Add --usb_path option to htool

examples/htool.c

@@ -1677,6 +1677,8 @@ static const struct htool_param GLOBAL_FLAGS[] = {
              "'1s', '1500ms')."},
     {HTOOL_FLAG_VALUE, .name = "usb_retry_delay", .default_value = "50ms",
      .desc = "Delay between USB open retries (e.g., '50ms', '10000us')."},
+    {HTOOL_FLAG_VALUE, .name = "usb_path", .default_value = "",
+     .desc = "Glob Pattern for matching the USB device path."},
     {HTOOL_FLAG_BOOL, .name = "version", .default_value = "false",
      .desc = "Print htool version."},
     {}};

examples/htool_usb.c

@@ -16,6 +16,7 @@
 
 #include <ctype.h>
 #include <errno.h>
+#include <fnmatch.h>
 #include <libusb.h>
 #include <stdbool.h>
 #include <stddef.h>
@@ -75,6 +76,7 @@ static void print_device(void* cb_param, libusb_device* dev,
   }
 
   libusb_device_handle* dev_handle;
+  char sys_path[256];
   rv = libusb_open(dev, &dev_handle);
   if (rv != LIBUSB_SUCCESS) {
     fprintf(stderr, " (unable to open device: %s)", libusb_strerror(rv));
@@ -95,6 +97,12 @@ static void print_device(void* cb_param, libusb_device* dev,
 cleanup2:
   libusb_close(dev_handle);
 cleanup:
+  rv = libhoth_get_usb_sys_path(dev, sys_path, sizeof(sys_path));
+  if (rv != LIBUSB_SUCCESS) {
+    fprintf(stderr, " (unable to get sys path: %s)", libusb_strerror(rv));
+  } else {
+    fprintf(stderr, " (%s)", sys_path);
+  }
   fprintf(stderr, "\n");
 }
 
@@ -256,6 +264,20 @@ bool filter_by_usb_product_substr(
   return strstr(product_name, usb_product_substr) != NULL;
 }
 
+static bool filter_by_usb_path_glob(
+    void* cb_param, libusb_device* dev,
+    const struct libusb_device_descriptor* descriptor) {
+  const char* glob_pattern = (const char*)cb_param;
+  char sys_path[256];
+  int rv = libhoth_get_usb_sys_path(dev, sys_path, sizeof(sys_path));
+  if (rv != LIBUSB_SUCCESS) {
+    fprintf(stderr, "libhoth_get_usb_sys_path failed: %s\n",
+            libusb_strerror(rv));
+    return false;
+  }
+  return fnmatch(glob_pattern, sys_path, 0) == 0;
+}
+
 bool filter_allow_all(void* cb_param, libusb_device* dev,
                       const struct libusb_device_descriptor* descriptor) {
   return true;
@@ -272,10 +294,13 @@ libusb_device* htool_libusb_device(void) {
   }
   const char* usb_loc_str;
   const char* usb_product_substr;
+  const char* usb_path_glob_str;
   int rv =
       htool_get_param_string(htool_global_flags(), "usb_loc", &usb_loc_str) ||
       htool_get_param_string(htool_global_flags(), "usb_product",
-                             &usb_product_substr);
+                             &usb_product_substr) ||
+      htool_get_param_string(htool_global_flags(), "usb_path",
+                             &usb_path_glob_str);
   if (rv) {
     return NULL;
   }
@@ -292,6 +317,10 @@ libusb_device* htool_libusb_device(void) {
     return select_device(ctx, filter_by_usb_product_substr,
                          (void*)usb_product_substr);
   }
+  if (strlen(usb_path_glob_str) > 0) {
+    return select_device(ctx, filter_by_usb_path_glob,
+                         (void*)usb_path_glob_str);
+  }
   return select_device(ctx, filter_allow_all, NULL);
 }
 

transports/libhoth_usb.c

@@ -15,6 +15,8 @@
 #include "transports/libhoth_usb.h"
 
 #include <libusb.h>
+#include <limits.h>
+#include <stdio.h>
 #include <stdlib.h>
 
 #include "transports/libhoth_device.h"
@@ -348,3 +350,39 @@ int libhoth_usb_get_device(libusb_context* ctx,
   libusb_free_device_list(device, /*unref_devices=*/1);
   return found_device ? LIBHOTH_OK : LIBHOTH_ERR_INTERFACE_NOT_FOUND;
 }
+
+int libhoth_get_usb_sys_path(libusb_device* dev, char* path, size_t path_len) {
+  struct libhoth_usb_loc loc;
+  char bus_port_path[PATH_MAX];
+  int ret;
+
+  if (dev == NULL || path == NULL || path_len == 0) {
+    return LIBUSB_ERROR_INVALID_PARAM;
+  }
+
+  ret = libhoth_get_usb_loc(dev, &loc);
+  if (ret) {
+    return ret;
+  }
+
+  ret = snprintf(bus_port_path, sizeof(bus_port_path),
+                 "/sys/bus/usb/devices/%d-%d", loc.bus, loc.ports[0]);
+  if (ret < 0 || (size_t)ret >= sizeof(bus_port_path)) {
+    return LIBUSB_ERROR_OVERFLOW;
+  }
+
+  for (int i = 1; i < loc.num_ports; i++) {
+    size_t current_len = strlen(bus_port_path);
+    ret = snprintf(bus_port_path + current_len,
+                   sizeof(bus_port_path) - current_len, ".%d", loc.ports[i]);
+    if (ret < 0 || current_len + (size_t)ret >= sizeof(bus_port_path)) {
+      return LIBUSB_ERROR_OVERFLOW;
+    }
+  }
+
+  if (realpath(bus_port_path, path) == NULL) {
+    return LIBUSB_ERROR_OTHER;
+  }
+
+  return LIBUSB_SUCCESS;
+}

transports/libhoth_usb.h

@@ -63,6 +63,10 @@ int libhoth_usb_get_device(libusb_context* ctx,
                            libusb_device** out);
 int libhoth_get_usb_loc(libusb_device* dev, struct libhoth_usb_loc* result);
 
+// Returns the sysfs path for the given libusb_device.
+// Returns LIBUSB_SUCCESS on success, or a libusb error code on failure.
+int libhoth_get_usb_sys_path(libusb_device* dev, char* path, size_t path_len);
+
 #ifdef __cplusplus
 }
 #endif