Move some small users of fstab to new C++ Fstab

Bug: 62292478
Test: tree-hugger
Change-Id: Ie2cc10e5168ef3b9dcc42f88e67a1ccd1175fcc5
diff --git a/bootloader_message/bootloader_message.cpp b/bootloader_message/bootloader_message.cpp
index aaeffdc..b933cbf 100644
--- a/bootloader_message/bootloader_message.cpp
+++ b/bootloader_message/bootloader_message.cpp
@@ -27,21 +27,22 @@
 #include <android-base/properties.h>
 #include <android-base/stringprintf.h>
 #include <android-base/unique_fd.h>
-#include <fs_mgr.h>
+#include <fstab/fstab.h>
 
 static std::string get_misc_blk_device(std::string* err) {
-  std::unique_ptr<fstab, decltype(&fs_mgr_free_fstab)> fstab(fs_mgr_read_fstab_default(),
-                                                             fs_mgr_free_fstab);
-  if (!fstab) {
+  Fstab fstab;
+  if (!ReadDefaultFstab(&fstab)) {
     *err = "failed to read default fstab";
     return "";
   }
-  fstab_rec* record = fs_mgr_get_entry_for_mount_point(fstab.get(), "/misc");
-  if (record == nullptr) {
-    *err = "failed to find /misc partition";
-    return "";
+  for (const auto& entry : fstab) {
+    if (entry.mount_point == "/misc") {
+      return entry.blk_device;
+    }
   }
-  return record->blk_device;
+
+  *err = "failed to find /misc partition";
+  return "";
 }
 
 // In recovery mode, recovery can get started and try to access the misc
diff --git a/uncrypt/uncrypt.cpp b/uncrypt/uncrypt.cpp
index d1970e5..4244af2 100644
--- a/uncrypt/uncrypt.cpp
+++ b/uncrypt/uncrypt.cpp
@@ -115,6 +115,7 @@
 #include <cutils/android_reboot.h>
 #include <cutils/sockets.h>
 #include <fs_mgr.h>
+#include <fstab/fstab.h>
 
 #include "otautil/error_code.h"
 
@@ -136,7 +137,7 @@
 static const std::string UNCRYPT_STATUS = "/cache/recovery/uncrypt_status";
 static const std::string UNCRYPT_SOCKET = "uncrypt";
 
-static struct fstab* fstab = nullptr;
+static Fstab fstab;
 
 static int write_at_offset(unsigned char* buffer, size_t size, int wfd, off64_t offset) {
     if (TEMP_FAILURE_RETRY(lseek64(wfd, offset, SEEK_SET)) == -1) {
@@ -162,18 +163,8 @@
     }
 }
 
-static struct fstab* read_fstab() {
-    fstab = fs_mgr_read_fstab_default();
-    if (!fstab) {
-        LOG(ERROR) << "failed to read default fstab";
-        return NULL;
-    }
-
-    return fstab;
-}
-
-static const char* find_block_device(const char* path, bool* encryptable,
-                                     bool* encrypted, bool* f2fs_fs) {
+static std::string find_block_device(const char* path, bool* encryptable, bool* encrypted,
+                                     bool* f2fs_fs) {
     // Look for a volume whose mount point is the prefix of path and
     // return its block device.  Set encrypted if it's currently
     // encrypted.
@@ -181,30 +172,29 @@
     // ensure f2fs_fs is set to false first.
     *f2fs_fs = false;
 
-    for (int i = 0; i < fstab->num_entries; ++i) {
-        struct fstab_rec* v = &fstab->recs[i];
-        if (!v->mount_point) {
+    for (const auto& entry : fstab) {
+        if (entry.mount_point.empty()) {
             continue;
         }
-        int len = strlen(v->mount_point);
-        if (strncmp(path, v->mount_point, len) == 0 &&
+        auto len = entry.mount_point.size();
+        if (android::base::StartsWith(path, entry.mount_point) &&
             (path[len] == '/' || path[len] == 0)) {
             *encrypted = false;
             *encryptable = false;
-            if (fs_mgr_is_encryptable(v) || fs_mgr_is_file_encrypted(v)) {
+            if (entry.is_encryptable() || entry.fs_mgr_flags.file_encryption) {
                 *encryptable = true;
                 if (android::base::GetProperty("ro.crypto.state", "") == "encrypted") {
                     *encrypted = true;
                 }
             }
-            if (strcmp(v->fs_type, "f2fs") == 0) {
+            if (entry.fs_type == "f2fs") {
                 *f2fs_fs = true;
             }
-            return v->blk_device;
+            return entry.blk_device;
         }
     }
 
-    return NULL;
+    return "";
 }
 
 static bool write_status_to_socket(int status, int socket) {
@@ -493,8 +483,8 @@
     bool encryptable;
     bool encrypted;
     bool f2fs_fs;
-    const char* blk_dev = find_block_device(path, &encryptable, &encrypted, &f2fs_fs);
-    if (blk_dev == nullptr) {
+    const std::string blk_dev = find_block_device(path, &encryptable, &encrypted, &f2fs_fs);
+    if (blk_dev.empty()) {
         LOG(ERROR) << "failed to find block device for " << path;
         return kUncryptBlockDeviceFindError;
     }
@@ -514,7 +504,7 @@
     // and /sdcard we leave the file alone.
     if (strncmp(path, "/data/", 6) == 0) {
         LOG(INFO) << "writing block map " << map_file;
-        return produce_block_map(path, map_file, blk_dev, encrypted, f2fs_fs, socket);
+        return produce_block_map(path, map_file, blk_dev.c_str(), encrypted, f2fs_fs, socket);
     }
 
     return 0;
@@ -654,7 +644,8 @@
         return 2;
     }
 
-    if ((fstab = read_fstab()) == nullptr) {
+    if (!ReadDefaultFstab(&fstab)) {
+        LOG(ERROR) << "failed to read default fstab";
         log_uncrypt_error_code(kUncryptFstabReadError);
         return 1;
     }