Add usb gadget support

Makefile

@@ -1,6 +1,6 @@
 CC = g++
 CFLAGS = -I./src/include
-SRCS = src/util.cpp src/configfsisomanager.cpp src/main.cpp
+SRCS = src/util.cpp src/configfsisomanager.cpp src/androidusbisomanager.cpp src/main.cpp
 OBJS = $(SRCS:.cpp=.o)
 TARGET = isodrive
 INSTALL_DIR = /usr/local/bin

src/androidusbisomanager.cpp

@@ -0,0 +1,49 @@
+#include <sys/stat.h>
+#include <sys/types.h>
+
+#include "androidusbisomanager.h"
+#include "util.h"
+#include <dirent.h>
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+
+bool usb_supported() { return isfile((char *)ANDROID0_SYSFS_ENABLE); }
+
+void usb_mount_iso(char *iso_path) {
+
+  if (usb_enabled())
+    usb_set_enabled(false);
+
+  sysfs_write((char *)ANDROID0_SYSFS_IMG_FILE, iso_path);
+
+  char *features = (char *)"mass_storage";
+
+  sysfs_write((char *)ANDROID0_SYSFS_FEATURES, features);
+
+  usb_set_enabled(true);
+}
+
+void usb_reset_iso() {
+  usb_mount_iso((char *)"");
+
+  if (usb_enabled())
+    usb_set_enabled(false);
+
+  char *features = (char *)"mtp";
+
+  sysfs_write((char *)ANDROID0_SYSFS_FEATURES, features);
+
+  usb_set_enabled(true);
+}
+
+bool usb_enabled() {
+  return strcmp(sysfs_read((char *)ANDROID0_SYSFS_ENABLE), "1") == 0;
+}
+
+void usb_set_enabled(bool enabled) {
+  if (enabled)
+    sysfs_write((char *)ANDROID0_SYSFS_ENABLE, (char *)"1");
+  else
+    sysfs_write((char *)ANDROID0_SYSFS_ENABLE, (char *)"0");
+}

src/configfsisomanager.cpp

@@ -2,39 +2,31 @@
 #include <sys/stat.h>
 #include <sys/types.h>
 
-#include "util.h"
 #include "configfsisomanager.h"
+#include "util.h"
 #include <dirent.h>
-#include <unistd.h>
-#include <string.h>
 #include <stdio.h>
+#include <string.h>
+#include <unistd.h>
 
-bool supported()
-{
-  return fs_mount_point((char *)"configfs") != nullptr;
-}
+bool supported() { return fs_mount_point((char *)"configfs") != nullptr; }
 
-char* get_gadget_root()
-{
-  char *configFsRoot  = fs_mount_point((char *)"configfs");
+char *get_gadget_root() {
+  char *configFsRoot = fs_mount_point((char *)"configfs");
   char *usbGadgetRoot = strjin(configFsRoot, (char *)"/usb_gadget/");
-  char *gadgetRoot    = nullptr;
+  char *gadgetRoot = nullptr;
 
   struct dirent *entry = nullptr;
-  DIR *dp              = nullptr;
+  DIR *dp = nullptr;
 
   dp = opendir(usbGadgetRoot);
 
-  if (dp != nullptr)
-  {
-    while ((entry = readdir(dp)))
-    {
-      if (entry->d_name[0] != '.')
-      {
+  if (dp != nullptr) {
+    while ((entry = readdir(dp))) {
+      if (entry->d_name[0] != '.') {
         char *gadget = strjin(usbGadgetRoot, entry->d_name);
 
-        if (sysfs_read(strjin(gadget, (char *)"/UDC")) != nullptr)
-        {
+        if (sysfs_read(strjin(gadget, (char *)"/UDC")) != nullptr) {
           gadgetRoot = gadget;
           break;
         }
@@ -44,28 +36,23 @@ char* get_gadget_root()
   return gadgetRoot;
 }
 
-char* get_config_root()
-{
+char *get_config_root() {
   char *gadgetRoot = get_gadget_root();
 
-  if (gadgetRoot == nullptr)
-  {
+  if (gadgetRoot == nullptr) {
     return nullptr;
   }
   char *usbConfigRoot = strjin(gadgetRoot, (char *)"/configs/");
-  char *configRoot    = nullptr;
+  char *configRoot = nullptr;
 
   struct dirent *entry = nullptr;
-  DIR *dp              = nullptr;
+  DIR *dp = nullptr;
 
   dp = opendir(usbConfigRoot);
 
