Add functions to directly expand variables by name

Replace all locally-created "$("+varname+")" and similar constructs
with calls to these new functions.

* src/expand.c (expand_variable_output): Call expand_string_output()
on the expansion of a variable value.  Replaces reference_variable().
(expand_variable_buf): Like expand_variable_output() but return the
starting location of the result.
(allocated_expand_variable): Like expand_variable_buf() but return
an allocated string.
(expand_string_buf): Call expand_variable_output().
* src/variable.h: Declare the new functions.
* src/function.c (func_call): Call expand_variable_output() instead
of expand_string_buf().
* src/main.c (decode_env_switches): Call expand_variable() instead
of expand_string().
* src/remake.c (library_search): Call allocated_expand_variable()
instead of expand_string() plus xstrdup().
* src/vpath.c (build_vpath_lists): Expand VPATH and GPATH using
expand_variable() instead of expand_string().
* src/w32/subproc/sub_proc.c (process_begin): Use expand_variable()
to expand SHELL.  Also use alloc() in case the result is larger than
PATH_MAX.

9 files changed, 103 insertions, 46 deletions

diff --git a/src/expand.c b/src/expand.c
index 25c71153..a72dfff7 100644
--- a/src/expand.c
+++ b/src/expand.c
@@ -83,7 +83,7 @@ initialize_variable_output ()
 {
   /* If we don't have a variable output buffer yet, get one.  */
 
-  if (variable_buffer == NULL)
+  if (!variable_buffer)
     {
       variable_buffer_length = 200;
       variable_buffer = xmalloc (variable_buffer_length);
@@ -221,42 +221,105 @@ recursively_expand_for_file (struct variable *v, struct file *file)
   return value;
 }
 
-/* Expand a simple reference to variable NAME, which is LENGTH chars long.  */
+/* Expand a simple reference to variable NAME, which is LENGTH chars long.
+   The result is written to PTR which must point into the variable_buffer.
+   Returns a pointer to the new end of the variable_buffer.  */
 
-#ifdef __GNUC__
-__inline
-#endif
-static char *
-reference_variable (char *o, const char *name, size_t length)
+char *
+expand_variable_output (char *ptr, const char *name, size_t length)
 {
   struct variable *v;
   char *value;
 
   v = lookup_variable (name, length);
 
-  if (v == 0)
+  if (!v)
     warn_undefined (name, length);
 
   /* If there's no variable by that name or it has no value, stop now.  */
-  if (v == 0 || (*v->value == '\0' && !v->append))
-    return o;
+  if (!v || (v->value[0] == '\0' && !v->append))
+    return ptr;
 
-  value = (v->recursive ? recursively_expand (v) : v->value);
+  value = v->recursive ? recursively_expand (v) : v->value;
 
-  o = variable_buffer_output (o, value, strlen (value));
+  ptr = variable_buffer_output (ptr, value, strlen (value));
 
   if (v->recursive)
     free (value);
 
-  return o;
+  return ptr;
+}
+
+/* Expand a simple reference to variable NAME, which is LENGTH chars long.
+   The result is written to BUF which must point into the variable_buffer.
+   If BUF is NULL, start at the beginning of the current variable_buffer.
+   Returns BUF, or the beginning of the buffer if BUF is NULL.  */
+
+char *
+expand_variable_buf (char *buf, const char *name, size_t length)
+{
+  if (!buf)
+    buf = initialize_variable_output ();
+
+  expand_variable_output (buf, name, length);
+
+  return buf;
+}
+
+/* Expand a simple reference to variable NAME, which is LENGTH chars long.
+   Returns an allocated buffer containing the value.  */
+
+char *
+allocated_expand_variable (const char *name, size_t length)
+{
+  char *obuf;
+  size_t olen;
+
+  install_variable_buffer (&obuf, &olen);
+
+  expand_variable_output (variable_buffer, name, length);
+
+  return swap_variable_buffer (obuf, olen);
+}
+
+/* Expand a simple reference to variable NAME, which is LENGTH chars long.
+   Error messages refer to the file and line where FILE's commands were found.
+   Expansion uses FILE's variable set list.
+   Returns an allocated buffer containing the value.  */
+
+char *
+allocated_expand_variable_for_file (const char *name, size_t length, struct file *file)
+{
+  char *result;
+  struct variable_set_list *savev;
+  const floc *savef;
+
+  if (!file)
+    return allocated_expand_variable (name, length);
+
+  savev = current_variable_set_list;
+  current_variable_set_list = file->variables;
+
+  savef = reading_file;
+  if (file->cmds && file->cmds->fileinfo.filenm)
+    reading_file = &file->cmds->fileinfo;
+  else
+    reading_file = NULL;
+
+  result = allocated_expand_variable (name, length);
+
+  current_variable_set_list = savev;
+  reading_file = savef;
+
+  return result;
 }
 
 /* Scan STRING for variable references and expansion-function calls.  Only
    LENGTH bytes of STRING are actually scanned.
    If LENGTH is SIZE_MAX, scan until a null byte is found.
 
