Exec: Support run exec in current task

There is a problem when vfork() calls execv() (or execl()) to start a new application:
When the parent thread calls vfork() it receives and gets the pid of the vforked task,
and not the pid of the desired execv'ed application.
see issue #3334

Signed-off-by: yangyalei <yangyalei@xiaomi.com>

binfmt/CMakeLists.txt

@@ -63,3 +63,4 @@ endif()
 
 target_sources(binfmt PRIVATE ${SRCS})
 target_include_directories(binfmt PRIVATE ${CMAKE_CURRENT_SOURCE_DIR})
+target_include_directories(binfmt PRIVATE ${CMAKE_SOURCE_DIR}/sched)

binfmt/Makefile

@@ -58,6 +58,8 @@ endif
 include libnxflat/Make.defs
 include libelf/Make.defs
 
+CFLAGS += ${INCDIR_PREFIX}$(TOPDIR)$(DELIM)sched
+
 AOBJS = $(ASRCS:.S=$(OBJEXT))
 COBJS = $(CSRCS:.c=$(OBJEXT))
 

binfmt/binfmt_exec.c

@@ -37,11 +37,11 @@
 #ifndef CONFIG_BINFMT_DISABLE
 
 /****************************************************************************
- * Public Functions
+ * Private Functions
  ****************************************************************************/
 
 /****************************************************************************
- * Name: exec_spawn
+ * Name: exec_internal
  *
  * Description:
  *   exec() configurable version, delivery the spawn attribute if this
@@ -64,6 +64,7 @@
  *   nexports - The number of symbols in the exports table.
  *   actions  - The spawn file actions
  *   attr     - The spawn attributes.
+ *   spawn    - Is spawn in new task.
  *
  * Returned Value:
  *   It returns the PID of the exec'ed module.  On failure, it returns
@@ -71,10 +72,11 @@
  *
  ****************************************************************************/
 
-int exec_spawn(FAR const char *filename, FAR char * const *argv,
+static int exec_internal(FAR const char *filename,
-               FAR char * const *envp, FAR const struct symtab_s *exports,
+                         FAR char * const *argv, FAR char * const *envp,
-               int nexports, FAR const posix_spawn_file_actions_t *actions,
+                         FAR const struct symtab_s *exports, int nexports,
-               FAR const posix_spawnattr_t *attr)
+                         FAR const posix_spawn_file_actions_t *actions,
+                         FAR const posix_spawnattr_t *attr, bool spawn)
 {
   FAR struct binary_s *bin;
   irqstate_t flags;
@@ -132,7 +134,7 @@ int exec_spawn(FAR const char *filename, FAR char * const *argv,
 
   /* Then start the module */
 
-  pid = exec_module(bin, filename, argv, envp, actions);
+  pid = exec_module(bin, filename, argv, envp, actions, spawn);
   if (pid < 0)
     {
       ret = pid;
@@ -175,6 +177,50 @@ errout:
   return ret;
 }
 
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: exec_spawn
+ *
+ * Description:
+ *   exec() configurable version, delivery the spawn attribute if this
+ *   process has special customization.
+ *
+ * Input Parameters:
+ *   filename - The path to the program to be executed. If
+ *              CONFIG_LIBC_ENVPATH is defined in the configuration, then
+ *              this may be a relative path from the current working
+ *              directory. Otherwise, path must be the absolute path to the
+ *              program.
+ *   argv     - A pointer to an array of string arguments. The end of the
+ *              array is indicated with a NULL entry.
+ *   envp     - A pointer to an array of environment strings. Terminated with
+ *              a NULL entry.
+ *   exports  - The address of the start of the caller-provided symbol
+ *              table. This symbol table contains the addresses of symbols
+ *              exported by the caller and made available for linking the
+ *              module into the system.
+ *   nexports - The number of symbols in the exports table.
+ *   actions  - The spawn file actions
+ *   attr     - The spawn attributes.
+ *
+ * Returned Value:
+ *   It returns the PID of the exec'ed module.  On failure, it returns
+ *   the negative errno value appropriately.
+ *
+ ****************************************************************************/
+
+int exec_spawn(FAR const char *filename, FAR char * const *argv,
+               FAR char * const *envp, FAR const struct symtab_s *exports,
+               int nexports, FAR const posix_spawn_file_actions_t *actions,
+               FAR const posix_spawnattr_t *attr)
+{
+  return exec_internal(filename, argv, envp,
+                       exports, nexports, actions, attr, true);
+}
+
 /****************************************************************************
  * Name: exec
  *
@@ -245,7 +291,8 @@ int exec(FAR const char *filename, FAR char * const *argv,
 {
   int ret;
 
