Backported fixes for bogus homedir bug to stable-2.0 branch.

Fixes http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=553174

physfs.c

@@ -605,18 +605,21 @@ static int freeDirHandle(DirHandle *dh, FileHandle *openList)
 
 static char *calculateUserDir(void)
 {
-    char *retval = NULL;
-    const char *str = NULL;
+    char *retval = __PHYSFS_platformGetUserDir();
+    if (retval != NULL)
+    {
+        /* make sure it really exists and is normalized. */
+        char *ptr = __PHYSFS_platformRealPath(retval);
+        allocator.Free(retval);
+        retval = ptr;
+    } /* if */
 
-    str = __PHYSFS_platformGetUserDir();
-    if (str != NULL)
-        retval = (char *) str;
-    else
+    if (retval == NULL)
     {
         const char *dirsep = PHYSFS_getDirSeparator();
         const char *uname = __PHYSFS_platformGetUserName();
+        const char *str = (uname != NULL) ? uname : "default";
 
-        str = (uname != NULL) ? uname : "default";
         retval = (char *) allocator.Malloc(strlen(baseDir) + strlen(str) +
                                            strlen(dirsep) + 6);
 
@@ -754,13 +757,6 @@ int PHYSFS_init(const char *argv0)
     BAIL_IF_MACRO(!appendDirSep(&baseDir), NULL, 0);
 
     userDir = calculateUserDir();
-    if (userDir != NULL)
-    {
-        ptr = __PHYSFS_platformRealPath(userDir);
-        allocator.Free(userDir);
-        userDir = ptr;
-    } /* if */
-
     if ((userDir == NULL) || (!appendDirSep(&userDir)))
     {
         allocator.Free(baseDir);

platform/posix.c

@@ -97,8 +97,21 @@ char *__PHYSFS_platformGetUserName(void)
 char *__PHYSFS_platformGetUserDir(void)
 {
     char *retval = __PHYSFS_platformCopyEnvironmentVariable("HOME");
+
+    /* if the environment variable was set, make sure it's really a dir. */
+    if (retval != NULL)
+    {
+        struct stat statbuf;
+        if ((stat(retval, &statbuf) == -1) || (S_ISDIR(statbuf.st_mode) == 0))
+        {
+            allocator.Free(retval);
+            retval = NULL;
+        } /* if */
+    } /* if */
+
     if (retval == NULL)
         retval = getUserDirByUID();
+
     return(retval);
 } /* __PHYSFS_platformGetUserDir */