* [PATCH v2] Cygwin: pipe: Give up to use query_hdl for non-cygwin apps.
@ 2024-03-03 11:38 Takashi Yano
0 siblings, 0 replies; only message in thread
From: Takashi Yano @ 2024-03-03 11:38 UTC (permalink / raw)
To: cygwin-patches; +Cc: Takashi Yano, Alisa, Sireneva, Johannes Schindelin
Non-cygwin app may call ReadFile() for empty pipe, which makes
NtQueryObject() for ObjectNameInformation block in fhandler_pipe::
get_query_hdl_per_process. Therefore, stop to try to get query_hdl
for non-cygwin apps.
Addresses: https://github.com/msys2/msys2-runtime/issues/202
Fixes: b531d6b06eeb ("Cygwin: pipe: Introduce temporary query_hdl.")
Reported-by: Alisa Sireneva, Johannes Schindelin <Johannes.Schindelin@gmx.de>
Reviewed-by:
Signed-off-by: Takashi Yano <takashi.yano@nifty.ne.jp>
---
winsup/cygwin/fhandler/pipe.cc | 62 ++++++++++------------------------
winsup/cygwin/release/3.5.2 | 4 +++
2 files changed, 22 insertions(+), 44 deletions(-)
diff --git a/winsup/cygwin/fhandler/pipe.cc b/winsup/cygwin/fhandler/pipe.cc
index 1a97108b5..bdc2e6a37 100644
--- a/winsup/cygwin/fhandler/pipe.cc
+++ b/winsup/cygwin/fhandler/pipe.cc
@@ -1197,53 +1197,29 @@ HANDLE
fhandler_pipe::get_query_hdl_per_process (WCHAR *name,
OBJECT_NAME_INFORMATION *ntfn)
{
- NTSTATUS status;
- ULONG len;
- DWORD n_process = 256;
- PSYSTEM_PROCESS_INFORMATION spi;
- do
- { /* Enumerate processes */
- DWORD nbytes = n_process * sizeof (SYSTEM_PROCESS_INFORMATION);
- spi = (PSYSTEM_PROCESS_INFORMATION) HeapAlloc (GetProcessHeap (),
- 0, nbytes);
- if (!spi)
- return NULL;
- status = NtQuerySystemInformation (SystemProcessInformation,
- spi, nbytes, &len);
- if (NT_SUCCESS (status))
- break;
- HeapFree (GetProcessHeap (), 0, spi);
- n_process *= 2;
- }
- while (n_process < (1L<<20) && status == STATUS_INFO_LENGTH_MISMATCH);
- if (!NT_SUCCESS (status))
- return NULL;
+ winpids pids ((DWORD) 0);
- /* In most cases, it is faster to check the processes in reverse order.
- To do this, store PIDs into an array. */
- DWORD *proc_pids = (DWORD *) HeapAlloc (GetProcessHeap (), 0,
- n_process * sizeof (DWORD));
- if (!proc_pids)
+ /* In most cases, it is faster to check the processes in reverse order. */
+ for (LONG i = (LONG) pids.npids - 1; i >= 0; i--)
{
- HeapFree (GetProcessHeap (), 0, spi);
- return NULL;
- }
- PSYSTEM_PROCESS_INFORMATION p = spi;
- n_process = 0;
- while (true)
- {
- proc_pids[n_process++] = (DWORD)(intptr_t) p->UniqueProcessId;
- if (!p->NextEntryOffset)
- break;
- p = (PSYSTEM_PROCESS_INFORMATION) ((char *) p + p->NextEntryOffset);
- }
- HeapFree (GetProcessHeap (), 0, spi);
+ NTSTATUS status;
+ ULONG len;
+
+ /* Non-cygwin app may call ReadFile() for empty pipe, which makes
+ NtQueryObject() for ObjectNameInformation block. Therefore, stop
+ to try to get query_hdl for non-cygwin apps. */
+ _pinfo *p = pids[i];
+ if (!p)
+ continue;
+ pid_t cygpid;
+ if (!(cygpid = cygwin_pid (p->dwProcessId)))
+ continue;
+ if (ISSTATE (p, PID_NOTCYGWIN))
+ continue;
- for (LONG i = (LONG) n_process - 1; i >= 0; i--)
- {
HANDLE proc = OpenProcess (PROCESS_DUP_HANDLE
| PROCESS_QUERY_INFORMATION,
- 0, proc_pids[i]);
+ 0, p->dwProcessId);
if (!proc)
continue;
@@ -1307,7 +1283,6 @@ fhandler_pipe::get_query_hdl_per_process (WCHAR *name,
query_hdl_proc = proc;
query_hdl_value = (HANDLE)(intptr_t) phi->Handles[j].HandleValue;
HeapFree (GetProcessHeap (), 0, phi);
- HeapFree (GetProcessHeap (), 0, proc_pids);
return h;
}
close_handle:
@@ -1317,6 +1292,5 @@ close_handle:
close_proc:
CloseHandle (proc);
}
- HeapFree (GetProcessHeap (), 0, proc_pids);
return NULL;
}
diff --git a/winsup/cygwin/release/3.5.2 b/winsup/cygwin/release/3.5.2
index 7d8df9489..efd30b64a 100644
--- a/winsup/cygwin/release/3.5.2
+++ b/winsup/cygwin/release/3.5.2
@@ -5,3 +5,7 @@ Fixes:
is already unmapped due to race condition. To avoid this issue,
shared console memory will be kept mapped if it belongs to CTTY.
Addresses: https://cygwin.com/pipermail/cygwin/2024-February/255561.html
+
+- Fix a problem that select() call for write-side of a pipe possibly
+ hangs with non-cygwin reader.
+ Addresses: https://github.com/msys2/msys2-runtime/issues/202
--
2.43.0
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