Refactor libc stubs into libwrap

The --wrap feature of GNU ld supports a cleaner framework for linking in
alternative implementations of libc functions without cpp hacks.
Place wrappers in separate object files to reduce static code size.

4 files changed, 24 insertions, 201 deletions

diff --git a/bsp/env/common.mk b/bsp/env/common.mk
index 8d91805..0f5e9a1 100644
--- a/bsp/env/common.mk
+++ b/bsp/env/common.mk
@@ -1,5 +1,13 @@
 # See LICENSE for license details.
 
+ifndef _SIFIVE_MK_COMMON
+_SIFIVE_MK_COMMON := # defined
+
+.PHONY: all
+all: $(TARGET)
+
+include $(BSP_BASE)/libwrap/libwrap.mk
+
 BOARD ?= freedom-e300-hifive1
 ENV_DIR = $(BSP_BASE)/env
 PLATFORM_DIR = $(ENV_DIR)/$(BOARD)
@@ -7,28 +15,32 @@ PLATFORM_DIR = $(ENV_DIR)/$(BOARD)
 ASM_SRCS += $(PLATFORM_DIR)/start.S
 ASM_SRCS += $(PLATFORM_DIR)/entry.S
 C_SRCS += $(PLATFORM_DIR)/init.c
-C_SRCS += $(ENV_DIR)/syscall.c
 
 LINKER_SCRIPT := $(PLATFORM_DIR)/link.lds
 
-INCLUDES += -I.
 INCLUDES += -I$(BSP_BASE)/include
 INCLUDES += -I$(ENV_DIR)
 INCLUDES += -I$(PLATFORM_DIR)
 
-CC := $(BSP_BASE)/../toolchain/bin/riscv32-unknown-elf-gcc
+TOOL_DIR = $(BSP_BASE)/../toolchain/bin
 
-LDFLAGS += -T $(LINKER_SCRIPT) -nostdlib -nostartfiles -lc -lgcc
+CC := $(TOOL_DIR)/riscv32-unknown-elf-gcc
+AR := $(TOOL_DIR)/riscv32-unknown-elf-ar
+
+LDFLAGS += -T $(LINKER_SCRIPT) -nostartfiles
 LDFLAGS += -L$(ENV_DIR)
 
-ASM_OBJS := $(patsubst %.S,%.o,$(ASM_SRCS))
-C_OBJS := $(patsubst %.c,%.o,$(C_SRCS))
+ASM_OBJS := $(ASM_SRCS:.S=.o)
+C_OBJS := $(C_SRCS:.c=.o)
 
 LINK_OBJS += $(ASM_OBJS) $(C_OBJS)
+LINK_DEPS += $(LINKER_SCRIPT)
+
+CLEAN_OBJS += $(TARGET) $(LINK_OBJS)
 
 CFLAGS += -g
 
-$(TARGET): $(LINK_OBJS) $(LINKER_SCRIPT)
+$(TARGET): $(LINK_OBJS) $(LINK_DEPS)
 	$(CC) $(CFLAGS) $(INCLUDES) $(LINK_OBJS) -o $@ $(LDFLAGS)
 
 $(ASM_OBJS): %.o: %.S $(HEADERS)
@@ -37,9 +49,8 @@ $(ASM_OBJS): %.o: %.S $(HEADERS)
 $(C_OBJS): %.o: %.c $(HEADERS)
 	$(CC) $(CFLAGS) $(INCLUDES) -c -o $@ $<
 
-all: $(TARGET)
-
+.PHONY: clean
 clean:
-	rm -f $(TARGET) $(LINK_OBJS)
+	rm -f $(CLEAN_OBJS)
 
-.PHONY: all clean
+endif # _SIFIVE_MK_COMMON
diff --git a/bsp/env/freedom-e300-arty/init.c b/bsp/env/freedom-e300-arty/init.c
index 1f26b19..a7e368e 100644
--- a/bsp/env/freedom-e300-arty/init.c
+++ b/bsp/env/freedom-e300-arty/init.c
@@ -1,5 +1,6 @@
 //See LICENSE for license details.
 #include <stdint.h>
+#include <stdio.h>
 #include <unistd.h>
 
 #include "platform.h"
diff --git a/bsp/env/freedom-e300-hifive1/init.c b/bsp/env/freedom-e300-hifive1/init.c
index 268d41e..c088079 100644
--- a/bsp/env/freedom-e300-hifive1/init.c
+++ b/bsp/env/freedom-e300-hifive1/init.c
@@ -1,4 +1,5 @@
 #include <stdint.h>
+#include <stdio.h>
 #include <unistd.h>
 
