On Sat, 28 Oct 2017 22:57:00 +0530
Nishanth Devarajan <ndev2...@gmail.com> wrote:
>
> +int read_prop(char *dev, char *prop, long *value)
> +{
> + char fname[41], buf[80], *endp;
> + ssize_t len;
> + int fd;
> + long result;
> +
> + sprintf(fname, "/sys/class/net/%s/%s", dev, prop);
> + fd = open(fname, O_RDONLY);
> + if (fd < 0) {
> + if (strcmp(prop, "tun_flags"))
> + fprintf(stderr, "open %s: %s\n", fname,
> + strerror(errno));
> + return -1;
> + }
> + len = read(fd, buf, sizeof(buf)-1);
> + close(fd);
> + if (len < 0) {
> + fprintf(stderr, "read %s: %s", fname, strerror(errno));
> + return -1;
> + }
> +
> + buf[len] = 0;
> + result = strtol(buf, &endp, 0);
> + if (*endp != '\n') {
> + fprintf(stderr, "Failed to parse %s\n", fname);
> + return -1;
> + }
> + *value = result;
> + return 0;
> +}
I know you copy and pasted this code, but it was already a mess.
1. It should use stdio (fopen/fgets)
2. It should not be looking for signed values (ie use strtoul)
3. It should not be special casing "tun_flags"
4. It needs to check for all possible parsing errors, with strtoul.
(hint read strtoul man page for how errors are reported).
