From 60593937ab46457c96f7a2e58184cbffbd79fb07 Mon Sep 17 00:00:00 2001
From: Pawan Wagh <waghpawan@google.com>
Date: Tue, 12 Nov 2024 08:44:37 +0000
Subject: Separate out ELF header reading function

Separate out ELF header reading code to be used for
alignment checks

Test: atest FileSystemUtilsTests
Bug: 371049373
Change-Id: I8179b8caa0d15d8fadb7b9f307b0d860df30b8b3
---
 .../com_android_internal_content_FileSystemUtils.cpp  | 19 +++++++++++--------
 .../com_android_internal_content_FileSystemUtils.h    | 10 ++++++++++
 2 files changed, 21 insertions(+), 8 deletions(-)

diff --git a/core/jni/com_android_internal_content_FileSystemUtils.cpp b/core/jni/com_android_internal_content_FileSystemUtils.cpp
index 6c72544a7958..76ead2a3ca31 100644
--- a/core/jni/com_android_internal_content_FileSystemUtils.cpp
+++ b/core/jni/com_android_internal_content_FileSystemUtils.cpp
@@ -22,7 +22,6 @@
 #include <android-base/hex.h>
 #include <android-base/unique_fd.h>
 #include <bionic/macros.h>
-#include <elf.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <inttypes.h>
@@ -204,7 +203,8 @@ bool punchHoles(const char *filePath, const uint64_t offset,
     return true;
 }
 
-bool punchHolesInElf64(const char *filePath, const uint64_t offset) {
+bool getLoadSegmentPhdrs(const char *filePath, const uint64_t offset,
+                         std::vector<Elf64_Phdr> &programHeaders) {
     // Open Elf file
     Elf64_Ehdr ehdr;
     std::ifstream inputStream(filePath, std::ifstream::in);
@@ -227,11 +227,6 @@ bool punchHolesInElf64(const char *filePath, const uint64_t offset) {
     uint64_t programHeaderOffset = ehdr.e_phoff;
     uint16_t programHeaderNum = ehdr.e_phnum;
 
-    IF_ALOGD() {
-        ALOGD("Punching holes in file: %s programHeaderOffset: %" PRIu64 " programHeaderNum: %hu",
-              filePath, programHeaderOffset, programHeaderNum);
-    }
-
     // if this is a zip file, also consider elf offset inside a file
     uint64_t phOffset;
     if (__builtin_add_overflow(offset, programHeaderOffset, &phOffset)) {
@@ -240,7 +235,6 @@ bool punchHolesInElf64(const char *filePath, const uint64_t offset) {
     }
     inputStream.seekg(phOffset);
 
-    std::vector<Elf64_Phdr> programHeaders;
     for (int headerIndex = 0; headerIndex < programHeaderNum; headerIndex++) {
         Elf64_Phdr header;
         inputStream.read((char *)&header, sizeof(header));
@@ -254,6 +248,15 @@ bool punchHolesInElf64(const char *filePath, const uint64_t offset) {
         programHeaders.push_back(header);
     }
 
+    return true;
+}
+
+bool punchHolesInElf64(const char *filePath, const uint64_t offset) {
+    std::vector<Elf64_Phdr> programHeaders;
+    if (!getLoadSegmentPhdrs(filePath, offset, programHeaders)) {
+        ALOGE("Failed to read program headers from ELF file.");
+        return false;
+    }
     return punchHoles(filePath, offset, programHeaders);
 }
 
diff --git a/core/jni/com_android_internal_content_FileSystemUtils.h b/core/jni/com_android_internal_content_FileSystemUtils.h
index 52445e2b4229..4a95686c5a0c 100644
--- a/core/jni/com_android_internal_content_FileSystemUtils.h
+++ b/core/jni/com_android_internal_content_FileSystemUtils.h
@@ -15,8 +15,11 @@
  */
 #pragma once
 
+#include <elf.h>
 #include <sys/types.h>
 
+#include <vector>
+
 namespace android {
 
 /*
@@ -35,4 +38,11 @@ bool punchHolesInElf64(const char* filePath, uint64_t offset);
  */
 bool punchHolesInZip(const char* filePath, uint64_t offset, uint16_t extraFieldLen);
 
+/*
+ * This function reads program headers from ELF file. ELF can be specified with file path directly
+ * or it should be at offset inside Apk. Program headers passed to function is populated.
+ */
+bool getLoadSegmentPhdrs(const char* filePath, const uint64_t offset,
+                         std::vector<Elf64_Phdr>& programHeaders);
+
 } // namespace android
\ No newline at end of file
-- 
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