From e2f3878a252af4d819ae33c0a9e77ab552f7a1a9 Mon Sep 17 00:00:00 2001
From: Michael Tremer <michael.tremer@ipfire.org>
Date: Wed, 1 Jan 2025 16:54:22 +0000
Subject: [PATCH] ELF: Add function to read the Build ID

Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>
---
 src/libpakfire/elf.c                 | 33 ++++++++++++++++++++++++++++
 src/libpakfire/include/pakfire/elf.h |  1 +
 2 files changed, 34 insertions(+)

diff --git a/src/libpakfire/elf.c b/src/libpakfire/elf.c
index 7db5e2792..5e59f74fe 100644
--- a/src/libpakfire/elf.c
+++ b/src/libpakfire/elf.c
@@ -24,6 +24,8 @@
 #include <pakfire/ctx.h>
 #include <pakfire/elf.h>
 #include <pakfire/file.h>
+#include <pakfire/hex.h>
+#include <pakfire/logging.h>
 #include <pakfire/string.h>
 
 // libelf
@@ -45,6 +47,9 @@ struct pakfire_elf {
 
 	// ELF Header
 	GElf_Ehdr ehdr;
+
+	// GNU Build ID
+	char* build_id;
 };
 
 static int pakfire_elf_init_libelf(struct pakfire_ctx* ctx) {
@@ -94,6 +99,8 @@ static int pakfire_elf_open_elf(struct pakfire_elf* self) {
 }
 
 static void pakfire_elf_free(struct pakfire_elf* self) {
+	if (self->build_id)
+		free(self->build_id);
 	if (self->elf)
 		elf_end(self->elf);
 	if (self->fd >= 0)
@@ -199,3 +206,29 @@ const char* pakfire_elf_path(struct pakfire_elf* self) {
 int pakfire_elf_type(struct pakfire_elf* self) {
 	return self->ehdr.e_type;
 }
+
+const char* pakfire_elf_build_id(struct pakfire_elf* self) {
+	const void* buffer = NULL;
+	ssize_t length;
+
+	if (!self->build_id) {
+		// Extract the GNU Build ID
+		length = dwelf_elf_gnu_build_id(self->elf, &buffer);
+		if (length < 0) {
+			ERROR(self->ctx, "Could not read the GNU Build ID from %s: %s\n",
+				self->path, elf_errmsg(-1));
+			return NULL;
+		}
+
+		// Convert the Build ID to hex
+		self->build_id = __pakfire_hexlify(buffer, length);
+		if (!self->build_id) {
+			ERROR(self->ctx, "Could not convert the Build ID into hex format: %m\n");
+			return NULL;
+		}
+
+		DEBUG(self->ctx, "%s has Build ID %s\n", self->path, self->build_id);
+	}
+
+	return self->build_id;
+}
diff --git a/src/libpakfire/include/pakfire/elf.h b/src/libpakfire/include/pakfire/elf.h
index fbfcf3091..a5038030a 100644
--- a/src/libpakfire/include/pakfire/elf.h
+++ b/src/libpakfire/include/pakfire/elf.h
@@ -39,6 +39,7 @@ struct pakfire_elf* pakfire_elf_unref(struct pakfire_elf* self);
 
 const char* pakfire_elf_path(struct pakfire_elf* self);
 int pakfire_elf_type(struct pakfire_elf* self);
+const char* pakfire_elf_build_id(struct pakfire_elf* self);
 
 #endif /* PAKFIRE_PRIVATE */
 
-- 
2.47.3