Re: [libvirt] [PATCH 1/2] util: Functions to update host network device's multicast filter

On 10/08/2014 09:36 AM, Laine Stump wrote: > On 10/06/2014 05:37 PM, akrowiak(a)linux.vnet.ibm.com wrote: >> From: Tony Krowiak <akrowiak(a)linux.vnet.ibm.com&gt; >> >> This patch provides the utility functions to needed to synchronize the >> changes made to a guest domain network device's multicast filter >> with the corresponding macvtap device's filter on the host: >> >> * Get/add/remove multicast MAC addresses >> * Get the macvtap device's RX filter list >> >> Signed-off-by: Tony Krowiak <akrowiak(a)linux.vnet.ibm.com&gt; >> --- >> +/** >> + * virMacAddrParseHex: >> + * @str: string hexadecimal representation of MAC address, e.g., "F801EFCE3aCB" >> + * @addr: 6-byte MAC address >> + * >> + * Parse the hexadecimal representation of a MAC address >> + * >> + * Return 0 upon success, or -1 in case of error. >> + */ >> +int >> +virMacAddrParseHex(const char* str, virMacAddrPtr addr) Wrong spacing around '*'.

>> +{ >> + if (strlen(str) != VIR_MAC_HEXLEN) >> + return -1; >> + >> + size_t iaddr; >> + size_t istr; >> + >> + >> + for (istr = 0, iaddr = 0; iaddr < VIR_MAC_BUFLEN; istr += 2, iaddr++) { >> + unsigned int hex; >> + >> + if (sscanf(&str[istr], "%02x", &hex) != 1) >> + break; > I'm not keen on sscanf(), but since we're already using it elsewhere, > and the existing virMacAddrParse uses the normally-blacklisted strtoul() > (and using virStrToLong_ui() on pieces of the string would require a > terminating character after each piece), I don't have a ready answer for > an alternative. Why not just open-code it? It's just two input bytes per iteration, and we already have a helper function that makes it a very short function. And strspn makes it easy to do input validation before starting the loop: int virMacAddrParseHex(const char *str, virMacAddrPtr addr) { size_t i; if (strspn(str, "0123456789abcdefABCDEF") != VIR_MAC_HEXLEN || str[VIR_MAC_HEXLEN]) return -1; for (i = 0; i < VIR_MAC_BUFLEN; i++) addr->addr[i] = (virHexToBin(str[2 * i]) << 4 | virHexToBin(str[2 * i + 1])); return 0; }

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