Don't repeat file that can't advance its position.

mossmann · mossmann · commit 45504ff39710 · 2022-09-23T06:48:01.000-04:00
This avoids a confusing condition when hackrf_transfer is reading from
stdin with -R in which it does not repeat previous data but repeatedly
restarts reading new data after the user types Ctrl-D to indicate EOF.

The -R option should repeat previous data or should do nothing if the
input file cannot be rewound.
diff --git a/host/hackrf-tools/src/hackrf_transfer.c b/host/hackrf-tools/src/hackrf_transfer.c
@@ -543,7 +543,7 @@ int tx_callback(hackrf_transfer* transfer)
 	}
 
 	/* Otherwise, the file ran short. If not repeating, this is the last data. */
-	if (!repeat) {
+	if ((!repeat) || (ftell(file) < 1)) {
 		tx_complete = true;
 		return 0;
 	}

Original file line number	Diff line number	Diff line change
`@@ -543,7 +543,7 @@ int tx_callback(hackrf_transfer* transfer)`
`543`	`543`	`}`
`544`	`544`
`545`	`545`	`/* Otherwise, the file ran short. If not repeating, this is the last data. */`
`546`		`- if (!repeat) {`
	`546`	`+ if ((!repeat) \|\| (ftell(file) < 1)) {`
`547`	`547`	`tx_complete = true;`
`548`	`548`	`return 0;`
`549`	`549`	`}`