during prioritization for man(1), correctly extract the section name

from the file name extension of gzipped manual page files; bug found
on Alpine Linux by Soeren Tempel <soeren at soeren hyphen tempel dot net>,
who also tested this patch

diff --git a/usr.bin/mandoc/main.c b/usr.bin/mandoc/main.c
index 6432280..a6c7341 100644 (file)
--- a/usr.bin/mandoc/main.c
+++ b/usr.bin/mandoc/main.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: main.c,v 1.259 2021/09/04 12:47:04 schwarze Exp $ */
+/* $OpenBSD: main.c,v 1.260 2021/09/04 22:37:26 schwarze Exp $ */
 /*
  * Copyright (c) 2010-2012, 2014-2021 Ingo Schwarze <schwarze@openbsd.org>
  * Copyright (c) 2008-2012 Kristaps Dzonsons <kristaps@bsd.lv>
@@ -131,7 +131,7 @@ main(int argc, char *argv[])
        struct mparse   *mp;            /* Opaque parser object. */
        const char      *conf_file;     /* -C: alternate config file. */
        const char      *os_s;          /* -I: Operating system for display. */
-       const char      *progname, *sec;
+       const char      *progname, *sec, *ep;
        char            *defpaths;      /* -M: override manpaths. */
        char            *auxpaths;      /* -m: additional manpaths. */
        char            *oarg;          /* -O: output option string. */
@@ -514,11 +514,16 @@ main(int argc, char *argv[])
                                        sec++; /* Prefer without suffix. */
                                if (*sec != '/')
                                        prio += 10; /* Wrong dir name. */
-                               if (search.sec != NULL &&
-                                   (strlen(sec) <= ssz  + 3 ||
-                                    strcmp(sec + strlen(sec) - ssz,
-                                     search.sec) != 0))
-                                       prio += 20; /* Wrong file ext. */
+                               if (search.sec != NULL) {
+                                       ep = strchr(sec, '\0');
+                                       if (ep - sec > 3 &&
+                                           strncmp(ep - 3, ".gz", 3) == 0)
+                                               ep -= 3;
+                                       if ((size_t)(ep - sec) < ssz + 3 ||
+                                           strncmp(ep - ssz, search.sec,
+                                            ssz) != 0)      /* Wrong file */
+                                               prio += 20;  /* extension. */
+                               }
                                if (prio >= best_prio)
                                        continue;
                                best_prio = prio;