Support mounting by device file on non Linux OS

- it`s possible to supply device path sscanf format string
  at configure stage. FreeBSD`s one supplied
- it`s possible to use <bus>/<device> format as a fallback option

configure.ac

@@ -49,6 +49,35 @@ AC_DEFINE_UNQUOTED(
     [Directory for temporary files]
 )
 
+dnl Configurable USB device path
+case $os_name in
+    Linux)
+        usb_devpath="/dev/bus/usb/%u/%u"
+        ;;
+    FreeBSD)
+        usb_devpath="/dev/usb/%u.%u.0"
+        ;;
+    *)
+        usb_devpath="%u/%u"
+        ;;
+esac
+AC_ARG_WITH(
+    [usbdev],
+    [AS_HELP_STRING([--with-usbdev=FILE],
+        [USB device path. String in sscanf() format])],
+    [usb_devpath="$withval"],
+    []
+)
+if test "x$usb_devpath" != "x%u/%u"; then
+    AC_DEFINE_UNQUOTED(
+        [USB_DEVPATH],
+        ["$usb_devpath"],
+        [USB device path format string]
+    )
+else
+    AC_MSG_WARN([Mounting by real device path is not supported. Fallback to <bus>/<device> notation]);
+fi
+
 AC_OUTPUT([
     makefile
     src/makefile
@@ -62,6 +91,7 @@ AC_MSG_NOTICE([
 
     prefix: ${prefix}
     tmpdir: ${tmpdir}
+    usbdev: ${usb_devpath}
 
     Now type 'make' to build $PACKAGE
 ])

src/simple-mtpfs-mtp-device.cpp

@@ -20,6 +20,7 @@
 #include <sstream>
 #include <vector>
 #include <cstring>
+#include <cstdint>
 #include <cstdlib>
 extern "C" {
 #  include <unistd.h>
@@ -120,14 +121,14 @@ bool MTPDevice::connect_priv(int dev_no, const std::string &dev_file)
 
 #ifndef HAVE_LIBUSB1
     if (!dev_file.empty()) {
-        std::string dev_path(smtpfs_realpath(dev_file));
+        uint8_t bnum, dnum;
+        dev_no = raw_devices_cnt;
 
-        for (dev_no = 0; dev_no < raw_devices_cnt; ++dev_no) {
-            std::string usb_devpath = smtpfs_usb_devpath(
-               raw_devices[dev_no].bus_location, raw_devices[dev_no].devnum);
-            if (usb_devpath == dev_path)
-                break;
-        }
+        if (smtpfs_usb_devpath(dev_file, &bnum, &dnum))
+            for (dev_no = 0; dev_no < raw_devices_cnt; ++dev_no)
+                if (bnum == raw_devices[dev_no].bus_location &&
+                    dnum == raw_devices[dev_no].devnum)
+                    break;
 
         if (dev_no == raw_devices_cnt) {
             logerr("Can not open such device '", dev_file, "'.\n");
@@ -648,7 +649,6 @@ bool MTPDevice::listDevices(bool verbose, const std::string &dev_file)
 {
     int raw_devices_cnt;
     LIBMTP_raw_device_t *raw_devices;
-    std::string dev_path;
 
     // Do not output LIBMTP debug stuff
     StreamHelper::off();
@@ -662,17 +662,15 @@ bool MTPDevice::listDevices(bool verbose, const std::string &dev_file)
         return false;
     }
 
-    if (!dev_file.empty()) {
-        dev_path = smtpfs_realpath(dev_file);
-        if (dev_path.empty()) {
-            std::cerr << "Can not open such device '" << dev_file << "'.\n";
-            return false;
-        }
+    uint8_t bnum, dnum;
+    if (!dev_file.empty() && !smtpfs_usb_devpath(dev_file, &bnum, &dnum)) {
+        std::cerr << "Can not open such device '" << dev_file << "'.\n";
+        return false;
     }
 
     for (int i = 0; i < raw_devices_cnt; ++i) {
         if (!dev_file.empty() &&
-            dev_path != smtpfs_usb_devpath(raw_devices[i].bus_location, raw_devices[i].devnum))
+            !(bnum == raw_devices[i].bus_location && dnum == raw_devices[i].devnum))
             continue;
         std::cout << i + 1 << ": "
             << (raw_devices[i].device_entry.vendor ? raw_devices[i].device_entry.vendor : "Unknown vendor ")

src/simple-mtpfs-util.cpp

@@ -16,6 +16,7 @@
 * ***** END LICENSE BLOCK ***** */
 
 #include <config.h>
+#include <cstdio>
 #include <cstring>
 #ifdef HAVE_LIBUSB1
 #  include <iomanip>
@@ -78,9 +79,6 @@ void StreamHelper::off()
     s_enabled = true;
 }
 
