Catch typos in .Sh names; suggested by jmc@.

I'm using a very simple, linear time / zero space fuzzy string
matching heuristic rather than a full Levenshtein metric, to keep
the code both simple and fast.

diff --git a/usr.bin/mandoc/mandoc.1 b/usr.bin/mandoc/mandoc.1
index 2df74ea..931aabf 100644 (file)
--- a/usr.bin/mandoc/mandoc.1
+++ b/usr.bin/mandoc/mandoc.1
@@ -1,4 +1,4 @@
-.\"    $OpenBSD: mandoc.1,v 1.130 2017/06/25 07:23:53 bentley Exp $
+.\"    $OpenBSD: mandoc.1,v 1.131 2017/06/25 17:42:37 schwarze Exp $
 .\"
 .\" Copyright (c) 2009, 2010, 2011 Kristaps Dzonsons <kristaps@bsd.lv>
 .\" Copyright (c) 2012, 2014-2017 Ingo Schwarze <schwarze@openbsd.org>
@@ -857,6 +857,11 @@ A single manual page contains two copies of the RCS identifier for
 the same operating system.
 Consider deleting the later instance and moving the first one up
 to the top of the page.
+.It Sy "typo in section name"
+.Pq mdoc
+Fuzzy string matching revealed that the argument of an
+.Ic \&Sh
+macro is similar, but not identical to a standard section name.
 .It Sy "useless macro"
 .Pq mdoc
 A

diff --git a/usr.bin/mandoc/mandoc.h b/usr.bin/mandoc/mandoc.h
index 3ffdb5f..9515490 100644 (file)
--- a/usr.bin/mandoc/mandoc.h
+++ b/usr.bin/mandoc/mandoc.h
@@ -1,4 +1,4 @@
-/*     $OpenBSD: mandoc.h,v 1.177 2017/06/24 18:58:09 schwarze Exp $ */
+/*     $OpenBSD: mandoc.h,v 1.178 2017/06/25 17:42:37 schwarze Exp $ */
 /*
  * Copyright (c) 2010, 2011, 2014 Kristaps Dzonsons <kristaps@bsd.lv>
  * Copyright (c) 2010-2017 Ingo Schwarze <schwarze@openbsd.org>
@@ -56,6 +56,7 @@ enum  mandocerr {
 
        MANDOCERR_DATE_LEGACY, /* legacy man(7) date format: Dd ... */
        MANDOCERR_RCS_REP, /* duplicate RCS id: ... */
+       MANDOCERR_SEC_TYPO,  /* typo in section name: Sh ... */
        MANDOCERR_MACRO_USELESS, /* useless macro: macro */
        MANDOCERR_BX, /* consider using OS macro: macro */
        MANDOCERR_ER_ORDER, /* errnos out of order: Er ... */

diff --git a/usr.bin/mandoc/mdoc_validate.c b/usr.bin/mandoc/mdoc_validate.c
index 46f0bae..0b45e79 100644 (file)
--- a/usr.bin/mandoc/mdoc_validate.c
+++ b/usr.bin/mandoc/mdoc_validate.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: mdoc_validate.c,v 1.257 2017/06/24 18:58:09 schwarze Exp $ */
+/*     $OpenBSD: mdoc_validate.c,v 1.258 2017/06/25 17:42:37 schwarze Exp $ */
 /*
  * Copyright (c) 2008-2012 Kristaps Dzonsons <kristaps@bsd.lv>
  * Copyright (c) 2010-2017 Ingo Schwarze <schwarze@openbsd.org>
@@ -58,6 +58,7 @@ static        void     check_toptext(struct roff_man *, int, int, const char *);
 static int      child_an(const struct roff_node *);
 static size_t          macro2len(enum roff_tok);
 static void     rewrite_macro2len(struct roff_man *, char **);
+static int      similar(const char *, const char *);
 
 static void     post_an(POST_ARGS);
 static void     post_an_norm(POST_ARGS);
@@ -2133,11 +2134,54 @@ post_sh_authors(POST_ARGS)
                    mdoc->last->line, mdoc->last->pos, NULL);
 }
 
+/*
+ * Return an upper bound for the string distance (allowing
+ * transpositions).  Not a full Levenshtein implementation
+ * because Levenshtein is quadratic in the string length
+ * and this function is called for every standard name,
+ * so the check for each custom name would be cubic.
+ * The following crude heuristics is linear, resulting
+ * in quadratic behaviour for checking one custom name,
+ * which does not cause measurable slowdown.
+ */
+static int
+similar(const char *s1, const char *s2)
+{
+       const int       maxdist = 3;
+       int             dist = 0;
+
+       while (s1[0] != '\0' && s2[0] != '\0') {
+               if (s1[0] == s2[0]) {
+                       s1++;
+                       s2++;
+                       continue;
+               }
+               if (++dist > maxdist)
+                       return INT_MAX;
+               if (s1[1] == s2[1]) {  /* replacement */
+                       s1++;
+                       s2++;
+               } else if (s1[0] == s2[1] && s1[1] == s2[0]) {
+                       s1 += 2;        /* transposition */
+                       s2 += 2;
+               } else if (s1[0] == s2[1])  /* insertion */
+                       s2++;
+               else if (s1[1] == s2[0])  /* deletion */
+                       s1++;
+               else
+                       return INT_MAX;
+       }
+       dist += strlen(s1) + strlen(s2);
+       return dist > maxdist ? INT_MAX : dist;
+}
+
 static void
 post_sh_head(POST_ARGS)
 {
        struct roff_node        *nch;
        const char              *goodsec;
+       const char *const       *testsec;
+       int                      dist, mindist;
        enum roff_sec            sec;
 
        /*
@@ -2175,8 +2219,25 @@ post_sh_head(POST_ARGS)
 
        /* We don't care about custom sections after this. */
 
-       if (sec == SEC_CUSTOM)
+       if (sec == SEC_CUSTOM) {
+               if ((nch = mdoc->last->child) == NULL ||
+                   nch->type != ROFFT_TEXT || nch->next != NULL)
+                       return;
+               goodsec = NULL;
+               mindist = INT_MAX;
+               for (testsec = secnames + 1; *testsec != NULL; testsec++) {
+                       dist = similar(nch->string, *testsec);
+                       if (dist < mindist) {
+                               goodsec = *testsec;
+                               mindist = dist;
+                       }
+               }
+               if (goodsec != NULL)
+                       mandoc_vmsg(MANDOCERR_SEC_TYPO, mdoc->parse,
+                           nch->line, nch->pos, "Sh %s instead of %s",
+                           nch->string, goodsec);
                return;
+       }
 
        /*
         * Check whether our non-custom section is being repeated or is

diff --git a/usr.bin/mandoc/read.c b/usr.bin/mandoc/read.c
index 61466c5..55f24b3 100644 (file)
--- a/usr.bin/mandoc/read.c
+++ b/usr.bin/mandoc/read.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: read.c,v 1.153 2017/06/24 18:58:09 schwarze Exp $ */
+/*     $OpenBSD: read.c,v 1.154 2017/06/25 17:42:37 schwarze Exp $ */
 /*
  * Copyright (c) 2008, 2009, 2010, 2011 Kristaps Dzonsons <kristaps@bsd.lv>
  * Copyright (c) 2010-2017 Ingo Schwarze <schwarze@openbsd.org>
@@ -94,6 +94,7 @@ static        const char * const      mandocerrs[MANDOCERR_MAX] = {
 
        "legacy man(7) date format",
        "duplicate RCS id",
+       "typo in section name",
        "useless macro",
        "consider using OS macro",
        "errnos out of order",