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Cygwin: serial: tcsetattr: set timeouts unconditionally 

tcsetattr checks if the VTIME and VMIN values changed and only
calls SetCommTimeouts if so.  That's a problem if tcsetattr
is supposed to set VTIME and VIMN to 0, because these are the
start values anyway.  But this requires to set ReadIntervalTimeout
to MAXDWORD, which just doesn't happen.

Fix this by dropping the over-optimization of checking the old
values before calling SetCommTimeouts,

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
This commit is contained in:
Corinna Vinschen 2020-03-23 12:13:35 +01:00
parent 72294cd211
commit 912c902615
1 changed files with 38 additions and 41 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

79
winsup/cygwin/fhandler_serial.cc
View File

@ -600,7 +600,6 @@ fhandler_serial::tcsetattr (int action, const struct termios *t)
bool dropDTR = false; bool dropDTR = false;
COMMTIMEOUTS to; COMMTIMEOUTS to;
DCB ostate, state; DCB ostate, state;
cc_t ovtime = vtime_, ovmin = vmin_;
int tmpDtr, tmpRts, res; int tmpDtr, tmpRts, res;
res = tmpDtr = tmpRts = 0; res = tmpDtr = tmpRts = 0;
@ -909,49 +908,47 @@ fhandler_serial::tcsetattr (int action, const struct termios *t)
debug_printf ("vtime %u, vmin %u", vtime_, vmin_); debug_printf ("vtime %u, vmin %u", vtime_, vmin_);
if (ovmin != vmin_ || ovtime != vtime_) memset (&to, 0, sizeof (to));
{
memset (&to, 0, sizeof (to));
if ((vmin_ > 0) && (vtime_ == 0)) if ((vmin_ > 0) && (vtime_ == 0))
{ {
/* Returns immediately with whatever is in buffer on a ReadFile(); /* Returns immediately with whatever is in buffer on a ReadFile();
or blocks if nothing found. We will keep calling ReadFile(); until or blocks if nothing found. We will keep calling ReadFile(); until
vmin_ characters are read */ vmin_ characters are read */
to.ReadIntervalTimeout = to.ReadTotalTimeoutMultiplier = MAXDWORD; to.ReadIntervalTimeout = to.ReadTotalTimeoutMultiplier = MAXDWORD;
to.ReadTotalTimeoutConstant = MAXDWORD - 1; to.ReadTotalTimeoutConstant = MAXDWORD - 1;
} }
else if ((vmin_ == 0) && (vtime_ > 0)) else if ((vmin_ == 0) && (vtime_ > 0))
{ {
/* set timeoout constant appropriately and we will only try to /* set timeoout constant appropriately and we will only try to
read one character in ReadFile() */ read one character in ReadFile() */
to.ReadTotalTimeoutConstant = vtime_ * 100; to.ReadTotalTimeoutConstant = vtime_ * 100;
to.ReadIntervalTimeout = to.ReadTotalTimeoutMultiplier = MAXDWORD; to.ReadIntervalTimeout = to.ReadTotalTimeoutMultiplier = MAXDWORD;
} }
else if ((vmin_ > 0) && (vtime_ > 0)) else if ((vmin_ > 0) && (vtime_ > 0))
{ {
/* time applies to the interval time for this case */ /* time applies to the interval time for this case */
to.ReadIntervalTimeout = vtime_ * 100; to.ReadIntervalTimeout = vtime_ * 100;
} }
else if ((vmin_ == 0) && (vtime_ == 0)) else if ((vmin_ == 0) && (vtime_ == 0))
{ {
/* returns immediately with whatever is in buffer as per /* returns immediately with whatever is in buffer as per
Time-Outs docs in Win32 SDK API docs */ Time-Outs docs in Win32 SDK API docs */
to.ReadIntervalTimeout = MAXDWORD; to.ReadIntervalTimeout = MAXDWORD;
} }
debug_printf ("ReadTotalTimeoutConstant %u, ReadIntervalTimeout %u, ReadTotalTimeoutMultiplier %u", debug_printf ("ReadTotalTimeoutConstant %u, ReadIntervalTimeout %u, "
to.ReadTotalTimeoutConstant, to.ReadIntervalTimeout, to.ReadTotalTimeoutMultiplier); "ReadTotalTimeoutMultiplier %u", to.ReadTotalTimeoutConstant,
to.ReadIntervalTimeout, to.ReadTotalTimeoutMultiplier);
if (!SetCommTimeouts(get_handle (), &to)) if (!SetCommTimeouts(get_handle (), &to))
{ {
/* SetCommTimeouts() failed. Keep track of this so we /* SetCommTimeouts() failed. Keep track of this so we
can set errno to EINVAL later and return failure */ can set errno to EINVAL later and return failure */
termios_printf ("SetCommTimeouts() failed, %E"); termios_printf ("SetCommTimeouts() failed, %E");
__seterrno (); __seterrno ();
res = -1; res = -1;
} }
}
return res; return res;
} }