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fix(unix): handle unsupported modem-control ioctls on Linux #235

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fix(unix): handle unsupported modem-control ioctls on Linux #235

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58 changes: 51 additions & 7 deletions src/serialport_unix.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -79,6 +79,30 @@ int ToDataBitsConstant(int dataBits) {
return -1;
}

bool isUnsupportedModemSetErrno(int code) {
if (code == ENOTTY || code == EINVAL) {
return true;
}
#ifdef EOPNOTSUPP
if (code == EOPNOTSUPP) {
return true;
}
#endif
#ifdef ENOSYS
if (code == ENOSYS) {
return true;
}
#endif
return false;
}

int applyModemBit(int fd, int mask, bool enabled) {
if (enabled) {
return ioctl(fd, TIOCMBIS, &mask);
}
return ioctl(fd, TIOCMBIC, &mask);
}

void OpenBaton::Execute() {

int flags = (O_RDWR | O_NOCTTY | O_NONBLOCK | O_CLOEXEC | O_SYNC);
Expand Down Expand Up @@ -392,20 +416,40 @@ void SetBaton::Execute() {
int result = 0;
if (brk) {
result = ioctl(fd, TIOCSBRK, NULL);
if (-1 == result) {
snprintf(errorString, sizeof(errorString), "Error: %s, cannot set", strerror(errno));
this->SetError(errorString);
return;
}
} else {
result = ioctl(fd, TIOCCBRK, NULL);
}

if (-1 == result) {
snprintf(errorString, sizeof(errorString), "Error: %s, cannot set", strerror(errno));
this->SetError(errorString);
return;
if (-1 == result && !isUnsupportedModemSetErrno(errno)) {
snprintf(errorString, sizeof(errorString), "Error: %s, cannot set", strerror(errno));
this->SetError(errorString);
return;
}
}

if (-1 == ioctl(fd, TIOCMSET, &bits)) {
snprintf(errorString, sizeof(errorString), "Error: %s, cannot set", strerror(errno));
int setErr = errno;
#if defined(__linux__) && defined(TIOCMBIS) && defined(TIOCMBIC)
if (isUnsupportedModemSetErrno(setErr)) {
if (-1 == applyModemBit(fd, TIOCM_RTS, rts) ||
-1 == applyModemBit(fd, TIOCM_DTR, dtr)) {
snprintf(errorString, sizeof(errorString), "Error: %s, cannot set", strerror(errno));
this->SetError(errorString);
return;
}
} else {
snprintf(errorString, sizeof(errorString), "Error: %s, cannot set", strerror(setErr));
this->SetError(errorString);
return;
}
#else
snprintf(errorString, sizeof(errorString), "Error: %s, cannot set", strerror(setErr));
this->SetError(errorString);
return;
#endif
}

#if defined(__linux__)
Expand Down