Program loading, build system for apps, and badly-made lib linking.

src/kernel/initrd.c

@@ -8,6 +8,7 @@
 #include "../libc/string.h"
 #include "initrd.h"
 #include "system.h"
+#include "kheap.h"
 
 static unsigned int octal_to_int(const char* str, size_t size)
 {
@@ -31,6 +32,18 @@ uint32_t tar_parse_size(const char* in)
 	return size;
 }
 
+uint32_t tar_get_size(tar_header_t* header)
+{
+	uint32_t size = 0;
+	char* size_str = header->size;
+
+	for (int i=0; i<11 && size_str[i] != '\0'; i++)
+	{
+		size = size*8 + (size_str[i]-'0');
+	}
+	return size;
+}
+
 void tar_find_file(uint8_t *tar_start, const char* filename)
 {
 	uint8_t *ptr = tar_start;
@@ -174,3 +187,52 @@ uint32_t tar_get_file_size(uint8_t* initrd, const char* filename)
 	}
 	return -1;
 }
+
+tar_header_t* tar_find(uint8_t* initrd, const char* filename)
+{
+	tar_header_t* header = (tar_header_t*)initrd;
+	while (header->filename[0] != '\0')
+	{
+		if (strcmp(header->filename, filename) == 0)
+		{
+			return header;
+		}
+
+		uint32_t file_size = tar_get_size(header);
+		uint32_t file_blocks = (file_size + 511)/512;
+		header = (tar_header_t*) ((uintptr_t)header+(file_blocks+1)*512);
+	}
+
+	return NULL;
+}
+
+void* tar_get_file_content(tar_header_t* header)
+{
+	return (void*) ((uintptr_t)header+512);
+}
+
+void* load_file_from_initrd(uint8_t* initrd, const char* filename)
+{
+	tar_header_t* file = tar_find(initrd, filename);
+	if (file == NULL)
+	{
+		printf("'%s' not found\n", filename);
+		return NULL;
+	}
+
+	uint32_t file_size = tar_get_size(file);
+
+	void* file_data = malloc(file_size);
+	if (file_data == NULL)
+	{
+		printf("Malloc error for file '%s'\n", filename);
+		return NULL;
+	}
+
+	void* file_content = tar_get_file_content(file);
+	memcpy(file_data, file_content, file_size);
+
+	printf("Loaded '%s' at 0x%x, size=%u\n", filename, (unsigned int)file_data, file_size);
+
+	return file_data;
+}

src/kernel/initrd.h

@@ -35,5 +35,6 @@ void ls_initrd(uint8_t* initrd, int verbose);
 void cat_initrd(uint8_t* initrd, const char* filename);
 int tar_file_to_buffer(uint8_t* initrd, const char* filename, char* buffer);
 uint32_t tar_get_file_size(uint8_t* initrd, const char* filename);
+void* load_file_from_initrd(uint8_t* initrd, const char* filename);
 
 #endif

src/kernel/kmain.c

@@ -118,6 +118,16 @@ void kmain(multiboot2_info *mb_info)
     printf("[debug] malloc test ptr1=0x%x, ptr2=0x%x\n", (unsigned int)ptr1, (unsigned int)ptr2); 
     free(ptr1); free(ptr2);
 
+    // usually the place where i do testing
+
+    void* binary_file = load_file_from_initrd((uint8_t*)initrd_addr, "./hello.bin");
+    if (binary_file == NULL)
+    {
+	printf("NOT LOADED...\n");
+    } else {
+	printf("LOADED!\n");
+    }
+
     timer_install();
     keyboard_install();
     printf("[kernel] spawning shell...\n"); 

src/programs/hello.c

@@ -0,0 +1,6 @@
+#include "../libc/stdio.h"
+
+void main()
+{
+	printf("Hello, world, from a PROGRAM!\n");
+}