init: use '/system' as the system mount point for force_normal_boot

We need to keep the right mount points in the fstab for other
processes to access (/ for system-as-root or /system otherwise).
Force_normal_boot devices are defacto not system-as-root,
since they're booting through the recovery ramdisk and therefore must
use /system as the system mount point.

Bug: 114062208
Test: boot pixel from recovery with force_normal_boot
Change-Id: Ib0e4e4f8a29299ecdcd35e8f1415551c4c9745ad
diff --git a/init/first_stage_mount.cpp b/init/first_stage_mount.cpp
index 79cfbcb..a901131 100644
--- a/init/first_stage_mount.cpp
+++ b/init/first_stage_mount.cpp
@@ -120,14 +120,18 @@
     return is_android_dt_value_expected("vbmeta/compatible", "android,vbmeta");
 }
 
-static bool IsRecoveryMode() {
+static bool ForceNormalBoot() {
     static bool force_normal_boot = []() {
         std::string cmdline;
         android::base::ReadFileToString("/proc/cmdline", &cmdline);
         return cmdline.find("androidboot.force_normal_boot=1") != std::string::npos;
     }();
 
-    return !force_normal_boot && access("/system/bin/recovery", F_OK) == 0;
+    return force_normal_boot;
+}
+
+static bool IsRecoveryMode() {
+    return !ForceNormalBoot() && access("/system/bin/recovery", F_OK) == 0;
 }
 
 static inline bool IsDmLinearEnabled() {
@@ -368,11 +372,15 @@
     // this case, we mount system first then pivot to it.  From that point on,
     // we are effectively identical to a system-as-root device.
     auto system_partition =
-            std::find_if(mount_fstab_recs_.begin(), mount_fstab_recs_.end(), [](const auto& rec) {
-                return rec->mount_point == "/system"s ||
-                       rec->mount_point == "/system_recovery_mount"s;
-            });
+            std::find_if(mount_fstab_recs_.begin(), mount_fstab_recs_.end(),
+                         [](const auto& rec) { return rec->mount_point == "/system"s; });
+
     if (system_partition != mount_fstab_recs_.end()) {
+        if (ForceNormalBoot()) {
+            free((*system_partition)->mount_point);
+            (*system_partition)->mount_point = strdup("/system_recovery_mount");
+        }
+
         if (!MountPartition(*system_partition)) {
             return false;
         }