linux-kernel - [PATCH] hcidump: add support for time64 based libc

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Message-Id: <20200110204903.3495832-1-arnd@arndb.de>
Date:   Fri, 10 Jan 2020 21:49:03 +0100
From:   Arnd Bergmann <arnd@...db.de>
To:     Bluez mailing list <linux-bluetooth@...r.kernel.org>
Cc:     y2038 Mailman List <y2038@...ts.linaro.org>,
        Johan Hedberg <johan.hedberg@...il.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Deepa Dinamani <deepa.kernel@...il.com>,
        Rich Felker <dalias@...c.org>, Guy Harris <guy@...m.mit.edu>,
        Arnd Bergmann <arnd@...db.de>
Subject: [PATCH] hcidump: add support for time64 based libc

musl is moving to a default of 64-bit time_t on all architectures,
glibc will follow later. This breaks reading timestamps through cmsg
data with the HCI_TIME_STAMP socket option.

Change both copies of hcidump to work on all architectures.  This also
fixes x32, which has never worked, and carefully avoids breaking sparc64,
which is another special case.

I have only compiled this on one architecture, please at least test
it to ensure there are no regressions. The toolchain binaries from
http://musl.cc/ should allow testing with a 64-bit time_t, but it may
be hard to build all the dependencies first.

libpcap has the same bug and needs a similar fix to work on future
32-bit Linux systems. Everything else apparently uses the generic
SO_TIMESTAMP timestamps, which work correctly when using new enough
kernels with a time64 libc.

Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 monitor/hcidump.c | 32 +++++++++++++++++++++++++++++++-
 tools/hcidump.c   | 33 +++++++++++++++++++++++++++++++--
 2 files changed, 62 insertions(+), 3 deletions(-)

diff --git a/monitor/hcidump.c b/monitor/hcidump.c
index 8b6f846d3..6d2330287 100644
--- a/monitor/hcidump.c
+++ b/monitor/hcidump.c
@@ -107,6 +107,36 @@ static int open_hci_dev(uint16_t index)
 	return fd;
 }
 
+static struct timeval hci_tstamp_read(void *data)
+{
+	struct timeval tv;
+
+	/*
+	 * On 64-bit architectures, the data matches the timeval
+	 * format. Note that on sparc64 this is different from
+	 * all others.
+	 */
+	if (sizeof(long) == 8) {
+		memcpy(&tv, data, sizeof(tv));
+	}
+
+	/*
+	 * On 32-bit architectures, the timeval definition may
+	 * use 32-bit or 64-bit members depending on the C
+	 * library and architecture.
+	 * The cmsg data however always contains a pair of
+	 * 32-bit values. Interpret as unsigned to make it work
+	 * past y2038.
+	 */
+	if (sizeof(long) == 4) {
+		unsigned int *stamp = data;
+		tv.tv_sec = stamp[0];
+		tv.tv_usec = stamp[1];
+	}
+
+	return tv;
+}
+
 static void device_callback(int fd, uint32_t events, void *user_data)
 {
 	struct hcidump_data *data = user_data;
@@ -150,7 +180,7 @@ static void device_callback(int fd, uint32_t events, void *user_data)
 				memcpy(&dir, CMSG_DATA(cmsg), sizeof(dir));
 				break;
 			case HCI_CMSG_TSTAMP:
-				memcpy(&ctv, CMSG_DATA(cmsg), sizeof(ctv));
+				ctv = hci_tstamp_read(CMSG_DATA(cmsg));
 				tv = &ctv;
 				break;
 			}
diff --git a/tools/hcidump.c b/tools/hcidump.c
index 33d429b6c..be14d0930 100644
--- a/tools/hcidump.c
+++ b/tools/hcidump.c
@@ -136,6 +136,36 @@ static inline int write_n(int fd, char *buf, int len)
 	return t;
 }
 
+static struct timeval hci_tstamp_read(void *data)
+{
+	struct timeval tv;
+
+	/*
+	 * On 64-bit architectures, the data matches the timeval
+	 * format. Note that on sparc64 this is different from
+	 * all others.
+	 */
+	if (sizeof(long) == 8) {
+		memcpy(&tv, data, sizeof(tv));
+	}
+
+	/*
+	 * On 32-bit architectures, the timeval definition may
+	 * use 32-bit or 64-bit members depending on the C
+	 * library and architecture.
+	 * The cmsg data however always contains a pair of
+	 * 32-bit values. Interpret as unsigned to make it work
+	 * past y2038.
+	 */
+	if (sizeof(long) == 4) {
+		unsigned int *stamp = data;
+		tv.tv_sec = stamp[0];
+		tv.tv_usec = stamp[1];
+	}
+
+	return tv;
+}
+
 static int process_frames(int dev, int sock, int fd, unsigned long flags)
 {
 	struct cmsghdr *cmsg;
@@ -230,8 +260,7 @@ static int process_frames(int dev, int sock, int fd, unsigned long flags)
 				frm.in = (uint8_t) dir;
 				break;
 			case HCI_CMSG_TSTAMP:
-				memcpy(&frm.ts, CMSG_DATA(cmsg),
-						sizeof(struct timeval));
+				frm.ts = hci_tstamp_read(CMSG_DATA(cmsg));
 				break;
 			}
 			cmsg = CMSG_NXTHDR(&msg, cmsg);
-- 
2.20.0