libusb(3): Implement libusb_init_context() and the needed structures and definitions.

Differential Revision:	https://reviews.freebsd.org/D38212
MFC after:	1 week
Sponsored by:	NVIDIA Networking

lib/libusb/Makefile

@@ -68,6 +68,7 @@ CFLAGS+=	-I ../../sys
 # LibUSB v1.0
 MLINKS += libusb.3 libusb_get_version.3
 MLINKS += libusb.3 libusb_init.3
+MLINKS += libusb.3 libusb_init_context.3
 MLINKS += libusb.3 libusb_exit.3
 MLINKS += libusb.3 libusb_has_capability.3
 MLINKS += libusb.3 libusb_strerror.3

lib/libusb/libusb.3

@@ -24,7 +24,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd October, 2, 2022
+.Dd January, 26, 2023
 .Dt LIBUSB 3
 .Os
 .Sh NAME
@@ -47,11 +47,26 @@ This function returns version information about LibUSB.
 .Pp
 .Ft int
 .Fn libusb_init "libusb_context **ctx"
-This function initialises libusb.
-It must be called at the beginning
-of the program, before other libusb routines are used.
-This function returns 0 on success or LIBUSB_ERROR on
-failure.
+Call this function before any other libusb v1.0 API function, to
+initialise a valid libusb v1.0 context.
+If the
+.Fa ctx
+argument is non-NULL, a pointer to the libusb context is stored at
+the given location.
+This function returns 0 upon success or LIBUSB_ERROR on failure.
+.Pp
+.Ft int
+.Fn libusb_init_context "libusb_context **ctx" "const struct libusb_init_option []" "int num_options"
+Call this function before any other libusb v1.0 API function, to
+initialise a valid libusb v1.0 context.
+If the
+.Fa ctx
+argument is non-NULL, a pointer to the libusb context is stored at
+the given location.
+Additional options, like the USB debug level, may be given using the
+second and third argument.
+If no options are needed, simply use libusb_init().
+This function returns 0 upon success or a LIBUSB_ERROR value on failure.
 .Pp
 .Ft void
 .Fn libusb_exit "libusb_context *ctx"

lib/libusb/libusb.h

@@ -266,6 +266,14 @@ typedef enum {
 	LIBUSB_HOTPLUG_EVENT_DEVICE_LEFT = 2,
 } libusb_hotplug_event;
 
+enum libusb_option {
+	LIBUSB_OPTION_LOG_LEVEL = 0,
+	LIBUSB_OPTION_USE_USBDK = 1,
+	LIBUSB_OPTION_NO_DEVICE_DISCOVERY = 2,
+	LIBUSB_OPTION_WEAK_AUTHORITY = 2,
+	LIBUSB_OPTION_MAX = 3,
+};
+
 /* libusb structures */
 
 struct libusb_context;
@@ -288,6 +296,13 @@ struct libusb_version {
 	const char *describe;
 };
 
+struct libusb_init_option {
+	enum libusb_option option;
+	union {
+		int64_t ival;
+	} value;
+};
+
 typedef struct libusb_context libusb_context;
 typedef struct libusb_device libusb_device;
 typedef struct libusb_device_handle libusb_device_handle;
@@ -465,6 +480,7 @@ const struct libusb_version *libusb_get_version(void);
 const char *libusb_strerror(int code);
 const char *libusb_error_name(int code);
 int	libusb_init(libusb_context ** context);
+int	libusb_init_context(libusb_context **, const struct libusb_init_option [], int num_options);
 void	libusb_exit(struct libusb_context *ctx);
 int	libusb_has_capability(uint32_t capability);
 

lib/libusb/libusb10.c

@@ -3,7 +3,7 @@
  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
  *
  * Copyright (c) 2009 Sylvestre Gallon. All rights reserved.
- * Copyright (c) 2009 Hans Petter Selasky. All rights reserved.
+ * Copyright (c) 2009-2023 Hans Petter Selasky
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -135,12 +135,22 @@ libusb_interrupt_event_handler(libusb_context *ctx)
 
 int
 libusb_init(libusb_context **context)
+{
+	return (libusb_init_context(context, NULL, 0));
+}
+
+int
+libusb_init_context(libusb_context **context,
+    const struct libusb_init_option option[], int num_options)
 {
 	struct libusb_context *ctx;
 	pthread_condattr_t attr;
 	char *debug, *ep;
 	int ret;
 
+	if (num_options < 0)
+		return (LIBUSB_ERROR_INVALID_PARAM);
+
 	ctx = malloc(sizeof(*ctx));
 	if (!ctx)
 		return (LIBUSB_ERROR_INVALID_PARAM);
@@ -150,8 +160,9 @@ libusb_init(libusb_context **context)
 	debug = getenv("LIBUSB_DEBUG");
 	if (debug != NULL) {
 		/*
-		 * If LIBUSB_DEBUG is set, we'll honor that and use it to
-		 * override libusb_set_debug calls.
+		 * If LIBUSB_DEBUG is set, we'll honor that first and
+		 * use it to override any future libusb_set_debug()
+		 * calls or init options.
 		 */
 		errno = 0;
 		ctx->debug = strtol(debug, &ep, 10);
@@ -166,7 +177,24 @@ libusb_init(libusb_context **context)
 			 */
 			ctx->debug = 0;
 		}
+	} else {
+		/*
+		 * If the LIBUSB_OPTION_LOG_LEVEL is set, honor that.
+		 */
+		for (int i = 0; i != num_options; i++) {
+			if (option[i].option != LIBUSB_OPTION_LOG_LEVEL)
+				continue;
+
+			ctx->debug = (int)option[i].value.ival;
+			if ((int64_t)ctx->debug == option[i].value.ival) {
+				ctx->debug_fixed = 1;
+			} else {
+				free(ctx);
+				return (LIBUSB_ERROR_INVALID_PARAM);
 			}
+		}
+	}
+
 	TAILQ_INIT(&ctx->pollfds);
 	TAILQ_INIT(&ctx->tr_done);
 	TAILQ_INIT(&ctx->hotplug_cbh);