isodrive: remove getprop depedency, allow switching cdrom and ro modes

README.md

@@ -10,6 +10,10 @@
 
 * `sudo make install` (optional)
 
+usage:
+
+* `isodrive {iso} {cdrom[0/1]} {readonly[1/0]}`
+
 mount
 
 * `sudo isodrive /full/path/to/file.iso`
@@ -18,5 +22,13 @@ umount
 
 * `sudo isodrive`
 
+mount (as cdrom)
+
+* `sudo isodrive /full/path/to/file.iso 1 1`
+
+mount (as read write)
+
+* `sudo isodrive /full/path/to/file.iso 0 0`
+
 
 Inspired by https://github.com/fredldotme/ISODriveUT

src/configfsisomanager.cpp

@@ -8,12 +8,16 @@
 #include <unistd.h>
 #include <string.h>
 
+bool supported()
+{
+	return fs_mount_point((char*)"configfs") != nullptr;
+}
+
 char *get_gadget_root()
 {
-	char *configFsRoot = fs_mount_point("configfs");
-	char *usbGadgetRoot = strjin(configFsRoot, "/usb_gadget/"); 
+	char *configFsRoot = fs_mount_point((char*)"configfs");
+	char *usbGadgetRoot = strjin(configFsRoot, (char*)"/usb_gadget/"); 
 	char *gadgetRoot = nullptr;
-	char *udc = nullptr;
 
 	struct dirent *entry = nullptr;
 	DIR *dp = nullptr;
@@ -23,10 +27,12 @@ char *get_gadget_root()
 		{
 			if (entry->d_name[0] != '.')
 			{
-				gadgetRoot = strjin(usbGadgetRoot, entry->d_name);
-				udc = sysfs_read(strjin(gadgetRoot, "/UDC"));
-				if (strcmp(udc, getprop("sys.usb.controller")) == 0)
+				char *gadget = strjin(usbGadgetRoot, entry->d_name);
+				if (sysfs_read(strjin(gadget, (char*)"/UDC")) != nullptr)
+				{
+					gadgetRoot = gadget;
 					break;
+				}
 			}
 		}
 	return gadgetRoot;
@@ -35,7 +41,11 @@ char *get_gadget_root()
 char *get_config_root()
 {
 	char *gadgetRoot = get_gadget_root();
-	char *usbConfigRoot = strjin(gadgetRoot, "/configs/");
+	if (gadgetRoot == nullptr)
+	{
+		return nullptr;
+	}
+	char *usbConfigRoot = strjin(gadgetRoot, (char*)"/configs/");
 	char *configRoot = nullptr;
 
 	struct dirent *entry = nullptr;
@@ -53,48 +63,57 @@ char *get_config_root()
 	return configRoot;
 }
 
-void mount_iso(char *iso_path)
+void mount_iso(char *iso_path, char *cdrom, char *ro)
 {
 	char *gadgetRoot = get_gadget_root();
+	if (gadgetRoot == nullptr)
+	{
+		std::cerr << "No active gadget found" << std::endl;
+		return;
+	}
 	char *configRoot = get_config_root();
-
-	char *functionRoot = strjin(gadgetRoot, "/functions");
-	char *massStorageRoot = strjin(functionRoot, "/mass_storage.0");
-	char *lunRoot = strjin(massStorageRoot, "/lun.0");
+	char *udc = get_udc();
+	printf("udc found %s\n", udc);
+	char *functionRoot = strjin(gadgetRoot, (char*)"/functions");
+	char *massStorageRoot = strjin(functionRoot, (char*)"/mass_storage.0");
+	char *lunRoot = strjin(massStorageRoot, (char*)"/lun.0");
 	
-	char *stallFile = strjin(massStorageRoot, "/stall");
-	char *udcFile = strjin(gadgetRoot, "/UDC");
-	char *lunFile = strjin(lunRoot, "/file");
-	char *lunCdRom = strjin(lunRoot, "/cdrom");
-	char *lunRo = strjin(lunRoot, "/ro");
+	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");
 
-	reset_udc();
+	set_udc((char*)"", gadgetRoot);
 	
 	if (!isdir(massStorageRoot))
 	{
 		mkdir(massStorageRoot, S_IRWXU | S_IRWXG | S_IROTH | S_IXOTH);
 	}
-	if (!isdir(strjin(configRoot, "/mass_storage.0")))
+	if (!isdir(strjin(configRoot, (char*)"/mass_storage.0")))
 	{
-		symlink(massStorageRoot, strjin(configRoot, "/mass_storage.0"));
+		symlink(massStorageRoot, strjin(configRoot, (char*)"/mass_storage.0"));
 	}
 	sysfs_write(lunFile, iso_path);
-	sysfs_write(lunCdRom, "0");
-	sysfs_write(lunRo, "1");
+	sysfs_write(lunCdRom, cdrom);
+	sysfs_write(lunRo, ro);
 
