freetdm: ftmod_libpri + ftmod_zt: some DAHDI drivers return an error of ELAST…

freetdm: ftmod_libpri + ftmod_zt: some DAHDI drivers return an error of ELAST (500) on read()/write() to indicate there are events pending.

Fixup zt_read() to handle this case correctly and rework ftmod_libpri's read wrapper function to not fail when the read function returns zero bytes.

NOTE: zt_write() has not been changed (some better way to handle these events is needed then)

This should fix these log messages:

   [WARNING] ftdm_io.c:3561 [s1c16][1:16] raw I/O read filed
   [CRIT] lpwrap_pri.c:125 span 1 D-READ FAIL! []
   [CRIT] lpwrap_pri.c:157 span 1 D-WRITE FAIL! []
   [ERR] ftmod_libpri.c:131 Short write: -1/6 (Unknown error 500)
Signed-off-by: Stefan Knoblich <s.knoblich@axsentis.de>

libs/freetdm/src/ftmod/ftmod_libpri/lpwrap_pri.c

@@ -134,17 +134,18 @@ static int __pri_lpwrap_read(struct pri *pri, void *buf, int buflen)
 	spri->errs = 0;
 	res = (int)len;
 
-	memset(&((unsigned char*)buf)[res], 0, 2);
-	res += 2;
-
+	if (res > 0) {
+		memset(&((unsigned char*)buf)[res], 0, 2);
+		res += 2;
 #ifdef IODEBUG
-	{
-		char bb[2048] = { 0 };
+		{
+			char bb[2048] = { 0 };
 
-		print_hex_bytes(buf, res - 2, bb, sizeof(bb));
-		ftdm_log(FTDM_LOG_DEBUG, "READ %d\n", res - 2);
-	}
+			print_hex_bytes(buf, res - 2, bb, sizeof(bb));
+			ftdm_log(FTDM_LOG_DEBUG, "READ %d\n", res - 2);
+		}
 #endif
+	}
 	return res;
 }
 

libs/freetdm/src/ftmod/ftmod_zt/ftmod_zt.c

@@ -35,6 +35,11 @@
 #include "private/ftdm_core.h"
 #include "ftmod_zt.h"
 
+/* used by dahdi to indicate there is no data available, but events to read */
+#ifndef ELAST
+#define ELAST 500
+#endif
+
 /**
  * \brief Zaptel globals
  */
@@ -1081,7 +1086,6 @@ FIO_SPAN_NEXT_EVENT_FUNCTION(zt_next_event)
 	}
 
 	return FTDM_FAIL;
-	
 }
 
 /**
@@ -1100,12 +1104,19 @@ static FIO_READ_FUNCTION(zt_read)
 		if ((r = read(ftdmchan->sockfd, data, *datalen)) > 0) {
 			break;
 		}
-		ftdm_sleep(10);
-		if (r == 0) {
-			errs--;
+		else if (r == 0) {
+			ftdm_sleep(10);
+			if (errs) errs--;
 		}
-	}
+		else {
+			if (errno == EAGAIN || errno == EINTR)
+				continue;
+			if (errno == ELAST)
+				break;
 
+			ftdm_log(FTDM_LOG_ERROR, "read failed: %s\n", strerror(errno));
+		}
+	}
 	if (r > 0) {
 		*datalen = r;
 		if (ftdmchan->type == FTDM_CHAN_TYPE_DQ921) {
@@ -1113,7 +1124,9 @@ static FIO_READ_FUNCTION(zt_read)
 		}
 		return FTDM_SUCCESS;
 	}
-
+	else if (errno == ELAST) {
+		return FTDM_SUCCESS;
+	}
 	return r == 0 ? FTDM_TIMEOUT : FTDM_FAIL;
 }