From c486d01297a366aae8dcd3f715d0bfd8b995949b Mon Sep 17 00:00:00 2001
From: Chris Dickens <christopher.a.dickens@gmail.com>
Date: Mon, 8 Feb 2021 09:27:20 -0800
Subject: [PATCH 1/2] linux_usbfs: Accept sysfs attributes not terminated with
 newline

Benjamin Berg reports that some CI systems that simulate sysfs devices
are causing libusb to report errors because such systems are not
conforming to the sysfs pattern of terminating attribute values with a
newline character. Reduce the severity of encountering such
non-conforming attibute values from an error that prevents enumeration
to a warning message.

Closes #857

Signed-off-by: Chris Dickens <christopher.a.dickens@gmail.com>
---
 libusb/os/linux_usbfs.c | 12 +++++++-----
 libusb/version_nano.h   |  2 +-
 2 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/libusb/os/linux_usbfs.c b/libusb/os/linux_usbfs.c
index 4882c0f..ebf8cfe 100644
--- a/libusb/os/linux_usbfs.c
+++ b/libusb/os/linux_usbfs.c
@@ -505,7 +505,7 @@ static int read_sysfs_attr(struct libusb_context *ctx,
 	if (fd < 0)
 		return fd;
 
-	r = read(fd, buf, sizeof(buf));
+	r = read(fd, buf, sizeof(buf) - 1);
 	if (r < 0) {
 		r = errno;
 		close(fd);
@@ -523,16 +523,18 @@ static int read_sysfs_attr(struct libusb_context *ctx,
 		return 0;
 	}
 
-	/* The kernel does *not* NULL-terminate the string, but every attribute
+	/* The kernel does *not* NUL-terminate the string, but every attribute
 	 * should be terminated with a newline character. */
 	if (!isdigit(buf[0])) {
 		usbi_err(ctx, "attribute %s doesn't have numeric value?", attr);
 		return LIBUSB_ERROR_IO;
 	} else if (buf[r - 1] != '\n') {
-		usbi_err(ctx, "attribute %s doesn't end with newline?", attr);
-		return LIBUSB_ERROR_IO;
+		usbi_warn(ctx, "attribute %s doesn't end with newline?", attr);
+	} else {
+		/* Remove the terminating newline character */
+		r--;
 	}
-	buf[r - 1] = '\0';
+	buf[r] = '\0';
 
 	errno = 0;
 	value = strtol(buf, &endptr, 10);
-- 
2.29.2