kernel: Add a way to parse numbers from C strings

After making this change I am now actually doubting if using
C strings is a good idea and maybe it should just always just the
string view library that userland makes use of.

But old code and the upcoming commits rely upon this so it is a change my
future less lazy self will do.

6 files changed, 97 insertions, 2 deletions

diff --git a/kernel/Makefile b/kernel/Makefile
index 7fd8310..a27b108 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -1,6 +1,6 @@
 CC="i686-sb-gcc"
 AS="i686-sb-as"
-OBJ = arch/i386/boot.o init/kernel.o cpu/gdt.o cpu/reload_gdt.o cpu/idt.o cpu/io.o libc/stdio/print.o drivers/keyboard.o log.o drivers/pit.o libc/string/memcpy.o libc/string/strlen.o libc/string/memcmp.o drivers/ata.o libc/string/memset.o cpu/syscall.o  read_eip.o libc/exit/assert.o process.o libc/string/strcpy.o arch/i386/mmu.o kmalloc.o fs/ext2.o fs/vfs.o fs/devfs.o cpu/spinlock.o random.o libc/string/strcmp.o crypto/ChaCha20/chacha20.o crypto/SHA1/sha1.o fs/tmpfs.o libc/string/isequal.o drivers/pst.o kubsan.o drivers/serial.o socket.o poll.o fs/fifo.o hashmap/hashmap.o fs/shm.o elf.o sched/scheduler.o libc/string/copy.o drivers/mouse.o libc/string/strlcpy.o libc/string/strcat.o drivers/vbe.o drivers/pci.o drivers/rtl8139.o network/ethernet.o network/arp.o network/bytes.o network/ipv4.o network/udp.o signal.o network/tcp.o drivers/ahci.o crypto/xoshiro256plusplus/xoshiro256plusplus.o arch/i386/interrupts.o cpu/isr.o lib/stack.o lib/buffered_write.o lib/list.o cpu/arch_inst.o cpu/int_syscall.o lib/ringbuffer.o lib/relist.o arch/i386/tsc.o arch/i386/asm_tsc.o drivers/cmos.o timer.o queue.o fonts.o drivers/ac97.o audio.o libc/ctype/isdigit.o
+OBJ = arch/i386/boot.o init/kernel.o cpu/gdt.o cpu/reload_gdt.o cpu/idt.o cpu/io.o libc/stdio/print.o drivers/keyboard.o log.o drivers/pit.o libc/string/memcpy.o libc/string/strlen.o libc/string/memcmp.o drivers/ata.o libc/string/memset.o cpu/syscall.o  read_eip.o libc/exit/assert.o process.o libc/string/strcpy.o arch/i386/mmu.o kmalloc.o fs/ext2.o fs/vfs.o fs/devfs.o cpu/spinlock.o random.o libc/string/strcmp.o crypto/ChaCha20/chacha20.o crypto/SHA1/sha1.o fs/tmpfs.o libc/string/isequal.o drivers/pst.o kubsan.o drivers/serial.o socket.o poll.o fs/fifo.o hashmap/hashmap.o fs/shm.o elf.o sched/scheduler.o libc/string/copy.o drivers/mouse.o libc/string/strlcpy.o libc/string/strcat.o drivers/vbe.o drivers/pci.o drivers/rtl8139.o network/ethernet.o network/arp.o network/bytes.o network/ipv4.o network/udp.o signal.o network/tcp.o drivers/ahci.o crypto/xoshiro256plusplus/xoshiro256plusplus.o arch/i386/interrupts.o cpu/isr.o lib/stack.o lib/buffered_write.o lib/list.o cpu/arch_inst.o cpu/int_syscall.o lib/ringbuffer.o lib/relist.o arch/i386/tsc.o arch/i386/asm_tsc.o drivers/cmos.o timer.o queue.o fonts.o drivers/ac97.o audio.o libc/ctype/isdigit.o libc/stdlib/parsenum.o libc/ctype/tolower.o
 CFLAGS = -std=c99 -O0 -fsanitize=vla-bound,shift-exponent,pointer-overflow,shift,signed-integer-overflow,bounds -ggdb -ffreestanding -Wall -Wextra -Wno-int-conversion -Wno-unused-parameter -Werror -mgeneral-regs-only -Wimplicit-fallthrough -I./libc/include/ -I. -Wno-pointer-sign -DKERNEL
 LDFLAGS=
 #CFLAGS = -std=c99 -O3 -flto -ggdb -ffreestanding -Wall -Wextra -Wno-int-conversion -Wno-unused-parameter -Werror -mgeneral-regs-only -Wimplicit-fallthrough -I./libc/include/ -I. -Wno-pointer-sign -DKERNEL
diff --git a/kernel/fs/devfs.c b/kernel/fs/devfs.c
index 833aab5..8e09b7c 100644
--- a/kernel/fs/devfs.c
+++ b/kernel/fs/devfs.c
@@ -64,7 +64,7 @@ int stdout_write(u8 *buffer, u64 offset, u64 len, vfs_fd_t *fd) {
 
