Fix handling of errno if external functions are invoked

If an external function in KLEE is invoked, it might update errno.
Previously, the errno specific variable in a state was only updated
if it was part of the executed instructions.
That opened up a timeframe that increased the likelihood of errno being
overwritten by another method call.

This patch fixes two issues:
* the errno of the KLEE process state is updated before the external
function call allowing to detect changes to it later on
* after the external call, the memory object of errno is directly
updated
with its new value, reducing the likelihood to be overwritten by
another
call

Additional features:
* Add support for `errno()` for Darwin as well.
* Simplified errno handling in POSIX layer

2 files changed, 7 insertions, 6 deletions

diff --git a/test/Runtime/POSIX/DirSeek.c b/test/Runtime/POSIX/DirSeek.c
index 3908b4e2..4c68a30c 100644
--- a/test/Runtime/POSIX/DirSeek.c
+++ b/test/Runtime/POSIX/DirSeek.c
@@ -1,4 +1,4 @@
-// RUN: %llvmgcc %s -emit-llvm -O0 -c -o %t2.bc
+// RUN: %llvmgcc %s -emit-llvm -O0 -c -g -o %t2.bc
 // RUN: rm -rf %t.klee-out %t.klee-out-tmp
 // RUN: %gentmp %t.klee-out-tmp
 // RUN: %klee --output-dir=%t.klee-out --run-in=%t.klee-out-tmp --libc=uclibc --posix-runtime --exit-on-error %t2.bc --sym-files 2 2
@@ -11,8 +11,8 @@
 
 // For this test really to work as intended it needs to be run in a
 // directory large enough to cause uclibc to do multiple getdents
-// calls (otherwise uclibc will handle the seeks itself). We should
-// create a bunch of files or something.
+// calls (otherwise uclibc will handle the seeks itself).
+// Therefore gentmp generates a directory with a specific amount of entries
 
 #include <assert.h>
 #include <stdio.h>
@@ -29,7 +29,6 @@ int main(int argc, char **argv) {
   assert(de);
   strcpy(first, de->d_name);
   off_t pos = telldir(d);
-  printf("pos: %ld\n", telldir(d));
   de = readdir(d);
   assert(de);
   strcpy(second, de->d_name);
@@ -41,9 +40,10 @@ int main(int argc, char **argv) {
   assert(strcmp(de->d_name, second) == 0);
 
   // Go to end, then back to 2nd
-  while (de)
+  while (de) {
     de = readdir(d);
-  assert(!errno);
+    assert(!errno);
+  }
   seekdir(d, pos);
   assert(telldir(d) == pos);
   de = readdir(d);
diff --git a/test/Runtime/POSIX/Ioctl.c b/test/Runtime/POSIX/Ioctl.c
index e8220276..f1caaf77 100644
--- a/test/Runtime/POSIX/Ioctl.c
+++ b/test/Runtime/POSIX/Ioctl.c
@@ -5,6 +5,7 @@
 #include <assert.h>
 #include <fcntl.h>
 #include <sys/stat.h>
+#include <sys/ioctl.h>
 #include <termios.h>
 #include <asm/ioctls.h>
 #include <errno.h>