[PATCH] cmp: add support for -n

[Walter Lozano]

Add support to for "-n" to cmp in order to compare at most n bytes.

Signed-off-by: Walter Lozano <walter.lozano at collabora.com>
---
 editors/cmp.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/editors/cmp.c b/editors/cmp.c
index e106d814e..e219f589a 100644
--- a/editors/cmp.c
+++ b/editors/cmp.c
@@ -35,9 +35,10 @@ static const char fmt_differ[] ALIGN1 = "%s %s differ: char %"OFF_FMT"u, line %u
 // This fmt_l_opt uses gnu-isms.  SUSv3 would be "%.0s%.0s%"OFF_FMT"u %o %o\n"
 static const char fmt_l_opt[] ALIGN1 = "%.0s%.0s%"OFF_FMT"u %3o %3o\n";
 
-#define OPT_STR "sl"
+#define OPT_STR "sln:"
 #define CMP_OPT_s (1<<0)
 #define CMP_OPT_l (1<<1)
+#define CMP_OPT_n (1<<2)
 
 int cmp_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int cmp_main(int argc UNUSED_PARAM, char **argv)
@@ -50,13 +51,16 @@ int cmp_main(int argc UNUSED_PARAM, char **argv)
 	int c1, c2;
 	unsigned opt;
 	int retval = 0;
+	char * n_arg = NULL;
+	int max_count = -1;
 
 	opt = getopt32(argv, "^"
 			OPT_STR
 			"\0" "-1"
 			IF_DESKTOP(":?4")
 			IF_NOT_DESKTOP(":?2")
-			":l--s:s--l"
+			":l--s:s--l",
+			&n_arg
 	);
 	argv += optind;
 
@@ -90,6 +94,9 @@ int cmp_main(int argc UNUSED_PARAM, char **argv)
 	else
 		fmt = fmt_differ;
 
+	if (opt & CMP_OPT_n)
+		max_count = atoi(n_arg);
+
 	if (ENABLE_DESKTOP) {
 		while (skip1) { getc(fp1); skip1--; }
 		while (skip2) { getc(fp2); skip2--; }
@@ -133,7 +140,7 @@ int cmp_main(int argc UNUSED_PARAM, char **argv)
 		if (c1 == '\n') {
 			++line_pos;
 		}
-	} while (c1 != EOF);
+	} while (c1 != EOF && (max_count == -1 || max_count >= 0 && char_pos < max_count));
 
 	die_if_ferror(fp1, filename1);
 	die_if_ferror(fp2, filename2);
-- 
2.30.2