
        if (*Name->Buffer == L'\\') {
            //
            // Skip the \ in the buffer moving forward a character and adjusting
            // the length
            //
            foundSlash = TRUE;
            Name->Buffer++;
            Name->Length -= sizeof(WCHAR);
            break;
        }
 
        //
        // Move backwards in the string
        //
        Name->Buffer--;
        Name->Length += sizeof(WCHAR);
    }
 
    if (foundSlash && Name->Length == 0) {
        //
        // Handle the case where a slash was found and it is the only character
        //
        Name->Buffer = NULL;
    }
    else if (foundSlash == FALSE) {
        //
        // Handle the case where no slash was found. In this case, Name->Buffer
        // points to one WCHAR before the beginning of the string.
        //
        Name->Length -= sizeof(WCHAR);
        Name->Buffer++;
    }
 
    //
    // Need to set MaximumLength to the same value as Length so that the struct
    // format is valid.
    //
    Name->MaximumLength = Name->Length;
}