Merge changes I9d0482d1,Ib82833be am: b87f1c1728
am: 43473d3a54

Change-Id: I64d1dcf789eea0c6a184368be869f04a2933b47e
diff --git a/init/devices.cpp b/init/devices.cpp
index 6cd3564..ad313a0 100644
--- a/init/devices.cpp
+++ b/init/devices.cpp
@@ -56,9 +56,6 @@
 #include "util.h"
 
 #define SYSFS_PREFIX    "/sys"
-static const char *firmware_dirs[] = { "/etc/firmware",
-                                       "/vendor/firmware",
-                                       "/firmware/image" };
 
 extern struct selabel_handle *sehandle;
 
@@ -79,16 +76,8 @@
     struct listnode plist;
 };
 
-struct platform_node {
-    char *name;
-    char *path;
-    int path_len;
-    struct listnode list;
-};
-
 static list_declare(sys_perms);
 static list_declare(dev_perms);
-static list_declare(platform_names);
 
 int add_dev_perms(const char *name, const char *attr,
                   mode_t perm, unsigned int uid, unsigned int gid,
@@ -153,17 +142,18 @@
     return perm_path_matches(subsys_path.c_str(), dp);
 }
 
-static void fixup_sys_perms(const char* upath, const char* subsystem) {
+static void fixup_sys_perms(const std::string& upath, const std::string& subsystem) {
     // upaths omit the "/sys" that paths in this list
     // contain, so we prepend it...
-    std::string path = std::string(SYSFS_PREFIX) + upath;
+    std::string path = SYSFS_PREFIX + upath;
 
     listnode* node;
     list_for_each(node, &sys_perms) {
         perms_* dp = &(node_to_item(node, perm_node, plist))->dp;
-        if (match_subsystem(dp, SYSFS_PREFIX "/class/%s/%s", path.c_str(), subsystem)) {
+        if (match_subsystem(dp, SYSFS_PREFIX "/class/%s/%s", path.c_str(), subsystem.c_str())) {
             ; // matched
-        } else if (match_subsystem(dp, SYSFS_PREFIX "/bus/%s/devices/%s", path.c_str(), subsystem)) {
+        } else if (match_subsystem(dp, SYSFS_PREFIX "/bus/%s/devices/%s", path.c_str(),
+                                   subsystem.c_str())) {
             ; // matched
         } else if (!perm_path_matches(path.c_str(), dp)) {
             continue;
@@ -209,7 +199,7 @@
     return 0600;
 }
 
-static void make_device(const char* path, const char* /*upath*/, int block, int major, int minor,
+static void make_device(const std::string& path, int block, int major, int minor,
                         const std::vector<std::string>& links) {
     unsigned uid;
     unsigned gid;
@@ -217,7 +207,7 @@
     dev_t dev;
     char *secontext = NULL;
 
-    mode = get_device_perm(path, links, &uid, &gid) | (block ? S_IFBLK : S_IFCHR);
+    mode = get_device_perm(path.c_str(), links, &uid, &gid) | (block ? S_IFBLK : S_IFCHR);
 
     if (sehandle) {
         std::vector<const char*> c_links;
@@ -225,7 +215,7 @@
             c_links.emplace_back(link.c_str());
         }
         c_links.emplace_back(nullptr);
-        if (selabel_lookup_best_match(sehandle, &secontext, path, &c_links[0], mode)) {
+        if (selabel_lookup_best_match(sehandle, &secontext, path.c_str(), &c_links[0], mode)) {
             PLOG(ERROR) << "Device '" << path << "' not created; cannot find SELinux label";
             return;
         }
@@ -244,10 +234,9 @@
     }
     /* If the node already exists update its SELinux label to handle cases when
      * it was created with the wrong context during coldboot procedure. */
-    if (mknod(path, mode, dev) && (errno == EEXIST) && secontext) {
-
+    if (mknod(path.c_str(), mode, dev) && (errno == EEXIST) && secontext) {
         char* fcon = nullptr;
-        int rc = lgetfilecon(path, &fcon);
+        int rc = lgetfilecon(path.c_str(), &fcon);
         if (rc < 0) {
             PLOG(ERROR) << "Cannot get SELinux label on '" << path << "' device";
             goto out;
@@ -256,13 +245,13 @@
         bool different = strcmp(fcon, secontext) != 0;
         freecon(fcon);
 
