Add memcpy_safe

ISO/IEC 9899:1999 §7.21.1/2 says:
Where an argument declared as size_t n specifies the length of the array
for a function, n can have the value zero on a call to that
function. Unless explicitly stated otherwise in the description of a
particular function in this subclause, pointer arguments on such a call
shall still have valid values, as described in 7.1.4.

In base64_append_width memcpy was called as memcpy(x, NULL, 0).  GCC 4.9
started making use of this and assumes This worked fine under -O0, but
does something strange under -O3.

This patch fixes a bug in base64_append_width(), fixes a possible bug in
journal_file_append_entry_internal(), and makes use of the new function
to simplify the code in other places.

1 files changed, 3 insertions, 3 deletions

diff --git a/src/journal/journal-file.c b/src/journal/journal-file.c
index 2973176c8d..da8039712f 100644
--- a/src/journal/journal-file.c
+++ b/src/journal/journal-file.c
@@ -1110,8 +1110,8 @@ static int journal_file_append_data(
         }
 #endif
 
-        if (compression == 0 && size > 0)
-                memcpy(o->data.payload, data, size);
+        if (compression == 0)
+                memcpy_safe(o->data.payload, data, size);
 
         r = journal_file_link_data(f, o, p, hash);
         if (r < 0)
@@ -1373,7 +1373,7 @@ static int journal_file_append_entry_internal(
                 return r;
 
         o->entry.seqnum = htole64(journal_file_entry_seqnum(f, seqnum));
-        memcpy(o->entry.items, items, n_items * sizeof(EntryItem));
+        memcpy_safe(o->entry.items, items, n_items * sizeof(EntryItem));
         o->entry.realtime = htole64(ts->realtime);
         o->entry.monotonic = htole64(ts->monotonic);
         o->entry.xor_hash = htole64(xor_hash);