win32: case-sensitivity in tab completion

The tab-completion code treated all matches as case-insensitive
because that's how Microsoft Windows handles filenames.

This is now inadequate, as shell builtins, functions and aliases
are case sensitive.

Modify the treatment of case-sensitivity in tab completion:

- Track whether each potential match is case-insensitive (filename)
  or case-sensitive (shell builtin, function or alias).

- When comparing matches use a case-insensitive comparison if either
  value is a filename.  Otherwise use a case-sensitive comparison.

Adds 64 bytes.

3 files changed, 62 insertions, 44 deletions

diff --git a/include/mingw.h b/include/mingw.h
index 8dd905c23..3cf0526f2 100644
--- a/include/mingw.h
+++ b/include/mingw.h
@@ -545,7 +545,6 @@ int kill_SIGTERM_by_handle(HANDLE process);
 
 char *is_prefixed_with_case(const char *string, const char *key) FAST_FUNC;
 char *is_suffixed_with_case(const char *string, const char *key) FAST_FUNC;
-void qsort_string_vector_case(char **sv, unsigned count) FAST_FUNC;
 
 #define VT_OUTPUT       1
 #define VT_INPUT        2
diff --git a/libbb/bb_qsort.c b/libbb/bb_qsort.c
index 7afddf468..505045533 100644
--- a/libbb/bb_qsort.c
+++ b/libbb/bb_qsort.c
@@ -17,15 +17,3 @@ void FAST_FUNC qsort_string_vector(char **sv, unsigned count)
 {
         qsort(sv, count, sizeof(char*), bb_pstrcmp);
 }
-
-#if ENABLE_PLATFORM_MINGW32
-static int bb_pstrcasecmp(const void *a, const void *b)
-{
-        return strcasecmp(*(char**)a, *(char**)b);
-}
-
-void FAST_FUNC qsort_string_vector_case(char **sv, unsigned count)
-{
-        qsort(sv, count, sizeof(char*), bb_pstrcasecmp);
-}
-#endif
diff --git a/libbb/lineedit.c b/libbb/lineedit.c
index 3abc97503..a6884c7e0 100644
--- a/libbb/lineedit.c
+++ b/libbb/lineedit.c
@@ -743,14 +743,6 @@ static void input_forward(void)
 //Also, perhaps "foo b<TAB> needs to complete to "foo bar" <cursor>,
 //not "foo bar <cursor>...
 
-# if ENABLE_PLATFORM_MINGW32
-/* use case-insensitive comparisons for filenames */
-#  define is_prefixed_with(s, k) is_prefixed_with_case(s, k)
-#  define qsort_string_vector(s, c) qsort_string_vector_case(s, c)
-#  define strcmp(s, t) strcasecmp(s, t)
-#  define strncmp(s, t, n) strncasecmp(s, t, n)
-# endif
-
 static void free_tab_completion_data(void)
 {
         if (matches) {
@@ -761,8 +753,15 @@ static void free_tab_completion_data(void)
         }
 }
 
-static void add_match(char *matched)
+#if !ENABLE_PLATFORM_MINGW32
+# define add_match(m, s) add_match(m)
+#endif
+
+static void add_match(char *matched, int sensitive)
 {
+# if ENABLE_PLATFORM_MINGW32
+        size_t len;
+# endif
         unsigned char *p = (unsigned char*)matched;
         while (*p) {
                 /* ESC attack fix: drop any string with control chars */
@@ -779,11 +778,26 @@ static void add_match(char *matched)
                 }
                 p++;
         }
+# if ENABLE_PLATFORM_MINGW32
+        /* The case-sensitivity flag is stored after NUL terminator */
+        len = strlen(matched);
+        matched = xrealloc(matched, len + 2);
+        matched[len + 1] = sensitive;
+# endif
         matches = xrealloc_vector(matches, 4, num_matches);
         matches[num_matches] = matched;
         num_matches++;
 }
 