-const char smtpfs_path_delimiter = '/';
-const std::string smtpfs_devbususb = "/dev/bus/usb/";
-
 std::string smtpfs_dirname(const std::string &path)
 {
     char *str = strdup(path.c_str());
@@ -154,15 +152,23 @@ bool smtpfs_remove_dir(const std::string &dirname)
     return true;
 }
 
-std::string smtpfs_usb_devpath(uint8_t bnum, uint8_t dnum)
+bool smtpfs_usb_devpath(const std::string &path, uint8_t *bnum, uint8_t *dnum)
 {
-    std::stringstream ss;
-    ss << smtpfs_devbususb
-       << std::setw(3) << std::setfill('0')
-       << static_cast<uint16_t>(bnum) << "/"
-       << std::setw(3) << std::setfill('0')
-       << static_cast<uint16_t>(dnum);
-    return ss.str();
+    unsigned int bus, dev;
+#ifdef USB_DEVPATH
+    std::string realpath(smtpfs_realpath(path));
+    if (realpath.empty() ||
+        sscanf(realpath.c_str(), USB_DEVPATH, &bus, &dev) != 2)
+#endif
+        if (sscanf(path.c_str(), "%u/%u", &bus, &dev) != 2)
+            return false;
+
+    if (bus > 255 || dev > 255)
+        return false;
+
+    *bnum = bus;
+    *dnum = dev;
+    return true;
 }
 
 #ifdef HAVE_LIBUSB1
@@ -198,10 +204,13 @@ LIBMTP_raw_device_t *smtpfs_raw_device_new_priv(libusb_device *usb_device)
 
 LIBMTP_raw_device_t *smtpfs_raw_device_new(const std::string &path)
 {
+    uint8_t bnum, dnum;
+    if (!smtpfs_usb_devpath(path, &bnum, &dnum))
+        return nullptr;
+
     if (libusb_init(NULL) != 0)
         return nullptr;
 
-    std::string dev_path(smtpfs_realpath(path));
     libusb_device **dev_list;
     ssize_t num_devs = libusb_get_device_list(NULL, &dev_list);
     if (!num_devs) {
@@ -212,9 +221,8 @@ LIBMTP_raw_device_t *smtpfs_raw_device_new(const std::string &path)
     libusb_device *dev = nullptr;
     for (auto i = 0; i < num_devs; ++i) {
         dev = dev_list[i];
-        uint8_t bnum = libusb_get_bus_number(dev_list[i]);
-        uint8_t dnum = libusb_get_device_address(dev_list[i]);
-        if (smtpfs_usb_devpath(bnum, dnum) == dev_path)
+        if (bnum == libusb_get_bus_number(dev_list[i]) &&
+            dnum == libusb_get_device_address(dev_list[i]))
             break;
         dev = nullptr;
     }

src/simple-mtpfs-util.h

@@ -44,11 +44,11 @@ std::string smtpfs_dirname(const std::string &path);
 std::string smtpfs_basename(const std::string &path);
 std::string smtpfs_realpath(const std::string &path);
 std::string smtpfs_get_tmpdir();
-std::string smtpfs_usb_devpath(uint8_t bnum, uint8_t dnum);
 
 bool smtpfs_create_dir(const std::string &dirname);
 bool smtpfs_remove_dir(const std::string &dirname);
 bool smtpfs_check_dir(const std::string &path);
+bool smtpfs_usb_devpath(const std::string &path, uint8_t *bnum, uint8_t *dnum);
 
 #ifdef HAVE_LIBUSB1
 LIBMTP_raw_device_t *smtpfs_raw_device_new(const std::string &path);