9 files changed, 102 insertions, 249 deletions

diff --git a/fsck_unshare_blocks.cpp b/fsck_unshare_blocks.cpp
index acc453cd7..ce6940a6b 100644
--- a/fsck_unshare_blocks.cpp
+++ b/fsck_unshare_blocks.cpp
@@ -121,7 +121,7 @@ bool do_fsck_unshare_blocks() {
 
   // Temporarily mount system so we can copy e2fsck_static.
   std::string system_root = get_system_root();
-  bool mounted = ensure_path_mounted_at(system_root.c_str(), "/mnt/system") != -1;
+  bool mounted = ensure_path_mounted_at(system_root, "/mnt/system") != -1;
   partitions.push_back(system_root);
 
   if (!mounted) {
diff --git a/install.cpp b/install.cpp
index 680937dd1..9d8943f7d 100644
--- a/install.cpp
+++ b/install.cpp
@@ -395,12 +395,8 @@ static int try_update_binary(const std::string& package, ZipArchiveHandle zip, b
   //   update attempt.
   //
 
-  // Convert the vector to a NULL-terminated char* array suitable for execv.
-  const char* chr_args[args.size() + 1];
-  chr_args[args.size()] = nullptr;
-  for (size_t i = 0; i < args.size(); i++) {
-    chr_args[i] = args[i].c_str();
-  }
+  // Convert the std::string vector to a NULL-terminated char* vector suitable for execv.
+  auto chr_args = StringVectorToNullTerminatedArray(args);
 
   pid_t pid = fork();
 
@@ -415,7 +411,7 @@ static int try_update_binary(const std::string& package, ZipArchiveHandle zip, b
   if (pid == 0) {
     umask(022);
     close(pipefd[0]);
-    execv(chr_args[0], const_cast<char**>(chr_args));
+    execv(chr_args[0], chr_args.data());
     // Bug: 34769056
     // We shouldn't use LOG/PLOG in the forked process, since they may cause
     // the child process to hang. This deadlock results from an improperly
@@ -595,9 +591,9 @@ static int really_install_package(const std::string& path, bool* wipe_cache, boo
 
   if (needs_mount) {
     if (path[0] == '@') {
-      ensure_path_mounted(path.substr(1).c_str());
+      ensure_path_mounted(path.substr(1));
     } else {
-      ensure_path_mounted(path.c_str());
+      ensure_path_mounted(path);
     }
   }
 
diff --git a/logging.cpp b/logging.cpp
index 50642a26b..283d11507 100644
--- a/logging.cpp
+++ b/logging.cpp
@@ -46,7 +46,7 @@ static const std::string LAST_LOG_FILTER = "recovery/last_log";
 // fopen(3)'s the given file, by mounting volumes and making parent dirs as necessary. Returns the
 // file pointer, or nullptr on error.
 static FILE* fopen_path(const std::string& path, const char* mode) {
-  if (ensure_path_mounted(path.c_str()) != 0) {
+  if (ensure_path_mounted(path) != 0) {
     LOG(ERROR) << "Can't mount " << path;
     return nullptr;
   }
diff --git a/recovery.cpp b/recovery.cpp
index de916c633..703923e81 100644
--- a/recovery.cpp
+++ b/recovery.cpp
@@ -294,7 +294,7 @@ bool SetUsbConfig(const std::string& state) {
 
 // Returns the selected filename, or an empty string.
 static std::string browse_directory(const std::string& path, Device* device) {
-  ensure_path_mounted(path.c_str());
+  ensure_path_mounted(path);
 
   std::unique_ptr<DIR, decltype(&closedir)> d(opendir(path.c_str()), closedir);
   if (!d) {
@@ -578,7 +578,7 @@ static void choose_recovery_file(Device* device) {
           log_file += "." + std::to_string(i);
         }
 
