initial musings about exec

5 files changed, 50 insertions, 10 deletions

diff --git a/common/elf.c b/common/elf.c
index 97d8fd7..b88be89 100644
--- a/common/elf.c
+++ b/common/elf.c
@@ -76,7 +76,7 @@ static vm_t __map_dyn(struct tcb *t, vm_t bin, uint8_t ei_c, vm_t phstart,
 	 * hacky, I know.*/
 }
 
-static vm_t __prepare_proc(struct tcb *t, uint8_t ei_c, vm_t elf)
+static vm_t __prepare_proc(struct tcb *t, uint8_t ei_c, vm_t elf, vm_t interp)
 {
 	short e_type = elf_header_prop(ei_c, elf, e_type);
 	if (e_type != ET_DYN && e_type != ET_EXEC)
@@ -97,9 +97,9 @@ static vm_t __prepare_proc(struct tcb *t, uint8_t ei_c, vm_t elf)
 }
 
 /* sets up all memory regions etc, returns the entry address */
-vm_t load_elf(struct tcb *t, vm_t b)
+vm_t load_elf(struct tcb *t, vm_t elf, vm_t interp)
 {
-	struct elf_ident *i = (struct elf_ident *)b;
+	struct elf_ident *i = (struct elf_ident *)elf;
 	if (i->ei_magic != cpu_to_be32(EI_MAGIC))
 		return 0;
 
@@ -107,5 +107,5 @@ vm_t load_elf(struct tcb *t, vm_t b)
 		return 0;
 
 	/* more sanity checks? */
-	return __prepare_proc(t, i->ei_class, b);
+	return __prepare_proc(t, i->ei_class, elf, interp);
 }
diff --git a/common/proc.c b/common/proc.c
index e88d37d..f09e7c1 100644
--- a/common/proc.c
+++ b/common/proc.c
@@ -45,7 +45,7 @@ stat_t init_proc(void *fdt, struct vmem *b)
 
 	/* TODO: this stuff should be placed in __sys_exec */
 	/* the binary gets to choose first what memory regions it requires */
-	t->entry = load_elf(t, get_init_base(fdt));
+	t->entry = load_elf(t, get_init_base(fdt), 0);
 	if (!t->entry)
 		return ERR_ADDR;
 
diff --git a/common/timer.c b/common/timer.c
index f36c90d..dadb88d 100644
--- a/common/timer.c
+++ b/common/timer.c
@@ -136,7 +136,7 @@ struct timer *find_timer(id_t cid)
 stat_t remove_timer(struct timer *t)
 {
 	if (!t)
-		return;
+		return ERR_INVAL;
 
 	struct sp_node *n = &timer_node_container(t)->sp_n;
 	sp_remove(&sp_root(__cpu_timers()), n);
diff --git a/common/uapi/proc.c b/common/uapi/proc.c
index e36c62e..3f715af 100644
--- a/common/uapi/proc.c
+++ b/common/uapi/proc.c
@@ -4,6 +4,8 @@
  */
 
 #include <apos/uapi.h>
+#include <apos/bits.h>
+#include <apos/mem_regions.h>
 
 SYSCALL_DEFINE0(create)(){
 	return (struct sys_ret){ OK, 0 };
@@ -23,8 +25,35 @@ SYSCALL_DEFINE0(fork)(){
 	return (struct sys_ret){ OK, 0 };
 }
 
-SYSCALL_DEFINE3(exec)(sys_arg_t bin, sys_arg_t argc, sys_arg_t argv){
+SYSCALL_DEFINE2(exec)(sys_arg_t bin, sys_arg_t interp){
 	/* TODO: execute new process, probably with more sensible argc passing */
+	struct tcb *r = cur_tcb();
+
+	/* mark binary to be kept */
+	struct mem_region *b = find_used_region(&r->sp_r, bin);
+	if (!b)
+		return (struct sys_ret){ERR_INVAL, 0};
+	__set_bit(b->flags, MR_KEEP);
+
+	struct mem_region *i = 0;
+	if (interp) {
+		/* mark interpreter to be kept */
+		i = find_used_region(&r->sp_r, interp);
+		if (!i)
+			return (struct sys_ret){ERR_INVAL, 1};
+		__set_bit(i->flags, MR_KEEP);
+	}
+
+	/* free everything except regions to be kept */
+	clear_uvmem(r, false);
+
+	/* restore to normal */
+	__clear_bit(b->flags, MR_KEEP);
+	if (interp)
+		__clear_bit(b->flags, MR_KEEP);
+
+	/* TODO: set entry? */
+	load_elf(r, b, i);
 	return (struct sys_ret){ OK, 0 };
 }
 
diff --git a/common/vmem.c b/common/vmem.c
index ae40748..3ea9ed7 100644
--- a/common/vmem.c
+++ b/common/vmem.c
@@ -25,15 +25,26 @@ static stat_t __free_mapped_region(struct tcb *t, struct mem_region *m)
 	return status;
 }
 
-stat_t destroy_uvmem(struct tcb *t)
+stat_t clear_uvmem(struct tcb *t, bool force)
 {
 	struct mem_region *m = find_first_region(&t->sp_r);
 	while (m) {
-		/* free all memory associated with used regions */
-		if (is_region_used(m))
+		/* if force is not set, free only regions that are not marked to
+		 * be kept and are owned.
+		 *
+		 * if force is set, free all owned regions.
+		 */
+		if (is_region_owned(m) && (force || !is_region_kept(m)))
 			__free_mapped_region(t, m);
 	}
 
+	return OK;
+}
+
+stat_t destroy_uvmem(struct tcb *t)
+{
+	/* force clear all regions */
+	clear_uvmem(t, true);
 	/* destroy region tree itself */
 	return destroy_region(&t->sp_r);
 }