-  if (dp != nullptr)
-  {
-    while ((entry = readdir(dp)))
-    {
-      if (entry->d_name[0] != '.')
-      {
+  if (dp != nullptr) {
+    while ((entry = readdir(dp))) {
+      if (entry->d_name[0] != '.') {
         configRoot = strjin(usbConfigRoot, entry->d_name);
         break;
       }
@@ -74,58 +61,51 @@ char* get_config_root()
   return configRoot;
 }
 
-void mount_iso(char *iso_path, char *cdrom, char *ro)
-{
+void mount_iso(char *iso_path, char *cdrom, char *ro) {
   char *gadgetRoot = get_gadget_root();
 
-  if (gadgetRoot == nullptr)
-  {
+  if (gadgetRoot == nullptr) {
     printf("No active gadget found\n");
     return;
   }
-  char *configRoot      = get_config_root();
-  char *udc             = get_udc();
-  char *functionRoot    = strjin(gadgetRoot, (char *)"/functions");
+  char *configRoot = get_config_root();
+  char *udc = get_udc();
+  char *functionRoot = strjin(gadgetRoot, (char *)"/functions");
   char *massStorageRoot = strjin(functionRoot, (char *)"/mass_storage.0");
-  char *lunRoot         = strjin(massStorageRoot, (char *)"/lun.0");
+  char *lunRoot = strjin(massStorageRoot, (char *)"/lun.0");
 
   char *stallFile = strjin(massStorageRoot, (char *)"/stall");
-  char *udcFile   = strjin(gadgetRoot, (char *)"/UDC");
-  char *lunFile   = strjin(lunRoot, (char *)"/file");
-  char *lunCdRom  = strjin(lunRoot, (char *)"/cdrom");
-  char *lunRo     = strjin(lunRoot, (char *)"/ro");
+  char *udcFile = strjin(gadgetRoot, (char *)"/UDC");
+  char *lunFile = strjin(lunRoot, (char *)"/file");
+  char *lunCdRom = strjin(lunRoot, (char *)"/cdrom");
+  char *lunRo = strjin(lunRoot, (char *)"/ro");
 
   set_udc((char *)"", gadgetRoot);
 
-  if (!isdir(massStorageRoot))
-  {
+  if (!isdir(massStorageRoot)) {
     mkdir(massStorageRoot, S_IRWXU | S_IRWXG | S_IROTH | S_IXOTH);
   }
 
-  if (!isdir(strjin(configRoot, (char *)"/mass_storage.0")))
-  {
+  if (!isdir(strjin(configRoot, (char *)"/mass_storage.0"))) {
     symlink(massStorageRoot, strjin(configRoot, (char *)"/mass_storage.0"));
   }
-  sysfs_write(lunFile,  iso_path);
+  sysfs_write(lunFile, iso_path);
   sysfs_write(lunCdRom, cdrom);
-  sysfs_write(lunRo,    ro);
+  sysfs_write(lunRo, ro);
 
   set_udc(udc, gadgetRoot);
 }
 
-void set_udc(char *udc, char *gadget)
-{
+void set_udc(char *udc, char *gadget) {
   char *udcFile = strjin(gadget, (char *)"/UDC");
 
   sysfs_write(udcFile, udc);
 }
 
-char* get_udc()
-{
+char *get_udc() {
   char *gadget_root = get_gadget_root();
 
-  if (gadget_root == nullptr)
-  {
+  if (gadget_root == nullptr) {
     return nullptr;
   }
   char *udcFile = strjin(gadget_root, (char *)"/UDC");

src/include/androidusbisomanager.h

@@ -0,0 +1,20 @@
+#ifndef ANDROIDUSBISOMANAGER_H
+#define ANDROIDUSBISOMANAGER_H
+
+#define ANDROID0_SYSFS_ENABLE "/sys/devices/virtual/android_usb/android0/enable"
+#define ANDROID0_SYSFS_IMG_FILE                                                \
+  "/sys/devices/virtual/android_usb/android0/f_mass_storage/lun/file"
+#define ANDROID0_SYSFS_FEATURES                                                \
+  "/sys/devices/virtual/android_usb/android0/functions"
+
+bool usb_supported();
+
+void usb_mount_iso(char *iso_path);
+void usb_umount_iso();
+void usb_reset_iso();
+
+bool usb_enabled();
+void usb_set_enabled(bool enabled);
+char *usb_get_udc();
+
+#endif // ifndef ANDROIDUSBISOMANAGER_H

src/include/configfsisomanager.h

@@ -1,16 +1,13 @@
 #ifndef CONFIGFSISOMANAGER_H
 #define CONFIGFSISOMANAGER_H
 
-bool  supported();
-char* get_gadget_root();
-char* get_config_root();
+bool supported();
+char *get_gadget_root();
+char *get_config_root();
 