-        if (ensure_path_mounted(log_file.c_str()) == 0 && access(log_file.c_str(), R_OK) == 0) {
+        if (ensure_path_mounted(log_file) == 0 && access(log_file.c_str(), R_OK) == 0) {
           entries.push_back(std::move(log_file));
         }
       };
@@ -842,7 +842,7 @@ static Device::BuiltinAction prompt_and_wait(Device* device, int status) {
       }
       case Device::MOUNT_SYSTEM:
         // the system partition is mounted at /mnt/system
-        if (ensure_path_mounted_at(get_system_root().c_str(), "/mnt/system") != -1) {
+        if (ensure_path_mounted_at(get_system_root(), "/mnt/system") != -1) {
           ui->Print("Mounted /system.\n");
         }
         break;
diff --git a/roots.cpp b/roots.cpp
index 7dc4ec3d9..6db0ca519 100644
--- a/roots.cpp
+++ b/roots.cpp
@@ -28,7 +28,7 @@
 #include <sys/wait.h>
 #include <unistd.h>
 
-#include <algorithm>
+#include <iostream>
 #include <string>
 #include <vector>
 
@@ -39,177 +39,59 @@
 #include <cryptfs.h>
 #include <ext4_utils/wipe.h>
 #include <fs_mgr.h>
+#include <fs_mgr/roots.h>
 #include <fs_mgr_dm_linear.h>
 
 #include "otautil/mounts.h"
+#include "otautil/sysutil.h"
 
-static struct fstab* fstab = nullptr;
-static bool did_map_logical_partitions = false;
-static constexpr const char* SYSTEM_ROOT = "/system";
+static Fstab fstab;
 
 extern struct selabel_handle* sehandle;
 
 void load_volume_table() {
-  fstab = fs_mgr_read_fstab_default();
-  if (!fstab) {
+  if (!ReadDefaultFstab(&fstab)) {
     LOG(ERROR) << "Failed to read default fstab";
     return;
   }
 
-  int ret = fs_mgr_add_entry(fstab, "/tmp", "ramdisk", "ramdisk");
-  if (ret == -1) {
-    LOG(ERROR) << "Failed to add /tmp entry to fstab";
-    fs_mgr_free_fstab(fstab);
-    fstab = nullptr;
-    return;
-  }
+  fstab.emplace_back(FstabEntry{
+      .mount_point = "/tmp", .fs_type = "ramdisk", .blk_device = "ramdisk", .length = 0 });
 
-  printf("recovery filesystem table\n");
-  printf("=========================\n");
-  for (int i = 0; i < fstab->num_entries; ++i) {
-    const Volume* v = &fstab->recs[i];
-    printf("  %d %s %s %s %" PRId64 "\n", i, v->mount_point, v->fs_type, v->blk_device, v->length);
+  std::cout << "recovery filesystem table" << std::endl << "=========================" << std::endl;
+  for (size_t i = 0; i < fstab.size(); ++i) {
+    const auto& entry = fstab[i];
+    std::cout << "  " << i << " " << entry.mount_point << " "
+              << " " << entry.fs_type << " " << entry.blk_device << " " << entry.length
+              << std::endl;
   }
-  printf("\n");
+  std::cout << std::endl;
 }
 
 Volume* volume_for_mount_point(const std::string& mount_point) {
-  return fs_mgr_get_entry_for_mount_point(fstab, mount_point);
-}
-
-// Finds the volume specified by the given path. fs_mgr_get_entry_for_mount_point() does exact match
-// only, so it attempts the prefixes recursively (e.g. "/cache/recovery/last_log",
-// "/cache/recovery", "/cache", "/" for a given path of "/cache/recovery/last_log") and returns the
-// first match or nullptr.
-static Volume* volume_for_path(const char* path) {
-  if (path == nullptr || path[0] == '\0') return nullptr;
-  std::string str(path);
-  while (true) {
-    Volume* result = fs_mgr_get_entry_for_mount_point(fstab, str);
-    if (result != nullptr || str == "/") {
-      return result;
-    }
-    size_t slash = str.find_last_of('/');
-    if (slash == std::string::npos) return nullptr;
-    if (slash == 0) {
-      str = "/";
-    } else {
-      str = str.substr(0, slash);
-    }
-  }
-  return nullptr;
+  auto it = std::find_if(fstab.begin(), fstab.end(), [&mount_point](const auto& entry) {
+    return entry.mount_point == mount_point;
+  });
+  return it == fstab.end() ? nullptr : &*it;
 }
 
