lib/syscall_shim: Adjust the sign of `errno` to be positive

Ensure that `errno` is assigned the positive value of what the raw
system calls return.

Signed-off-by: Sergiu Moga <sergiu.moga@protonmail.com>
Reviewed-by: Simon Kuenzer <simon.kuenzer@neclab.eu>
Tested-by: Unikraft CI <monkey@unikraft.io>
GitHub-Pull-Request: #236

diff --git a/lib/syscall_shim/include/uk/syscall.h b/lib/syscall_shim/include/uk/syscall.h
index c58bae58c35c3eb533b6ed4094cefa07cf063520..9c4348c1ac91c9f0c5b5052b33f9cd465e5dfb07 100644 (file)
--- a/lib/syscall_shim/include/uk/syscall.h
+++ b/lib/syscall_shim/include/uk/syscall.h
@@ -201,7 +201,7 @@ typedef long uk_syscall_arg_t;
                long ret = rname(                                       \
                        UK_ARG_MAPx(x, UK_S_ARG_CAST_LONG, __VA_ARGS__)); \
                if (ret < 0 && PTRISERR(ret)) {                         \
-                       errno = (int) PTR2ERR(ret);                     \
+                       errno = -(int) PTR2ERR(ret);                    \
                        return -1;                                      \
                }                                                       \
                return ret;                                             \