libbpf: Remove any use of reallocarray() in libbpf

Re-implement glibc's reallocarray() for libbpf internal-only use.
reallocarray(), unfortunately, is not available in all versions of glibc, so
requires extra feature detection and using reallocarray() stub from
<tools/libc_compat.h> and COMPAT_NEED_REALLOCARRAY. All this complicates build
of libbpf unnecessarily and is just a maintenance burden. Instead, it's
trivial to implement libbpf-specific internal version and use it throughout
libbpf.

Which is what this patch does, along with converting some realloc() uses that
should really have been reallocarray() in the first place.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200819013607.3607269-2-andriin@fb.com

1 files changed, 10 insertions, 11 deletions

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 0276cf85d763..2653bcee73b7 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -44,7 +44,6 @@
 #include <sys/vfs.h>
 #include <sys/utsname.h>
 #include <sys/resource.h>
-#include <tools/libc_compat.h>
 #include <libelf.h>
 #include <gelf.h>
 #include <zlib.h>
@@ -567,7 +566,7 @@ bpf_object__add_program(struct bpf_object *obj, void *data, size_t size,
 	progs = obj->programs;
 	nr_progs = obj->nr_programs;
 
-	progs = reallocarray(progs, nr_progs + 1, sizeof(progs[0]));
+	progs = libbpf_reallocarray(progs, nr_progs + 1, sizeof(progs[0]));
 	if (!progs) {
 		/*
 		 * In this case the original obj->programs
@@ -1292,7 +1291,7 @@ static struct bpf_map *bpf_object__add_map(struct bpf_object *obj)
 		return &obj->maps[obj->nr_maps++];
 
 	new_cap = max((size_t)4, obj->maps_cap * 3 / 2);
-	new_maps = realloc(obj->maps, new_cap * sizeof(*obj->maps));
+	new_maps = libbpf_reallocarray(obj->maps, new_cap, sizeof(*obj->maps));
 	if (!new_maps) {
 		pr_warn("alloc maps for object failed\n");
 		return ERR_PTR(-ENOMEM);
@@ -2721,8 +2720,8 @@ static int bpf_object__elf_collect(struct bpf_object *obj)
 				continue;
 			}
 
-			sects = reallocarray(sects, nr_sects + 1,
-					     sizeof(*obj->efile.reloc_sects));
+			sects = libbpf_reallocarray(sects, nr_sects + 1,
+						    sizeof(*obj->efile.reloc_sects));
 			if (!sects) {
 				pr_warn("reloc_sects realloc failed\n");
 				return -ENOMEM;
@@ -2925,7 +2924,7 @@ static int bpf_object__collect_externs(struct bpf_object *obj)
 			continue;
 
 		ext = obj->externs;
-		ext = reallocarray(ext, obj->nr_extern + 1, sizeof(*ext));
+		ext = libbpf_reallocarray(ext, obj->nr_extern + 1, sizeof(*ext));
 		if (!ext)
 			return -ENOMEM;
 		obj->externs = ext;
@@ -4362,9 +4361,9 @@ static struct ids_vec *bpf_core_find_cands(const struct btf *local_btf,
 			pr_debug("CO-RE relocating [%d] %s %s: found target candidate [%d] %s %s\n",
 				 local_type_id, btf_kind_str(local_t),
 				 local_name, i, targ_kind, targ_name);
-			new_ids = reallocarray(cand_ids->data,
-					       cand_ids->len + 1,
-					       sizeof(*cand_ids->data));
+			new_ids = libbpf_reallocarray(cand_ids->data,
+						      cand_ids->len + 1,
+						      sizeof(*cand_ids->data));
 			if (!new_ids) {
 				err = -ENOMEM;
 				goto err_out;
@@ -5231,7 +5230,7 @@ bpf_program__reloc_text(struct bpf_program *prog, struct bpf_object *obj,
 			return -LIBBPF_ERRNO__RELOC;
 		}
 		new_cnt = prog->insns_cnt + text->insns_cnt;
-		new_insn = reallocarray(prog->insns, new_cnt, sizeof(*insn));
+		new_insn = libbpf_reallocarray(prog->insns, new_cnt, sizeof(*insn));
 		if (!new_insn) {
 			pr_warn("oom in prog realloc\n");
 			return -ENOMEM;
@@ -5473,7 +5472,7 @@ static int bpf_object__collect_map_relos(struct bpf_object *obj,
 		moff /= bpf_ptr_sz;
 		if (moff >= map->init_slots_sz) {
 			new_sz = moff + 1;
-			tmp = realloc(map->init_slots, new_sz * host_ptr_sz);
+			tmp = libbpf_reallocarray(map->init_slots, new_sz, host_ptr_sz);
 			if (!tmp)
 				return -ENOMEM;
 			map->init_slots = tmp;