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Commit 1ce6a9fc authored by Thomas Richter's avatar Thomas Richter Committed by Daniel Borkmann
Browse files

bpf: fix build error in libbpf with EXTRA_CFLAGS="-Wp, -D_FORTIFY_SOURCE=2 -O2" 



Commit 531b014e ("tools: bpf: make use of reallocarray") causes
a compiler error when building the perf tool in the linux-next tree.
Compile file tools/lib/bpf/libbpf.c on a FEDORA 28 installation with
gcc compiler version: gcc (GCC) 8.0.1 20180324 (Red Hat 8.0.1-0.20)
shows this error message:

  [root@p23lp27] # make V=1 EXTRA_CFLAGS="-Wp,-D_FORTIFY_SOURCE=2 -O2"
  [...]
  make -f /home6/tmricht/linux-next/tools/build/Makefile.build
  	dir=./util/scripting-engines obj=libperf
  libbpf.c: In function ‘bpf_object__elf_collect’:
  libbpf.c:811:15: error: ignoring return value of ‘strerror_r’,
  		declared with attribute warn_unused_result [-Werror=unused-result]
       strerror_r(-err, errmsg, sizeof(errmsg));
                 ^
  cc1: all warnings being treated as errors
  mv: cannot stat './.libbpf.o.tmp': No such file or directory
  /home6/tmricht/linux-next/tools/build/Makefile.build:96: recipe for target 'libbpf.o' failed

Replace all occurrences of strerror() by calls to strerror_r(). To
keep the compiler quiet also use the return value from strerror_r()
otherwise a 'variable set but not use' warning which is treated as
error terminates the compile.

Fixes: 531b014e ("tools: bpf: make use of reallocarray")
Suggested-by: default avatarJakub Kicinski <jakub.kicinski@netronome.com>
Suggested-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: default avatarThomas Richter <tmricht@linux.ibm.com>
Reviewed-by: default avatarHendrik Brueckner <brueckner@linux.ibm.com>
Reviewed-by: default avatarJakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
parent 2e96187b

tools/lib/bpf/libbpf.c

+29 −13
Original line number Diff line number Diff line
@@ -467,8 +467,10 @@ static int bpf_object__elf_init(struct bpf_object *obj) 
	} else {

		obj->efile.fd = open(obj->path, O_RDONLY);

		if (obj->efile.fd < 0) {

			pr_warning("failed to open %s: %s\n", obj->path,

					strerror(errno));

			char errmsg[STRERR_BUFSIZE];

			char *cp = strerror_r(errno, errmsg, sizeof(errmsg));



			pr_warning("failed to open %s: %s\n", obj->path, cp);

			return -errno;

		}
@@ -807,10 +809,11 @@ static int bpf_object__elf_collect(struct bpf_object *obj) 
						      data->d_size, name, idx);

			if (err) {

				char errmsg[STRERR_BUFSIZE];

				char *cp = strerror_r(-err, errmsg,

						      sizeof(errmsg));



				strerror_r(-err, errmsg, sizeof(errmsg));

				pr_warning("failed to alloc program %s (%s): %s",

					   name, obj->path, errmsg);

					   name, obj->path, cp);

			}

		} else if (sh.sh_type == SHT_REL) {

			void *reloc = obj->efile.reloc;
@@ -1104,6 +1107,7 @@ bpf_object__create_maps(struct bpf_object *obj) 
	for (i = 0; i < obj->nr_maps; i++) {

		struct bpf_map *map = &obj->maps[i];

		struct bpf_map_def *def = &map->def;

		char *cp, errmsg[STRERR_BUFSIZE];

		int *pfd = &map->fd;



		if (map->fd >= 0) {
@@ -1131,8 +1135,9 @@ bpf_object__create_maps(struct bpf_object *obj) 


