On Mon, Jan 8, 2018 at 1:31 PM, Caio Marcelo de Oliveira Filho
[off-list ref] wrote:

+1

On Mon, Jan 08, 2018 at 01:28:29PM -0800, Lucas De Marchi wrote:

quoted

Not a perfect solution for overriding syscall(), but at least
it makes the testsuite to pass in a modified nsswitch.conf (one that has
a module which calls syscall() to get the thread id).
---

v2:
      - Check nextlib_syscall rather than nextlib to avoid races in
        multithreaded programs
      - Add error message in case we fail to get symbol

 testsuite/init_module.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/testsuite/init_module.c b/testsuite/init_module.c
index 199186b..c70147e 100644
--- a/testsuite/init_module.c
+++ b/testsuite/init_module.c

@@ -355,6 +355,26 @@ TS_EXPORT long int syscall(long int __sysno, ...)
              return ret;
      }

+     if (__sysno == __NR_gettid) {
+             static void *nextlib = NULL;
+             static long (*nextlib_syscall)(long number, ...);
+
+             if (nextlib_syscall == NULL) {
+#ifdef RTLD_NEXT
+                     nextlib = RTLD_NEXT;
+#else
+                     nextlib = dlopen("libc.so.6", RTLD_LAZY);
+#endif
+                     nextlib_syscall = dlsym(nextlib, "syscall");
+                     if (nextlib_syscall == NULL) {
+                             fprintf(stderr, "FIXME FIXME FIXME: libc is missing syscall symbol\n");

I added a call to dlerror() here and applied.

thanks for reviewing.

Lucas De Marchi