The levenshtein algorithm requires exception handling
when making dynamic allocations strings.

Signed-off-by: Paran Lee <p4ranlee@gmail.com>
---
 tools/perf/util/help-unknown-cmd.c |  6 +++++-
 tools/perf/util/levenshtein.c      | 16 ++++++++++------
 2 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/tools/perf/util/help-unknown-cmd.c b/tools/perf/util/help-unknown-cmd.c
index ab9e16123626..a70ef339b8af 100644
--- a/tools/perf/util/help-unknown-cmd.c
+++ b/tools/perf/util/help-unknown-cmd.c
@@ -74,10 +74,14 @@ const char *help_unknown_cmd(const char *cmd)
 
 	if (main_cmds.cnt) {
 		/* This reuses cmdname->len for similarity index */
-		for (i = 0; i < main_cmds.cnt; ++i)
+		for (i = 0; i < main_cmds.cnt; ++i) {
 			main_cmds.names[i]->len =
 				levenshtein(cmd, main_cmds.names[i]->name, 0, 2, 1, 4);
 
+			if(main_cmds.names[i]->len == -ENOMEM)
+				goto end;
+		}
+
 		qsort(main_cmds.names, main_cmds.cnt,
 		      sizeof(*main_cmds.names), levenshtein_compare);
 
diff --git a/tools/perf/util/levenshtein.c b/tools/perf/util/levenshtein.c
index 6a6712635aa4..0f0f244f142b 100644
--- a/tools/perf/util/levenshtein.c
+++ b/tools/perf/util/levenshtein.c
@@ -45,11 +45,17 @@ int levenshtein(const char *string1, const char *string2,
 		int w, int s, int a, int d)
 {
 	int len1 = strlen(string1), len2 = strlen(string2);
-	int *row0 = malloc(sizeof(int) * (len2 + 1));
-	int *row1 = malloc(sizeof(int) * (len2 + 1));
-	int *row2 = malloc(sizeof(int) * (len2 + 1));
+	int *rows, *row0, *row1, *row2;
 	int i, j;
 
+	rows = malloc(3 * sizeof(int) * (len2 + 1));
+	if(!rows)
+		return -ENOMEM;
+
+	row0 = &rows[0];
+	row1 = &rows[1];
+	row2 = &rows[2];
+
 	for (j = 0; j <= len2; j++)
 		row1[j] = j * a;
 	for (i = 0; i < len1; i++) {
@@ -79,9 +85,7 @@ int levenshtein(const char *string1, const char *string2,
 	}
 
 	i = row1[len2];
-	free(row0);
-	free(row1);
-	free(row2);
+	free(rows);
 
 	return i;
 }
-- 
2.34.1

23. 3. 15. 15:11에 Paran Lee 이(가) 쓴 글:
> The levenshtein algorithm requires exception handling
> when making dynamic allocations strings.

Sorry about that. I modified the code to make it behave incorrectly.

>  	int len1 = strlen(string1), len2 = strlen(string2);
> -	int *row0 = malloc(sizeof(int) * (len2 + 1));
> -	int *row1 = malloc(sizeof(int) * (len2 + 1));
> -	int *row2 = malloc(sizeof(int) * (len2 + 1));
> +	int *rows, *row0, *row1, *row2;
>  	int i, j;
>  
> +	rows = malloc(3 * sizeof(int) * (len2 + 1));
> +	if(!rows)
> +		return -ENOMEM;
> +
> +	row0 = &rows[0];
> +	row1 = &rows[1];
> +	row2 = &rows[2];
> +
>  	for (j = 0; j <= len2; j++)
>  		row1[j] = j * a;
>  	for (i = 0; i < len1; i++) {
> @@ -79,9 +85,7 @@ int levenshtein(const char *string1, const char *string2,
>  	}
>  
>  	i = row1[len2];
> -	free(row0);
> -	free(row1);
> -	free(row2);
> +	free(rows);
>  
>  	return i;
>  }

I'll think about it a bit more and figure out how to patch it up to make
it look better.

BR
Paran Lee