Re: [PATCH 03/14] relocatable: support UNIXROOT in relocate() on EMX

[Bruno Haible]

Followup to this patch from 2014-12-09: A bit more consistent coding style:
- The argument 'pathname' must be non-NULL. No need to test it against NULL.
- Make use of ISSLASH macro consistently.
- For characters, I find a comparison with '\0' clearer than a boolean negation.
  Limit boolean expressions to booleans.
- Better use the memcpy-before-strcpy idiom than strcpy-before-strcpy. The
  former makes it clear that the programmer has thought about the length of the
  strings.


2017-05-16  Bruno Haible  <br...@clisp.org>

        relocate: Simplify EMX specific code.
        * lib/relocatable.c (relocate): Assume pathname is non-NULL. Use
        ISSLASH macro consistently. Avoid dangerous string concatenation idiom.

diff --git a/lib/relocatable.c b/lib/relocatable.c
index c42398e..189aee4 100644
--- a/lib/relocatable.c
+++ b/lib/relocatable.c
@@ -542,27 +542,26 @@ relocate (const char *pathname)
 # ifdef __KLIBC__
 #  undef strncmp
 
-  if (pathname && strncmp (pathname, "/@unixroot", 10) == 0
-      && (pathname[10] == '\0' || pathname[10] == '/' || pathname[10] == '\\'))
+  if (strncmp (pathname, "/@unixroot", 10) == 0
+      && (pathname[10] == '\0' || ISSLASH (pathname[10])))
     {
       /* kLIBC itself processes /@unixroot prefix */
-
       return pathname;
     }
   else
 # endif
-  if (pathname && ISSLASH (pathname[0]))
+  if (ISSLASH (pathname[0]))
     {
       const char *unixroot = getenv ("UNIXROOT");
 
-      if (unixroot && HAS_DEVICE (unixroot) && !unixroot[2])
+      if (unixroot && HAS_DEVICE (unixroot) && unixroot[2] == '\0')
         {
           char *result = (char *) xmalloc (2 + strlen (pathname) + 1);
 #ifdef NO_XMALLOC
           if (result != NULL)
 #endif
             {
-              strcpy (result, unixroot);
+              memcpy (result, unixroot, 2);
               strcpy (result + 2, pathname);
               return result;
             }