From f9dba1be6f2f717d76f49433d3554eadededf591 Mon Sep 17 00:00:00 2001
From: Eugene Syromyatnikov <evgsyr@gmail.com>
Date: Tue, 4 Sep 2018 19:20:36 +0200
Subject: [PATCH] count: add ability to sort on errors field

For completeness.

* count.c (error_cmp): New function.
(set_sortby): Add sort keys for errors field.
* strace.1.in (.SH OPTIONS) <-S>: Document it.
* strace.c (usage): Likewise.
* tests/strace-S.test: Check it.

Co-Authored-by: Dmitry V. Levin <ldv@altlinux.org>
---
 count.c             | 13 +++++++++++++
 strace.1.in         |  1 +
 strace.c            |  3 ++-
 tests/strace-S.test |  4 ++++
 4 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/count.c b/count.c
index 57af23f8..a1cdf823 100644
--- a/count.c
+++ b/count.c
@@ -86,6 +86,17 @@ count_cmp(const void *a, const void *b)
 	return (m < n) ? 1 : (m > n) ? -1 : 0;
 }
 
+static int
+error_cmp(const void *a, const void *b)
+{
+	const unsigned int *a_int = a;
+	const unsigned int *b_int = b;
+	unsigned int m = counts[*a_int].errors;
+	unsigned int n = counts[*b_int].errors;
+
+	return (m < n) ? 1 : (m > n) ? -1 : 0;
+}
+
 static int (*sortfun)(const void *, const void *);
 
 void
@@ -100,6 +111,8 @@ set_sortby(const char *sortby)
 		{ time_cmp,	"total_time" },
 		{ count_cmp,	"calls" },
 		{ count_cmp,	"count" },
+		{ error_cmp,	"error" },
+		{ error_cmp,	"errors" },
 		{ syscall_cmp,	"name" },
 		{ syscall_cmp,	"syscall" },
 		{ syscall_cmp,	"syscall_name" },
diff --git a/strace.1.in b/strace.1.in
index 1437bb72..3ac46bac 100644
--- a/strace.1.in
+++ b/strace.1.in
@@ -796,6 +796,7 @@ Sort the output of the histogram printed by the
 option by the specified criterion.  Legal values are
 .BR time " (or " time_total " or " total_time ),
 .BR calls " (or " count ),
+.BR errors " (or " error ),
 .BR name " (or " syscall " or " syscall_name ),
 and
 .BR nothing " (or " none );
diff --git a/strace.c b/strace.c
index 59097e14..8d9e465c 100644
--- a/strace.c
+++ b/strace.c
@@ -276,7 +276,8 @@ Statistics:\n\
                  summary\n\
   -C             like -c but also print regular output\n\
   -O overhead    set overhead for tracing syscalls to OVERHEAD usecs\n\
-  -S sortby      sort syscall counts by: time, calls, name, nothing (default %s)\n\
+  -S sortby      sort syscall counts by: time, calls, errors, name, nothing\n\
+                 (default %s)\n\
   -w             summarise syscall latency (default is system time)\n\
 \n\
 Filtering:\n\
diff --git a/tests/strace-S.test b/tests/strace-S.test
index 25f095e2..55a01c49 100755
--- a/tests/strace-S.test
+++ b/tests/strace-S.test
@@ -43,3 +43,7 @@ for s in name syscall syscall_name; do
 	test_c "$s" '' \
 		'/^[[:space:]]+[0-9]/ s/^'"$c$c$c$c"'([[:space:]]+[0-9]+)?'"$c"'$/\6/p'
 done
+for s in error errors; do
+	test_c "$s" '-n -r' \
+		'/^[[:space:]]+[0-9]/ s/^'"$c$c$c$c"'([[:space:]]+([0-9]+))?'"$c"'$/\6/p'
+done
-- 
2.40.0