   int rc = len;
   for (; len--;) {
-    putc(*buffer++);
+    write_serial(*buffer++);
   }
   return rc;
 }
diff --git a/kernel/includes/ctype.h b/kernel/includes/ctype.h
index 4f9a3b3..f6be4f2 100644
--- a/kernel/includes/ctype.h
+++ b/kernel/includes/ctype.h
@@ -1 +1,2 @@
 int isdigit(int c);
+int tolower(int c);
diff --git a/kernel/includes/stdlib.h b/kernel/includes/stdlib.h
new file mode 100644
index 0000000..3b24fb6
--- /dev/null
+++ b/kernel/includes/stdlib.h
@@ -0,0 +1,4 @@
+#include <typedefs.h>
+
+u64 parse_u64(const char *restrict str, char **restrict endptr, int base,
+              int *err);
diff --git a/kernel/libc/ctype/tolower.c b/kernel/libc/ctype/tolower.c
new file mode 100644
index 0000000..f1bb163
--- /dev/null
+++ b/kernel/libc/ctype/tolower.c
@@ -0,0 +1,7 @@
+#include <ctype.h>
+
+int tolower(int c) {
+  if (c >= 'A' && c <= 'Z')
+    return c - 'A' + 'a';
+  return c;
+}
diff --git a/kernel/libc/stdlib/parsenum.c b/kernel/libc/stdlib/parsenum.c
new file mode 100644
index 0000000..3990c7b
--- /dev/null
+++ b/kernel/libc/stdlib/parsenum.c
@@ -0,0 +1,83 @@
+#include <assert.h>
+#include <ctype.h>
+#include <errno.h>
+#include <limits.h>
+#include <stdlib.h>
+
+#define MAX_64 0xFFFFFFFFFFFFFFFF
+
+extern int errno;
+int get_value(char c, long base) {
+  int r;
+  int l = tolower(c);
+  if (l >= '0' && l <= '9') {
+    r = l - '0';
+  } else if (l >= 'a' && l <= 'z') {
+    r = (l - 'a') + 10;
+  } else {
+    return -1;
+  }
+  if (r >= base) {
+    return -1;
+  }
+  return r;
+}
+
+u64 parse_u64(const char *restrict str, char **restrict endptr, int base,
+              int *err) {
+  if (err) {
+    *err = 0;
+  }
+  u64 ret_value = 0;
+  if (endptr) {
+    *endptr = (char *)str;
+  }
+  if (!*str) {
+    return ret_value;
+  }
+
+  if (0 == base) {
+    char prefix = *str;
+    if ('0' == prefix) {
+      str++;
+      if ('x' == tolower(*str)) {
+        str++;
+        base = 16;
+      } else {
+        base = 8;
+      }
+    } else {
+      base = 10;
+    }
+  }
+
+  if (2 <= base && 36 >= base) {
+    for (; *str; str++) {
+      int val = get_value(*str, base);
+      if (-1 == val) {
+        break;
+      }
+      if (-1 == val) {
+        break;
+      }
+      ret_value *= base;
+      if (ret_value > MAX_64 - val) {
+        if (err) {
+          *err = 1;
+        }
+        return 0;
+      }
+
+      ret_value += val;
+    }
+  } else {
+    if (err) {
+      *err = 1;
+    }
+    return 0;
+  }
+  if (endptr) {
+    *endptr = (char *)str;
+  }
+  return ret_value;
+}