-void  mount_iso(char *iso_path,
-                char *cdrom,
-                char *ro);
-void  umount_iso();
-void  set_udc(char *udc,
-              char *gadget);
-char* get_udc();
+void mount_iso(char *iso_path, char *cdrom, char *ro);
+void umount_iso();
+void set_udc(char *udc, char *gadget);
+char *get_udc();
 
 #endif // ifndef CONFIGFSISOMANAGER_H

src/include/util.h

@@ -1,12 +1,11 @@
 #ifndef UTIL_H
 #define UTIL_H
 
-char* fs_mount_point(char *filesystem_type);
-char* strjin(char *w1,
-             char *w2);
-bool  isdir(char *path);
-char* sysfs_read(char *path);
-void  sysfs_write(char *path,
-                  char *content);
+char *fs_mount_point(char *filesystem_type);
+char *strjin(char *w1, char *w2);
+bool isdir(char *path);
+bool isfile(char *path);
+char *sysfs_read(char *path);
+void sysfs_write(char *path, char *content);
 
 #endif // ifndef UTIL_H

src/main.cpp

@@ -1,83 +1,80 @@
+#include "androidusbisomanager.h"
 #include "configfsisomanager.h"
-#include <unistd.h>
 #include <stdio.h>
 #include <string.h>
+#include <unistd.h>
 
-int print_help()
-{
-    printf("Usage:\n");
-    printf("isodrive [FILE]... [OPTION]...\n");
-    printf("Mounts the given FILE as a bootable device using configfs.\n");
-    printf(
-      "Run without any arguments to unmount any mounted files and display this help message.\n\n");
+int print_help() {
+  printf("Usage:\n");
+  printf("isodrive [FILE]... [OPTION]...\n");
+  printf("Mounts the given FILE as a bootable device using configfs.\n");
+  printf("Run without any arguments to unmount any mounted files and display "
+         "this help message.\n\n");
 
-    printf("Optional arguments:\n");
-    printf("-rw\t Mounts the file in read write mode.\n");
-    printf("-cdrom\t Mounts the file as a cdrom.\n\n");
-    printf("UMOUNT:\n");
+  printf("Optional arguments:\n");
+  printf("-rw\t Mounts the file in read write mode.\n");
+  printf("-cdrom\t Mounts the file as a cdrom.\n\n");
+  printf("UMOUNT:\n");
 
-    return 1;
+  return 1;
 }
 
-int main(int argc, char *argv[])
-{
-  char *iso_target = (char *)"";
-  char *cdrom      = (char *)"0";
-  char *ro         = (char *)"1";
-
-  for (int i = 1; i < argc; i++)
-  {
-    if (strcmp(argv[i], "-rw") == 0)
-    {
-      ro = (char *)"0";
-    }
-    else if (strcmp(argv[i], "-cdrom") == 0)
-    {
-      cdrom = (char *)"1";
-    }
-    else if(strcmp(iso_target, "") == 0)
-    {
-      iso_target = argv[i];
-    }
-  }
-
-  if (argc == 1)
-  {
-    return print_help();
-  }
-
-  else if (!supported())
-  {
-    printf("Device does not support configfs usb gadget\n");
-    return 1;
-  }
-
-  else if (getuid() != 0)
-  {
-    printf("Permission denied\n");
-    return 1;
-  }
-
-  else
-  {
-    printf("MOUNT:\n");
-  }
-
-  if (strcmp(ro, "1") != 0 && strcmp(ro, "0") != 0)
-  {
+void configs(char *iso_target, char *cdrom, char *ro) {
+  if (strcmp(ro, "1") != 0 && strcmp(ro, "0") != 0) {
     printf("\nFaled to parse -rw argument. Defaulting to ro\n");
     printf("Check --help for more usage info\n");
     ro = (char *)"0";
   }
 
