From: Rong Tao rongtao@cestc.cn
Copy libbpf_strlcpy() from libbpf_internal.h to bpf_util.h, and rename it to bpf_strlcpy(), then replace selftests strncpy()/libbpf_strlcpy() with bpf_strlcpy(), fix compile warning.
The libbpf_internal.h header cannot be used directly here, because references to cgroup_helpers.c in samples/bpf will generate compilation errors. We also can't add libbpf_strlcpy() directly to bpf_util.h, because the definition of libbpf_strlcpy() in libbpf_internal.h is duplicated. In order not to modify the libbpf code, add a new function bpf_strlcpy() to selftests bpf_util.h.
How to reproduce this compilation warning:
$ make -C samples/bpf cgroup_helpers.c: In function ‘__enable_controllers’: cgroup_helpers.c:80:17: warning: ‘strncpy’ specified bound 4097 equals destination size [-Wstringop-truncation] 80 | strncpy(enable, controllers, sizeof(enable)); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Signed-off-by: Rong Tao rongtao@cestc.cn --- tools/testing/selftests/bpf/bpf_util.h | 19 ++++++++++++++ tools/testing/selftests/bpf/cgroup_helpers.c | 3 ++- tools/testing/selftests/bpf/xsk.c | 26 +++----------------- 3 files changed, 25 insertions(+), 23 deletions(-)
diff --git a/tools/testing/selftests/bpf/bpf_util.h b/tools/testing/selftests/bpf/bpf_util.h index a3352a64c067..10587a29b967 100644 --- a/tools/testing/selftests/bpf/bpf_util.h +++ b/tools/testing/selftests/bpf/bpf_util.h @@ -20,6 +20,25 @@ static inline unsigned int bpf_num_possible_cpus(void) return possible_cpus; }
+/* Copy up to sz - 1 bytes from zero-terminated src string and ensure that dst + * is zero-terminated string no matter what (unless sz == 0, in which case + * it's a no-op). It's conceptually close to FreeBSD's strlcpy(), but differs + * in what is returned. Given this is internal helper, it's trivial to extend + * this, when necessary. Use this instead of strncpy inside libbpf source code. + */ +static inline void bpf_strlcpy(char *dst, const char *src, size_t sz) +{ + size_t i; + + if (sz == 0) + return; + + sz--; + for (i = 0; i < sz && src[i]; i++) + dst[i] = src[i]; + dst[i] = '\0'; +} + #define __bpf_percpu_val_align __attribute__((__aligned__(8)))
#define BPF_DECLARE_PERCPU(type, name) \ diff --git a/tools/testing/selftests/bpf/cgroup_helpers.c b/tools/testing/selftests/bpf/cgroup_helpers.c index e914cc45b766..dd1aa5afcf5a 100644 --- a/tools/testing/selftests/bpf/cgroup_helpers.c +++ b/tools/testing/selftests/bpf/cgroup_helpers.c @@ -13,6 +13,7 @@ #include <ftw.h>
#include "cgroup_helpers.h" +#include "bpf_util.h"
/* * To avoid relying on the system setup, when setup_cgroup_env is called @@ -77,7 +78,7 @@ static int __enable_controllers(const char *cgroup_path, const char *controllers enable[len] = 0; close(fd); } else { - strncpy(enable, controllers, sizeof(enable)); + bpf_strlcpy(enable, controllers, sizeof(enable)); }
snprintf(path, sizeof(path), "%s/cgroup.subtree_control", cgroup_path); diff --git a/tools/testing/selftests/bpf/xsk.c b/tools/testing/selftests/bpf/xsk.c index 0b3ff49c740d..39d349509ba4 100644 --- a/tools/testing/selftests/bpf/xsk.c +++ b/tools/testing/selftests/bpf/xsk.c @@ -33,6 +33,7 @@ #include <bpf/bpf.h> #include <bpf/libbpf.h> #include "xsk.h" +#include "bpf_util.h"
#ifndef SOL_XDP #define SOL_XDP 283 @@ -521,25 +522,6 @@ static int xsk_create_bpf_link(struct xsk_socket *xsk) return 0; }
-/* Copy up to sz - 1 bytes from zero-terminated src string and ensure that dst - * is zero-terminated string no matter what (unless sz == 0, in which case - * it's a no-op). It's conceptually close to FreeBSD's strlcpy(), but differs - * in what is returned. Given this is internal helper, it's trivial to extend - * this, when necessary. Use this instead of strncpy inside libbpf source code. - */ -static inline void libbpf_strlcpy(char *dst, const char *src, size_t sz) -{ - size_t i; - - if (sz == 0) - return; - - sz--; - for (i = 0; i < sz && src[i]; i++) - dst[i] = src[i]; - dst[i] = '\0'; -} - static int xsk_get_max_queues(struct xsk_socket *xsk) { struct ethtool_channels channels = { .cmd = ETHTOOL_GCHANNELS }; @@ -552,7 +534,7 @@ static int xsk_get_max_queues(struct xsk_socket *xsk) return -errno;
ifr.ifr_data = (void *)&channels; - libbpf_strlcpy(ifr.ifr_name, ctx->ifname, IFNAMSIZ); + bpf_strlcpy(ifr.ifr_name, ctx->ifname, IFNAMSIZ); err = ioctl(fd, SIOCETHTOOL, &ifr); if (err && errno != EOPNOTSUPP) { ret = -errno; @@ -771,7 +753,7 @@ static int xsk_create_xsk_struct(int ifindex, struct xsk_socket *xsk) }
ctx->ifindex = ifindex; - libbpf_strlcpy(ctx->ifname, ifname, IFNAMSIZ); + bpf_strlcpy(ctx->ifname, ifname, IFNAMSIZ);
xsk->ctx = ctx; xsk->ctx->has_bpf_link = xsk_probe_bpf_link(); @@ -958,7 +940,7 @@ static struct xsk_ctx *xsk_create_ctx(struct xsk_socket *xsk, ctx->refcount = 1; ctx->umem = umem; ctx->queue_id = queue_id; - libbpf_strlcpy(ctx->ifname, ifname, IFNAMSIZ); + bpf_strlcpy(ctx->ifname, ifname, IFNAMSIZ);
ctx->fill = fill; ctx->comp = comp;