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Introduce serialport_write_nonblock()

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It seems useful to have a generic and platform-independent method to
read and write to a serial port without blocking. This is the write part.

This allows to get rid of the explicit temporary disabling of blocking I/O in
serprog's sp_synchronize().

Corresponding to flashrom svn r1662.

Signed-off-by: Stefan Tauner <stefan.tauner@alumni.tuwien.ac.at>
Acked-by: Stefan Tauner <stefan.tauner@alumni.tuwien.ac.at>
This commit is contained in:
Stefan Tauner
2013-04-01 00:45:45 +00:00
parent 00e1608501
commit ae3d83765c
3 changed files with 78 additions and 14 deletions
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72
serial.c
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@ -431,3 +431,75 @@ int serialport_read_nonblock(unsigned char *c, unsigned int readcnt, unsigned in
}
return ret;
}
/* Tries up to timeout ms to write writecnt characters from the array starting at buf. Returns
* 0 on success, positive values on temporary errors (e.g. timeouts) and negative ones on permanent errors.
* If really_wrote is not NULL, this function sets its contents to the number of bytes written successfully. */
int serialport_write_nonblock(unsigned char *buf, unsigned int writecnt, unsigned int timeout, unsigned int *really_wrote)
{
int ret = 1;
/* disable blocked i/o and declare platform-specific variables */
#ifdef _WIN32
DWORD rv;
COMMTIMEOUTS oldTimeout;
COMMTIMEOUTS newTimeout = {
.ReadIntervalTimeout = MAXDWORD,
.ReadTotalTimeoutMultiplier = 0,
.ReadTotalTimeoutConstant = 0,
.WriteTotalTimeoutMultiplier = 0,
.WriteTotalTimeoutConstant = 0
};
if(!GetCommTimeouts(sp_fd, &oldTimeout)) {
msg_perr_strerror("Could not get serial port timeout settings: ");
return -1;
}
if(!SetCommTimeouts(sp_fd, &newTimeout)) {
msg_perr_strerror("Could not set serial port timeout settings: ");
return -1;
}
#else
ssize_t rv;
const int flags = fcntl(sp_fd, F_GETFL);
fcntl(sp_fd, F_SETFL, flags | O_NONBLOCK);
#endif
int i;
int wr_bytes = 0;
for (i = 0; i < timeout; i++) {
msg_pspew("writecnt %d wr_bytes %d\n", writecnt, wr_bytes);
#ifdef _WIN32
WriteFile(sp_fd, buf + wr_bytes, writecnt - wr_bytes, &rv, NULL);
msg_pspew("wrote %lu bytes\n", rv);
#else
rv = write(sp_fd, buf + wr_bytes, writecnt - wr_bytes);
msg_pspew("wrote %zd bytes\n", rv);
#endif
if ((rv == -1) && (errno != EAGAIN)) {
msg_perr_strerror("Serial port write error: ");
ret = -1;
break;
}
if (rv > 0) {
wr_bytes += rv;
if (wr_bytes == writecnt) {
msg_pspew("write successful\n");
ret = 0;
break;
}
}
internal_delay(1000); /* 1ms units */
}
if (really_wrote != NULL)
*really_wrote = wr_bytes;
/* restore original blocking behavior */
#ifdef _WIN32
if (!SetCommTimeouts(sp_fd, &oldTimeout)) {
msg_perr_strerror("Could not restore serial port timeout settings: ");
#else
if (fcntl(sp_fd, F_SETFL, flags) != 0) {
#endif
return -1;
}
return ret;
}