sys/newlib: Split stubs and make modules provide non-stubs

Makefile.dep

@@ -369,12 +369,50 @@ endif
 ifneq (,$(filter newlib,$(USEMODULE)))
   # allow custom newlib syscalls implementations by adding
   # newlib_syscalls_XXX to USEMODULE
-  ifeq (,$(filter newlib_syscalls_%,$(USEMODULE)))
+  # Once all syscall are split into "real" implementations and stubs, this
+  # module should go away
+  ifeq (,$(filter-out newlib_syscalls_riot_%,$(filter newlib_syscalls_%,$(USEMODULE))))
     USEMODULE += newlib_syscalls_default
   endif
-  ifeq (,$(filter stdio_rtt,$(USEMODULE)))
+  # If xtimer is available, use it to provide the clock function, but only if
+  # the stub module was not explicitly selected
+  ifeq (,$(filter newlib_stubs_clock,$(USEMODULE)))
+    ifneq (,$(filter xtimer,$(USEMODULE)))
+      USEMODULE += newlib_syscalls_riot_clock
+    endif
+  endif
+  ifeq (,$(filter newlib_stubs_time,$(USEMODULE)))
+    ifneq (,$(filter periph_rtc,$(USEMODULE)))
+      USEMODULE += newlib_syscalls_riot_time
+    endif
+  endif
+  ifeq (,$(filter newlib_stubs_rw newlib_stubs_fs,$(USEMODULE)))
+    ifneq (,$(filter vfs,$(USEMODULE)))
+      USEMODULE += newlib_syscalls_riot_vfs
+    endif
+  endif
+  ifeq (,$(filter newlib_stubs_rw vfs,$(USEMODULE)))
+      USEMODULE += newlib_syscalls_riot_serial_rw
+  endif
+  ifeq (,$(filter newlib_stubs_rw stdio_rtt,$(USEMODULE)))
     USEMODULE += stdio_uart
   endif
+  ifeq (,$(filter vfs newlib_syscalls_riot_vfs,$(USEMODULE)))
+      USEMODULE += newlib_stubs_fs
+  endif
+   USEMODULE += newlib_syscalls_riot_sbrk
+endif
+
+ifneq (,$(filter newlib_syscalls_riot_serial_rw,$(USEMODULE)))
+  USEMODULE += stdio_uart
+endif
+
+ifneq (,$(filter newlib_syscalls_riot_%,$(USEMODULE)))
+  USEMODULE += newlib_syscalls_riot
+endif
+
+ifneq (,$(filter newlib_stubs_%,$(USEMODULE)))
+  USEMODULE += newlib_stubs
 endif
 
 ifneq (,$(filter posix_sockets,$(USEMODULE)))

makefiles/pseudomodules.inc.mk

@@ -132,4 +132,8 @@ PSEUDOMODULES += crypto_aes_precalculated
 # This pseudomodule causes a loop in AES to be unrolled (more flash, less CPU)
 PSEUDOMODULES += crypto_aes_unroll
 
+# Newlib system call implementation and stubs are submodules
+PSEUDOMODULES += newlib_syscalls_riot_%
+PSEUDOMODULES += newlib_stubs_%
+
 # Packages may also add modules to PSEUDOMODULES in their `Makefile.include`.

sys/Makefile.include

@@ -68,6 +68,14 @@ ifneq (,$(filter newlib_syscalls_default,$(USEMODULE)))
   include $(RIOTBASE)/sys/newlib_syscalls_default/Makefile.include
 endif
 
+ifneq (,$(filter newlib_stubs_%,$(USEMODULE)))
+  include $(RIOTBASE)/sys/newlib_stubs/Makefile.include
+endif
+
+ifneq (,$(filter newlib_syscalls_riot_%,$(USEMODULE)))
+  include $(RIOTBASE)/sys/newlib_syscalls_riot/Makefile.include
+endif
+
 ifneq (,$(filter arduino,$(USEMODULE)))
   include $(RIOTBASE)/sys/arduino/Makefile.include
 endif

