Infinite loop

[duvh93]

Use case:

AT+CMGF=1
OK
AT+CMGS=+31628870634
> This is the text message.→
+CMGS: 45
OK

Line of code where it gets stuck:

do {
line = fgets(buf, (int)sizeof(buf), modem);
if (line == NULL) {
fprintf(stderr, "EOF from modem\n");
return EXIT_FAILURE;
}
strcpy(buf2, line);
strip_cr(buf2);
res = fputs(buf2, output);
if (res < 0) {
fprintf(stderr, "failed to write '%s' to output file (res = %d)\n", buf2, res);
return EXIT_FAILURE;
}
} while (! is_final_result(line));

DISCLAIMER: I am far from being a sw developer, just wanted to write my linux sms utility using this nice piece of code.

If the device expects to be written again then it will never provide the "end of transmission" hence the fgets keeps listening.

Using a serial terminal emulators you can see that (look at the usecase I have reported) and you (user) keep writing giving the expected terminator at the end (ascii 26 in my case).

[beralt]

This project is on my account, although I'm not the original author. For this specific use-case I cannot remember exactly how to use it but I do know that the is_final_result call should fix it. I think you might need to add the > to the conditions listed there that mark 'end of command'.