 // Mount the volume specified by path at the given mount_point.
-int ensure_path_mounted_at(const char* path, const char* mount_point) {
-  Volume* v = volume_for_path(path);
-  if (v == nullptr) {
-    LOG(ERROR) << "unknown volume for path [" << path << "]";
-    return -1;
-  }
-  if (strcmp(v->fs_type, "ramdisk") == 0) {
-    // The ramdisk is always mounted.
-    return 0;
-  }
-
-  if (!scan_mounted_volumes()) {
-    LOG(ERROR) << "Failed to scan mounted volumes";
-    return -1;
-  }
-
-  if (!mount_point) {
-    mount_point = v->mount_point;
-  }
-
-  // If we can't acquire the block device for a logical partition, it likely
-  // was never created. In that case we try to create it.
-  if (fs_mgr_is_logical(v) && !fs_mgr_update_logical_partition(v)) {
-    if (did_map_logical_partitions) {
-      LOG(ERROR) << "Failed to find block device for partition";
-      return -1;
-    }
-    std::string super_name = fs_mgr_get_super_partition_name();
-    if (!android::fs_mgr::CreateLogicalPartitions(super_name)) {
-      LOG(ERROR) << "Failed to create logical partitions";
-      return -1;
-    }
-    did_map_logical_partitions = true;
-    if (!fs_mgr_update_logical_partition(v)) {
-      LOG(ERROR) << "Failed to find block device for partition";
-      return -1;
-    }
-  }
-
-  const MountedVolume* mv = find_mounted_volume_by_mount_point(mount_point);
-  if (mv != nullptr) {
-    // Volume is already mounted.
-    return 0;
-  }
-
-  mkdir(mount_point, 0755);  // in case it doesn't already exist
-
-  if (strcmp(v->fs_type, "ext4") == 0 || strcmp(v->fs_type, "squashfs") == 0 ||
-      strcmp(v->fs_type, "vfat") == 0 || strcmp(v->fs_type, "f2fs") == 0) {
-    int result = mount(v->blk_device, mount_point, v->fs_type, v->flags, v->fs_options);
-    if (result == -1 && fs_mgr_is_formattable(v)) {
-      PLOG(ERROR) << "Failed to mount " << mount_point << "; formatting";
-      bool crypt_footer = fs_mgr_is_encryptable(v) && !strcmp(v->key_loc, "footer");
-      if (fs_mgr_do_format(v, crypt_footer) == 0) {
-        result = mount(v->blk_device, mount_point, v->fs_type, v->flags, v->fs_options);
-      } else {
-        PLOG(ERROR) << "Failed to format " << mount_point;
-        return -1;
-      }
-    }
-
-    if (result == -1) {
-      PLOG(ERROR) << "Failed to mount " << mount_point;
-      return -1;
-    }
-    return 0;
-  }
-
-  LOG(ERROR) << "unknown fs_type \"" << v->fs_type << "\" for " << mount_point;
-  return -1;
+int ensure_path_mounted_at(const std::string& path, const std::string& mount_point) {
+  return android::fs_mgr::EnsurePathMounted(&fstab, path, mount_point) ? 0 : -1;
 }
 
-int ensure_path_mounted(const char* path) {
+int ensure_path_mounted(const std::string& path) {
   // Mount at the default mount point.
-  return ensure_path_mounted_at(path, nullptr);
+  return android::fs_mgr::EnsurePathMounted(&fstab, path) ? 0 : -1;
 }
 
-int ensure_path_unmounted(const char* path) {
-  const Volume* v = volume_for_path(path);
-  if (v == nullptr) {
-    LOG(ERROR) << "unknown volume for path [" << path << "]";
-    return -1;
-  }
-  if (strcmp(v->fs_type, "ramdisk") == 0) {
-    // The ramdisk is always mounted; you can't unmount it.
-    return -1;
-  }
-
-  if (!scan_mounted_volumes()) {
-    LOG(ERROR) << "Failed to scan mounted volumes";
-    return -1;
-  }
-
-  MountedVolume* mv = find_mounted_volume_by_mount_point(v->mount_point);
-  if (mv == nullptr) {
-    // Volume is already unmounted.
-    return 0;
-  }
-
-  return unmount_mounted_volume(mv);
+int ensure_path_unmounted(const std::string& path) {
+  return android::fs_mgr::EnsurePathUnmounted(&fstab, path) ? 0 : -1;
 }
 
