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Fix for "Resource temporarily unavailable" error in tty read() (#78)

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This commit is contained in:
Victor Antonovich 2021-11-12 18:04:31 +03:00
parent 4cd68c1bb8
commit 1efb812013
2 changed files with 55 additions and 36 deletions
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90
src/conn.c
View File

@ -227,7 +227,7 @@ conn_read(int d, void *buf, size_t nbytes)
{ /* trying read from descriptor while breaked by signals */
rc = read(d, buf, nbytes);
} while (rc == -1 && errno == EINTR);
return (rc < 0) ? RC_ERR : rc;
return (rc < 0) ? (errno == EAGAIN ? RC_EAGAIN : RC_ERR) : rc;
}
#include <stdio.h>
@ -622,59 +622,77 @@ conn_loop(void)
}
rc = conn_read(tty.fd, tty.rxbuf + tty.ptrbuf,
tty.rxlen - tty.ptrbuf + tty.rxoffset);
if (rc <= 0)
if (rc == RC_EAGAIN)
{ /* some tty devices seem to be set as ready to be read by select()
while no data is available (see #78) */
#ifdef LOG
logw(5, "tty: read(): no data available");
#endif
}
else if (rc <= 0)
{ /* error - make attempt to reinitialize serial port */
#ifdef LOG
logw(0, "tty: error in read() (%s)", rc ? strerror(errno) : "port closed");
#endif
tty_reinit();
}
else
{
#ifdef DEBUG
logw(7, "tty: read %d bytes", rc);
#endif
if (tty.ptrbuf - tty.rxoffset < 3 && tty.ptrbuf - tty.rxoffset + rc >= 3) {
/* we received more than 3 bytes from header - address, request id and bytes count */
if (!tty.rxoffset) {
/* offset is unknown */
unsigned char i;
for (i = 0; i < tty.ptrbuf - tty.rxoffset + rc - 1; i++) {
if (tty.rxbuf[i] == tty.txbuf[0] && tty.rxbuf[i+1] == tty.txbuf[1]) {
if (tty.ptrbuf - tty.rxoffset < 3 && tty.ptrbuf - tty.rxoffset + rc >= 3) {
/* we received more than 3 bytes from header - address, request id and bytes count */
if (!tty.rxoffset) {
/* offset is unknown */
unsigned char i;
for (i = 0; i < tty.ptrbuf - tty.rxoffset + rc - 1; i++) {
if (tty.rxbuf[i] == tty.txbuf[0] && tty.rxbuf[i+1] == tty.txbuf[1]) {
#ifdef DEBUG
logw(5, "tty: rx offset is %d", i);
logw(5, "tty: rx offset is %d", i);
#endif
tty.rxoffset = i;
break;
tty.rxoffset = i;
break;
}
}
switch (tty.txbuf[1]) {
case 1:
case 2:
case 3:
case 4:
i = 5 + tty.rxbuf[tty.rxoffset + 2];
break;
default:
i = tty.rxlen;
break;
}
if (i + tty.rxoffset > TTY_BUFSIZE)
i = TTY_BUFSIZE - tty.rxoffset;
if (i != tty.rxlen) {
#ifdef DEBUG
logw(5, "tty: rx len changed from %d to %d", tty.rxlen, i);
#endif
tty.rxlen = i;
}
}
switch (tty.txbuf[1]) {
case 1:
case 2:
case 3:
case 4:
i = 5 + tty.rxbuf[tty.rxoffset + 2];
break;
default:
i = tty.rxlen;
break;
}
if (i + tty.rxoffset > TTY_BUFSIZE)
i = TTY_BUFSIZE - tty.rxoffset;
if (i != tty.rxlen) {
#ifdef DEBUG
logw(5, "tty: rx len changed from %d to %d", tty.rxlen, i);
#endif
tty.rxlen = i;
}
}
tty.ptrbuf += rc;
logw(5, "tty: read %d bytes of %d, offset %d", tty.ptrbuf, tty.rxlen + tty.rxoffset, tty.rxoffset);
if (tty.ptrbuf == tty.rxlen + tty.rxoffset)
state_tty_set(&tty, TTY_PROC);
}
tty.ptrbuf += rc;
logw(5, "tty: read %d bytes of %d, offset %d", tty.ptrbuf, tty.rxlen + tty.rxoffset, tty.rxoffset);
if (tty.ptrbuf == tty.rxlen + tty.rxoffset)
state_tty_set(&tty, TTY_PROC);
}
else if (tty.state != TTY_PROC)
{ /* drop unexpected tty data */
if ((rc = conn_read(tty.fd, tty.rxbuf, BUFSIZE)) <= 0)
rc = conn_read(tty.fd, tty.rxbuf, BUFSIZE);
if (rc == RC_EAGAIN)
{ /* some tty devices seem to be set as ready to be read by select()
while no data is available (see #78) */
#ifdef LOG
logw(5, "tty: read(): no data available");
#endif
}
else if (rc <= 0)
{ /* error - make attempt to reinitialize serial port */
#ifdef LOG
logw(0, "tty: error in read() (%s)", rc ? strerror(errno) : "port closed");

1
src/globals.h
View File

@ -84,6 +84,7 @@
#define RC_TIMEOUT -3
#define RC_AOPEN -4
#define RC_ACLOSE -5
#define RC_EAGAIN -6
/* Internal string buffers size */
#if defined(PATH_MAX)