refactor in preparation for allocating multiple segments

1 files changed, 52 insertions, 28 deletions

diff --git a/preload.c b/preload.c
index c34f976..841ddbb 100644
--- a/preload.c
+++ b/preload.c
@@ -58,11 +58,11 @@ struct segptr {
 };
 
 struct malloc_state {
-	struct segptr seg;
+	struct segptr *seg;
 	struct malloc_chunk free;
 };
 
-static 	struct malloc_state *m;
+static 	struct malloc_state m;
 
 static int in_use(struct malloc_chunk *c)
 {
@@ -86,7 +86,7 @@ static struct segptr *chunk_to_segment(struct malloc_chunk *c)
 {
 	struct segptr *sp;
 
-	for (sp = &m->seg; sp != NULL; sp = sp->next)
+	for (sp = m.seg; sp != NULL; sp = sp->next)
 		if (sp->base <= (char *)c &&
 		    (char *)c < sp->base + SEG_SIZE)
 			return sp;
@@ -113,6 +113,8 @@ static struct malloc_chunk *next_chunk(struct malloc_chunk *c)
 	struct segptr *seg = chunk_to_segment(c);
 	void *n = (char*)c + chunk_size(c);
 
+	ASSERT(seg != NULL);
+
 	ASSERT((char *)n > seg->base &&
 	       (char *)n <= seg->base + SEG_SIZE);
 	if (n == seg->base + SEG_SIZE)
@@ -130,7 +132,7 @@ static struct malloc_chunk *prev_chunk(struct malloc_chunk *c)
 
 static void link_free_chunk(struct malloc_chunk *c)
 {
-	struct malloc_chunk *f = &m->free;
+	struct malloc_chunk *f = &m.free;
 	struct malloc_chunk *b = f->bk;
 
 	c->fd = f;
@@ -152,35 +154,35 @@ static void unlink_free_chunk(struct malloc_chunk *c)
 static void show_segment(void)
 {
 	struct malloc_chunk *c;
+	struct segptr *seg;
+	int i;
 
 	if (!debug)
 		return;
 
-	printf("SHOW SEGMENT\n");
-	for (c = (struct malloc_chunk *)m->seg.base; c != NULL; c = next_chunk(c)) {
-		printf("%p:%d:%d:%04x:%04x", c, in_use(c), prev_in_use(c),
-		       c->prev_foot, chunk_size(c));
-		if (!in_use(c))
-			printf(":%p:%p", c->fd, c->bk);
-		printf("\n");
+	for (i = 0, seg = m.seg; seg != NULL; i++, seg = seg->next) {
+		printf("SHOW SEGMENT %i\n", i);
+		for (c = (struct malloc_chunk *)seg->base; c != NULL; c = next_chunk(c)) {
+			printf("%p:%d:%d:%04x:%04x", c, in_use(c), prev_in_use(c),
+			       c->prev_foot, chunk_size(c));
+			if (!in_use(c))
+				printf(":%p:%p", c->fd, c->bk);
+			printf("\n");
+		}
 	}
-
 	printf("SHOW SEGMENT END\n");
 }
 
-void __attribute__ ((constructor)) preload_setup(void)
+static int use_secret = 1;
+
+static void alloc_segment(void)
 {
 	int fd;
 	int ret;
 	void *p;
+	struct segptr *seg, *sp, **psp;
+	const size_t ssize = pad_request(sizeof(*seg));
 	struct malloc_chunk *c;
-	const size_t msize = pad_request(sizeof(*m));
-	int use_secret = 1;
-
-	if (getenv("MALLOC_DEBUG") != NULL)
-		debug = 1;
-	if (getenv("NO_SECRET_MEM") != NULL)
-		use_secret = 0;
 
 	if (use_secret)
 		fd = memfd_create("secure", MFD_CLOEXEC|MFD_SECRET);
@@ -198,28 +200,50 @@ void __attribute__ ((constructor)) preload_setup(void)
 
 	p = mmap(NULL, SEG_SIZE, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
 	check(p == MAP_FAILED, "mmap");
+	close(fd);
 
 	DEBUG("initial malloc at 0x%p-0x%p\n", p, p+SEG_SIZE);
 	c = p;
-	m = chunk2mem(c);
-	memset(m, 0, sizeof(*m));
-	c->head = msize | CINUSE_BIT | PINUSE_BIT;
-	m->seg.base = p;
+	seg = chunk2mem(c);
+	memset(seg, 0, sizeof(*seg));
+	seg->base = p;
+	c->head = ssize | CINUSE_BIT | PINUSE_BIT;
+	c->prev_foot = 0;
+
+	if (m.seg == NULL) {
+		m.seg = seg;
+	} else {
+		for (sp = m.seg; sp->next == NULL; sp = sp->next)
+			;
+		sp->next = seg;
+	}
 	c = next_chunk(c);
+	printf("NEXT CHUNK %p\n", c);
 	c->head = (size_t)(((char *)p + SEG_SIZE) - (char *)c) | PINUSE_BIT;
-	c->prev_foot = msize;
+	c->prev_foot = ssize;
 	DEBUG("next chunk at 0x%p, head=%x, prev=%x\n", c, chunk_size(c), c->prev_foot);
-	m->free.fd = &m->free;
-	m->free.bk = &m->free;
 
 	link_free_chunk(c);
 }
 
+void __attribute__ ((constructor)) preload_setup(void)
+{
+	if (getenv("MALLOC_DEBUG") != NULL)
+		debug = 1;
+	if (getenv("NO_SECRET_MEM") != NULL)
+		use_secret = 0;
+
+	m.free.fd = &m.free;
+	m.free.bk = &m.free;
+	m.seg = NULL;
+	alloc_segment();
+}
+
 static struct malloc_chunk *find_free(size_t size)
 {
 	struct malloc_chunk *c, *found = NULL;
 
-	for (c = m->free.fd; c != &m->free; c = c->fd) {
+	for (c = m.free.fd; c != &m.free; c = c->fd) {
 		if (chunk_size(c) < size)
 			continue;
 		if (found && chunk_size(found) < chunk_size(c))