 static int exec_cmd(const std::vector<std::string>& args) {
-  CHECK_NE(static_cast<size_t>(0), args.size());
-
-  std::vector<char*> argv(args.size());
-  std::transform(args.cbegin(), args.cend(), argv.begin(),
-                 [](const std::string& arg) { return const_cast<char*>(arg.c_str()); });
-  argv.push_back(nullptr);
+  CHECK(!args.empty());
+  auto argv = StringVectorToNullTerminatedArray(args);
 
   pid_t child;
   if ((child = fork()) == 0) {
@@ -248,17 +130,17 @@ static int64_t get_file_size(int fd, uint64_t reserve_len) {
   return computed_size;
 }
 
-int format_volume(const char* volume, const char* directory) {
-  const Volume* v = volume_for_path(volume);
+int format_volume(const std::string& volume, const std::string& directory) {
+  const FstabEntry* v = android::fs_mgr::GetEntryForPath(&fstab, volume);
   if (v == nullptr) {
     LOG(ERROR) << "unknown volume \"" << volume << "\"";
     return -1;
   }
-  if (strcmp(v->fs_type, "ramdisk") == 0) {
+  if (v->fs_type == "ramdisk") {
     LOG(ERROR) << "can't format_volume \"" << volume << "\"";
     return -1;
   }
-  if (strcmp(v->mount_point, volume) != 0) {
+  if (v->mount_point != volume) {
     LOG(ERROR) << "can't give path \"" << volume << "\" to format_volume";
     return -1;
   }
@@ -266,16 +148,16 @@ int format_volume(const char* volume, const char* directory) {
     LOG(ERROR) << "format_volume: Failed to unmount \"" << v->mount_point << "\"";
     return -1;
   }
-  if (strcmp(v->fs_type, "ext4") != 0 && strcmp(v->fs_type, "f2fs") != 0) {
+  if (v->fs_type != "ext4" && v->fs_type != "f2fs") {
     LOG(ERROR) << "format_volume: fs_type \"" << v->fs_type << "\" unsupported";
     return -1;
   }
 
   // If there's a key_loc that looks like a path, it should be a block device for storing encryption
   // metadata. Wipe it too.
-  if (v->key_loc != nullptr && v->key_loc[0] == '/') {
+  if (!v->key_loc.empty() && v->key_loc[0] == '/') {
     LOG(INFO) << "Wiping " << v->key_loc;
-    int fd = open(v->key_loc, O_WRONLY | O_CREAT, 0644);
+    int fd = open(v->key_loc.c_str(), O_WRONLY | O_CREAT, 0644);
     if (fd == -1) {
       PLOG(ERROR) << "format_volume: Failed to open " << v->key_loc;
       return -1;
@@ -287,9 +169,8 @@ int format_volume(const char* volume, const char* directory) {
   int64_t length = 0;
   if (v->length > 0) {
     length = v->length;
-  } else if (v->length < 0 ||
-             (v->key_loc != nullptr && strcmp(v->key_loc, "footer") == 0)) {
-    android::base::unique_fd fd(open(v->blk_device, O_RDONLY));
+  } else if (v->length < 0 || v->key_loc == "footer") {
+    android::base::unique_fd fd(open(v->blk_device.c_str(), O_RDONLY));
     if (fd == -1) {
       PLOG(ERROR) << "format_volume: failed to open " << v->blk_device;
       return -1;
@@ -303,7 +184,7 @@ int format_volume(const char* volume, const char* directory) {
     }
   }
 
