win32: try to make working directory names consistent

Standardise the path names used for the current working directory by:

- resolving with realpath(3);
- making the drive name or host name uppercase.

The first only really works for physical drives; results for mapped
drives are patchy.

The standardisation is applied in two places:

- at the end of updatepwd() in ash;
- when a symbolic link is resolved in mingw_chdir().

3 files changed, 28 insertions, 1 deletions

diff --git a/include/mingw.h b/include/mingw.h
index 1ec5292d8..07f9857e9 100644
--- a/include/mingw.h
+++ b/include/mingw.h
@@ -530,3 +530,4 @@ char *get_system_drive(void);
 int chdir_system_drive(void);
 char *xabsolute_path(char *path);
 char *get_drive_cwd(const char *path, char *buffer, int size);
+void fix_path_case(char *path);
diff --git a/shell/ash.c b/shell/ash.c
index 68512799e..6bc1dba24 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -2980,6 +2980,7 @@ updatepwd(const char *dir)
         if (new > lim)
                 STUNPUTC(new);
         *new = 0;
+        fix_path_case((char *)stackblock());
         return stackblock();
 #else
         char *new;
diff --git a/win32/mingw.c b/win32/mingw.c
index 22a3ede58..3f80b53f1 100644
--- a/win32/mingw.c
+++ b/win32/mingw.c
@@ -1208,8 +1208,11 @@ int mingw_chdir(const char *dirname)
         int ret = -1;
         const char *realdir = dirname;
 
-        if (lstat(dirname, &st) == 0 && S_ISLNK(st.st_mode))
+        if (lstat(dirname, &st) == 0 && S_ISLNK(st.st_mode)) {
                 realdir = auto_string(xmalloc_readlink(dirname));
+                if (realdir)
+                        fix_path_case((char *)realdir);
+        }
 
         if (realdir)
                 ret = chdir(realdir);
@@ -1715,3 +1718,25 @@ char *get_drive_cwd(const char *path, char *buffer, int size)
         bs_to_slash(buffer);
         return buffer;
 }
+
+void fix_path_case(char *path)
+{
+        char resolved[PATH_MAX];
+        int len;
+
+        // Canonicalise path: for physical drives this makes case match
+        // what's stored on disk.  For mapped drives, not so much.
+        if (realpath(path, resolved) && strcasecmp(path, resolved) == 0)
+                strcpy(path, resolved);
+
+        // make drive letter or UNC hostname uppercase
+        len = root_len(path);
+        if (len == 2) {
+                *path = toupper(*path);
+        }
+        else if (len != 0) {
+                for (path+=2; !is_path_sep(*path); ++path) {
+                        *path = toupper(*path);
+                }
+        }
+}