Rely on $PWD instead of getcwd() more often

Fixes https://github.com/fish-shell/fish-shell/issues/696

env.cpp

@@ -507,6 +507,20 @@ int env_set_pwd()
     return 1;
 }
 
+wcstring env_get_pwd_slash(void)
+{
+    env_var_t pwd = env_get_string(L"PWD");
+    if (pwd.missing_or_empty())
+    {
+        return L"";
+    }
+    if (! string_suffixes_string(L"/", pwd))
+    {
+        pwd.push_back(L'/');
+    }
+    return pwd;
+}
+
 /**
    Set up default values for various variables if not defined.
  */

env.h

@@ -213,14 +213,12 @@ const char * const * env_export_arr(bool recalc);
 */
 wcstring_list_t env_get_names(int flags);
 
-
-
-/**
-   Update the PWD variable
-   directory
-*/
+/** Update the PWD variable directory */
 int env_set_pwd();
 
+/* Returns the PWD with a terminating slash */
+wcstring env_get_pwd_slash();
+
 class env_vars_snapshot_t
 {
     std::map<wcstring, wcstring> vars;

highlight.cpp

@@ -1320,14 +1320,12 @@ void highlight_shell(const wcstring &buff, std::vector<int> &color, size_t pos,
     std::fill(color.begin(), color.end(), -1);
 
     /* Do something sucky and get the current working directory on this background thread. This should really be passed in. Note that we also need this as a vector (of one directory). */
-    const wcstring working_directory = get_working_directory();
+    const wcstring working_directory = env_get_pwd_slash();
 
     /* Tokenize the string */
     tokenize(buff.c_str(), color, pos, error, working_directory, vars);
 
-    /*
-      Locate and syntax highlight cmdsubsts recursively
-    */
+    /* Locate and syntax highlight cmdsubsts recursively */
 
     wchar_t * const subbuff = wcsdup(buff.c_str());
     wchar_t * subpos = subbuff;

history.cpp

@@ -1639,7 +1639,7 @@ file_detection_context_t::file_detection_context_t(history_t *hist, const wcstri
     history(hist),
     command(cmd),
     when(time(NULL)),
-    working_directory(get_working_directory())
+    working_directory(env_get_pwd_slash())
 {
 }
 

path.cpp

@@ -446,18 +446,3 @@ bool paths_are_same_file(const wcstring &path1, const wcstring &path2)
         return false;
     }
 }
-
-wcstring get_working_directory(void)
-{
-    wcstring wd = L"./";
-    wchar_t dir_path[4096];
-    const wchar_t *cwd = wgetcwd(dir_path, 4096);
-    if (cwd)
-    {
-        wd = cwd;
-        /* Make sure the working directory ends with a slash */
-        if (! wd.empty() && wd.at(wd.size() - 1) != L'/')
-            wd.push_back(L'/');
-    }
-    return wd;
-}

path.h

@@ -78,7 +78,4 @@ bool path_is_valid(const wcstring &path, const wcstring &working_directory);
 /** Returns whether the two paths refer to the same file */
 bool paths_are_same_file(const wcstring &path1, const wcstring &path2);
 
-/* Returns the current working directory as returned by wgetcwd */
-wcstring get_working_directory(void);
-
 #endif

reader.cpp

@@ -1275,7 +1275,7 @@ struct autosuggestion_context_t
         cursor_pos(pos),
         searcher(*history, term, HISTORY_SEARCH_TYPE_PREFIX),
         detector(history, term),
-        working_directory(get_working_directory()),
+        working_directory(env_get_pwd_slash()),
         vars(env_vars_snapshot_t::highlighting_keys),
         generation_count(s_generation_count),
         has_tried_reloading(false)