Don't allow null chars in various strings

Various places that now reject null chars inside strings
- Primitive file operations reject it in filenames.
- Primitive environment variable operations reject it in
  names and values.
- os:cmd() reject it in its input.

Also '=' characters are rejected by primitive environment
variable operations in environment variable names.

Documentation has been updated to document null characters
in these types of data as invalid. Currently these operations
accept null chars at the end of strings, but that will change
in the future.

1 files changed, 48 insertions, 0 deletions

diff --git a/erts/emulator/beam/sys.h b/erts/emulator/beam/sys.h
index 704d567337..ce751acdd3 100644
--- a/erts/emulator/beam/sys.h
+++ b/erts/emulator/beam/sys.h
@@ -1341,4 +1341,52 @@ int erts_get_printable_characters(void);
 
 void erts_init_sys_common_misc(void);
 
+ERTS_GLB_INLINE Sint erts_raw_env_7bit_ascii_char_need(int encoding);
+ERTS_GLB_INLINE byte *erts_raw_env_7bit_ascii_char_put(byte c, byte *p,
+                                                       int encoding);
+ERTS_GLB_INLINE int  erts_raw_env_char_is_7bit_ascii_char(byte c, byte *p,
+                                                          int encoding);
+ERTS_GLB_INLINE byte *erts_raw_env_next_char(byte *p, int encoding);
+
+#if ERTS_GLB_INLINE_INCL_FUNC_DEF
+
+ERTS_GLB_INLINE Sint
+erts_raw_env_7bit_ascii_char_need(int encoding)
+{
+    return (encoding == ERL_FILENAME_WIN_WCHAR) ? 2 : 1;
+}
+
+ERTS_GLB_INLINE byte *
+erts_raw_env_7bit_ascii_char_put(byte c,
+                                 byte *p,
+                                 int encoding)
+{
+    *(p++) = c;
+    if (encoding == ERL_FILENAME_WIN_WCHAR)
+        *(p++) = 0;
+    return p;
+}
+
+ERTS_GLB_INLINE int
+erts_raw_env_char_is_7bit_ascii_char(byte c,
+                                     byte *p,
+                                     int encoding)
+{
+    if (encoding == ERL_FILENAME_WIN_WCHAR)
+        return (p[0] == c) & (p[1] == 0);
+    else
+        return p[0] == c;
+}
+
+ERTS_GLB_INLINE byte *
+erts_raw_env_next_char(byte *p, int encoding)
+{
+    if (encoding == ERL_FILENAME_WIN_WCHAR)
+        return p + 2;
+    else
+        return p + 1;
+}
+
+#endif /* #if ERTS_GLB_INLINE_INCL_FUNC_DEF */
+
 #endif