[bootlin/training-materials updates] master: serial-{get, reset}-counter: Print errno string upon error (d8271829)

[Miquel Raynal]

Repository : https://github.com/bootlin/training-materials
On branch  : master
Link       : https://github.com/bootlin/training-materials/commit/d8271829b68e2ecf4bbdb5e92bae4421a9b0e3b9

>---------------------------------------------------------------

commit d8271829b68e2ecf4bbdb5e92bae4421a9b0e3b9
Author: Miquel Raynal <miquel.raynal at bootlin.com>
Date:   Tue Jun 22 11:56:54 2021 +0200

    serial-{get,reset}-counter: Print errno string upon error
    
    Signed-off-by: Miquel Raynal <miquel.raynal at bootlin.com>


>---------------------------------------------------------------

d8271829b68e2ecf4bbdb5e92bae4421a9b0e3b9
 .../linux-kernel/modules/nfsroot/root/serial/serial-get-counter.c | 8 ++++++--
 .../modules/nfsroot/root/serial/serial-reset-counter.c            | 8 ++++++--
 2 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/lab-data/linux-kernel/modules/nfsroot/root/serial/serial-get-counter.c b/lab-data/linux-kernel/modules/nfsroot/root/serial/serial-get-counter.c
index 7cf799ed..36b4a73f 100644
--- a/lab-data/linux-kernel/modules/nfsroot/root/serial/serial-get-counter.c
+++ b/lab-data/linux-kernel/modules/nfsroot/root/serial/serial-get-counter.c
@@ -4,6 +4,8 @@
 #include <sys/stat.h>
 #include <fcntl.h>
 #include <stdlib.h>
+#include <string.h>
+#include <errno.h>
 
 #define SERIAL_RESET_COUNTER 0
 #define SERIAL_GET_COUNTER 1
@@ -20,13 +22,15 @@ int main(int argc, char *argv[])
 
 	fd = open(argv[1], O_RDWR);
 	if (fd < 0) {
-		fprintf(stderr, "Unable to open %s\n", argv[1]);
+		fprintf(stderr, "Unable to open %s: %s\n", argv[1],
+			strerror(errno));
 		exit(1);
 	}
 
 	ret = ioctl(fd, SERIAL_GET_COUNTER, &val);
 	if (ret < 0) {
-		fprintf(stderr, "Unable to get counter\n");
+		fprintf(stderr, "Unable to get counter: %s\n",
+			strerror(errno));
 		exit(1);
 	}
 
diff --git a/lab-data/linux-kernel/modules/nfsroot/root/serial/serial-reset-counter.c b/lab-data/linux-kernel/modules/nfsroot/root/serial/serial-reset-counter.c
index 6e5e8267..aff144e0 100644
--- a/lab-data/linux-kernel/modules/nfsroot/root/serial/serial-reset-counter.c
+++ b/lab-data/linux-kernel/modules/nfsroot/root/serial/serial-reset-counter.c
@@ -4,6 +4,8 @@
 #include <sys/stat.h>
 #include <fcntl.h>
 #include <stdlib.h>
+#include <string.h>
+#include <errno.h>
 
 #define SERIAL_RESET_COUNTER 0
 #define SERIAL_GET_COUNTER 1
@@ -19,13 +21,15 @@ int main(int argc, char *argv[])
 
 	fd = open(argv[1], O_RDWR);
 	if (fd < 0) {
-		fprintf(stderr, "Unable to open %s\n", argv[1]);
+		fprintf(stderr, "Unable to open %s: %s\n", argv[1],
+			strerror(errno));
 		exit(1);
 	}
 
 	ret = ioctl(fd, SERIAL_RESET_COUNTER);
 	if (ret < 0) {
-		fprintf(stderr, "Unable to reset counter\n");
+		fprintf(stderr, "Unable to reset counter: %s\n",
+			strerror(errno));
 		exit(1);
 	}