--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/smsc-sendmt/read_pdu.c	Sun Aug 27 16:36:28 2023 -0800
@@ -0,0 +1,38 @@
+/*
+ * This module implements the reading of hex-encoded SMS-DELIVER TPDU
+ * from stdin.
+ */
+
+#include <stdio.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+
+extern int decode_hex_line(const char *inbuf, uint8_t *outbuf, unsigned outmax);
+
+uint8_t tpdu_buf[176];
+unsigned tpdu_len;
+
+void read_pdu_from_stdin(void)
+{
+	char linebuf[512], *nl;
+	int rc;
+
+	if (!fgets(linebuf, sizeof(linebuf), stdin)) {
+		fprintf(stderr, "error: empty stdin is not acceptable\n");
+		exit(1);
+	}
+	nl = strchr(linebuf, '\n');
+	if (!nl) {
+		fprintf(stderr,
+			"error: stdin line is too long or unterminated\n");
+		exit(1);
+	}
+	*nl = '\0';
+	rc = decode_hex_line(linebuf, tpdu_buf, sizeof(tpdu_buf));
+	if (rc <= 0) {
+		fprintf(stderr, "error: stdin line is not a valid hex PDU\n");
+		exit(1);
+	}
+	tpdu_len = rc;
+}