From b8863f6a03868c6817e9fc08c79dff8a6f95ed0b Mon Sep 17 00:00:00 2001
From: Avichal Rakesh <arakesh@google.com>
Date: Thu, 12 Jan 2023 18:15:09 -0800
Subject: [PATCH] camera: Fix prefix length path for External Camera HAL

The default External Camera HAL accidentally used `sizeof` on a `char *`
to get the length of the string. This "worked" because the string in
question "/dev/" has length of 5, while on a 32-bit system `char *`
has a size of 4. This difference of 1 was handled a few lines later.

However on 64-bit system `sizeof(char *)` returns 8 which breaks the
logic later in code.

As `sizeof` was being used as a proxy for strlen, this CL converts the
uses C++'s std::char_traits::length to determine the string lengths
at compile time.

Bug: 265168485
Test: Manually tested that the calculated length is correct after the
      fix.
Change-Id: I92481a2bcb74fdbbb483ef552168debf07b2d68a
---
 .../default/ExternalCameraProviderImpl_2_4.cpp  | 17 +++++++++--------
 .../default/ExternalCameraProviderImpl_2_7.cpp  |  9 +++++----
 2 files changed, 14 insertions(+), 12 deletions(-)

diff --git a/camera/provider/2.4/default/ExternalCameraProviderImpl_2_4.cpp b/camera/provider/2.4/default/ExternalCameraProviderImpl_2_4.cpp
index 4fc743748a..04db7f33ee 100644
--- a/camera/provider/2.4/default/ExternalCameraProviderImpl_2_4.cpp
+++ b/camera/provider/2.4/default/ExternalCameraProviderImpl_2_4.cpp
@@ -18,15 +18,16 @@
 //#define LOG_NDEBUG 0
 #include <log/log.h>
 
-#include <regex>
-#include <sys/inotify.h>
+#include <cutils/properties.h>
 #include <errno.h>
 #include <linux/videodev2.h>
-#include <cutils/properties.h>
-#include "ExternalCameraProviderImpl_2_4.h"
+#include <sys/inotify.h>
+#include <regex>
+#include <string>
 #include "ExternalCameraDevice_3_4.h"
 #include "ExternalCameraDevice_3_5.h"
 #include "ExternalCameraDevice_3_6.h"
+#include "ExternalCameraProviderImpl_2_4.h"
 
 namespace android {
 namespace hardware {
@@ -41,10 +42,10 @@ namespace {
 // "device@<version>/external/<id>"
 const std::regex kDeviceNameRE("device@([0-9]+\\.[0-9]+)/external/(.+)");
 const int kMaxDevicePathLen = 256;
-const char* kDevicePath = "/dev/";
-constexpr char kPrefix[] = "video";
-constexpr int kPrefixLen = sizeof(kPrefix) - 1;
-constexpr int kDevicePrefixLen = sizeof(kDevicePath) + kPrefixLen + 1;
+constexpr const char* kDevicePath = "/dev/";
+constexpr const char* kPrefix = "video";
+constexpr int kPrefixLen = std::char_traits<char>::length(kPrefix);
+constexpr int kDevicePrefixLen = std::char_traits<char>::length(kDevicePath) + kPrefixLen;
 
 bool matchDeviceName(int cameraIdOffset,
                      const hidl_string& deviceName, std::string* deviceVersion,
diff --git a/camera/provider/2.7/default/ExternalCameraProviderImpl_2_7.cpp b/camera/provider/2.7/default/ExternalCameraProviderImpl_2_7.cpp
index b63e3bb88b..62ce074404 100644
--- a/camera/provider/2.7/default/ExternalCameraProviderImpl_2_7.cpp
+++ b/camera/provider/2.7/default/ExternalCameraProviderImpl_2_7.cpp
@@ -23,6 +23,7 @@
 #include <linux/videodev2.h>
 #include <sys/inotify.h>
 #include <regex>
+#include <string>
 #include "ExternalCameraDevice_3_4.h"
 #include "ExternalCameraDevice_3_5.h"
 #include "ExternalCameraDevice_3_6.h"
@@ -39,10 +40,10 @@ namespace {
 // "device@<version>/external/<id>"
 const std::regex kDeviceNameRE("device@([0-9]+\\.[0-9]+)/external/(.+)");
 const int kMaxDevicePathLen = 256;
-const char* kDevicePath = "/dev/";
-constexpr char kPrefix[] = "video";
-constexpr int kPrefixLen = sizeof(kPrefix) - 1;
-constexpr int kDevicePrefixLen = sizeof(kDevicePath) + kPrefixLen + 1;
+constexpr const char* kDevicePath = "/dev/";
+constexpr const char* kPrefix = "video";
+constexpr int kPrefixLen = std::char_traits<char>::length(kPrefix);
+constexpr int kDevicePrefixLen = std::char_traits<char>::length(kDevicePath) + kPrefixLen;
 
 bool matchDeviceName(int cameraIdOffset, const hidl_string& deviceName, std::string* deviceVersion,
                      std::string* cameraDevicePath) {