Fix adb device ip parsing

The parser assumed that its input was a NUL-terminated string, but it
was not the case: it is just the raw output of "adb devices ip route".

In practice, it was harmless, since the output always ended with '\n'
(which was replaced by '\0' on truncation), but it was incorrect
nonetheless.

Always write a '\0' at the end of the buffer, and explicitly parse as a
NUL-terminated string. For that purpose, avoid the error-prone
sc_str_truncate() util function.

app/src/adb/adb.c

@@ -446,7 +446,7 @@ sc_adb_get_device_ip(struct sc_intr *intr, const char *serial, unsigned flags) {
 
     // "adb shell ip route" output should contain only a few lines
     char buf[1024];
-    ssize_t r = sc_pipe_read_all_intr(intr, pid, pout, buf, sizeof(buf));
+    ssize_t r = sc_pipe_read_all_intr(intr, pid, pout, buf, sizeof(buf) - 1);
     sc_pipe_close(pout);
 
     bool ok = process_check_success_intr(intr, pid, "ip route", flags);
@@ -458,8 +458,8 @@ sc_adb_get_device_ip(struct sc_intr *intr, const char *serial, unsigned flags) {
         return NULL;
     }
 
-    assert((size_t) r <= sizeof(buf));
-    if (r == sizeof(buf) && buf[sizeof(buf) - 1] != '\0')  {
+    assert((size_t) r < sizeof(buf));
+    if (r == sizeof(buf) - 1)  {
         // The implementation assumes that the output of "ip route" fits in the
         // buffer in a single pass
         LOGW("Result of \"ip route\" does not fit in 1Kb. "
@@ -467,5 +467,8 @@ sc_adb_get_device_ip(struct sc_intr *intr, const char *serial, unsigned flags) {
         return NULL;
     }
 
-    return sc_adb_parse_device_ip_from_output(buf, r);
+    // It is parsed as a NUL-terminated string
+    buf[r] = '\0';
+
+    return sc_adb_parse_device_ip_from_output(buf);
 }