sys/newlib_stubs/Makefile

@@ -0,0 +1,3 @@
+SUBMODULES = 1
+
+include $(RIOTBASE)/Makefile.base

sys/newlib_stubs/Makefile.include

@@ -0,0 +1,15 @@
+ifneq (,$(filter newlib_stubs_clock,$(USEMODULE)))
+  UNDEF += $(BINDIR)/newlib_stubs/clock.o
+endif
+
+ifneq (,$(filter newlib_stubs_time,$(USEMODULE)))
+  UNDEF += $(BINDIR)/newlib_stubs/time.o
+endif
+
+ifneq (,$(filter newlib_stubs_fs,$(USEMODULE)))
+  UNDEF += $(BINDIR)/newlib_stubs/fs.o
+endif
+
+ifneq (,$(filter newlib_stubs_rw,$(USEMODULE)))
+  UNDEF += $(BINDIR)/newlib_stubs/rw.o
+endif

sys/newlib_stubs/clock.c

@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2018 FU Berlin
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser
+ * General Public License v2.1. See the file LICENSE in the top level
+ * directory for more details.
+ */
+
+/**
+ * @ingroup     sys_newlib_stubs
+ * @{
+ *
+ * @file
+ * @brief       Provide stub for _times_r (process' CPU time).
+ *
+ * By providing _times_r this module indirectly provides a stub for clock().
+ * If a real implementation is needed, see the newlib_syscalls_clock module.
+ *
+ * @author      Juan Carrano <j.carrano@fu-berlin.de>
+ *
+ * @}
+ */
+
+#include <reent.h>
+#include <errno.h>
+#include <sys/times.h>
+
+/**
+ * Current process times (not implemented).
+ *
+ * @param[out]  ptms    Not modified.
+ *
+ * @return  -1, this function always fails. errno is set to ENOSYS.
+ */
+clock_t _times_r(struct _reent *ptr, struct tms *ptms)
+{
+    (void)ptms;
+    ptr->_errno = ENOSYS;
+
+    return (-1);
+}

sys/newlib_stubs/doc.txt

@@ -0,0 +1,22 @@
+/**
+ * @ingroup  sys
+ * @defgroup sys_newlib_stubs Newlib system call stubs
+ *
+ *
+ * These module provide stubs (functions that always return an error) for the
+ * system calls required by newlib:
+ *
+ *  - File handling: _open_r, _close_r, _lseek_r, _read_r, _write_r, _stat_r,
+ *    _fstat_r, _link_r, _unlink_r, _fcntl_r
+ *  - Process control: _execve_r, _wait_r, _fork_r, _getpid_r
+ *  - Memory management: _sbrk_r
+ *  - Timekeeping: _gettimeofday_r, _times_r
+ *
+ * Stubs for these functions can be found in the newlib source, under newlib/libc/reent/.
+ *
+ * Stubs may be needed if an external module uses a standard library function
+ * that depends on a syscall, but it is not desired to pull in the code needed
+ * to support it (for example, there is no point in having VFS if there is no
+ * storage support.) In many of these cases it is perfectly acceptable if those
+ * functions do nothing but fail.
+ */