-  if (strcmp(v->fs_type, "ext4") == 0) {
+  if (v->fs_type == "ext4") {
     static constexpr int kBlockSize = 4096;
     std::vector<std::string> mke2fs_args = {
       "/system/bin/mke2fs", "-F", "-t", "ext4", "-b", std::to_string(kBlockSize),
@@ -326,7 +207,7 @@ int format_volume(const char* volume, const char* directory) {
     }
 
     int result = exec_cmd(mke2fs_args);
-    if (result == 0 && directory != nullptr) {
+    if (result == 0 && !directory.empty()) {
       std::vector<std::string> e2fsdroid_args = {
         "/system/bin/e2fsdroid", "-e", "-f", directory, "-a", volume, v->blk_device,
       };
@@ -355,7 +236,7 @@ int format_volume(const char* volume, const char* directory) {
   }
 
   int result = exec_cmd(make_f2fs_cmd);
-  if (result == 0 && directory != nullptr) {
+  if (result == 0 && !directory.empty()) {
     cmd = "/sbin/sload.f2fs";
     // clang-format off
     std::vector<std::string> sload_f2fs_cmd = {
@@ -374,31 +255,29 @@ int format_volume(const char* volume, const char* directory) {
   return 0;
 }
 
-int format_volume(const char* volume) {
-  return format_volume(volume, nullptr);
+int format_volume(const std::string& volume) {
+  return format_volume(volume, "");
 }
 
 int setup_install_mounts() {
-  if (fstab == nullptr) {
+  if (fstab.empty()) {
     LOG(ERROR) << "can't set up install mounts: no fstab loaded";
     return -1;
   }
-  for (int i = 0; i < fstab->num_entries; ++i) {
-    const Volume* v = fstab->recs + i;
-
+  for (const FstabEntry& entry : fstab) {
     // We don't want to do anything with "/".
-    if (strcmp(v->mount_point, "/") == 0) {
+    if (entry.mount_point == "/") {
       continue;
     }
 
-    if (strcmp(v->mount_point, "/tmp") == 0 || strcmp(v->mount_point, "/cache") == 0) {
-      if (ensure_path_mounted(v->mount_point) != 0) {
-        LOG(ERROR) << "Failed to mount " << v->mount_point;
+    if (entry.mount_point == "/tmp" || entry.mount_point == "/cache") {
+      if (ensure_path_mounted(entry.mount_point) != 0) {
+        LOG(ERROR) << "Failed to mount " << entry.mount_point;
         return -1;
       }
     } else {
-      if (ensure_path_unmounted(v->mount_point) != 0) {
-        LOG(ERROR) << "Failed to unmount " << v->mount_point;
+      if (ensure_path_unmounted(entry.mount_point) != 0) {
+        LOG(ERROR) << "Failed to unmount " << entry.mount_point;
         return -1;
       }
     }
@@ -407,13 +286,9 @@ int setup_install_mounts() {
 }
 
 bool logical_partitions_mapped() {
-  return did_map_logical_partitions;
+  return android::fs_mgr::LogicalPartitionsMapped();
 }
 
 std::string get_system_root() {
-  if (volume_for_mount_point(SYSTEM_ROOT) == nullptr) {
-    return "/";
-  } else {
-    return SYSTEM_ROOT;
-  }
+  return android::fs_mgr::GetSystemRoot();
 }
diff --git a/roots.h b/roots.h
index 314eb5f26..341f90529 100644
--- a/roots.h
+++ b/roots.h
@@ -19,7 +19,7 @@
 
 #include <string>
 
-typedef struct fstab_rec Volume;
+typedef struct FstabEntry Volume;
 
 // Load and parse volume data from /etc/recovery.fstab.
 void load_volume_table();
@@ -29,25 +29,25 @@ Volume* volume_for_mount_point(const std::string& mount_point);
 
 // Make sure that the volume 'path' is on is mounted.  Returns 0 on
 // success (volume is mounted).
-int ensure_path_mounted(const char* path);
+int ensure_path_mounted(const std::string& path);
 
 // Similar to ensure_path_mounted, but allows one to specify the mount_point.
-int ensure_path_mounted_at(const char* path, const char* mount_point);
+int ensure_path_mounted_at(const std::string& path, const std::string& mount_point);
 
 // Make sure that the volume 'path' is on is unmounted.  Returns 0 on
 // success (volume is unmounted);
-int ensure_path_unmounted(const char* path);
+int ensure_path_unmounted(const std::string& path);
 
 // Reformat the given volume (must be the mount point only, eg
 // "/cache"), no paths permitted.  Attempts to unmount the volume if
 // it is mounted.
-int format_volume(const char* volume);
+int format_volume(const std::string& volume);
 
