Ben Chan
7ae32d6c61
The while loop in mm_charset_get_encoded_len() iterates through each valid UTF-8 encoded character in the given NULL-terminated UTF-8 string. It uses g_utf8_find_next_char() to find the position of the next character. In case, g_utf8_find_next_char() returns NULL, it tries to find the end (i.e. the NULL character) of the string. This patch fixes the following issues in the while loop: 1. The loop uses both 'next' and 'end' to track the position of the next character in the string. When g_utf8_find_next_char() returns a non-NULL value, 'next' is essentially the same as 'end'. When g_utf8_find_next_char() returns NULL, 'next' remains NULL while 'end' is adjusted to track the end of the string (but is done incorrectly as described in #2). After the 'p = next' assignment, the 'while (*p)' check results in a NULL dereference. 'p' should thus be set to 'end' instead of 'next'. 'next' is thus redundant and can be removed. 2. When g_utf8_find_next_char() returns NULL and 'end' is adjusted to track the end of string, the 'while (*end++)' loop stops when finding the NULL character, but 'end' is advanced past the NULL character. After the 'p = end' assignment, the 'while (*p)' check results in a dereference of out-of-bounds pointer. 'while (*++end)' should be used instead given that 'p' doesn't point to a NULL character when 'end = p' happens. 'end' will be updated to point to the NULL character. After the 'p = end' assignment (fixed in #1), the 'while (*p)' check will properly stop the loop.
ModemManager. ModemManager provides a unified high level API for communicating with mobile broadband modems, regardless of the protocol used to communicate with the actual device (Generic AT, vendor-specific AT, QCDM, QMI, MBIM...). Using. ModemManager is a system daemon and is not meant to be used directly from the command line. However, since it provides a DBus API, it is possible to use 'dbus-send' commands or the new 'mmcli' command line interface to control it from the terminal. The devices are queried from udev and automatically updated based on hardware events, although a manual re-scan can also be requested to look for RS232 modems. Implementation. ModemManager is a DBus system bus activated service (meaning it's started automatically when a request arrives). It is written in C, using glib and gio. Several GInterfaces specify different features that the modems support, including the generic MMIfaceModem3gpp and MMIfaceModemCdma which provice basic operations for 3GPP (GSM, UMTS, LTE) or CDMA (CDMA1x, EV-DO) modems. If a given feature is not available in the modem, the specific interface will not be exported in DBus. Plugins. Plugins are loaded on startup, and must implement the MMPlugin interface. It consists of a couple of methods which tell the daemon whether the plugin supports a port and to create custom MMBroadbandModem implementations. It most likely makes sense to derive custom modem implementations from one of the generic classes and just add (or override) operations which are not standard. There are multiple fully working plugins in the plugins/ directory that can be used as an example for writing new plugins. Writing new plugins is highly encouraged! The plugin API is open for changes, so if you're writing a plugin and need to add or change some public method, feel free to suggest it! License. The ModemManager and mmcli binaries are both GPLv2+. The libmm-glib library is LGPLv2+.