update sbuff macros to catch more corner cases

FR_SBUFF_IN() is for reading from the sbuff.
FR_SBUFF_OUT() is for writing to the sbuff.

Using the same description for both is very confusing.  Allowing
a writeable sbuff to take 'char const*' input is bad.

diff --git a/src/lib/util/sbuff.h b/src/lib/util/sbuff.h
index e058dbcd6c6251933f636751425e8fe43373b03d..0f226f9915e15ff2e43ca49e8ef79d8a4f58b168 100644 (file)
--- a/src/lib/util/sbuff.h
+++ b/src/lib/util/sbuff.h
@@ -512,7 +512,7 @@ do { \
                                                                 fr_sbuff_ptr(_sbuff_or_marker)->eof, \
                                                                 0x01)
 
-/** Creates a compound literal to pass into functions which accept a sbuff
+/** Creates an empty sbuff which can then be used as a destination for printing
  *
  * @note The return value of the function should be used to determine how much
  *      data was written to the buffer.
@@ -523,7 +523,10 @@ do { \
 #define FR_SBUFF_OUT(_start, _len_or_end) \
 ((fr_sbuff_t){ \
        .buff_i         = _start, \
-       .start_i        = _start, \
+       .start_i        = _Generic((_start), \
+                               char *          : _start, \
+                               uint8_t *       : _start \
+                       ), \
        .end_i          = _Generic((_len_or_end), \
                                size_t          : (char const *)(_start) + ((size_t)(_len_or_end) - 1), \
                                long            : (char const *)(_start) + ((size_t)(_len_or_end) - 1), \
@@ -533,10 +536,10 @@ do { \
                                char const *    : (char const *)(_len_or_end) \
                        ), \
        .p_i            = _start, \
-       .is_const       = IS_CONST(char *, _start) \
+       .is_const       = false, \
 })
 
-/** Creates a compound literal to pass into functions which accept a sbuff
+/** Creates an sbuff from existing data, so the caller can read from it.
  *
  * @note The return value of the function should be used to determine how much
  *      data was written to the buffer.
@@ -547,7 +550,12 @@ do { \
 #define FR_SBUFF_IN(_start, _len_or_end) \
 ((fr_sbuff_t){ \
        .buff_i         = _start, \
-       .start_i        = _start, \
+       .start_i        = _Generic((_start), \
+                               char *          : _start, \
+                               char const *    : _start, \
+                               uint8_t *       : _start, \
+                               uint8_t const * : _start \
+                       ), \
        .end_i          = _Generic((_len_or_end), \
                                size_t          : (char const *)(_start) + (size_t)(_len_or_end), \
                                long            : (char const *)(_start) + (size_t)(_len_or_end), \
@@ -557,7 +565,7 @@ do { \
                                char const *    : (char const *)(_len_or_end) \
                        ), \
        .p_i            = _start, \
-       .is_const       = IS_CONST(char *, _start) \
+       .is_const       = true, \
 })
 
 #define FR_SBUFF_IN_STR(_start) FR_SBUFF_IN(_start, strlen(_start))