 // Reformat the given volume (must be the mount point only, eg
 // "/cache"), no paths permitted.  Attempts to unmount the volume if
 // it is mounted.
 // Copies 'directory' to root of the newly formatted volume
-int format_volume(const char* volume, const char* directory);
+int format_volume(const std::string& volume, const std::string& directory);
 
 // Ensure that all and only the volumes that packages expect to find
 // mounted (/tmp and /cache) are mounted.  Returns 0 on success.
diff --git a/screen_ui.cpp b/screen_ui.cpp
index 575605452..7fa41c4e4 100644
--- a/screen_ui.cpp
+++ b/screen_ui.cpp
@@ -252,6 +252,7 @@ int GraphicMenu::DrawItems(int x, int y, int screen_width, bool long_press) cons
 
     draw_funcs_.SetColor(UIElement::MENU);
   }
+  offset += draw_funcs_.DrawHorizontalRule(y + offset);
 
   return offset;
 }
diff --git a/tests/Android.bp b/tests/Android.bp
index 5165ccb33..1d6a056f6 100644
--- a/tests/Android.bp
+++ b/tests/Android.bp
@@ -94,6 +94,7 @@ librecovery_static_libs = [
     "libhidltransport",
     "libhwbinder_noltopgo",
     "libbinderthreadstate",
+    "liblp",
     "libvndksupport",
     "libtinyxml2",
 ]
diff --git a/updater/install.cpp b/updater/install.cpp
index ccde409df..0e1028bd1 100644
--- a/updater/install.cpp
+++ b/updater/install.cpp
@@ -393,17 +393,20 @@ Value* UnmountFn(const char* name, State* state, const std::vector<std::unique_p
   return StringValue(mount_point);
 }
 
-static int exec_cmd(const char* path, char* const argv[]) {
+static int exec_cmd(const std::vector<std::string>& args) {
+  CHECK(!args.empty());
+  auto argv = StringVectorToNullTerminatedArray(args);
+
   pid_t child;
   if ((child = vfork()) == 0) {
-    execv(path, argv);
+    execv(argv[0], argv.data());
     _exit(EXIT_FAILURE);
   }
 
   int status;
   waitpid(child, &status, 0);
   if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) {
-    LOG(ERROR) << path << " failed with status " << WEXITSTATUS(status);
+    LOG(ERROR) << args[0] << " failed with status " << WEXITSTATUS(status);
   }
   return WEXITSTATUS(status);
 }
@@ -453,62 +456,52 @@ Value* FormatFn(const char* name, State* state, const std::vector<std::unique_pt
   }
 
   if (fs_type == "ext4") {
-    const char* mke2fs_argv[] = { "/system/bin/mke2fs", "-t",    "ext4", "-b", "4096",
-                                  location.c_str(),     nullptr, nullptr };
-    std::string size_str;
+    std::vector<std::string> mke2fs_args = {
+      "/system/bin/mke2fs", "-t", "ext4", "-b", "4096", location
+    };
     if (size != 0) {
-      size_str = std::to_string(size / 4096LL);
-      mke2fs_argv[6] = size_str.c_str();
+      mke2fs_args.push_back(std::to_string(size / 4096LL));
     }
 
-    int status = exec_cmd(mke2fs_argv[0], const_cast<char**>(mke2fs_argv));
-    if (status != 0) {
+    if (auto status = exec_cmd(mke2fs_args); status != 0) {
       LOG(ERROR) << name << ": mke2fs failed (" << status << ") on " << location;
       return StringValue("");
     }
 
