sort: fix -kN,M handling (was including last separator into the comparison)

Testcase:

$ printf '%s\n' a/a:a a:b | sort -t: -k1,1
a:b
a/a:a

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

2 files changed, 16 insertions, 4 deletions

diff --git a/coreutils/sort.c b/coreutils/sort.c
index 1cb4c3e3f..36f02543b 100644
--- a/coreutils/sort.c
+++ b/coreutils/sort.c
@@ -25,14 +25,14 @@
 //usage:     "\n        -f      Ignore case"
 //usage:     "\n        -g      General numerical sort"
 //usage:     "\n        -i      Ignore unprintable characters"
-//usage:     "\n        -k      Sort key"
 //usage:     "\n        -M      Sort month"
 //usage:        )
+//-h, --human-numeric-sort: compare human readable numbers (e.g., 2K 1G)
 //usage:     "\n        -n      Sort numbers"
 //usage:        IF_FEATURE_SORT_BIG(
 //usage:     "\n        -o      Output to file"
-//usage:     "\n        -k      Sort by key"
-//usage:     "\n        -t CHAR Key separator"
+//usage:     "\n        -t CHAR Field separator"
+//usage:     "\n        -k N[,M] Sort by Nth field"
 //usage:        )
 //usage:     "\n        -r      Reverse sort order"
 //usage:        IF_FEATURE_SORT_BIG(
@@ -143,6 +143,9 @@ static char *get_key(char *str, struct sort_key *key, int flags)
                                         }
                                 }
                         }
+                        /* Remove last delim: "abc:def:" => "abc:def" */
+                        if (key_separator && j && end != 0)
+                                end--;
                 }
                 if (!j) start = end;
         }
@@ -163,7 +166,8 @@ static char *get_key(char *str, struct sort_key *key, int flags)
                 if (start > len) start = len;
         }
         /* Make the copy */
-        if (end < start) end = start;
+        if (end < start)
+                end = start;
         str = xstrndup(str+start, end-start);
         /* Handle -d */
         if (flags & FLAG_d) {
diff --git a/testsuite/sort.tests b/testsuite/sort.tests
index 68fa3e405..c4b223464 100755
--- a/testsuite/sort.tests
+++ b/testsuite/sort.tests
@@ -98,6 +98,14 @@ testing "sort with non-default leading delim 3" "sort -n -k3 -t/ input" "\
 //b/1
 " ""
 
+testing "sort with non-default leading delim 4" "sort -t: -k1,1 input" "\
+a:b
+a/a:a
+" "\
+a/a:a
+a:b
+" ""
+
 testing "sort -u should consider field only when discarding" "sort -u -k2 input" "\
 a c
 " "\