Fix libc header dependencies

Turns out we had a bunch of silly dependencies on libc headers that are
not included with freestanding compilers. Fix all this and change the
CFLAGS to exclude libc headers and only include the built-in compiler
path.

Add our own versions of assert.h, errno.h, limits.h, and move malloc.h
and string.h together into a new path used as -isystem, so these headers
can be included using #include <>.

Remove a bunch of other dependencies in third-party code.

Add a strnlen function.

Disable building the libfdt overlay code for now, as it needs a strtoul
implementation. We can throw that in if/when we decide to use overlays.

Signed-off-by: Hector Martin <marcan@marcan.st>

Makefile

@@ -1,9 +1,22 @@
 ARCH := aarch64-linux-gnu-
 
+ifeq ($(USE_CLANG),1)
+CC := clang --target=$(ARCH)
+AS := clang --target=$(ARCH)
+LD := ld.lld
+OBJCOPY := llvm-objcopy
+else
+CC := $(ARCH)gcc
+AS := $(ARCH)gcc
+LD := $(ARCH)ld
+OBJCOPY := $(ARCH)objcopy
+endif
+
 CFLAGS := -O2 -Wall -Wundef -Werror=strict-prototypes -fno-common -fno-PIE \
 	-Werror=implicit-function-declaration -Werror=implicit-int \
 	-Wsign-compare -Wunused-parameter -Wno-multichar \
 	-ffreestanding -fpic -ffunction-sections -fdata-sections \
+	-nostdinc -isystem $(shell $(CC) -print-file-name=include) -isystem sysinc \
 	-fno-stack-protector -mgeneral-regs-only -mstrict-align -march=armv8.2-a
 
 LDFLAGS := -T m1n1.ld -EL -maarch64elf --no-undefined -X -Bsymbolic \
@@ -19,7 +32,7 @@ TINF_OBJECTS := $(patsubst %,tinf/%, \
 DLMALLOC_OBJECTS := dlmalloc/malloc.o
 
 LIBFDT_OBJECTS := $(patsubst %,libfdt/%, \
-	fdt_addresses.o fdt_empty_tree.o fdt_overlay.o fdt_ro.o fdt_rw.o fdt_strerror.o fdt_sw.o \
+	fdt_addresses.o fdt_empty_tree.o fdt_ro.o fdt_rw.o fdt_strerror.o fdt_sw.o \
 	fdt_wip.o fdt.o)
 
 OBJECTS := adt.o bootlogo_128.o bootlogo_256.o chickens.o exception.o exception_asm.o fb.o \
@@ -37,24 +50,12 @@ TARGET := m1n1.macho
 
 DEPDIR := build/.deps
 
-ifeq ($(USE_CLANG),1)
-CC := clang --target=$(ARCH)
-AS := clang --target=$(ARCH)
-LD := ld.lld
-OBJCOPY := llvm-objcopy
-else
-CC := $(ARCH)gcc
-AS := $(ARCH)gcc
-LD := $(ARCH)ld
-OBJCOPY := $(ARCH)objcopy
-endif
-
 .PHONY: all clean format
 all: build/$(TARGET) $(DTBS)
 clean:
 	rm -rf build/*
 format:
-	clang-format -i src/*.c src/*.h
+	clang-format -i src/*.c src/*.h sysinc/*.h
 
 build/dtb/%.dtb: dts/%.dts
 	@echo "  DTC   $@"

src/dlmalloc/malloc_config.h

@@ -1,5 +1,8 @@
+/* SPDX-License-Identifier: MIT */
+
+#include <string.h>
+
 #include "../heapblock.h"
-#include "../string.h"
 #include "../utils.h"
 
 #define HAVE_MORECORE 1
@@ -13,15 +16,16 @@
 #define NO_MALLINFO           1
 #define NO_MALLOC_STATS       1
 #define malloc_getpagesize    16384
-#define LACKS_UNISTD_H        1
 #define LACKS_FCNTL_H         1
-#define LACKS_SYS_PARAM_H     1
 #define LACKS_SYS_MMAN_H      1
+#define LACKS_SYS_PARAM_H     1
+#define LACKS_SYS_TYPES_H     1
 #define LACKS_STRINGS_H       1
 #define LACKS_STRING_H        1
 #define LACKS_STDLIB_H        1
 #define LACKS_SCHED_H         1
 #define LACKS_TIME_H          1
+#define LACKS_UNISTD_H        1
 #define MALLOC_FAILURE_ACTION panic("dlmalloc: out of memory\n");
 
