diff options
| -rw-r--r-- | libraries/base/cbits/inputReady.c | 46 |
1 files changed, 30 insertions, 16 deletions
diff --git a/libraries/base/cbits/inputReady.c b/libraries/base/cbits/inputReady.c index ab2a1c2197..ddeee664d6 100644 --- a/libraries/base/cbits/inputReady.c +++ b/libraries/base/cbits/inputReady.c @@ -17,6 +17,9 @@ * descriptor 'fd' within 'msecs' milliseconds (or indefinitely if 'msecs' is * negative). "Input is available" is defined as 'can I safely read at least a * *character* from this file object without blocking?' + * + * This function blocks until either `msecs` have passed, or input is + * available. */ int fdReady(int fd, int write, int msecs, int isSock) @@ -100,7 +103,7 @@ fdReady(int fd, int write, int msecs, int isSock) } else { DWORD rc; HANDLE hFile = (HANDLE)_get_osfhandle(fd); - DWORD avail; + DWORD avail = 0; Time remaining = MSToTime(msecs); @@ -187,23 +190,34 @@ fdReady(int fd, int write, int msecs, int isSock) // WaitForMultipleObjects() doesn't work for pipes (it // always returns WAIT_OBJECT_0 even when no data is // available). If the HANDLE is a pipe, therefore, we try - // PeekNamedPipe: + // PeekNamedPipe(): // - rc = PeekNamedPipe( hFile, NULL, 0, NULL, &avail, NULL ); - if (rc != 0) { - if (avail != 0) { - return 1; + // PeekNamedPipe() does not block, so if it returns that + // there is no new data, we have to sleep and try again. + while (avail == 0) { + rc = PeekNamedPipe( hFile, NULL, 0, NULL, &avail, NULL ); + if (rc != 0) { + if (avail != 0) { + return 1; + } else { // no new data + if (msecs > 0) { + Time now = getProcessElapsedTime(); + if (now >= endTime) return 0; + Sleep(1); // 1 millisecond (smallest possible time on Windows) + continue; + } else { + return 0; + } + } } else { - return 0; - } - } else { - rc = GetLastError(); - if (rc == ERROR_BROKEN_PIPE) { - return 1; // this is probably what we want - } - if (rc != ERROR_INVALID_HANDLE && rc != ERROR_INVALID_FUNCTION) { - maperrno(); - return -1; + rc = GetLastError(); + if (rc == ERROR_BROKEN_PIPE) { + return 1; // this is probably what we want + } + if (rc != ERROR_INVALID_HANDLE && rc != ERROR_INVALID_FUNCTION) { + maperrno(); + return -1; + } } } /* PeekNamedPipe didn't work - fall through to the general case */ |