-        if (different && lsetfilecon(path, secontext)) {
+        if (different && lsetfilecon(path.c_str(), secontext)) {
             PLOG(ERROR) << "Cannot set '" << secontext << "' SELinux label on '" << path << "' device";
         }
     }
 
 out:
-    chown(path, uid, -1);
+    chown(path.c_str(), uid, -1);
     if (setegid(AID_ROOT)) {
         PLOG(FATAL) << "setegid(AID_ROOT) failed";
     }
@@ -273,75 +262,25 @@
     }
 }
 
-void add_platform_device(const char* path) {
-    int path_len = strlen(path);
-    struct platform_node *bus;
-    const char *name = path;
+// TODO: Move this to be a member variable of a future devices class.
+std::vector<std::string> platform_devices;
 
-    if (!strncmp(path, "/devices/", 9)) {
-        name += 9;
-        if (!strncmp(name, "platform/", 9))
-            name += 9;
-    }
-
-    LOG(VERBOSE) << "adding platform device " << name << " (" << path << ")";
-
-    bus = (platform_node*) calloc(1, sizeof(struct platform_node));
-    bus->path = strdup(path);
-    bus->path_len = path_len;
-    bus->name = bus->path + (name - path);
-    list_add_tail(&platform_names, &bus->list);
-}
-
-/*
- * given a path that may start with a platform device, find the length of the
- * platform device prefix.  If it doesn't start with a platform device, return
- * 0.
- */
-static struct platform_node *find_platform_device(const char *path)
-{
-    int path_len = strlen(path);
-    struct listnode *node;
-    struct platform_node *bus;
-
-    list_for_each_reverse(node, &platform_names) {
-        bus = node_to_item(node, struct platform_node, list);
-        if ((bus->path_len < path_len) &&
-                (path[bus->path_len] == '/') &&
-                !strncmp(path, bus->path, bus->path_len))
-            return bus;
-    }
-
-    return NULL;
-}
-
-void remove_platform_device(const char* path) {
-    struct listnode *node;
-    struct platform_node *bus;
-
-    list_for_each_reverse(node, &platform_names) {
-        bus = node_to_item(node, struct platform_node, list);
-        if (!strcmp(path, bus->path)) {
-            LOG(INFO) << "removing platform device " << bus->name;
-            free(bus->path);
-            list_remove(node);
-            free(bus);
-            return;
+// Given a path that may start with a platform device, find the length of the
+// platform device prefix.  If it doesn't start with a platform device, return false
+bool find_platform_device(const std::string& path, std::string* out_path) {
+    out_path->clear();
+    // platform_devices is searched backwards, since parents are added before their children,
+    // and we want to match as deep of a child as we can.
+    for (auto it = platform_devices.rbegin(); it != platform_devices.rend(); ++it) {
+        auto platform_device_path_length = it->length();
+        if (platform_device_path_length < path.length() &&
+            path[platform_device_path_length] == '/' &&
+            android::base::StartsWith(path, it->c_str())) {
+            *out_path = *it;
+            return true;
         }
     }
-}
-
-static void destroy_platform_devices() {
-    struct listnode* node;
-    struct listnode* n;
-    struct platform_node* bus;
-
-    list_for_each_safe(node, n, &platform_names) {
-        list_remove(node);
-        bus = node_to_item(node, struct platform_node, list);
-        free(bus->path);
-        free(bus);
-    }
+    return false;
 }
 
 /* Given a path that may start with a PCI device, populate the supplied buffer
@@ -398,19 +337,11 @@
     return true;
 }
 
-static void parse_event(const char *msg, struct uevent *uevent)
-{
-    uevent->action = "";
-    uevent->path = "";
-    uevent->subsystem = "";
-    uevent->firmware = "";
+void parse_event(const char* msg, uevent* uevent) {
+    uevent->partition_num = -1;
     uevent->major = -1;
     uevent->minor = -1;
-    uevent->partition_name = NULL;
-    uevent->partition_num = -1;
-    uevent->device_name = NULL;
-
-        /* currently ignoring SEQNUM */
+    // currently ignoring SEQNUM
     while(*msg) {
         if(!strncmp(msg, "ACTION=", 7)) {
             msg += 7;
@@ -441,30 +372,26 @@
             uevent->device_name = msg;
         }
 
