Merge branch 'libbpf-stringify-error-codes-in-log-messages'

Mykyta Yatsenko says:

====================
libbpf: stringify error codes in log messages

From: Mykyta Yatsenko <yatsenko@meta.com>

Libbpf may report error in 2 ways:
 1. Numeric errno
 2. Errno's text representation, returned by strerror
Both ways may be confusing for users: numeric code requires people to
know how to find its meaning and strerror may be too generic and
unclear.

These patches modify libbpf error reporting by swapping numeric codes
and strerror with the standard short error name, for example:
"failed to attach: -22" becomes "failed to attach: -EINVAL".
====================

Link: https://patch.msgid.link/20241111212919.368971-1-mykyta.yatsenko5@gmail.com
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>

1 files changed, 12 insertions, 9 deletions

diff --git a/tools/lib/bpf/linker.c b/tools/lib/bpf/linker.c
index f83c1c29982c..cf71d149fe26 100644
--- a/tools/lib/bpf/linker.c
+++ b/tools/lib/bpf/linker.c
@@ -20,6 +20,7 @@
 #include "btf.h"
 #include "libbpf_internal.h"
 #include "strset.h"
+#include "str_error.h"
 
 #define BTF_EXTERN_SEC ".extern"
 
@@ -306,7 +307,7 @@ static int init_output_elf(struct bpf_linker *linker, const char *file)
 	linker->fd = open(file, O_WRONLY | O_CREAT | O_TRUNC | O_CLOEXEC, 0644);
 	if (linker->fd < 0) {
 		err = -errno;
-		pr_warn("failed to create '%s': %d\n", file, err);
+		pr_warn("failed to create '%s': %s\n", file, errstr(err));
 		return err;
 	}
 
@@ -560,7 +561,7 @@ static int linker_load_obj_file(struct bpf_linker *linker, const char *filename,
 	obj->fd = open(filename, O_RDONLY | O_CLOEXEC);
 	if (obj->fd < 0) {
 		err = -errno;
-		pr_warn("failed to open file '%s': %d\n", filename, err);
+		pr_warn("failed to open file '%s': %s\n", filename, errstr(err));
 		return err;
 	}
 	obj->elf = elf_begin(obj->fd, ELF_C_READ_MMAP, NULL);
@@ -670,7 +671,8 @@ static int linker_load_obj_file(struct bpf_linker *linker, const char *filename,
 				obj->btf = btf__new(data->d_buf, shdr->sh_size);
 				err = libbpf_get_error(obj->btf);
 				if (err) {
-					pr_warn("failed to parse .BTF from %s: %d\n", filename, err);
+					pr_warn("failed to parse .BTF from %s: %s\n",
+						filename, errstr(err));
 					return err;
 				}
 				sec->skipped = true;
@@ -680,7 +682,8 @@ static int linker_load_obj_file(struct bpf_linker *linker, const char *filename,
 				obj->btf_ext = btf_ext__new(data->d_buf, shdr->sh_size);
 				err = libbpf_get_error(obj->btf_ext);
 				if (err) {
-					pr_warn("failed to parse .BTF.ext from '%s': %d\n", filename, err);
+					pr_warn("failed to parse .BTF.ext from '%s': %s\n",
+						filename, errstr(err));
 					return err;
 				}
 				sec->skipped = true;
@@ -2774,14 +2777,14 @@ static int finalize_btf(struct bpf_linker *linker)
 
 	err = finalize_btf_ext(linker);
 	if (err) {
-		pr_warn(".BTF.ext generation failed: %d\n", err);
+		pr_warn(".BTF.ext generation failed: %s\n", errstr(err));
 		return err;
 	}
 
 	opts.btf_ext = linker->btf_ext;
 	err = btf__dedup(linker->btf, &opts);
 	if (err) {
-		pr_warn("BTF dedup failed: %d\n", err);
+		pr_warn("BTF dedup failed: %s\n", errstr(err));
 		return err;
 	}
 
@@ -2799,7 +2802,7 @@ static int finalize_btf(struct bpf_linker *linker)
 
 	err = emit_elf_data_sec(linker, BTF_ELF_SEC, 8, raw_data, raw_sz);
 	if (err) {
-		pr_warn("failed to write out .BTF ELF section: %d\n", err);
+		pr_warn("failed to write out .BTF ELF section: %s\n", errstr(err));
 		return err;
 	}
 
@@ -2811,7 +2814,7 @@ static int finalize_btf(struct bpf_linker *linker)
 
 		err = emit_elf_data_sec(linker, BTF_EXT_ELF_SEC, 8, raw_data, raw_sz);
 		if (err) {
-			pr_warn("failed to write out .BTF.ext ELF section: %d\n", err);
+			pr_warn("failed to write out .BTF.ext ELF section: %s\n", errstr(err));
 			return err;
 		}
 	}
@@ -2987,7 +2990,7 @@ static int finalize_btf_ext(struct bpf_linker *linker)
 	err = libbpf_get_error(linker->btf_ext);
 	if (err) {
 		linker->btf_ext = NULL;
-		pr_warn("failed to parse final .BTF.ext data: %d\n", err);
+		pr_warn("failed to parse final .BTF.ext data: %s\n", errstr(err));
 		goto out;
 	}