tools: libbpf: move library error code into a separate file

libbpf_strerror() depends on XSI-compliant (POSIX) version of
strerror_r(), which prevents us from using GNU-extensions in
libbpf.c, like reallocarray() or dup3().  Move error printing
code into a separate file to allow it to continue using POSIX
strerror_r().

No functional changes.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

3 files changed, 75 insertions, 49 deletions

diff --git a/tools/lib/bpf/Build b/tools/lib/bpf/Build
index 6070e655042d..13a861135127 100644
--- a/tools/lib/bpf/Build
+++ b/tools/lib/bpf/Build
@@ -1 +1 @@
-libbpf-y := libbpf.o bpf.o nlattr.o btf.o
+libbpf-y := libbpf.o bpf.o nlattr.o btf.o libbpf_errno.o
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 06cd534d2fba..f732237610e5 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -95,54 +95,6 @@ void libbpf_set_print(libbpf_print_fn_t warn,
 
 #define STRERR_BUFSIZE  128
 
-#define ERRNO_OFFSET(e)         ((e) - __LIBBPF_ERRNO__START)
-#define ERRCODE_OFFSET(c)       ERRNO_OFFSET(LIBBPF_ERRNO__##c)
-#define NR_ERRNO        (__LIBBPF_ERRNO__END - __LIBBPF_ERRNO__START)
-
-static const char *libbpf_strerror_table[NR_ERRNO] = {
-        [ERRCODE_OFFSET(LIBELF)]        = "Something wrong in libelf",
-        [ERRCODE_OFFSET(FORMAT)]        = "BPF object format invalid",
-        [ERRCODE_OFFSET(KVERSION)]      = "'version' section incorrect or lost",
-        [ERRCODE_OFFSET(ENDIAN)]        = "Endian mismatch",
-        [ERRCODE_OFFSET(INTERNAL)]      = "Internal error in libbpf",
-        [ERRCODE_OFFSET(RELOC)]         = "Relocation failed",
-        [ERRCODE_OFFSET(VERIFY)]        = "Kernel verifier blocks program loading",
-        [ERRCODE_OFFSET(PROG2BIG)]      = "Program too big",
-        [ERRCODE_OFFSET(KVER)]          = "Incorrect kernel version",
-        [ERRCODE_OFFSET(PROGTYPE)]      = "Kernel doesn't support this program type",
-        [ERRCODE_OFFSET(WRNGPID)]       = "Wrong pid in netlink message",
-        [ERRCODE_OFFSET(INVSEQ)]        = "Invalid netlink sequence",
-};
-
-int libbpf_strerror(int err, char *buf, size_t size)
-{
-        if (!buf || !size)
-                return -1;
-
-        err = err > 0 ? err : -err;
-
-        if (err < __LIBBPF_ERRNO__START) {
-                int ret;
-
-                ret = strerror_r(err, buf, size);
-                buf[size - 1] = '\0';
-                return ret;
-        }
-
-        if (err < __LIBBPF_ERRNO__END) {
-                const char *msg;
-
-                msg = libbpf_strerror_table[ERRNO_OFFSET(err)];
-                snprintf(buf, size, "%s", msg);
-                buf[size - 1] = '\0';
-                return 0;
-        }
-
-        snprintf(buf, size, "Unknown libbpf error %d", err);
-        buf[size - 1] = '\0';
-        return -1;
-}
-
 #define CHECK_ERR(action, err, out) do {        \
         err = action;                   \
         if (err)                        \
diff --git a/tools/lib/bpf/libbpf_errno.c b/tools/lib/bpf/libbpf_errno.c
new file mode 100644
index 000000000000..d9ba851bd7f9
--- /dev/null
+++ b/tools/lib/bpf/libbpf_errno.c
@@ -0,0 +1,74 @@
+// SPDX-License-Identifier: LGPL-2.1
+
+/*
+ * Copyright (C) 2013-2015 Alexei Starovoitov <ast@kernel.org>
+ * Copyright (C) 2015 Wang Nan <wangnan0@huawei.com>
+ * Copyright (C) 2015 Huawei Inc.
+ * Copyright (C) 2017 Nicira, Inc.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License (not later!)
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this program; if not,  see <http://www.gnu.org/licenses>
+ */
+
+#include <stdio.h>
+#include <string.h>
+
+#include "libbpf.h"
+
+#define ERRNO_OFFSET(e)         ((e) - __LIBBPF_ERRNO__START)
+#define ERRCODE_OFFSET(c)       ERRNO_OFFSET(LIBBPF_ERRNO__##c)
+#define NR_ERRNO        (__LIBBPF_ERRNO__END - __LIBBPF_ERRNO__START)
+
+static const char *libbpf_strerror_table[NR_ERRNO] = {
+        [ERRCODE_OFFSET(LIBELF)]        = "Something wrong in libelf",
+        [ERRCODE_OFFSET(FORMAT)]        = "BPF object format invalid",
+        [ERRCODE_OFFSET(KVERSION)]      = "'version' section incorrect or lost",
+        [ERRCODE_OFFSET(ENDIAN)]        = "Endian mismatch",
+        [ERRCODE_OFFSET(INTERNAL)]      = "Internal error in libbpf",
+        [ERRCODE_OFFSET(RELOC)]         = "Relocation failed",
+        [ERRCODE_OFFSET(VERIFY)]        = "Kernel verifier blocks program loading",
+        [ERRCODE_OFFSET(PROG2BIG)]      = "Program too big",
+        [ERRCODE_OFFSET(KVER)]          = "Incorrect kernel version",
+        [ERRCODE_OFFSET(PROGTYPE)]      = "Kernel doesn't support this program type",
+        [ERRCODE_OFFSET(WRNGPID)]       = "Wrong pid in netlink message",
+        [ERRCODE_OFFSET(INVSEQ)]        = "Invalid netlink sequence",
+};
+
+int libbpf_strerror(int err, char *buf, size_t size)
+{
+        if (!buf || !size)
+                return -1;
+
+        err = err > 0 ? err : -err;
+
+        if (err < __LIBBPF_ERRNO__START) {
+                int ret;
+
+                ret = strerror_r(err, buf, size);
+                buf[size - 1] = '\0';
+                return ret;
+        }
+
+        if (err < __LIBBPF_ERRNO__END) {
+                const char *msg;
+
+                msg = libbpf_strerror_table[ERRNO_OFFSET(err)];
+                snprintf(buf, size, "%s", msg);
+                buf[size - 1] = '\0';
+                return 0;
+        }
+
+        snprintf(buf, size, "Unknown libbpf error %d", err);
+        buf[size - 1] = '\0';
+        return -1;
+}