diff options
Diffstat (limited to 'third_party/git/compat/poll/poll.c')
| -rw-r--r-- | third_party/git/compat/poll/poll.c | 31 |
1 files changed, 28 insertions, 3 deletions
diff --git a/third_party/git/compat/poll/poll.c b/third_party/git/compat/poll/poll.c index afa6d245846a..0e95dd493c94 100644 --- a/third_party/git/compat/poll/poll.c +++ b/third_party/git/compat/poll/poll.c @@ -139,10 +139,22 @@ win32_compute_revents (HANDLE h, int *p_sought) INPUT_RECORD *irbuffer; DWORD avail, nbuffer; BOOL bRet; + IO_STATUS_BLOCK iosb; + FILE_PIPE_LOCAL_INFORMATION fpli; + static PNtQueryInformationFile NtQueryInformationFile; + static BOOL once_only; switch (GetFileType (h)) { case FILE_TYPE_PIPE: + if (!once_only) + { + NtQueryInformationFile = (PNtQueryInformationFile)(void (*)(void)) + GetProcAddress (GetModuleHandleW (L"ntdll.dll"), + "NtQueryInformationFile"); + once_only = TRUE; + } + happened = 0; if (PeekNamedPipe (h, NULL, 0, NULL, &avail, NULL) != 0) { @@ -154,9 +166,22 @@ win32_compute_revents (HANDLE h, int *p_sought) else { - /* It was the write-end of the pipe. Unfortunately there is no - reliable way of knowing if it can be written without blocking. - Just say that it's all good. */ + /* It was the write-end of the pipe. Check if it is writable. + If NtQueryInformationFile fails, optimistically assume the pipe is + writable. This could happen on Win9x, where NtQueryInformationFile + is not available, or if we inherit a pipe that doesn't permit + FILE_READ_ATTRIBUTES access on the write end (I think this should + not happen since WinXP SP2; WINE seems fine too). Otherwise, + ensure that enough space is available for atomic writes. */ + memset (&iosb, 0, sizeof (iosb)); + memset (&fpli, 0, sizeof (fpli)); + + if (!NtQueryInformationFile + || NtQueryInformationFile (h, &iosb, &fpli, sizeof (fpli), + FilePipeLocalInformation) + || fpli.WriteQuotaAvailable >= PIPE_BUF + || (fpli.OutboundQuota < PIPE_BUF && + fpli.WriteQuotaAvailable == fpli.OutboundQuota)) happened |= *p_sought & (POLLOUT | POLLWRNORM | POLLWRBAND); } return happened; |