[PATCH iproute2 3/3] utils: ll_map: Make network device name fixed size array of char
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STALE3217d
From: Serhey Popovych <hidden>
Date: 2017-12-20 07:38:08
Subsystem:
library code, the rest · Maintainers:
Andrew Morton, Linus Torvalds
Network device names are fixed in size and never exceed IFNAMSIZ (16 bytes). Make name fixed size array to always malloc() same size chunk of memory and use memcpy()/memcmp() with constant IFNAMSIZ to benefit from possible compiler optimizations replacing call to a function with two/four load/store instructions on 64/32 bit systems. Check if IFLA_IFNAME attribute present in netlink message (should always) and use strncpy() to pad name with zeros. Signed-off-by: Serhey Popovych <redacted> --- lib/ll_map.c | 20 ++++++++++++-------- 1 file changed, 12 insertions(+), 8 deletions(-)
diff --git a/lib/ll_map.c b/lib/ll_map.c
index abe7bdc..fcbf0fb 100644
--- a/lib/ll_map.c
+++ b/lib/ll_map.c@@ -30,7 +30,7 @@ struct ll_cache { unsigned flags; unsigned index; unsigned short type; - char name[]; + char name[IFNAMSIZ]; }; #define IDXMAP_SIZE 1024
@@ -71,7 +71,7 @@ static struct ll_cache *ll_get_by_name(const char *name) struct ll_cache *im = container_of(n, struct ll_cache, name_hash); - if (strncmp(im->name, name, IFNAMSIZ) == 0) + if (!strcmp(im->name, name)) return im; }
@@ -82,7 +82,7 @@ int ll_remember_index(const struct sockaddr_nl *who, struct nlmsghdr *n, void *arg) { unsigned int h; - const char *ifname; + char ifname[IFNAMSIZ]; struct ifinfomsg *ifi = NLMSG_DATA(n); struct ll_cache *im; struct rtattr *tb[IFLA_MAX+1];
@@ -105,17 +105,21 @@ int ll_remember_index(const struct sockaddr_nl *who, } parse_rtattr(tb, IFLA_MAX, IFLA_RTA(ifi), IFLA_PAYLOAD(n)); - ifname = rta_getattr_str(tb[IFLA_IFNAME]); - if (ifname == NULL) + + if (!tb[IFLA_IFNAME]) + return 0; + strncpy(ifname, rta_getattr_str(tb[IFLA_IFNAME]), IFNAMSIZ); + if (!ifname[0]) return 0; + ifname[IFNAMSIZ - 1] = '\0'; if (im) { /* change to existing entry */ - rehash = strcmp(im->name, ifname); + rehash = memcmp(im->name, ifname, IFNAMSIZ); if (rehash) hlist_del(&im->name_hash); } else { - im = malloc(sizeof(*im) + strlen(ifname) + 1); + im = malloc(sizeof(*im)); if (!im) return 0; im->index = ifi->ifi_index;
@@ -133,7 +137,7 @@ int ll_remember_index(const struct sockaddr_nl *who, h = namehash(ifname) & (IDXMAP_SIZE - 1); hlist_add_head(&im->name_hash, &name_head[h]); - strcpy(im->name, ifname); + memcpy(im->name, ifname, IFNAMSIZ); } return 0;
--
1.7.10.4