sys/newlib_stubs/fs.c

@@ -0,0 +1,91 @@
+/*
+ * Copyright (C) 2018 Freie Universität Berlin
+ *               2015 Kaspar Schleiser <kaspar@schleiser.de>
+ *               2014 Freie Universität Berlin
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser General
+ * Public License v2.1. See the file LICENSE in the top level directory for more
+ * details.
+ */
+
+/**
+ * @ingroup    sys_newlib_stubs
+ * @{
+ *
+ * @file
+ * @brief       Stubs for filesystem routines.
+ *
+ * @author      Michael Baar <michael.baar@fu-berlin.de>
+ * @author      Stefan Pfeiffer <pfeiffer@inf.fu-berlin.de>
+ * @author      Hauke Petersen <hauke.petersen@fu-berlin.de>
+ * @author      Kaspar Schleiser <kaspar@schleiser.de>
+ * @author      Juan I Carrano <j.carrano@fu-berlin.de>
+ *
+ * @}
+ */
+
+#include <reent.h>
+#include <errno.h>
+
+/* Stubs to avoid linking errors, these functions do not have any effect */
+int _open_r(struct _reent *r, const char *name, int flags, int mode)
+{
+    (void) name;
+    (void) flags;
+    (void) mode;
+    r->_errno = ENODEV;
+    return -1;
+}
+
+int _close_r(struct _reent *r, int fd)
+{
+    (void) fd;
+    r->_errno = ENODEV;
+    return -1;
+}
+
+_off_t _lseek_r(struct _reent *r, int fd, _off_t pos, int dir)
+{
+    (void) fd;
+    (void) pos;
+    (void) dir;
+    r->_errno = ENODEV;
+    return -1;
+}
+
+int _fstat_r(struct _reent *r, int fd, struct stat *st)
+{
+    (void) fd;
+    (void) st;
+    r->_errno = ENODEV;
+    return -1;
+}
+
+int _stat_r(struct _reent *r, const char *name, struct stat *st)
+{
+    (void) name;
+    (void) st;
+    r->_errno = ENODEV;
+    return -1;
+}
+
+int _unlink_r(struct _reent *r, const char *path)
+{
+    (void) path;
+    r->_errno = ENODEV;
+    return -1;
+}
+
+/*
+ * Riot does not support hard links (that's why the error is ENOSYS instead
+ * of ENODEV.
+ */
+int _link_r(struct _reent *ptr, const char *old_name, const char *new_name)
+{
+    (void)old_name;
+    (void)new_name;
+
+    ptr->_errno = ENOSYS;
+
+    return -1;
+}

sys/newlib_stubs/rw.c

@@ -0,0 +1,56 @@
+/*
+ * Copyright (C) 2018 Freie Universität Berlin
+ *               2015 Kaspar Schleiser <kaspar@schleiser.de>
+ *               2014 Freie Universität Berlin
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser General
+ * Public License v2.1. See the file LICENSE in the top level directory for more
+ * details.
+ */
+
+/**
+ * @ingroup    sys_newlib_stubs
+ * @{
+ *
+ * @file
+ * @brief       Stubs for read() and write()
+ *
+ * This modules makes reads and write to any file descriptor fail with EBADF.
+ *
+ * @author      Juan I Carrano <j.carrano@fu-berlin.de>
+ *
+ * @}
+ */
+
+#include <reent.h>
+#include <errno.h>
+
+/**
+ * Stub for read().
+ *
+ * Always fails with errno = EBADF.
+ */
+_ssize_t _read_r(struct _reent *r, int fd, void *buffer, size_t count)
+{
+    (void)r;
+    (void)fd;
+    (void)buffer;
+    (void)count;
+    r->_errno = EBADF;
+    return -1;
+}
+
+/**
+ * Stub for write().
+ *
+ * Always fails with errno = EBADF.
+ */
+_ssize_t _write_r(struct _reent *r, int fd, const void *data, size_t count)
+{
+    (void)r;
+    (void)fd;
+    (void)data;
+    (void)count;
+    r->_errno = EBADF;
+    return -1;
+}

sys/newlib_stubs/time.c

@@ -0,0 +1,43 @@
+/*
+ * Copyright (C) 2018 FU Berlin
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser
+ * General Public License v2.1. See the file LICENSE in the top level
+ * directory for more details.
+ */
+
+/**
+ * @ingroup     sys_newlib_stubs
+ * @{
+ *
+ * @file
+ * @brief       Provide stub for _gettimeofday_r (wall time).
+ *
+ * @author      Juan Carrano <j.carrano@fu-berlin.de>
+ *
+ * @}
+ */
+
+#include <reent.h>
+#include <errno.h>
+#include <sys/time.h>
+
+/**
+ * Get wall time in milliseconds since the epoch (not implemented).
+ *
+ * This is a stub that always fails for systems without RTC.
+ *
+ * @param[out]  r    Reentrant structure.
+ * @param[out]  tp   Not modified.
+ * @param  tpz   Not used.
+ *
+ * @return  -1, this function always fails. errno is set to ENOSYS.
+ */
+int _gettimeofday_r(struct _reent *r, struct timeval *restrict tp,
+                    void *restrict tzp)
+{
+    (void) tp;
+    (void) tzp;
+    r->_errno = ENOSYS;
+    return -1;
+}