ash: avoid duplicated slashes in output of type/command builtins

Microsoft developers have a penchant for adding trailing slashes to
entries in PATH:

   C:/Windows/System32/WindowsPowerShell/v1.0/
   C:/Windows/System32/OpenSSH/

The 'type' and 'command -v' shell builtins return paths with duplicated
slashes for executables in those directories.  See GitHub issue #191.

Bonus fixes:

- handle backslashes as well as slashes in concat_path_file()
- convert backslashes to slashes in the output of 'type', 'command -v'

2 files changed, 10 insertions, 0 deletions

diff --git a/libbb/concat_path_file.c b/libbb/concat_path_file.c
index 5b4b7f113..81c7481ca 100644
--- a/libbb/concat_path_file.c
+++ b/libbb/concat_path_file.c
@@ -21,8 +21,14 @@ char* FAST_FUNC concat_path_file(const char *path, const char *filename)
 
         if (!path)
                 path = "";
+#if ENABLE_PLATFORM_MINGW32
+        lc = last_char_is(path, '/') ?: last_char_is(path, '\\');
+        while (*filename == '/' || *filename == '\\')
+                filename++;
+#else
         lc = last_char_is(path, '/');
         while (*filename == '/')
                 filename++;
+#endif
         return xasprintf("%s%s%s", path, (lc==NULL ? "/" : ""), filename);
 }
diff --git a/shell/ash.c b/shell/ash.c
index b51a3fb82..3c53b25ff 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -2860,6 +2860,9 @@ padvance_magic(const char **path, const char *name, int magic)
 
         if (len) {
                 q = mempcpy(q, start, len);
+#if ENABLE_PLATFORM_MINGW32
+                if (q[-1] != '/' && q[-1] != '\\')
+#endif
                 *q++ = '/';
         }
         strcpy(q, name);
@@ -9160,6 +9163,7 @@ describe_command(char *command, const char *path, int describe_command_verbose)
                 }
 #if ENABLE_PLATFORM_MINGW32
                 add_win32_extension(p);
+                bs_to_slash(p);
 #endif
                 if (describe_command_verbose) {
                         out1fmt(" is %s", p);