-    const char* e2fsdroid_argv[] = { "/system/bin/e2fsdroid", "-e",   "-a", mount_point.c_str(),
-                                     location.c_str(),        nullptr };
-    status = exec_cmd(e2fsdroid_argv[0], const_cast<char**>(e2fsdroid_argv));
-    if (status != 0) {
+    if (auto status = exec_cmd({ "/system/bin/e2fsdroid", "-e", "-a", mount_point, location });
+        status != 0) {
       LOG(ERROR) << name << ": e2fsdroid failed (" << status << ") on " << location;
       return StringValue("");
     }
     return StringValue(location);
-  } else if (fs_type == "f2fs") {
+  }
+
+  if (fs_type == "f2fs") {
     if (size < 0) {
       LOG(ERROR) << name << ": fs_size can't be negative for f2fs: " << fs_size;
       return StringValue("");
     }
-    std::string num_sectors = std::to_string(size / 512);
-
-    const char* f2fs_path = "/sbin/mkfs.f2fs";
-    const char* f2fs_argv[] = { "mkfs.f2fs",
-                                "-g", "android",
-                                "-w", "512",
-                                location.c_str(),
-                                (size < 512) ? nullptr : num_sectors.c_str(),
-                                nullptr };
-    int status = exec_cmd(f2fs_path, const_cast<char**>(f2fs_argv));
-    if (status != 0) {
+    std::vector<std::string> f2fs_args = {
+      "/sbin/mkfs.f2fs", "-g", "android", "-w", "512", location
+    };
+    if (size >= 512) {
+      f2fs_args.push_back(std::to_string(size / 512));
+    }
+    if (auto status = exec_cmd(f2fs_args); status != 0) {
       LOG(ERROR) << name << ": mkfs.f2fs failed (" << status << ") on " << location;
       return StringValue("");
     }
 
-    const char* sload_argv[] = { "/sbin/sload.f2fs", "-t", mount_point.c_str(), location.c_str(),
-                                 nullptr };
-    status = exec_cmd(sload_argv[0], const_cast<char**>(sload_argv));
-    if (status != 0) {
+    if (auto status = exec_cmd({ "/sbin/sload.f2fs", "-t", mount_point, location }); status != 0) {
       LOG(ERROR) << name << ": sload.f2fs failed (" << status << ") on " << location;
       return StringValue("");
     }
 
     return StringValue(location);
-  } else {
-    LOG(ERROR) << name << ": unsupported fs_type \"" << fs_type << "\" partition_type \""
-               << partition_type << "\"";
   }
 
+  LOG(ERROR) << name << ": unsupported fs_type \"" << fs_type << "\" partition_type \""
+             << partition_type << "\"";
   return nullptr;
 }
 
@@ -675,17 +668,12 @@ Value* RunProgramFn(const char* name, State* state, const std::vector<std::uniqu
     return ErrorAbort(state, kArgsParsingFailure, "%s() Failed to parse the argument(s)", name);
   }
 
-  char* args2[argv.size() + 1];
-  for (size_t i = 0; i < argv.size(); i++) {
-    args2[i] = &args[i][0];
-  }
-  args2[argv.size()] = nullptr;
-
-  LOG(INFO) << "about to run program [" << args2[0] << "] with " << argv.size() << " args";
+  auto exec_args = StringVectorToNullTerminatedArray(args);
+  LOG(INFO) << "about to run program [" << exec_args[0] << "] with " << argv.size() << " args";
 
   pid_t child = fork();
   if (child == 0) {
-    execv(args2[0], args2);
+    execv(exec_args[0], exec_args.data());
     PLOG(ERROR) << "run_program: execv failed";
     _exit(EXIT_FAILURE);
   }
@@ -909,20 +897,12 @@ Value* Tune2FsFn(const char* name, State* state, const std::vector<std::unique_p
     return ErrorAbort(state, kArgsParsingFailure, "%s() could not read args", name);
   }
 
-  char* args2[argv.size() + 1];
-  // Tune2fs expects the program name as its args[0]
-  args2[0] = const_cast<char*>(name);
-  if (args2[0] == nullptr) {
-    return nullptr;
-  }
-  for (size_t i = 0; i < argv.size(); ++i) {
-    args2[i + 1] = &args[i][0];
-  }
+  // tune2fs expects the program name as its first arg.
+  args.insert(args.begin(), "tune2fs");
+  auto tune2fs_args = StringVectorToNullTerminatedArray(args);
 
-  // tune2fs changes the file system parameters on an ext2 file system; it
-  // returns 0 on success.
-  int result = tune2fs_main(argv.size() + 1, args2);
-  if (result != 0) {
+  // tune2fs changes the filesystem parameters on an ext2 filesystem; it returns 0 on success.
+  if (auto result = tune2fs_main(tune2fs_args.size() - 1, tune2fs_args.data()); result != 0) {
     return ErrorAbort(state, kTune2FsFailure, "%s() returned error code %d", name, result);
   }
   return StringValue("t");