-        /* advance to after the next \0 */
+        // advance to after the next \0
         while(*msg++)
             ;
     }
 
     if (LOG_UEVENTS) {
-        LOG(INFO) << android::base::StringPrintf("event { '%s', '%s', '%s', '%s', %d, %d }",
-                                                 uevent->action, uevent->path, uevent->subsystem,
-                                                 uevent->firmware, uevent->major, uevent->minor);
+        LOG(INFO) << "event { '" << uevent->action << "', '" << uevent->path << "', '"
+                  << uevent->subsystem << "', '" << uevent->firmware << "', " << uevent->major
+                  << ", " << uevent->minor << " }";
     }
 }
 
 std::vector<std::string> get_character_device_symlinks(uevent* uevent) {
-    platform_node* pdev = find_platform_device(uevent->path);
-    if (!pdev) return {};
+    std::string parent_device;
+    if (!find_platform_device(uevent->path, &parent_device)) return {};
 
-    /* skip "/devices/platform/<driver>" */
-    std::string parent = std::string(uevent->path);
-    auto parent_start = parent.find('/', pdev->path_len);
-    if (parent_start == std::string::npos) return {};
+    // skip path to the parent driver
+    std::string path = uevent->path.substr(parent_device.length());
 
-    parent.erase(0, parent_start);
-
-    if (!android::base::StartsWith(parent, "/usb")) return {};
+    if (!android::base::StartsWith(path, "/usb")) return {};
 
     // skip root hub name and device. use device interface
     // skip 3 slashes, including the first / by starting the search at the 1st character, not 0th.
@@ -472,13 +399,13 @@
     // e.g. "/usb/usb_device/name/tty2-1:1.0" -> "name"
 
     std::string::size_type start = 0;
-    start = parent.find('/', start + 1);
+    start = path.find('/', start + 1);
     if (start == std::string::npos) return {};
 
-    start = parent.find('/', start + 1);
+    start = path.find('/', start + 1);
     if (start == std::string::npos) return {};
 
-    auto end = parent.find('/', start + 1);
+    auto end = path.find('/', start + 1);
     if (end == std::string::npos) return {};
 
     start++;  // Skip the first '/'
@@ -486,11 +413,10 @@
     auto length = end - start;
     if (length == 0) return {};
 
-    auto name_string = parent.substr(start, length);
+    auto name_string = path.substr(start, length);
 
-    // TODO: remove std::string() when uevent->subsystem is an std::string
     std::vector<std::string> links;
-    links.emplace_back("/dev/usb/" + std::string(uevent->subsystem) + name_string);
+    links.emplace_back("/dev/usb/" + uevent->subsystem + name_string);
 
     mkdir("/dev/usb", 0755);
 
@@ -516,12 +442,19 @@
 
 std::vector<std::string> get_block_device_symlinks(uevent* uevent) {
     std::string device;
-    struct platform_node* pdev;
     std::string type;
 
-    pdev = find_platform_device(uevent->path);
-    if (pdev) {
-        device = pdev->name;
+    if (find_platform_device(uevent->path, &device)) {
+        // Skip /devices/platform or /devices/ if present
+        static const std::string devices_platform_prefix = "/devices/platform/";
+        static const std::string devices_prefix = "/devices/";
+
+        if (android::base::StartsWith(device, devices_platform_prefix.c_str())) {
+            device = device.substr(devices_platform_prefix.length());
+        } else if (android::base::StartsWith(device, devices_prefix.c_str())) {
+            device = device.substr(devices_prefix.length());
+        }
+
         type = "platform";
     } else if (find_pci_device_prefix(uevent->path, &device)) {
         type = "pci";
@@ -537,7 +470,7 @@
 
     auto link_path = "/dev/block/" + type + "/" + device;
 
-    if (uevent->partition_name) {
+    if (!uevent->partition_name.empty()) {
         std::string partition_name_sanitized(uevent->partition_name);
         sanitize_partition_name(&partition_name_sanitized);
         if (partition_name_sanitized != uevent->partition_name) {
@@ -551,57 +484,51 @@
         links.emplace_back(link_path + "/by-num/p" + std::to_string(uevent->partition_num));
     }
 
