Merge tag 'nolibc-20251130-for-6.19-1' of git://git.kernel.org/pub/scm/linux/kernel/git/nolibc/linux-nolibc

Pull nolibc updates from Thomas Weißschuh:

 - Preparations to the use of nolibc in UML:
     - Cleanup of sparse warnings
     - Library mode without _start()
     - More consistency when disabling errno

 - Unconditional installation of all architecture support files

 - Always 64-bit wide ino_t and off_t

 - Various cleanups and bug fixes

* tag 'nolibc-20251130-for-6.19-1' of git://git.kernel.org/pub/scm/linux/kernel/git/nolibc/linux-nolibc: (25 commits)
  selftests/nolibc: error out on linker warnings
  selftests/nolibc: use lld to link loongarch binaries
  tools/nolibc: remove more __nolibc_enosys() fallbacks
  tools/nolibc: remove now superfluous overflow check in llseek
  tools/nolibc: use 64-bit off_t
  tools/nolibc: prefer the llseek syscall
  tools/nolibc: handle 64-bit off_t for llseek
  tools/nolibc: use 64-bit ino_t
  tools/nolibc: avoid using plain integer as NULL pointer
  tools/nolibc: add support for fchdir()
  tools/nolibc: clean up outdated comments in generic arch.h
  tools/nolibc: make the "headers" target install all supported archs
  tools/nolibc: add the more portable inttypes.h
  tools/nolibc: provide the portable sys/select.h
  tools/nolibc: add missing memchr() to string.h
  tools/nolibc: fix misleading help message regarding installation path
  tools/nolibc: add uio.h with readv and writev
  tools/nolibc: add option to disable runtime
  tools/nolibc: use __fallthrough__ rather than fallthrough
  tools/nolibc: implement %m if errno is not defined
  ...

1 files changed, 103 insertions, 0 deletions

diff --git a/tools/include/nolibc/sys/select.h b/tools/include/nolibc/sys/select.h
new file mode 100644
index 000000000000..2a5619c01277
--- /dev/null
+++ b/tools/include/nolibc/sys/select.h
@@ -0,0 +1,103 @@
+/* SPDX-License-Identifier: LGPL-2.1 OR MIT */
+
+#include "../nolibc.h"
+
+#ifndef _NOLIBC_SYS_SELECT_H
+#define _NOLIBC_SYS_SELECT_H
+
+#include <linux/time.h>
+#include <linux/unistd.h>
+
+/* commonly an fd_set represents 256 FDs */
+#ifndef FD_SETSIZE
+#define FD_SETSIZE     256
+#endif
+
+#define FD_SETIDXMASK (8 * sizeof(unsigned long))
+#define FD_SETBITMASK (8 * sizeof(unsigned long)-1)
+
+/* for select() */
+typedef struct {
+	unsigned long fds[(FD_SETSIZE + FD_SETBITMASK) / FD_SETIDXMASK];
+} fd_set;
+
+#define FD_CLR(fd, set) do {						\
+		fd_set *__set = (set);					\
+		int __fd = (fd);					\
+		if (__fd >= 0)						\
+			__set->fds[__fd / FD_SETIDXMASK] &=		\
+				~(1U << (__fd & FD_SETBITMASK));	\
+	} while (0)
+
+#define FD_SET(fd, set) do {						\
+		fd_set *__set = (set);					\
+		int __fd = (fd);					\
+		if (__fd >= 0)						\
+			__set->fds[__fd / FD_SETIDXMASK] |=		\
+				1 << (__fd & FD_SETBITMASK);		\
+	} while (0)
+
+#define FD_ISSET(fd, set) ({						\
+			fd_set *__set = (set);				\
+			int __fd = (fd);				\
+		int __r = 0;						\
+		if (__fd >= 0)						\
+			__r = !!(__set->fds[__fd / FD_SETIDXMASK] &	\
+1U << (__fd & FD_SETBITMASK));						\
+		__r;							\
+	})
+
+#define FD_ZERO(set) do {						\
+		fd_set *__set = (set);					\
+		int __idx;						\
+		int __size = (FD_SETSIZE+FD_SETBITMASK) / FD_SETIDXMASK;\
+		for (__idx = 0; __idx < __size; __idx++)		\
+			__set->fds[__idx] = 0;				\
+	} while (0)
+
+/*
+ * int select(int nfds, fd_set *read_fds, fd_set *write_fds,
+ *            fd_set *except_fds, struct timeval *timeout);
+ */
+
+static __attribute__((unused))
+int sys_select(int nfds, fd_set *rfds, fd_set *wfds, fd_set *efds, struct timeval *timeout)
+{
+#if defined(__ARCH_WANT_SYS_OLD_SELECT) && !defined(__NR__newselect)
+	struct sel_arg_struct {
+		unsigned long n;
+		fd_set *r, *w, *e;
+		struct timeval *t;
+	} arg = { .n = nfds, .r = rfds, .w = wfds, .e = efds, .t = timeout };
+	return my_syscall1(__NR_select, &arg);
+#elif defined(__NR__newselect)
+	return my_syscall5(__NR__newselect, nfds, rfds, wfds, efds, timeout);
+#elif defined(__NR_select)
+	return my_syscall5(__NR_select, nfds, rfds, wfds, efds, timeout);
+#elif defined(__NR_pselect6)
+	struct timespec t;
+
+	if (timeout) {
+		t.tv_sec  = timeout->tv_sec;
+		t.tv_nsec = timeout->tv_usec * 1000;
+	}
+	return my_syscall6(__NR_pselect6, nfds, rfds, wfds, efds, timeout ? &t : NULL, NULL);
+#else
+	struct __kernel_timespec t;
+
+	if (timeout) {
+		t.tv_sec  = timeout->tv_sec;
+		t.tv_nsec = timeout->tv_usec * 1000;
+	}
+	return my_syscall6(__NR_pselect6_time64, nfds, rfds, wfds, efds, timeout ? &t : NULL, NULL);
+#endif
+}
+
+static __attribute__((unused))
+int select(int nfds, fd_set *rfds, fd_set *wfds, fd_set *efds, struct timeval *timeout)
+{
+	return __sysret(sys_select(nfds, rfds, wfds, efds, timeout));
+}
+
+
+#endif /* _NOLIBC_SYS_SELECT_H */