 #include "platform.h"
diff --git a/bsp/env/syscall.c b/bsp/env/syscall.c
deleted file mode 100644
index 1b5de50..0000000
--- a/bsp/env/syscall.c
+++ /dev/null
@@ -1,190 +0,0 @@
-// See LICENSE for license details.
-
-/* This is an incomplete version of a syscall library, 
- * which really only supports simple reads and writes over UART.
- */
-
-#include <stdint.h>
-#include <stdlib.h>
-#include <stddef.h>
-#include <unistd.h>
-#include <errno.h>
-#include <sys/stat.h>
-#include <sys/times.h>
-#include <stdio.h>
-#include <string.h>
-
-#include "platform.h"
-
-void write_hex(int fd, uint32_t hex)
-{
-  uint8_t ii;
-  uint8_t jj;
-  char towrite;
-  write(fd , "0x", 2);
-  for (ii = 8 ; ii > 0; ii--) {
-    jj = ii - 1;
-    uint8_t digit = ((hex & (0xF << (jj*4))) >> (jj*4));
-    towrite = digit < 0xA ? ('0' + digit) : ('A' +  (digit - 0xA));
-    write(fd, &towrite, 1);
-  }
-}
-
-void _exit(int code)
-{
-  //volatile uint32_t* leds = (uint32_t*) (GPIO_BASE_ADDR + GPIO_OUT_OFFSET);
-  const char * message = "\nProgam has exited with code:";
-  
-  //*leds = (~(code));
-
-  write(STDERR_FILENO, message, strlen(message));
-  write_hex(STDERR_FILENO, code);
-  write(STDERR_FILENO, "\n", 1);
-
-  while (1) ;
-}
-
-void *sbrk(ptrdiff_t incr)
-{
-  extern char _end[];
-  extern char _heap_end[];
-  static char *curbrk = _end;
-
-  if ((curbrk + incr < _end) || (curbrk + incr > _heap_end))
-    return NULL - 1;
-
-  curbrk += incr;
-  return curbrk - incr;
-}
-
-static int stub(int err)
-{
-  return -1;
-}
-
-int open(const char* name, int flags, int mode)
-{
-  return stub(ENOENT);
-}
-
-int openat(int dirfd, const char* name, int flags, int mode)
-{
-  return stub(ENOENT);
-}
-
-int close(int fd)
-{
-  return stub(EBADF);
-}
-
-int execve(const char* name, char* const argv[], char* const env[])
-{
-  return stub(ENOMEM);
-}
-
-int fork()
-{
-  return stub(EAGAIN);
-}
-
-int fstat(int fd, struct stat *st)
-{
-  if (isatty(fd)) {
-    st->st_mode = S_IFCHR;
-    return 0;
-  }
-
-  return stub(EBADF);
-}
-
-int getpid()
-{
-  return 1;
-}
-
-int isatty(int fd)
-{
-  if (fd == STDOUT_FILENO || fd == STDERR_FILENO)
-    return 1;
-
-  return 0;
-}
-
-int kill(int pid, int sig)
-{
-  return stub(EINVAL);
-}
-
-int link(const char *old_name, const char *new_name)
-{
-  return stub(EMLINK);
-}
-
-off_t lseek(int fd, off_t ptr, int dir)
-{
-  if (isatty(fd))
-    return 0;
-
-  return stub(EBADF);
-}
-
-ssize_t read(int fd, void* ptr, size_t len)
-{
-  uint8_t * current = (uint8_t *)ptr;
-  volatile uint32_t * uart_rx = (uint32_t *)(UART0_BASE_ADDR + UART_REG_RXFIFO);
-  volatile uint8_t * uart_rx_cnt = (uint8_t *)(UART0_BASE_ADDR + UART_REG_RXCTRL + 2);
-
-  ssize_t result = 0;
-  
-  if (isatty(fd)) {
-    for (current = (uint8_t *)ptr;
-        (current < ((uint8_t *)ptr) + len) && (*uart_rx_cnt > 0);
-        current ++) {
-      *current = *uart_rx;
-      result++;
-    }
-    return result;
-  }
- 
-  return stub(EBADF);
-}
-
-int stat(const char* file, struct stat* st)
-{
-  return stub(EACCES);
-}
-
-clock_t times(struct tms* buf)
-{
-  return stub(EACCES);
-}
-
-int unlink(const char* name)
-{
-  return stub(ENOENT);
-}
-
-int wait(int* status)
-{
-  return stub(ECHILD);
-}
-
-ssize_t write(int fd, const void* ptr, size_t len)
-{
-  const uint8_t * current = (const char *)ptr;
-
-  if (isatty(fd)) {
-    for (size_t jj = 0; jj < len; jj++) {
-      while (UART0_REG(UART_REG_TXFIFO) & 0x80000000) ;
-      UART0_REG(UART_REG_TXFIFO) = current[jj];
-
-      if (current[jj] == '\n') {
-        while (UART0_REG(UART_REG_TXFIFO) & 0x80000000) ;
-        UART0_REG(UART_REG_TXFIFO) = '\r';
-      }
-    }
-    return len;
-  } 
-
-  return stub(EBADF);
-}