-    // TODO: remove uevent_path when uevent->path is an std::string
-    std::string uevent_path = uevent->path;
-    auto last_slash = uevent_path.rfind('/');
-    links.emplace_back(link_path + "/" + uevent_path.substr(last_slash + 1));
+    auto last_slash = uevent->path.rfind('/');
+    links.emplace_back(link_path + "/" + uevent->path.substr(last_slash + 1));
 
     return links;
 }
 
-static void make_link_init(const char* oldpath, const char* newpath) {
-  const char* slash = strrchr(newpath, '/');
-  if (!slash) return;
+static void make_link_init(const std::string& oldpath, const std::string& newpath) {
+    if (mkdir_recursive(dirname(newpath.c_str()), 0755)) {
+        PLOG(ERROR) << "Failed to create directory " << dirname(newpath.c_str());
+    }
 
-  if (mkdir_recursive(dirname(newpath), 0755)) {
-    PLOG(ERROR) << "Failed to create directory " << dirname(newpath);
-  }
-
-  if (symlink(oldpath, newpath) && errno != EEXIST) {
-    PLOG(ERROR) << "Failed to symlink " << oldpath << " to " << newpath;
-  }
+    if (symlink(oldpath.c_str(), newpath.c_str()) && errno != EEXIST) {
+        PLOG(ERROR) << "Failed to symlink " << oldpath << " to " << newpath;
+    }
 }
 
-static void remove_link(const char* oldpath, const char* newpath) {
-  std::string path;
-  if (android::base::Readlink(newpath, &path) && path == oldpath) unlink(newpath);
+static void remove_link(const std::string& oldpath, const std::string& newpath) {
+    std::string path;
+    if (android::base::Readlink(newpath, &path) && path == oldpath) unlink(newpath.c_str());
 }
 
-static void handle_device(const char* action, const char* devpath, const char* path, int block,
+static void handle_device(const std::string& action, const std::string& devpath, int block,
                           int major, int minor, const std::vector<std::string>& links) {
-    if(!strcmp(action, "add")) {
-        make_device(devpath, path, block, major, minor, links);
+    if (action == "add") {
+        make_device(devpath, block, major, minor, links);
         for (const auto& link : links) {
-            make_link_init(devpath, link.c_str());
+            make_link_init(devpath, link);
         }
     }
 
-    if(!strcmp(action, "remove")) {
+    if (action == "remove") {
         for (const auto& link : links) {
-            remove_link(devpath, link.c_str());
+            remove_link(devpath, link);
         }
-        unlink(devpath);
+        unlink(devpath.c_str());
     }
 }
 
-static void handle_platform_device_event(struct uevent *uevent)
-{
-    const char *path = uevent->path;
-
-    if (!strcmp(uevent->action, "add"))
-        add_platform_device(path);
-    else if (!strcmp(uevent->action, "remove"))
-        remove_platform_device(path);
+void handle_platform_device_event(uevent* uevent) {
+    if (uevent->action == "add") {
+        platform_devices.emplace_back(uevent->path);
+    } else if (uevent->action == "remove") {
+        auto it = std::find(platform_devices.begin(), platform_devices.end(), uevent->path);
+        if (it != platform_devices.end()) platform_devices.erase(it);
+    }
 }
 
 static void handle_block_device_event(uevent* uevent) {
@@ -615,11 +542,11 @@
     std::string devpath = base + name;
 
     std::vector<std::string> links;
-    if (!strncmp(uevent->path, "/devices/", 9))
+    if (android::base::StartsWith(uevent->path, "/devices")) {
         links = get_block_device_symlinks(uevent);
+    }
 
-    handle_device(uevent->action, devpath.c_str(), uevent->path, 1, uevent->major, uevent->minor,
-                  links);
+    handle_device(uevent->action, devpath, 1, uevent->major, uevent->minor, links);
 }
 
 static void handle_generic_device_event(uevent* uevent) {
@@ -627,7 +554,7 @@
     if (uevent->major < 0 || uevent->minor < 0) return;
 
     std::string name = android::base::Basename(uevent->path);
-    ueventd_subsystem* subsystem = ueventd_subsystem_find_by_name(uevent->subsystem);
+    ueventd_subsystem* subsystem = ueventd_subsystem_find_by_name(uevent->subsystem.c_str());
 
     std::string devpath;
 
