Improve friendliness of --cmdhelp

If no match is found, print the closest. Quite handy when
you can't quite remember the exact option name.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

diff --git a/parse.c b/parse.c
index ee7ddf29d4605cc29d6aaabdd43420ad868cfde1..79565754b804ff12880071912b4d1305b15f7c08 100644 (file)
--- a/parse.c
+++ b/parse.c
@@ -437,7 +437,46 @@ int parse_option(const char *opt, struct fio_option *options, void *data)
        return 1;
 }
 
-int show_cmd_help(struct fio_option *options, const char *name)
+/*
+ * Option match, levenshtein distance. Handy for not quite remembering what
+ * the option name is.
+ */
+static int string_distance(const char *s1, const char *s2)
+{
+       unsigned int s1_len = strlen(s1);
+       unsigned int s2_len = strlen(s2);
+       unsigned int *p, *q, *r;
+       unsigned int i, j;
+
+       p = malloc(sizeof(unsigned int) * (s2_len + 1));
+       q = malloc(sizeof(unsigned int) * (s2_len + 1));
+
+       p[0] = 0;
+       for (i = 1; i <= s2_len; i++)
+               p[i] = p[i - 1] + 1;
+
+       for (i = 1; i <= s1_len; i++) {
+               q[0] = p[0] + 1;
+               for (j = 1; j <= s2_len; j++) {
+                       unsigned int sub = p[j - 1];
+
+                       if (s1[i - 1] != s2[j - 1])
+                               sub++;
+
+                       q[j] = min(p[j] + 1, min(q[j - 1] + 1, sub));
+               }
+               r = p;
+               p = q;
+               q = r;
+       }
+
+       i = p[s2_len];
+       free(p);
+       free(q);
+       return i;
+}
+
+static void show_option_help(struct fio_option *o)
 {
        const char *typehelp[] = {
                "string (opt=bla)",
@@ -450,18 +489,41 @@ int show_cmd_help(struct fio_option *options, const char *name)
                "boolean value (opt=1)",
                "no argument (opt)",
        };
-       struct fio_option *o;
+
+       printf("%20s: %s\n", "type", typehelp[o->type]);
+       printf("%20s: %s\n", "default", o->def ? o->def : "no default");
+       show_option_range(o);
+       show_option_values(o);
+}
+
+int show_cmd_help(struct fio_option *options, const char *name)
+{
+       struct fio_option *o, *closest;
+       unsigned int best_dist;
        int found = 0;
        int show_all = 0;
 
        if (!name || !strcmp(name, "all"))
                show_all = 1;
 
+       closest = NULL;
+       best_dist = -1;
        for (o = &options[0]; o->name; o++) {
                int match = 0;
 
-               if (name && !strcmp(name, o->name))
-                       match = 1;
+               if (name) {
+                       if (!strcmp(name, o->name))
+                               match = 1;
+                       else {
+                               unsigned int dist;
+
+                               dist = string_distance(name, o->name);
+                               if (dist < best_dist) {
+                                       best_dist = dist;
+                                       closest = o;
+                               }
+                       }
+               }
 
                if (show_all || match) {
                        found = 1;
@@ -473,16 +535,20 @@ int show_cmd_help(struct fio_option *options, const char *name)
                if (!match)
                        continue;
 
-               printf("%20s: %s\n", "type", typehelp[o->type]);
-               printf("%20s: %s\n", "default", o->def ? o->def : "no default");
-               show_option_range(o);
-               show_option_values(o);
+               show_option_help(o);
        }
 
        if (found)
                return 0;
 
-       printf("No such command: %s\n", name);
+       printf("No such command: %s", name);
+       if (closest) {
+               printf(" - showing closest match\n");
+               printf("%20s: %s\n", closest->name, closest->help);
+               show_option_help(closest);
+       } else
+               printf("\n");
+
        return 1;
 }
 

diff --git a/parse.h b/parse.h
index 214e56b4769d9c5a5faa3b2589e6b85f5e81b3ad..1a71864fa12157715cdb2fd03567a5f1eb0808bc 100644 (file)
--- a/parse.h
+++ b/parse.h
@@ -67,4 +67,11 @@ typedef int (fio_opt_str_set_fn)(void *);
 
 #define td_var(start, offset)  ((void *) start + (offset))
 
+#ifndef min
+#define min(a, b)      ((a) < (b) ? (a) : (b))
+#endif
+#ifndef max
+#define max(a, b)      ((a) > (b) ? (a) : (b))
+#endif
+
 #endif