-   Write the results to BUF, which must point into 'variable_buffer'.  If
-   BUF is NULL, start at the beginning of the current 'variable_buffer'.
+   Write the results to BUF, which must point into variable_buffer.  If
+   BUF is NULL, start at the beginning of the current variable_buffer.
 
    Return a pointer to BUF, or to the beginning of the new buffer if BUF is
    NULL.
@@ -445,7 +508,7 @@ expand_string_buf (char *buf, const char *string, size_t length)
             if (colon == 0)
               /* This is an ordinary variable reference.
                  Look up the value of the variable.  */
-                o = reference_variable (o, beg, end - beg);
+                o = expand_variable_output (o, beg, end - beg);
 
             free (abeg);
           }
@@ -457,7 +520,7 @@ expand_string_buf (char *buf, const char *string, size_t length)
 
           /* A $ followed by a random char is a variable reference:
              $a is equivalent to $(a).  */
-          o = reference_variable (o, p, 1);
+          o = expand_variable_output (o, p, 1);
 
           break;
         }
diff --git a/src/function.c b/src/function.c
index 8f46ec60..5ca28f85 100644
--- a/src/function.c
+++ b/src/function.c
@@ -2613,7 +2613,6 @@ func_call (char *o, char **argv, const char *funcname UNUSED)
 {
   static unsigned int max_args = 0;
   char *fname;
-  char *body;
   size_t flen;
   unsigned int i;
   int saved_args;
@@ -2651,13 +2650,6 @@ func_call (char *o, char **argv, const char *funcname UNUSED)
   if (v == 0 || *v->value == '\0')
     return o;
 
-  body = alloca (flen + 4);
-  body[0] = '$';
-  body[1] = '(';
-  memcpy (body + 2, fname, flen);
-  body[flen+2] = ')';
-  body[flen+3] = '\0';
-
   /* Set up arguments $(1) .. $(N).  $(0) is the function name.  */
 
   push_new_variable_scope ();
@@ -2683,14 +2675,14 @@ func_call (char *o, char **argv, const char *funcname UNUSED)
       define_variable (num, strlen (num), "", o_automatic, 0);
     }
 
-  /* Expand the body in the context of the arguments, adding the result to
+  /* Expand the function in the context of the arguments, adding the result to
      the variable buffer.  */
 
   v->exp_count = EXP_COUNT_MAX;
 
   saved_args = max_args;
   max_args = i;
-  o = expand_string_buf (o, body, flen+3);
+  o = expand_variable_output (o, fname, flen);
   max_args = saved_args;
 
   v->exp_count = 0;
diff --git a/src/job.c b/src/job.c
index c7313fdb..d7b584f5 100644
--- a/src/job.c
+++ b/src/job.c
@@ -1882,7 +1882,7 @@ new_job (struct file *file)
              nm, c->file->name);
       else
         {
-          char *newer = allocated_expand_string_for_file ("$?", c->file);
+          char *newer = allocated_expand_variable_for_file (STRING_SIZE_TUPLE ("?"), c->file);
           if (newer[0] != '\0')
             {
               OSSS (message, 0, _("%s: update target '%s' due to: %s"),
@@ -3637,7 +3637,7 @@ construct_command_argv (char *line, char **restp, struct file *file,
     int save = warn_undefined_variables_flag;
     warn_undefined_variables_flag = 0;
 
-    shell = allocated_expand_string_for_file ("$(SHELL)", file);
+    shell = allocated_expand_variable_for_file (STRING_SIZE_TUPLE ("SHELL"), file);
 #if MK_OS_W32
     /*
      * Convert to forward slashes so that construct_command_argv_internal()
@@ -3702,7 +3702,7 @@ construct_command_argv (char *line, char **restp, struct file *file,
     else
       shellflags = allocated_expand_string_for_file (var->value, file);
 
-    ifs = allocated_expand_string_for_file ("$(IFS)", file);
+    ifs = allocated_expand_variable_for_file (STRING_SIZE_TUPLE ("IFS"), file);
 
     warn_undefined_variables_flag = save;
   }
diff --git a/src/main.c b/src/main.c
index 86497e70..16bbb83a 100644
--- a/src/main.c
+++ b/src/main.c
@@ -3328,19 +3328,12 @@ decode_switches (int argc, const char **argv, enum variable_origin origin)
 static void
 decode_env_switches (const char *envar, size_t len, enum variable_origin origin)
 {
-  char *varref = alloca (2 + len + 2);
   char *value, *p, *buf;
   int argc;
   const char **argv;
 