@@ -651,11 +578,10 @@
         // TODO: Remove std::string()
         devpath = std::string(subsystem->dirname) + "/" + devname;
         mkdir_recursive(android::base::Dirname(devpath), 0755);
-    } else if (!strncmp(uevent->subsystem, "usb", 3)) {
-        if (!strcmp(uevent->subsystem, "usb")) {
-            if (uevent->device_name) {
-                // TODO: Remove std::string
-                devpath = "/dev/" + std::string(uevent->device_name);
+    } else if (android::base::StartsWith(uevent->subsystem, "usb")) {
+        if (uevent->subsystem == "usb") {
+            if (!uevent->device_name.empty()) {
+                devpath = "/dev/" + uevent->device_name;
             } else {
                 // This imitates the file system that would be created
                 // if we were using devfs instead.
@@ -675,18 +601,18 @@
 
     auto links = get_character_device_symlinks(uevent);
 
-    handle_device(uevent->action, devpath.c_str(), uevent->path, 0, uevent->major, uevent->minor,
-                  links);
+    handle_device(uevent->action, devpath, 0, uevent->major, uevent->minor, links);
 }
 
 static void handle_device_event(struct uevent *uevent)
 {
-    if (!strcmp(uevent->action,"add") || !strcmp(uevent->action, "change") || !strcmp(uevent->action, "online"))
+    if (uevent->action == "add" || uevent->action == "change" || uevent->action == "online") {
         fixup_sys_perms(uevent->path, uevent->subsystem);
+    }
 
-    if (!strncmp(uevent->subsystem, "block", 5)) {
+    if (uevent->subsystem == "block") {
         handle_block_device_event(uevent);
-    } else if (!strncmp(uevent->subsystem, "platform", 8)) {
+    } else if (uevent->subsystem == "platform") {
         handle_platform_device_event(uevent);
     } else {
         handle_generic_device_event(uevent);
@@ -719,7 +645,7 @@
 
     LOG(INFO) << "firmware: loading '" << uevent->firmware << "' for '" << uevent->path << "'";
 
-    std::string root = android::base::StringPrintf("/sys%s", uevent->path);
+    std::string root = "/sys" + uevent->path;
     std::string loading = root + "/loading";
     std::string data = root + "/data";
 
@@ -735,9 +661,12 @@
         return;
     }
 
+    static const char* firmware_dirs[] = {"/etc/firmware/", "/vendor/firmware/",
+                                          "/firmware/image/"};
+
 try_loading_again:
     for (size_t i = 0; i < arraysize(firmware_dirs); i++) {
-        std::string file = android::base::StringPrintf("%s/%s", firmware_dirs[i], uevent->firmware);
+        std::string file = firmware_dirs[i] + uevent->firmware;
         android::base::unique_fd fw_fd(open(file.c_str(), O_RDONLY|O_CLOEXEC));
         struct stat sb;
         if (fw_fd != -1 && fstat(fw_fd, &sb) != -1) {
@@ -761,8 +690,7 @@
 }
 
 static void handle_firmware_event(uevent* uevent) {
-    if (strcmp(uevent->subsystem, "firmware")) return;
-    if (strcmp(uevent->action, "add")) return;
+    if (uevent->subsystem != "firmware" || uevent->action != "add") return;
 
     // Loading the firmware in a child means we can do that in parallel...
     // (We ignore SIGCHLD rather than wait for our children.)
@@ -796,7 +724,7 @@
         msg[n] = '\0';
         msg[n+1] = '\0';
 
-        struct uevent uevent;
+        uevent uevent;
         parse_event(msg, &uevent);
         coldboot_action_t act = handle_uevent(&uevent);
         if (should_stop_coldboot(act))
@@ -940,7 +868,7 @@
 }
 
 void device_close() {
-    destroy_platform_devices();
+    platform_devices.clear();
     device_fd.reset();
     selinux_status_close();
 }
diff --git a/init/devices.h b/init/devices.h
index f6183c9..b8b039f 100644
--- a/init/devices.h
+++ b/init/devices.h
@@ -36,12 +36,12 @@
 };
 
 struct uevent {
-    const char* action;
-    const char* path;
-    const char* subsystem;
-    const char* firmware;
-    const char* partition_name;
-    const char* device_name;
+    std::string action;
+    std::string path;
+    std::string subsystem;
+    std::string firmware;
+    std::string partition_name;
+    std::string device_name;
     int partition_num;
     int major;
     int minor;
@@ -59,10 +59,11 @@
 int get_device_fd();
 