		*pfd = bpf_create_map_xattr(&create_attr);

		if (*pfd < 0 && create_attr.btf_key_type_id) {

			cp = strerror_r(errno, errmsg, sizeof(errmsg));

			pr_warning("Error in bpf_create_map_xattr(%s):%s(%d). Retrying without BTF.\n",

				   map->name, strerror(errno), errno);

				   map->name, cp, errno);

			create_attr.btf_fd = 0;

			create_attr.btf_key_type_id = 0;

			create_attr.btf_value_type_id = 0;
@@ -1145,9 +1150,9 @@ bpf_object__create_maps(struct bpf_object *obj) 
			size_t j;



			err = *pfd;

			cp = strerror_r(errno, errmsg, sizeof(errmsg));

			pr_warning("failed to create map (name: '%s'): %s\n",

				   map->name,

				   strerror(errno));

				   map->name, cp);

			for (j = 0; j < i; j++)

				zclose(obj->maps[j].fd);

			return err;
@@ -1299,6 +1304,7 @@ load_program(enum bpf_prog_type type, enum bpf_attach_type expected_attach_type, 
	     char *license, u32 kern_version, int *pfd, int prog_ifindex)

{

	struct bpf_load_program_attr load_attr;

	char *cp, errmsg[STRERR_BUFSIZE];

	char *log_buf;

	int ret;
@@ -1328,7 +1334,8 @@ load_program(enum bpf_prog_type type, enum bpf_attach_type expected_attach_type, 
	}



	ret = -LIBBPF_ERRNO__LOAD;

	pr_warning("load bpf program failed: %s\n", strerror(errno));

	cp = strerror_r(errno, errmsg, sizeof(errmsg));

	pr_warning("load bpf program failed: %s\n", cp);



	if (log_buf && log_buf[0] != '\0') {

		ret = -LIBBPF_ERRNO__VERIFY;
@@ -1627,6 +1634,7 @@ int bpf_object__load(struct bpf_object *obj) 


static int check_path(const char *path)

{

	char *cp, errmsg[STRERR_BUFSIZE];

	struct statfs st_fs;

	char *dname, *dir;

	int err = 0;
@@ -1640,7 +1648,8 @@ static int check_path(const char *path) 


	dir = dirname(dname);

	if (statfs(dir, &st_fs)) {

		pr_warning("failed to statfs %s: %s\n", dir, strerror(errno));

		cp = strerror_r(errno, errmsg, sizeof(errmsg));

		pr_warning("failed to statfs %s: %s\n", dir, cp);

		err = -errno;

	}

	free(dname);
@@ -1656,6 +1665,7 @@ static int check_path(const char *path) 
int bpf_program__pin_instance(struct bpf_program *prog, const char *path,

			      int instance)

{

	char *cp, errmsg[STRERR_BUFSIZE];

	int err;



	err = check_path(path);
@@ -1674,7 +1684,8 @@ int bpf_program__pin_instance(struct bpf_program *prog, const char *path, 
	}



	if (bpf_obj_pin(prog->instances.fds[instance], path)) {

		pr_warning("failed to pin program: %s\n", strerror(errno));

		cp = strerror_r(errno, errmsg, sizeof(errmsg));

		pr_warning("failed to pin program: %s\n", cp);

		return -errno;

	}

	pr_debug("pinned program '%s'\n", path);
@@ -1684,13 +1695,16 @@ int bpf_program__pin_instance(struct bpf_program *prog, const char *path, 


static int make_dir(const char *path)

{

	char *cp, errmsg[STRERR_BUFSIZE];

	int err = 0;



	if (mkdir(path, 0700) && errno != EEXIST)

		err = -errno;



	if (err)

		pr_warning("failed to mkdir %s: %s\n", path, strerror(-err));

	if (err) {

		cp = strerror_r(-err, errmsg, sizeof(errmsg));

		pr_warning("failed to mkdir %s: %s\n", path, cp);

	}

	return err;

}
@@ -1737,6 +1751,7 @@ int bpf_program__pin(struct bpf_program *prog, const char *path) 


int bpf_map__pin(struct bpf_map *map, const char *path)

{

	char *cp, errmsg[STRERR_BUFSIZE];

	int err;



	err = check_path(path);
@@ -1749,7 +1764,8 @@ int bpf_map__pin(struct bpf_map *map, const char *path) 
	}



	if (bpf_obj_pin(map->fd, path)) {

		pr_warning("failed to pin map: %s\n", strerror(errno));

		cp = strerror_r(errno, errmsg, sizeof(errmsg));

		pr_warning("failed to pin map: %s\n", cp);

		return -errno;

	}