1 files changed, 173 insertions, 1 deletions

diff --git a/miniany/libc-freestanding.c b/miniany/libc-freestanding.c
index fdec615..2bcdf0c 100644
--- a/miniany/libc-freestanding.c
+++ b/miniany/libc-freestanding.c
@@ -62,7 +62,8 @@ enum {
 enum {
 	SYSCALL_EXIT = 1,
 	SYSCALL_READ = 3,
-	SYSCALL_WRITE = 4
+	SYSCALL_WRITE = 4,
+	SYSCALL_BRK = 45
 };
 
 enum {
@@ -71,6 +72,10 @@ enum {
 
 int errno;
 
+enum {
+	ENOMEM = 1
+};
+
 int syscall1( int id, int arg0 )
 {
 	int retval;
@@ -245,3 +250,170 @@ void exit( int status )
 {
 	syscall1( SYSCALL_EXIT, status );
 }
+
+int system_brk( char *addr )
+{
+	return syscall1( SYSCALL_BRK, (int )addr );
+}
+
+char *current_brk = 0;
+
+int brk( char *addr )
+{
+	char *p;
+	
+	p = (char *)system_brk( addr );
+	if( (int)p < 0 ) {
+		return -1;
+	}
+	if( p == current_brk ) {
+		errno = ENOMEM;
+		return -1;
+	}
+
+	current_brk = p;
+	
+	return 0;
+}
+
+char *sbrk( int inc )
+{
+	char *old_brk;
+	int res;
+
+	if( current_brk == 0 ) {
+		brk( 0 );
+	}
+	
+	if( inc == 0 ) {
+		return current_brk;
+	}
+	
+	old_brk = current_brk;
+	
+	res = brk( ( char *)current_brk + inc );
+	if( res == -1 ) {
+		return (char *)-1;
+	}
+	
+	return old_brk;
+}
+
+struct mem_header {
+	int size;
+	int used;
+	struct mem_header *next;
+	int align;
+};
+
+struct mem_header *mem_head = NULL;
+struct mem_header *mem_tail = NULL;
+char *initial_brk = NULL;
+
+int mem_align( int n )
+{
+	return ( n + sizeof( int ) - 1 ) & ~( sizeof( int ) - 1 );
+}
+
+char *malloc( int size )
+{
+	int total_size;
+	char *ptr;
+	struct mem_header *header;
+	
+	total_size = mem_align( sizeof( struct mem_header ) + size );
+	
+	header = mem_head;
+	while( header != NULL ) {
+		if( !header->used && header->size >= size ) {
+			header->used = 1;
+			return (char *)( header + 1 );
+		}
+		header = header->next;
+	}
+	
+	if( initial_brk == NULL ) {
+		initial_brk = sbrk( 0 );
+	}
+	
+	ptr = sbrk( total_size );
+	if( ptr == (char *)-1 ) {
+		return NULL;
+	}
+	
+	header = (struct mem_header *)ptr;
+	header->size = size;
+	header->used = 1;
+	header->next = NULL;
+	
+	if( mem_head == NULL ) {
+		mem_head = header;
+	}
+	if( mem_tail != NULL ) {
+		mem_tail->next = header;
+	}
+	mem_tail = header;
+		
+	return (char *)( header + 1 );
+}
+
+void free( char *ptr )
+{
+	struct mem_header *header, *tmp;
+	char *actual_brk;
+	
+	if( ptr == NULL ) {
+		putstring( "warning: freeing a NULL pointer\n" );
+		return;
+	}
+	
+	header = (struct mem_header *)ptr - 1;
+	if( !header->used ) {
+		putstring( "warning: double free in linked list detected\n" );
+		return;
+	}
+	header->used = 0;
+	
+	actual_brk = sbrk( 0 );
+	if( (char *)ptr + header->size == actual_brk ) {
+		tmp = mem_head;
+		while( tmp != NULL ) {
+			if( tmp->next == mem_tail ) {
+				tmp->next = NULL;
+				mem_tail = tmp;
+			}
+			tmp = tmp->next;
+		}
+		if( mem_head == mem_tail ) {
+			mem_head = NULL;
+			mem_tail = NULL;
+		}
+		sbrk( - header->size - sizeof( struct mem_header ) );
+	}
+}
+
+char *memcpy( char *d, char *s, int len )
+{
+	char *p;
+	char *q;
+		
+	p = s;
+	q = d;
+	while( len-- ) {
+		*q = *p;
+		q++;
+		p++;
+	}
+	
+	return d;
+}
+
+char *strdup( char *s )
+{
+	char *c;
+	
+	c = malloc( strlen( s ) + 1 );
+	memcpy( c, s, strlen( s ) + 1 );
+	
+	return c;
+}