 // Exposed for testing
-void add_platform_device(const char* path);
-void remove_platform_device(const char* path);
+extern std::vector<std::string> platform_devices;
+bool find_platform_device(const std::string& path, std::string* out_path);
 std::vector<std::string> get_character_device_symlinks(uevent* uevent);
 std::vector<std::string> get_block_device_symlinks(uevent* uevent);
 void sanitize_partition_name(std::string* string);
+void handle_platform_device_event(uevent* uevent);
 
 #endif /* _INIT_DEVICES_H */
diff --git a/init/devices_test.cpp b/init/devices_test.cpp
index 5be0d88..693fb54 100644
--- a/init/devices_test.cpp
+++ b/init/devices_test.cpp
@@ -22,12 +22,26 @@
 #include <android-base/scopeguard.h>
 #include <gtest/gtest.h>
 
+void add_platform_device(const std::string& path) {
+    uevent uevent = {
+        .action = "add", .subsystem = "platform", .path = path,
+    };
+    handle_platform_device_event(&uevent);
+}
+
+void remove_platform_device(const std::string& path) {
+    uevent uevent = {
+        .action = "remove", .subsystem = "platform", .path = path,
+    };
+    handle_platform_device_event(&uevent);
+}
+
 template <std::vector<std::string> (*Function)(uevent*)>
 void test_get_symlinks(const std::string& platform_device_name, uevent* uevent,
                        const std::vector<std::string> expected_links) {
-    add_platform_device(platform_device_name.c_str());
+    add_platform_device(platform_device_name);
     auto platform_device_remover = android::base::make_scope_guard(
-        [&platform_device_name]() { remove_platform_device(platform_device_name.c_str()); });
+        [&platform_device_name]() { remove_platform_device(platform_device_name); });
 
     std::vector<std::string> result = Function(uevent);
 
@@ -41,6 +55,36 @@
     }
 }
 
+TEST(devices, handle_platform_device_event) {
+    platform_devices.clear();
+    add_platform_device("/devices/platform/some_device_name");
+    ASSERT_EQ(1U, platform_devices.size());
+    remove_platform_device("/devices/platform/some_device_name");
+    ASSERT_EQ(0U, platform_devices.size());
+}
+
+TEST(devices, find_platform_device) {
+    platform_devices.clear();
+    add_platform_device("/devices/platform/some_device_name");
+    add_platform_device("/devices/platform/some_device_name/longer");
+    add_platform_device("/devices/platform/other_device_name");
+    EXPECT_EQ(3U, platform_devices.size());
+
+    std::string out_path;
+    EXPECT_FALSE(find_platform_device("/devices/platform/not_found", &out_path));
+    EXPECT_EQ("", out_path);
+
+    EXPECT_FALSE(
+        find_platform_device("/devices/platform/some_device_name_with_same_prefix", &out_path));
+
+    EXPECT_TRUE(
+        find_platform_device("/devices/platform/some_device_name/longer/longer_child", &out_path));
+    EXPECT_EQ("/devices/platform/some_device_name/longer", out_path);
+
+    EXPECT_TRUE(find_platform_device("/devices/platform/some_device_name/other_child", &out_path));
+    EXPECT_EQ("/devices/platform/some_device_name", out_path);
+}
+
 TEST(devices, get_character_device_symlinks_success) {
     const char* platform_device = "/devices/platform/some_device_name";
     uevent uevent = {
@@ -127,7 +171,7 @@
     const char* platform_device = "/devices/soc.0/f9824900.sdhci";
     uevent uevent = {
         .path = "/devices/soc.0/f9824900.sdhci/mmc_host/mmc0/mmc0:0001/block/mmcblk0",
-        .partition_name = nullptr,
+        .partition_name = "",
         .partition_num = -1,
     };
     std::vector<std::string> expected_result{"/dev/block/platform/soc.0/f9824900.sdhci/mmcblk0"};
@@ -156,7 +200,7 @@
     const char* platform_device = "/devices/soc.0/f9824900.sdhci";
     uevent uevent = {
         .path = "/devices/soc.0/f9824900.sdhci/mmc_host/mmc0/mmc0:0001/block/mmcblk0p1",
-        .partition_name = nullptr,
+        .partition_name = "",
         .partition_num = 1,
     };
     std::vector<std::string> expected_result{
@@ -185,9 +229,7 @@
 TEST(devices, get_block_device_symlinks_success_pci) {
     const char* platform_device = "/devices/do/not/match";
     uevent uevent = {
-        .path = "/devices/pci0000:00/0000:00:1f.2/mmcblk0",
-        .partition_name = nullptr,
-        .partition_num = -1,
+        .path = "/devices/pci0000:00/0000:00:1f.2/mmcblk0", .partition_name = "", .partition_num = -1,
     };
     std::vector<std::string> expected_result{"/dev/block/pci/pci0000:00/0000:00:1f.2/mmcblk0"};
 
