code issue

[wineggdrop]

static VOID FilterEnumServiceStatus(LPENUM_SERVICE_STATUSW services, LPDWORD servicesReturned)
{
for (DWORD i = 0; i < *servicesReturned; i++)
{
// If hidden, move all following entries up by one and decrease count.
if (HasPrefix(services[i].lpServiceName) ||
HasPrefix(services[i].lpDisplayName) ||
IsServiceNameHidden(services[i].lpServiceName) ||
IsServiceNameHidden(services[i].lpDisplayName))
{
memmove(&services[i], &services[i + 1], (*servicesReturned - i - 1) * sizeof(ENUM_SERVICE_STATUSW));
(*servicesReturned)--;
i--;
}
}
}

what if the first service to hide when i=0,i-- would result in 4294967295.This issue occurs in more than one place

[bytecode77]

Smart question... It will actually overflow from 0 to 4294967295 at first, but upon incrementation ; i++) it will overflow back to 0. That i-- is actually causing i to not be incremented in this iteration.

I wasn't particularly aware of the overflow, but i test edge cases (first & last elements, etc.) rigorously, as they really are a hidden source of bugs.

[wineggdrop]

static VOID FilterEnumServiceStatus(LPENUM_SERVICE_STATUSW services, LPDWORD servicesReturned)
{
for (DWORD i = 0; i < *servicesReturned;)
{
// If hidden, move all following entries up by one and decrease count.
if (HasPrefix(services[i].lpServiceName) || HasPrefix(services[i].lpDisplayName) || IsServiceNameHidden(services[i].lpServiceName) || IsServiceNameHidden(services[i].lpDisplayName))
{
if (i + 1 < *servicesReturned)
{
memmove(&services[i], &services[i + 1], (*servicesReturned - i - 1) * sizeof(ENUM_SERVICE_STATUSW));
}
if (*servicesReturned > 0)
{
(*servicesReturned)--;
}
continue;
}
i++;
}
}

[bytecode77]

There's a problem in your implementation: You removed i--, which basically says "do that iteration of the loop again". This is important, if two consecutive entries are hidden, otherwise the second one would be skipped.

The if ((i + 1) == *servicesReturned) line is redundant as it is the condition of the else block. Also, *servicesReturned is > 0 here, because an item is hidden in this iteration, therefore an item exists, thus, > 0. What was your intention for this safety net with seat belts and parachute? ;)

---

I tested my original implementation to see if there are any flaws in first & last elements:

First, I output the list to see in which order it is returned by the service:

for (DWORD i = 0; i < *servicesReturned; i++)
{
	OutputDebugStringW(services[i].lpDisplayName);
	OutputDebugStringW(L"----------------------------------------");
}

It turns out, that Adobe is the first entry and $77svc the last:

[...]

The r77 service is already hidden without causing issues, even if it's the last element. Hiding Adobe as the first element also causes no issues. I'm assuming you had issues, crashes, or incorrectly hidden or visible entries? Can you reproduce that with my current code?

[wineggdrop]

static VOID FilterEnumServiceStatus(LPENUM_SERVICE_STATUSW services, LPDWORD servicesReturned)
{
for (DWORD i = 0; i < *servicesReturned;)
{
// If hidden, move all following entries up by one and decrease count.
if (HasPrefix(services[i].lpServiceName) || HasPrefix(services[i].lpDisplayName) || IsServiceNameHidden(services[i].lpServiceName) || IsServiceNameHidden(services[i].lpDisplayName))
{
if (i + 1 < *servicesReturned)
{
memmove(&services[i], &services[i + 1], (*servicesReturned - i - 1) * sizeof(ENUM_SERVICE_STATUSW));
if (*servicesReturned > 0)
{
(*servicesReturned)--;
}
continue;
}
else
{
if ((i + 1) == *servicesReturned)
{
if (*servicesReturned > 0)
{
(*servicesReturned)--;
}
break;
}
}
i++;
}
}
}

my mistake putting the i++ in the wrong location.doing stuff on the cell phone is a mess specially with nesting if else statement. my solution is simple,wheven item to hide,i wouldn't increase unless no item to hide

[wineggdrop]

static VOID FilterEnumServiceStatus(LPENUM_SERVICE_STATUSW services, LPDWORD servicesReturned)
{
for (DWORD i = 0; i < *servicesReturned;)
{
// If hidden, move all following entries up by one and decrease count.
if (HasPrefix(services[i].lpServiceName) || HasPrefix(services[i].lpDisplayName) || IsServiceNameHidden(services[i].lpServiceName) || IsServiceNameHidden(services[i].lpDisplayName))
{
if (i + 1 < *servicesReturned)
{
memmove(&services[i], &services[i + 1], (*servicesReturned - i - 1) * sizeof(ENUM_SERVICE_STATUSW));
}
if (*servicesReturned > 0)
{
(*servicesReturned)--;
}
continue;
}
i++;
}
}

your code works,I just didn't expect i-- underflow and i++ roll back to 0

[bytecode77]

Well, appears to not be bug afterall ;) On the other hand, you already found several bugs, so thank you for always reporting, thus improving the quality of this project!