+# if ENABLE_PLATFORM_MINGW32
+static int is_case_sensitive(const char *p)
+{
+        while (*p++)
+                ;
+        return *p;
+}
+# endif
+
 # if ENABLE_FEATURE_USERNAME_COMPLETION
 /* Replace "~user/..." with "/homedir/...".
  * The parameter is malloced, free it or return it
@@ -835,7 +849,7 @@ static NOINLINE unsigned complete_username(const char *ud)
         while ((pw = getpwent()) != NULL) {
                 /* Null usernames should result in all users as possible completions. */
                 if (/* !ud[0] || */ is_prefixed_with(pw->pw_name, ud)) {
-                        add_match(xasprintf("~%s/", pw->pw_name));
+                        add_match(xasprintf("~%s/", pw->pw_name), TRUE);
                 }
         }
         endpwent(); /* don't keep password file open */
@@ -944,7 +958,7 @@ static NOINLINE unsigned complete_cmd_dir_file(const char *command, int type)
                 const char *p = applet_names;
                 while (*p) {
                         if (strncmp(basecmd, p, baselen) == 0 && is_applet_preferred(p))
-                                add_match(xstrdup(p));
+                                add_match(xstrdup(p), TRUE);
                         while (*p++ != '\0')
                                 continue;
                 }
@@ -957,7 +971,7 @@ static NOINLINE unsigned complete_cmd_dir_file(const char *command, int type)
                                 if (!b)
                                         break;
                                 if (strncmp(basecmd, b, baselen) == 0)
-                                        add_match(xstrdup(b));
+                                        add_match(xstrdup(b), TRUE);
                         }
                 }
 # endif
@@ -991,7 +1005,11 @@ static NOINLINE unsigned complete_cmd_dir_file(const char *command, int type)
                         if (!basecmd[0] && DOT_OR_DOTDOT(name_found))
                                 continue;
                         /* match? */
+# if ENABLE_PLATFORM_MINGW32
+                        if (strncasecmp(basecmd, name_found, baselen) != 0)
+# else
                         if (strncmp(basecmd, name_found, baselen) != 0)
+# endif
                                 continue; /* no */
 
                         found = concat_path_file(lpath, name_found);
@@ -1025,7 +1043,7 @@ static NOINLINE unsigned complete_cmd_dir_file(const char *command, int type)
                                         goto cont;
                         }
                         /* add it to the list */
-                        add_match(found);
+                        add_match(found, FALSE);
                         continue;
  cont:
                         free(found);
@@ -1297,11 +1315,17 @@ static NOINLINE void input_tab(smallint *lastWasTab)
         size_t len_found;
         /* Length of string used for matching */
         unsigned match_pfx_len = match_pfx_len;
-#if ENABLE_PLATFORM_MINGW32
+# if ENABLE_PLATFORM_MINGW32
+        int chosen_index = 0;
+        int chosen_sens = FALSE;
         unsigned orig_pfx_len;
         char *target;
         const char *source;
-#endif
+#  define first_match 0
+# else
+#  define chosen_index 0
+#  define first_match 1
+# endif
         int find_type;
 # if ENABLE_UNICODE_SUPPORT
         /* cursor pos in command converted to multibyte form */
@@ -1366,9 +1390,9 @@ static NOINLINE void input_tab(smallint *lastWasTab)
         {
                 const char *e = match_buf + strlen(match_buf);
                 const char *s = e - match_pfx_len;
-#if ENABLE_PLATFORM_MINGW32
+# if ENABLE_PLATFORM_MINGW32
                 orig_pfx_len = match_pfx_len;
-#endif
+# endif
                 while (s < e)
                         if (is_special_char(*s++))
                                 match_pfx_len++;
@@ -1399,15 +1423,30 @@ static NOINLINE void input_tab(smallint *lastWasTab)
                 if (!matches)
                         goto ret; /* no matches at all */
                 /* Find common prefix */
-                chosen_match = xstrdup(matches[0]);
+# if ENABLE_PLATFORM_MINGW32
+                /* Any comparison involving a filename must be case-insensitive.
+                 * The chosen match should be case-sensitive, if possible */
+                for (unsigned i = 0; i < num_matches; ++i) {
+                        if (is_case_sensitive(matches[i])) {
+                                chosen_index = i;
+                                chosen_sens = TRUE;
+                                break;
+                        }
+                }
+# endif
+                chosen_match = xstrdup(matches[chosen_index]);
                 for (cp = chosen_match; *cp; cp++) {
                         unsigned n;
-                        for (n = 1; n < num_matches; n++) {
-# if !ENABLE_PLATFORM_MINGW32
-                                if (matches[n][cp - chosen_match] != *cp) {
-# else
-                                if (tolower(matches[n][cp - chosen_match]) != tolower(*cp)) {
+                        for (n = first_match; n < num_matches; n++) {
+# if ENABLE_PLATFORM_MINGW32
+                                if (!is_case_sensitive(matches[n]) || !chosen_sens) {
+                                        if (tolower(matches[n][cp - chosen_match]) !=
+                                                        tolower(*cp)) {
+                                                goto stop;
+                                        }
+                                } else
 # endif
+                                if (matches[n][cp - chosen_match] != *cp) {
                                         goto stop;
                                 }
                         }
@@ -1493,14 +1532,6 @@ static NOINLINE void input_tab(smallint *lastWasTab)
         free(chosen_match);
         free(match_buf);
 }
-
-# if ENABLE_PLATFORM_MINGW32
-#  undef is_prefixed_with
-#  undef qsort_string_vector
-#  undef strcmp
-#  undef strncmp
-# endif
-
 #endif  /* FEATURE_TAB_COMPLETION */