@@ -197,7 +239,7 @@
 TEST(devices, get_block_device_symlinks_pci_bad_format) {
     const char* platform_device = "/devices/do/not/match";
     uevent uevent = {
-        .path = "/devices/pci//mmcblk0", .partition_name = nullptr, .partition_num = -1,
+        .path = "/devices/pci//mmcblk0", .partition_name = "", .partition_num = -1,
     };
     std::vector<std::string> expected_result{};
 
@@ -207,7 +249,7 @@
 TEST(devices, get_block_device_symlinks_success_vbd) {
     const char* platform_device = "/devices/do/not/match";
     uevent uevent = {
-        .path = "/devices/vbd-1234/mmcblk0", .partition_name = nullptr, .partition_num = -1,
+        .path = "/devices/vbd-1234/mmcblk0", .partition_name = "", .partition_num = -1,
     };
     std::vector<std::string> expected_result{"/dev/block/vbd/1234/mmcblk0"};
 
@@ -217,7 +259,7 @@
 TEST(devices, get_block_device_symlinks_vbd_bad_format) {
     const char* platform_device = "/devices/do/not/match";
     uevent uevent = {
-        .path = "/devices/vbd-/mmcblk0", .partition_name = nullptr, .partition_num = -1,
+        .path = "/devices/vbd-/mmcblk0", .partition_name = "", .partition_num = -1,
     };
     std::vector<std::string> expected_result{};
 
@@ -228,7 +270,7 @@
     const char* platform_device = "/devices/soc.0/f9824900.sdhci";
     uevent uevent = {
         .path = "/devices/soc.0/not_the_device/mmc_host/mmc0/mmc0:0001/block/mmcblk0p1",
-        .partition_name = nullptr,
+        .partition_name = "",
         .partition_num = -1,
     };
     std::vector<std::string> expected_result;
diff --git a/init/init.cpp b/init/init.cpp
index 6c09c99..6c1c541 100644
--- a/init/init.cpp
+++ b/init/init.cpp
@@ -958,7 +958,7 @@
     const std::string syspath = "/sys/block/" + device_name;
 
     device_init(syspath.c_str(), [&](uevent* uevent) -> coldboot_action_t {
-        if (uevent->device_name && device_name == uevent->device_name) {
+        if (uevent->device_name == device_name) {
             LOG(VERBOSE) << "early_mount: creating dm-verity device : " << dm_device;
             return COLDBOOT_STOP;
         }
@@ -1055,21 +1055,17 @@
         return;
     }
     device_init(nullptr, [=](uevent* uevent) -> coldboot_action_t {
-        if (!strncmp(uevent->subsystem, "firmware", 8)) {
-            return COLDBOOT_CONTINUE;
-        }
-
         // we need platform devices to create symlinks
-        if (!strncmp(uevent->subsystem, "platform", 8)) {
+        if (uevent->subsystem == "platform") {
             return COLDBOOT_CREATE;
         }
 
         // Ignore everything that is not a block device
-        if (strncmp(uevent->subsystem, "block", 5)) {
+        if (uevent->subsystem != "block") {
             return COLDBOOT_CONTINUE;
         }
 
-        if (uevent->partition_name) {
+        if (!uevent->partition_name.empty()) {
             // match partition names to create device nodes for partitions
             // both partition_names and uevent->partition_name have A/B suffix when A/B is used
             auto iter = partition_names->find(uevent->partition_name);