don't fail to map library/executable with zero-length segment maps

reportedly the GNU linker can emit such segments, causing spurious
failure to load due to mmap with a length of zero producing EINVAL.
no action is required for such a load map (it's effectively a nop in
the program headers table) so just treat it as always successful.

diff --git a/ldso/dynlink.c b/ldso/dynlink.c
index 6b868c8..aaadcce 100644 (file)
--- a/ldso/dynlink.c
+++ b/ldso/dynlink.c
@@ -579,6 +579,7 @@ static void *mmap_fixed(void *p, size_t n, int prot, int flags, int fd, off_t of
 {
        static int no_map_fixed;
        char *q;
+       if (!n) return p;
        if (!no_map_fixed) {
                q = mmap(p, n, prot, flags|MAP_FIXED, fd, off);
                if (!DL_NOMMU_SUPPORT || q != MAP_FAILED || errno != EINVAL)