[hackers] [st] Fix memmove() invocation with src/dst being NULL || sin

[git]

commit 56abffb4b67f235d20de30f29ba027ab34c171e3
Author: sin <s...@2f30.org>
Date:   Wed Apr 15 09:43:06 2015 +0100

    Fix memmove() invocation with src/dst being NULL
    
    This fixes a segmentation fault on some systems.

diff --git a/st.c b/st.c
index b1d3791..bb8c365 100644
--- a/st.c
+++ b/st.c
@@ -2788,8 +2788,11 @@ tresize(int col, int row) {
                free(term.line[i]);
                free(term.alt[i]);
        }
-       memmove(term.line, term.line + i, row * sizeof(Line));
-       memmove(term.alt, term.alt + i, row * sizeof(Line));
+       /* ensure that both src and dst are not NULL */
+       if (i > 0) {
+               memmove(term.line, term.line + i, row * sizeof(Line));
+               memmove(term.alt, term.alt + i, row * sizeof(Line));
+       }
        for(i += row; i < term.row; i++) {
                free(term.line[i]);
                free(term.alt[i]);