-	set_udc();
+	set_udc(udc, gadgetRoot);
 }
 
-void reset_udc()
+void set_udc(char *udc, char *gadget)
+{
+	char *udcFile = strjin(gadget, (char*)"/UDC");
+	sysfs_write(udcFile, udc);
+}
+
+char *get_udc()
 {
 	char *gadget_root = get_gadget_root();
-	char *udcFile = strjin(gadget_root, "/UDC");
-	sysfs_write(udcFile, "");
-}
-
-void set_udc()
-{
-	char *gadget_root = get_gadget_root();
-	char *udcFile = strjin(gadget_root, "/UDC");
-	sysfs_write(udcFile, getprop("sys.usb.controller"));
+	if (gadget_root == nullptr)
+	{
+		return nullptr;
+	}
+	char *udcFile = strjin(gadget_root, (char*)"/UDC");
+	return sysfs_read(udcFile);
 }

src/include/configfsisomanager.h

@@ -1,11 +1,12 @@
 #ifndef CONFIGFSISOMANAGER_H
 #define CONFIGFSISOMANAGER_H
 
+bool supported();
 char *get_gadget_root();
 char *get_config_root();
 
-void mount_iso(char *iso_path);
-void set_udc();
-void reset_udc();
+void mount_iso(char *iso_path, char *cdrom, char *ro);
+void set_udc(char *udc, char *gadget);
+char *get_udc();
 
 #endif

src/include/util.h

@@ -6,8 +6,6 @@ char *strjin(char *w1, char *w2);
 bool isdir(char *path);
 char *sysfs_read(char *path);
 void sysfs_write(char *path, char *content);
-char *getprop(char *key);
-void trim(char *s);
 
 #endif
 

src/main.cpp

@@ -5,6 +5,14 @@
 
 int main(int argc, char* argv[]){
 	char *iso_target = argv[1];
+	char *cdrom = (char*)"0";
+	char *ro = (char*)"1";
+
+	if (!supported())
+	{
+		std::cerr << "Device does not support configfs usb gadget" << std::endl;
+		return 1;
+	}
 	if (getuid() != 0)
 	{
 		std::cerr << "Permission denied" << std::endl;
@@ -14,5 +22,17 @@ int main(int argc, char* argv[]){
 	{
 		iso_target = "";
 	}
-	mount_iso(iso_target);
+
+	if (argc > 2)
+	{
+		cdrom = argv[2];
+	}
+	if (argc > 3)
+	{
+		ro = argv[3];
+	}
+
+	mount_iso(iso_target, cdrom, ro);
+
+	return 0;
 }

src/util.cpp

@@ -11,24 +11,13 @@
 #include <memory>
 #include <cstdio>
 
-// https://stackoverflow.com/a/123724
-void trim(char *s)
-{
-	char * p = s;
-	int l = strlen(p);
-	while(isspace(p[l - 1])) p[--l] = 0;
-	while(* p && isspace(* p)) ++p, --l;
-
-	memmove(s, p, l + 1);
-}
-
 char *fs_mount_point(char *filesystem_type) {
 	struct mntent *ent;
 	FILE *mounts;
-	char *mount_point = NULL;
+	char *mount_point = nullptr;
 
 	mounts = setmntent("/proc/mounts", "r");
-	while (NULL != (ent = getmntent(mounts))) {
+	while (nullptr != (ent = getmntent(mounts))) {
 		if (strcmp(ent->mnt_fsname, filesystem_type) == 0)
 		{
 			mount_point = ent->mnt_dir;
@@ -73,21 +62,12 @@ char *sysfs_read(char *path)
 	}
 	sysfsFile >> value;
 	sysfsFile.close();
+	if (value.empty())
+	{
+		return nullptr;
+	}
 	char *result = new char[value.length() + 1];
 	strcpy(result, value.c_str());
 	return result;
 	
 }
-
-char *getprop(char *key)
-{
-	std::array<char, 128> buffer;
-	char *value;
-	char *cmd = strjin("getprop ", key);
-	std::unique_ptr<FILE, decltype(&pclose)> pipe(popen(cmd, "r"), pclose);
-	while (fgets(buffer.data(), buffer.size(), pipe.get()) != nullptr)
-		value = strjin("", buffer.data());
-	trim(value);
-	return value;
-
-}