-  if (strcmp(cdrom, "1") != 0 && strcmp(cdrom, "0") != 0)
-  {
+  if (strcmp(cdrom, "1") != 0 && strcmp(cdrom, "0") != 0) {
     printf("\nFailed to parse -cdrom argument. Defaulting to disabled\n");
     printf("Check --help for more usage info\n");
     cdrom = (char *)"0";
   }
 
   mount_iso(iso_target, cdrom, ro);
+}
 
+void usb(char *iso_target) {
+  if (strcmp(iso_target, (char *)""))
+    usb_reset_iso();
+  else
+    usb_mount_iso(iso_target);
+}
+
+int main(int argc, char *argv[]) {
+  char *iso_target = (char *)"";
+  char *cdrom = (char *)"0";
+  char *ro = (char *)"1";
+
+  for (int i = 1; i < argc; i++) {
+    if (strcmp(argv[i], "-rw") == 0) {
+      ro = (char *)"0";
+    } else if (strcmp(argv[i], "-cdrom") == 0) {
+      cdrom = (char *)"1";
+    } else if (strcmp(iso_target, "") == 0) {
+      iso_target = argv[i];
+    }
+  }
+
+  if (argc == 1) {
+    return print_help();
+  }
+
+  else if (getuid() != 0) {
+    printf("Permission denied\n");
+    return 1;
+  }
+
+  else {
+    printf("MOUNT:\n");
+  }
+
+  if (usb_supported())
+    usb(iso_target);
+  else if (supported())
+    configs(iso_target, cdrom, ro);
+  else
+    printf("Device does not support isodrive\n");
   return 0;
 }

src/util.cpp

@@ -1,49 +1,43 @@
+#include <array>
+#include <cstdio>
+#include <dirent.h>
 #include <fcntl.h>
+#include <fstream>
+#include <memory>
 #include <mntent.h>
+#include <sstream>
 #include <stdio.h>
 #include <string.h>
 #include <sys/stat.h>
 #include <unistd.h>
-#include <fstream>
-#include <sstream>
-#include <array>
-#include <memory>
-#include <cstdio>
-#include <dirent.h>
 
-char* fs_mount_point(char *filesystem_type)
-{
+char *fs_mount_point(char *filesystem_type) {
   struct mntent *ent;
   FILE *mounts;
   char *mount_point = nullptr;
 
   mounts = setmntent("/proc/mounts", "r");
 
-  while (nullptr != (ent = getmntent(mounts)))
-  {
-    if (strcmp(ent->mnt_fsname, filesystem_type) == 0)
-    {
+  while (nullptr != (ent = getmntent(mounts))) {
+    if (strcmp(ent->mnt_fsname, filesystem_type) == 0) {
       mount_point = ent->mnt_dir;
       break;
     }
   }
 
   // Alternate search location on Android
-  if (mount_point == nullptr)
-  {
+  if (mount_point == nullptr) {
     const char *alt_usb_gadget = "/config/usb_gadget";
-    DIR *dir                   = opendir(alt_usb_gadget);
+    DIR *dir = opendir(alt_usb_gadget);
 
-    if (dir)
-    {
+    if (dir) {
       mount_point = (char *)"/config";
     }
   }
   return mount_point;
 }
 
-char* strjin(char *w1, char *w2)
-{
+char *strjin(char *w1, char *w2) {
   char *s = new char[strlen(w1) + strlen(w2) + 1];
 
   strcpy(s, w1);
@@ -51,38 +45,42 @@ char* strjin(char *w1, char *w2)
   return s;
 }
 
-bool isdir(char *path)
-{
+bool isdir(char *path) {
   struct stat sb;
 
   if (stat(path, &sb) == 0)
-    return true;
+    return S_ISDIR(sb.st_mode);
   else
     return false;
 }
 
-void sysfs_write(char *path, char *content)
-{
+bool isfile(char *path) {
+  struct stat sb;
+
+  if (stat(path, &sb) == 0)
+    return S_ISREG(sb.st_mode);
+  else
+    return false;
+}
+
+void sysfs_write(char *path, char *content) {
   printf("Write: %s -> %s\n", content, path);
   std::ofstream sysfsFile(path);
   sysfsFile << content << std::endl;
   sysfsFile.close();
 }
 
-char* sysfs_read(char *path)
-{
-  std::string   value;
+char *sysfs_read(char *path) {
+  std::string value;
   std::ifstream sysfsFile(path);
 
-  if (!sysfsFile.is_open())
-  {
+  if (!sysfsFile.is_open()) {
     return nullptr;
   }
   sysfsFile >> value;
   sysfsFile.close();
 
-  if (value.empty())
-  {
+  if (value.empty()) {
     return nullptr;
   }
   char *result = new char[value.length() + 1];