 static void *sbrk(intptr_t inc)

src/exception.c

@@ -188,7 +188,6 @@ void exc_sync(u64 *regs)
             default:
                 printf("Unknown HVC: 0x%x\n", imm);
                 break;
-
         }
     } else {
         if (!(exc_guard & GUARD_SILENT))

src/heapblock.c

@@ -1,7 +1,6 @@
 /* SPDX-License-Identifier: MIT */
 
-#include <assert.h>
-
+#include "assert.h"
 #include "heapblock.h"
 #include "types.h"
 #include "utils.h"

src/kboot.c

@@ -1,8 +1,7 @@
 /* SPDX-License-Identifier: MIT */
 
-#include <assert.h>
-
 #include "adt.h"
+#include "assert.h"
 #include "exception.h"
 #include "kboot.h"
 #include "malloc.h"

src/libfdt/libfdt_env.h

@@ -10,7 +10,6 @@
 #include <stdbool.h>
 #include <stddef.h>
 #include <stdint.h>
-#include <stdlib.h>
 #include <string.h>
 #include <limits.h>
 

src/payload.c

@@ -1,8 +1,7 @@
 /* SPDX-License-Identifier: MIT */
 
-#include <assert.h>
-
 #include "payload.h"
+#include "assert.h"
 #include "heapblock.h"
 #include "kboot.h"
 #include "smp.h"

src/string.c

@@ -147,6 +147,17 @@ size_t strlen(const char *s)
     return rc;
 }
 
+size_t strnlen(const char *s, size_t n)
+{
+    size_t rc = 0;
+
+    while (rc < n && s[rc]) {
+        ++rc;
+    }
+
+    return rc;
+}
+
 char *strchr(const char *s, int c)
 {
     do {

src/types.h

@@ -3,6 +3,7 @@
 #ifndef TYPES_H
 #define TYPES_H
 
+#include <limits.h>
 #include <stddef.h>
 #include <stdint.h>
 
@@ -31,15 +32,6 @@ typedef s64 ptrdiff_t;
     type *name =                                                                                   \
         (type *)(((u32)(_al__##name)) + ((alignment) - (((u32)(_al__##name)) & ((alignment)-1))))
 
-#define INT_MAX  ((int)0x7fffffff)
-#define UINT_MAX ((unsigned int)0xffffffff)
-
-#define LONG_MAX  ((long)0x7fffffffffffffffl)
-#define ULONG_MAX ((unsigned long)0xfffffffffffffffful)
-
-#define LLONG_MAX  LONG_MAX
-#define ULLONG_MAX ULLONG_MAX
-
 #define HAVE_PTRDIFF_T 1
 #define HAVE_UINTPTR_T 1
 #define UPTRDIFF_T     uintptr_t

sysinc/assert.h

@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: MIT */
+
+#ifndef ASSERT_H
+#define ASSERT_H
+
+void __assert_fail(const char *assertion, const char *file, unsigned int line,
+                   const char *function);
+
+#define assert(expression)                                                                         \
+    ((expression) ? (void)0 : __assert_fail(#expression, __FILE__, __LINE__, __func__))
+
+/* Requires C11 */
+#define static_assert _Static_assert
+
+#endif

sysinc/errno.h

@@ -0,0 +1,9 @@
+/* SPDX-License-Identifier: MIT */
+
+#ifndef ERRNO_H
+#define ERRNO_H
+
+#define ENOMEM 12
+#define EINVAL 22
+
+#endif

sysinc/limits.h

@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: MIT */
+
+#ifndef LIMITS_H
+#define LIMITS_H
+
+#define INT_MAX  (0x7fffffff)
+#define UINT_MAX (0xffffffffu)
+
+#define LONG_MAX  (0x7fffffffffffffffl)
+#define ULONG_MAX (0xfffffffffffffffful)
+
+#define LLONG_MAX  LONG_MAX
+#define ULLONG_MAX ULLONG_MAX
+
+#endif

sysinc/string.h

@@ -15,6 +15,7 @@ char *strncpy(char *s1, const char *s2, size_t n);
 int strcmp(const char *s1, const char *s2);
 int strncmp(const char *s1, const char *s2, size_t n);
 size_t strlen(const char *s);
+size_t strnlen(const char *s, size_t n);
 char *strchr(const char *s, int c);
 char *strrchr(const char *s, int c);