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

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Commit 531b014e7a ("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: 531b014e7a ("tools: bpf: make use of reallocarray")
Suggested-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Suggested-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Reviewed-by: Hendrik Brueckner <brueckner@linux.ibm.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This commit is contained in:
Thomas Richter 2018-07-30 10:53:23 +02:00 committed by Daniel Borkmann
parent 2e96187b69
commit 1ce6a9fc15
1 changed files with 29 additions and 13 deletions
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42
tools/lib/bpf/libbpf.c
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@ -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 @@ out:
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;
}