sh: improve command completion

When multiple matches are found, we keep the provided string on the
input line and print unique matches as suggestions.

But the multiple matches might be the same command found in different
directories, so we should deduplicate the matches first and then decide
whether to autocomplete the command or not, based on the number of
unique matches.

1 files changed, 19 insertions, 21 deletions

diff --git a/bin/sh/histedit.c b/bin/sh/histedit.c
index b680a99c4ace..1a1e11e6f885 100644
--- a/bin/sh/histedit.c
+++ b/bin/sh/histedit.c
@@ -590,7 +590,7 @@ static char
 	char *free_path = NULL, *path;
 	const char *dirname;
 	char **matches = NULL;
-	size_t i = 0, size = 16, j, k;
+	size_t i = 0, size = 16, uniq;
 	size_t curpos = end - start;
 
 	if (start > 0 || memchr("/.~", text[0], 3) != NULL)
@@ -639,6 +639,21 @@ static char
 	}
 out:
 	free(free_path);
+	if (i == 0) {
+		free(matches);
+		return (NULL);
+	}
+	uniq = 1;
+	if (i > 1) {
+		qsort_s(matches + 1, i, sizeof(matches[0]), comparator,
+			(void *)(intptr_t)curpos);
+		for (size_t k = 2; k <= i; k++)
+			if (strcmp(matches[uniq] + curpos, matches[k] + curpos) == 0)
+				free(matches[k]);
+			else
+				matches[++uniq] = matches[k];
+	}
+	matches[uniq + 1] = NULL;
 	/*
 	 * matches[0] is special: it's not a real matching file name but a common
 	 * prefix for all matching names. It can't be null, unlike any other
@@ -648,30 +663,13 @@ out:
 	 * string in matches[0] which is the reason to copy the full name of the
 	 * only match.
 	 */
-	if (i == 0) {
-		free(matches);
-		return (NULL);
-	} else if (i == 1) {
-		matches[0] = strdup(matches[1]);
-		matches[2] = NULL;
-		if (matches[0] != NULL)
-			return (matches);
-	} else
-		matches[0] = strdup(text);
+	matches[0] = strdup(uniq == 1 ? matches[1] : text);
 	if (matches[0] == NULL) {
-		for (j = 1; j <= i; j++)
-			free(matches[j]);
+		for (size_t k = 1; k <= uniq; k++)
+			free(matches[k]);
 		free(matches);
 		return (NULL);
 	}
-	qsort_s(matches + 1, i, sizeof(matches[0]), comparator,
-		(void *)(intptr_t)curpos);
-	for (j = 1, k = 2; k <= i; k++)
-		if (strcmp(matches[j] + curpos, matches[k] + curpos) == 0)
-			free(matches[k]);
-		else
-			matches[++j] = matches[k];
-	matches[j + 1] = NULL;
 	return (matches);
 }