dev-libs/libusb/files/0005-CHROMIUM-linux_usbfs-parse-devpath-in-sysfs-to-get-p.patch

From 928485b96863d8273b84f3fbce823c4de943aa4e Mon Sep 17 00:00:00 2001
From: Dmitry Torokhov <dtor@chromium.org>
Date: Fri, 7 Jun 2019 14:11:31 -0700
Subject: [PATCH 5/6] CHROMIUM: linux_usbfs: parse devpath in sysfs to get port
 numbers

On linux, when sysfs is available, we can parse "devpath" attribute to
get port data. This is helpful when we do not have full USB device tree
present in libsysfs.

Signed-off-by: Dmitry Torokhov <dtor@chromium.org>
---
 libusb/os/linux_usbfs.c | 65 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 65 insertions(+)

diff --git a/libusb/os/linux_usbfs.c b/libusb/os/linux_usbfs.c
index 9461f565..3e8177ac 100644
--- a/libusb/os/linux_usbfs.c
+++ b/libusb/os/linux_usbfs.c
@@ -92,6 +92,11 @@ static unsigned int max_iso_packet_len = 0;
 /* is sysfs available (mounted) ? */
 static int sysfs_available = -1;
 
+/* Linux v2.6.33 (commit 9af23624ae2c7978313b46e58fdc4ca5d8b799f5) adds
+ * devpath sysfs attribute containing list of ports on the way to the
+ * root port the device is connected to, so from then on we can use it. */
+static int sysfs_has_devpath = -1;
+
 /* how many times have we initted (and not exited) ? */
 static int init_count = 0;
 
@@ -386,6 +391,11 @@ static int op_init(struct libusb_context *ctx)
 
 	usbi_dbg(ctx, "max iso packet length is (likely) %u bytes", max_iso_packet_len);
 
+	if (sysfs_has_devpath == -1) {
+		/* sysfs has devpath since Linux 2.6.33 */
+		sysfs_has_devpath = kernel_version_ge(&kversion,2,6,33);
+	}
+
 	if (sysfs_available == -1) {
 		struct statfs statfsbuf;
 
@@ -396,6 +406,7 @@ static int op_init(struct libusb_context *ctx)
 		} else {
 			usbi_warn(ctx, "sysfs not mounted");
 			sysfs_available = 0;
+			sysfs_has_devpath = 0;
 		}
 	}
 
@@ -1027,6 +1038,56 @@ static int device_speed_from_kernel(struct libusb_context *ctx, int speed)
 	}
 }
 
+static int device_ports_from_sysfs(struct libusb_context *ctx,
+	struct linux_device_priv *priv, const char *sysfs_dir)
+{
+	char buf[LINE_MAX];
+	char *str, *rest, *port;
+	int fd;
+	FILE *f;
+	int count;
+
+	fd = open_sysfs_attr(ctx, sysfs_dir, "devpath");
+	if (fd < 0)
+		return fd;
+
+	f = fdopen(fd, "r");
+	if (!f) {
+		usbi_err(ctx, "fdopen failed errno=%d", errno);
+		close(fd);
+		return LIBUSB_ERROR_OTHER;
+	}
+
+	str = fgets(buf, sizeof(buf), f);
+	fclose(f);
+
+	if (!str)
+		return LIBUSB_ERROR_IO;
+
+	/* Count number of "dots" delimiting port numbers. We do not care if
+	 * we get malformed path with multiple consecutive dots, as it will
+	 * simply result in allocating a few extra bytes for the ports
+	 * array. */
+	count = 1; /* We should have at least one port */
+	while (*str != 0) {
+		if (*str == '.')
+			count++;
+		str++;
+	}
+
+	priv->ports = malloc(count);
+	if (!priv->ports)
+		return LIBUSB_ERROR_NO_MEM;
+
+	for (port = strtok_r(buf, ".\n", &rest);
+	     port != NULL;
+	     port = strtok_r(NULL, ".\n", &rest)) {
+		priv->ports[priv->num_ports++] = atoi(port);
+	}
+
+	return LIBUSB_SUCCESS;
+}
+
 static int initialize_from_sysfs(struct libusb_device *dev, const char *sysfs_dir)
 {
 	struct linux_device_priv *priv = usbi_get_device_priv(dev);
@@ -1053,6 +1114,10 @@ static int initialize_from_sysfs(struct libusb_device *dev, const char *sysfs_di
 	/* sysfs descriptors are in bus-endian format */
 	usbi_localize_device_descriptor(&dev->device_descriptor);
 
+	/* try filling port info to the best of our abilities */
+	if (sysfs_has_devpath)
+		device_ports_from_sysfs(ctx, priv, sysfs_dir);
+
 	return LIBUSB_SUCCESS;
 }
 
-- 
2.38.1.584.g0f3c55d4c2-goog