   /* Get the variable's value.  */
-  p = varref;
-  *(p++) = '$';
-  *(p++) = '(';
-  p = mempcpy (p, envar, len);
-  *(p++) = ')';
-  *p = '\0';
-  value = expand_string (varref);
+  value = expand_variable (envar, len);
 
   /* Skip whitespace, and check for an empty value.  */
   NEXT_TOKEN (value);
diff --git a/src/read.c b/src/read.c
index 14f9dcee..bae836f2 100644
--- a/src/read.c
+++ b/src/read.c
@@ -186,7 +186,7 @@ read_all_makefiles (const char **makefiles)
     char *name, *p;
     size_t length;
 
-    value = allocated_expand_string ("$(MAKEFILES)");
+    value = allocated_expand_variable (STRING_SIZE_TUPLE ("MAKEFILES"));
 
     /* Set NAME to the start of next token and LENGTH to its length.
        MAKEFILES is updated for finding remaining tokens.  */
@@ -3071,7 +3071,7 @@ tilde_expand (const char *name)
         int save = warn_undefined_variables_flag;
         warn_undefined_variables_flag = 0;
 
-        home_dir = allocated_expand_string ("$(HOME)");
+        home_dir = allocated_expand_variable (STRING_SIZE_TUPLE ("HOME"));
 
         warn_undefined_variables_flag = save;
       }
diff --git a/src/remake.c b/src/remake.c
index 7c841f5d..d5cd3b38 100644
--- a/src/remake.c
+++ b/src/remake.c
@@ -1717,7 +1717,7 @@ library_search (const char *lib, FILE_TIMESTAMP *mtime_ptr)
 
   const char **dp;
 
-  libpatterns = xstrdup (expand_string ("$(.LIBPATTERNS)"));
+  libpatterns = allocated_expand_variable (STRING_SIZE_TUPLE (".LIBPATTERNS"));
 
   /* Skip the '-l'.  */
   lib += 2;
diff --git a/src/variable.h b/src/variable.h
index 195cc360..bfba63f5 100644
--- a/src/variable.h
+++ b/src/variable.h
@@ -136,6 +136,12 @@ char *expand_argument (const char *str, const char *end);
 char *recursively_expand_for_file (struct variable *v, struct file *file);
 #define recursively_expand(v) recursively_expand_for_file ((v), NULL)
 
+char *expand_variable_output (char *ptr, const char *name, size_t length);
+char *expand_variable_buf (char *buf, const char *name, size_t length);
+#define expand_variable(n,l) expand_variable_buf (NULL, (n), (l));
+char *allocated_expand_variable (const char *name, size_t length);
+char *allocated_expand_variable_for_file (const char *name, size_t length, struct file *file);
+
 /* function.c */
 int handle_function (char **op, const char **stringp);
 int pattern_matches (const char *pattern, const char *percent, const char *str);
diff --git a/src/vpath.c b/src/vpath.c
index 873a9c94..25c41e30 100644
--- a/src/vpath.c
+++ b/src/vpath.c
@@ -71,7 +71,8 @@ build_vpath_lists (void)
   /* If there is a VPATH variable with a nonnull expanded value, construct the
      general VPATH list from it.  */
 
-  p = expand_string ("$(strip $(VPATH))");
+  p = expand_variable ("VPATH", 5);
+  NEXT_TOKEN (p);
 
   if (*p != '\0')
     {
@@ -95,7 +96,8 @@ build_vpath_lists (void)
   /* If there is a GPATH variable with a nonnull expanded value, construct the
      GPATH list from it.  */
 
-  p = expand_string ("$(strip $(GPATH))");
+  p = expand_variable ("GPATH", 5);
+  NEXT_TOKEN (p);
 
   if (*p != '\0')
     {
diff --git a/src/w32/subproc/sub_proc.c b/src/w32/subproc/sub_proc.c
index be32d9ef..4c1611d3 100644
--- a/src/w32/subproc/sub_proc.c
+++ b/src/w32/subproc/sub_proc.c
@@ -566,10 +566,10 @@ process_begin(
         char *shell_name = 0;
         int file_not_found=0;
         HANDLE exec_handle;
-        char exec_fname[MAX_PATH];
+        char exec_fname[MAX_PATH+1];
         const char *path_var = NULL;
         char **ep;
-        char buf[MAX_PATH];
+        char buf[MAX_PATH+1];
         DWORD bytes_returned;
         DWORD flags;
         char *command_line;
@@ -614,8 +614,9 @@ process_begin(
                         char *new_argv0;
                         char **argvi = argv;
                         size_t arglen = 0;
+                        char *exp = expand_variable ("SHELL", 5);
 
-                        strcpy(buf, expand_string ("$(SHELL)"));
+                        memcpy (buf, exp, strlen(exp) + 1);
                         shell_name = &buf[0];
                         strcpy(exec_fname, "-c");
                         /* Construct a single command string in argv[0].  */