add comment about mkhtemp calling convention

Signed-off-by: Leah Rowe <leah@libreboot.org>

1 files changed, 15 insertions, 0 deletions

diff --git a/util/libreboot-utils/lib/mkhtemp.c b/util/libreboot-utils/lib/mkhtemp.c
index e1ca0a10..84723a08 100644
--- a/util/libreboot-utils/lib/mkhtemp.c
+++ b/util/libreboot-utils/lib/mkhtemp.c
@@ -39,6 +39,21 @@ new_tmpdir(int *fd, char **path)
 	return new_tmp_common(fd, path, MKHTEMP_DIR);
 }
 
+/* WARNING:
+ * on error, *path (at **path) may be
+   NULL, or if the error pertains to
+   an actual TMPDIR, set. if set, it
+   will be using *static* memory and
+   must not be freed. on success,
+   a pointer to heap memory is set
+   instead.
+ * see:
+ * env_tmpdir()
+ * this is for error reports if e.g.
+ * TMPDIR isn't found (but is set)
+ * if TMPDIR isn't set, it will
+ * default to /tmp or /var/tmp
+ */
 int
 new_tmp_common(int *fd, char **path, int type)
 {