From a0fb3098ccbc2d19db0d839086137f8fe3868bfd Mon Sep 17 00:00:00 2001
From: Emil Velikov <emil.l.velikov@gmail.com>
Date: Wed, 7 May 2025 18:58:11 +0100
Subject: [PATCH] libkmod: return the errno from kmod_elf_new()

Rework the function signature and return the error code instead of the
stripped module. Thus we no longer explicitly set errno.

Reference: https://github.com/kmod-project/kmod/issues/244
Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>
Link: https://github.com/kmod-project/kmod/pull/346
Signed-off-by: Lucas De Marchi <lucas.de.marchi@gmail.com>
---
 libkmod/libkmod-elf.c      | 16 +++++++---------
 libkmod/libkmod-file.c     |  6 +++++-
 libkmod/libkmod-internal.h |  2 +-
 testsuite/init_module.c    |  6 ++++--
 4 files changed, 17 insertions(+), 13 deletions(-)

diff --git a/libkmod/libkmod-elf.c b/libkmod/libkmod-elf.c
index 9b2ceca7..0fc95348 100644
--- a/libkmod/libkmod-elf.c
+++ b/libkmod/libkmod-elf.c
@@ -305,7 +305,7 @@ static void kmod_elf_save_sections(struct kmod_elf *elf)
 	}
 }
 
-struct kmod_elf *kmod_elf_new(const void *memory, off_t size)
+int kmod_elf_new(const void *memory, off_t size, struct kmod_elf **out_elf)
 {
 	struct kmod_elf *elf;
 	size_t shdrs_size, shdr_size;
@@ -318,15 +318,13 @@ struct kmod_elf *kmod_elf_new(const void *memory, off_t size)
 	assert_cc(sizeof(uint32_t) == sizeof(Elf64_Word));
 
 	elf = malloc(sizeof(struct kmod_elf));
-	if (elf == NULL) {
-		return NULL;
-	}
+	if (elf == NULL)
+		return -ENOMEM;
 
 	err = elf_identify(elf, memory, size);
 	if (err < 0) {
 		free(elf);
-		errno = -err;
-		return NULL;
+		return err;
 	}
 
 	elf->memory = memory;
@@ -388,12 +386,12 @@ struct kmod_elf *kmod_elf_new(const void *memory, off_t size)
 	}
 
 	kmod_elf_save_sections(elf);
-	return elf;
+	*out_elf = elf;
+	return 0;
 
 invalid:
 	free(elf);
-	errno = EINVAL;
-	return NULL;
+	return -EINVAL;
 }
 
 void kmod_elf_unref(struct kmod_elf *elf)
diff --git a/libkmod/libkmod-file.c b/libkmod/libkmod-file.c
index 0eeb00a4..23057fa6 100644
--- a/libkmod/libkmod-file.c
+++ b/libkmod/libkmod-file.c
@@ -71,7 +71,11 @@ struct kmod_elf *kmod_file_get_elf(struct kmod_file *file)
 		return NULL;
 	}
 
-	file->elf = kmod_elf_new(file->memory, file->size);
+	err = kmod_elf_new(file->memory, file->size, &file->elf);
+	if (err) {
+		errno = -err;
+		return NULL;
+	}
 	return file->elf;
 }
 
diff --git a/libkmod/libkmod-internal.h b/libkmod/libkmod-internal.h
index be26e0d2..17e6e5f5 100644
--- a/libkmod/libkmod-internal.h
+++ b/libkmod/libkmod-internal.h
@@ -152,7 +152,7 @@ struct kmod_modversion {
 	const char *symbol;
 };
 
-_nonnull_all_ struct kmod_elf *kmod_elf_new(const void *memory, off_t size);
+_must_check_ _nonnull_all_ int kmod_elf_new(const void *memory, off_t size, struct kmod_elf **elf);
 _nonnull_all_ void kmod_elf_unref(struct kmod_elf *elf);
 _must_check_ _nonnull_all_ const void *kmod_elf_get_memory(const struct kmod_elf *elf);
 _must_check_ _nonnull_all_ int kmod_elf_get_modinfo_strings(const struct kmod_elf *elf, char ***array);
diff --git a/testsuite/init_module.c b/testsuite/init_module.c
index ccb43b0c..35630d89 100644
--- a/testsuite/init_module.c
+++ b/testsuite/init_module.c
@@ -239,9 +239,11 @@ long init_module(void *mem, unsigned long len, const char *args)
 		return -1;
 	}
 
-	elf = kmod_elf_new(mem, len);
-	if (elf == NULL)
+	err = kmod_elf_new(mem, len, &elf);
+	if (err < 0) {
+		errno = -err;
 		return -1;
+	}
 
 	err = kmod_elf_get_section(elf, ".gnu.linkonce.this_module", &off, &bufsize);
 	buf = (const char *)kmod_elf_get_memory(elf) + off;
-- 
2.47.2