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Code Snippet - Query Semaphore
Author:Arkon
Category:Win32API
File Size:~ 1.20 KB
Uploaded at:15-Jul-06 09:13:31 am
Description:
  Shows how to query the count of aquires left on the Semaphore using an undocumented API.
  
When using a Semaphore synchronization object
sometimes you would like to know how many "aquires" are left to be done.
Therefore there's the NtQuerySemaphore function which resides in NTDLL.DLL.

typedef struct _SEMAINFO {
UINT Count;
UINT Limit;
} SEMAINFO, *PSEMAINFO;

#define SEMAQUERYINFOCLASS 0
typedef long (WINAPI *NtQuerySemaphorePtr)(HANDLE Handle, UINT InfoClass, PSEMAINFO SemaInfo, UINT InfoSize, PUINT RetLen);
NtQuerySemaphorePtr NtQuerySemaphore = NULL;
UINT WINAPI QuerySemaphore(HANDLE hSemaphore)
{
SEMAINFO SemInfo;
UINT RetLen;
NtQuerySemaphore(hSemaphore, SEMAQUERYINFOCLASS, &SemInfo, sizeof(SemInfo), &RetLen);
// You can check return value if you like.
return SemInfo.Count;
}

// Init code:
HMODULE g_ntdll = LoadLibrary("ntdll.dll");
NtQuerySemaphore = (NtQuerySemaphorePtr)GetProcAddress(g_ntdll, "NtQuerySemaphore");

// Usage example:
HANDLE h = CreateSemaphore(NULL, 4, 5, "mysem");
WaitForSingleObject(h, 0);
WaitForSingleObject(h, 0);
WaitForSingleObject(h, 0);
printf("Semaphore has been acquired %d times.\n", 4-QuerySemaphore(h));
ReleaseSemaphore(h, 3, NULL);
CloseHandle(h);

// Destroy code:
FreeLibrary(g_ntdll);
=0){ mysqli_data_seek($res,$row); $resrow = (is_numeric($col)) ? mysqli_fetch_row($res) : mysqli_fetch_assoc($res); if (isset($resrow[$col])){ return $resrow[$col]; } } return false; } function ViewComments($pt, $pid, $topic, $conn) { $res = mysqli_query($conn, "SELECT ThreadID FROM CommentThreads WHERE ParentType='$pt' AND ParentID='$pid'") or die("type+id not found"); if (mysqli_num_rows($res) == 0) { echo "\r\n"; // no comments for this thread, just let the user enter one. echo ""; echo ""; echo "
User Contributed Comments(None)
"; displaySubmissionForm($pt, $pid, "", "", "", $topic); echo "
"; return; } $threadid = mysqli_result($res, 0); $res = mysqli_query($conn, "SELECT * FROM Comments WHERE ThreadID='$threadid' ORDER BY Date ASC") or die("no entries"); $colsel = 0; $index = 0; $bgcolors = Array(0 => "#5d88bb", 1 => "#6699dd"); $comments_count = mysqli_num_rows($res); echo ""; if ($comments_count != 0) { echo ""; echo ""; } //comments exist end if echo "
User Contributed Comments(" .$comments_count .")
\r\n"; while($comment = mysqli_fetch_array($res)) { $index = $index + 1; // Point to last inserted comment... if ($index == $comments_count) echo "\r\n"; $submitter = $comment[Name]; // Add email if exists if (strlen($comment[EMail])) { $submitter = "$submitter"; } echo ""; $colsel = ($colsel + 1) & 1; } echo "
 [" .strval($index) ."] " .$submitter ." | " .$comment[Date] ."

" .$comment[Comment] ."
"; displaySubmissionForm($pt, $pid, "", "", "", $topic); echo "
"; } return; function displaySubmissionForm($pt, $pid, $comment, $name, $email, $topic) { //if (strlen($comment) == 0) $comment = ""; if (strlen($name) != 0) $name = "value=\"" .$name ."\""; if (strlen($email) != 0) $email = "value=\"" .$email ."\""; print << NOTE:
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END; } ?>