* fileio.c (file_name_as_directory): Use const pointers when appropriate.

(Fexpand_file_name): Likewise.  In particular, newdir might
point at constant storage, so make it a const pointer.

2 files changed, 25 insertions, 18 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 1a7f0bbf7b0..9393cec02a9 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -3,6 +3,9 @@
         * fileio.c (file_name_as_directory, directory_file_name):
         (barf_or_query_if_file_exists, auto_save_error, auto_save_1):
         Now static.
+        (file_name_as_directory): Use const pointers when appropriate.
+        (Fexpand_file_name): Likewise.  In particular, newdir might
+        point at constant storage, so make it a const pointer.
 
         * minibuf.c (choose_minibuf_frame_1): Now static.
         (Ftry_completion, Fall_completions): Rename or remove locals
diff --git a/src/fileio.c b/src/fileio.c
index e68fcbc65b5..4b25d08f20d 100644
--- a/src/fileio.c
+++ b/src/fileio.c
@@ -434,7 +434,7 @@ get a current directory to run processes in.  */)
 
 
 static char *
-file_name_as_directory (char *out, char *in)
+file_name_as_directory (char *out, const char *in)
 {
   int size = strlen (in) - 1;
 
@@ -728,7 +728,8 @@ filesystem tree, not (expand-file-name ".."  dirname).  */)
 {
   /* These point to SDATA and need to be careful with string-relocation
      during GC (via DECODE_FILE).  */
-  char *nm, *newdir;
+  char *nm;
+  const char *newdir;
   /* This should only point to alloca'd data.  */
   char *target;
 
@@ -1013,21 +1014,23 @@ filesystem tree, not (expand-file-name ".."  dirname).  */)
   if (!newdir && drive)
     {
       /* Get default directory if needed to make nm absolute. */
+      char *adir = NULL;
       if (!IS_DIRECTORY_SEP (nm[0]))
         {
-          newdir = alloca (MAXPATHLEN + 1);
-          if (!getdefdir (toupper (drive) - 'A' + 1, newdir))
-            newdir = NULL;
+          adir = alloca (MAXPATHLEN + 1);
+          if (!getdefdir (toupper (drive) - 'A' + 1, adir))
+            adir = NULL;
         }
-      if (!newdir)
+      if (!adir)
         {
           /* Either nm starts with /, or drive isn't mounted. */
-          newdir = alloca (4);
-          newdir[0] = DRIVE_LETTER (drive);
-          newdir[1] = ':';
-          newdir[2] = '/';
-          newdir[3] = 0;
+          adir = alloca (4);
+          adir[0] = DRIVE_LETTER (drive);
+          adir[1] = ':';
+          adir[2] = '/';
+          adir[3] = 0;
         }
+      newdir = adir;
     }
 #endif /* DOS_NT */
 
@@ -1074,7 +1077,7 @@ filesystem tree, not (expand-file-name ".."  dirname).  */)
              when we have pointers into lisp strings, we accomplish this
              indirectly by prepending newdir to nm if necessary, and using
              cwd (or the wd of newdir's drive) as the new newdir. */
-
+          char *adir;
           if (IS_DRIVE (newdir[0]) && IS_DEVICE_SEP (newdir[1]))
             {
               drive = (unsigned char) newdir[0];
@@ -1087,14 +1090,15 @@ filesystem tree, not (expand-file-name ".."  dirname).  */)
               strcat (tmp, nm);
               nm = tmp;
             }
-          newdir = alloca (MAXPATHLEN + 1);
+          adir = alloca (MAXPATHLEN + 1);
           if (drive)
             {
-              if (!getdefdir (toupper (drive) - 'A' + 1, newdir))
+              if (!getdefdir (toupper (drive) - 'A' + 1, adir))
                 newdir = "/";
             }
           else
-            getwd (newdir);
+            getwd (adir);
+          newdir = adir;
         }
 
       /* Strip off drive name from prefix, if present. */
@@ -1111,13 +1115,13 @@ filesystem tree, not (expand-file-name ".."  dirname).  */)
 #ifdef WINDOWSNT
           if (IS_DIRECTORY_SEP (newdir[0]) && IS_DIRECTORY_SEP (newdir[1]))
             {
-              char *p;
-              newdir = strcpy (alloca (strlen (newdir) + 1), newdir);
-              p = newdir + 2;
+              char *adir = strcpy (alloca (strlen (newdir) + 1), newdir);
+              char *p = adir + 2;
               while (*p && !IS_DIRECTORY_SEP (*p)) p++;
               p++;
               while (*p && !IS_DIRECTORY_SEP (*p)) p++;
               *p = 0;
+              newdir = adir;
             }
           else
 #endif