-  ret = exec_spawn(filename, argv, envp, exports, nexports, NULL, NULL);
+  ret = exec_internal(filename, argv, envp,
+                      exports, nexports, NULL, NULL, false);
   if (ret < 0)
     {
       set_errno(-ret);

binfmt/binfmt_execmodule.c

@@ -36,6 +36,7 @@
 #include <nuttx/arch.h>
 #include <nuttx/kmalloc.h>
 #include <nuttx/sched.h>
+#include <sched/sched.h>
 #include <nuttx/spawn.h>
 #include <nuttx/binfmt/binfmt.h>
 
@@ -96,6 +97,91 @@ static void exec_ctors(FAR void *arg)
 }
 #endif
 
+/****************************************************************************
+ * Name: exec_swap
+ *
+ * Description:
+ *   swap the pid of tasks, and reverse parent-child relationship.
+ *
+ * Input Parameters:
+ *   ptcb  - parent task tcb.
+ *   chtcb - child task tcb.
+ *
+ * Returned Value:
+ *   none
+ *
+ ****************************************************************************/
+
+static void exec_swap(FAR struct tcb_s *ptcb, FAR struct tcb_s *chtcb)
+{
+  int        pndx;
+  int        chndx;
+  pid_t      pid;
+  irqstate_t flags;
+#ifdef HAVE_GROUP_MEMBERS
+  FAR pid_t  *tg_members;
+#endif
+#ifdef CONFIG_SCHED_HAVE_PARENT
+#  ifdef CONFIG_SCHED_CHILD_STATUS
+  FAR struct child_status_s *tg_children;
+#  else
+  uint16_t   tg_nchildren;
+#  endif
+#endif
+
+  DEBUGASSERT(ptcb);
+  DEBUGASSERT(chtcb);
+
+  flags = enter_critical_section();
+
+  pndx  = PIDHASH(ptcb->pid);
+  chndx = PIDHASH(chtcb->pid);
+
+  DEBUGASSERT(g_pidhash[pndx]);
+  DEBUGASSERT(g_pidhash[chndx]);
+
+  /* Exchange g_pidhash index */
+
+  g_pidhash[pndx] = chtcb;
+  g_pidhash[chndx] = ptcb;
+
+  /* Exchange pid */
+
+  pid = chtcb->pid;
+  chtcb->pid = ptcb->pid;
+  ptcb->pid = pid;
+
+  /* Exchange group info. This will reverse parent-child relationship */
+
+  pid = chtcb->group->tg_pid;
+  chtcb->group->tg_pid = ptcb->group->tg_pid;
+  ptcb->group->tg_pid = pid;
+
+  pid = chtcb->group->tg_ppid;
+  chtcb->group->tg_ppid = ptcb->group->tg_ppid;
+  ptcb->group->tg_ppid = pid;
+
+#ifdef HAVE_GROUP_MEMBERS
+  tg_members = chtcb->group->tg_members;
+  chtcb->group->tg_members = ptcb->group->tg_members;
+  ptcb->group->tg_members = tg_members;
+#endif
+
+#ifdef CONFIG_SCHED_HAVE_PARENT
+#  ifdef CONFIG_SCHED_CHILD_STATUS
+  tg_children = chtcb->group->tg_children;
+  chtcb->group->tg_children = ptcb->group->tg_children;
+  ptcb->group->tg_children = tg_children;
+#  else
+  tg_nchildren = chtcb->group->tg_nchildren;
+  chtcb->group->tg_nchildren = ptcb->group->tg_nchildren;
+  ptcb->group->tg_nchildren = tg_nchildren;
+#  endif
+#endif
+
+  leave_critical_section(flags);
+}
+
 /****************************************************************************
  * Public Functions
  ****************************************************************************/
@@ -116,7 +202,8 @@ static void exec_ctors(FAR void *arg)
 int exec_module(FAR struct binary_s *binp,
                 FAR const char *filename, FAR char * const *argv,
                 FAR char * const *envp,
-                FAR const posix_spawn_file_actions_t *actions)
+                FAR const posix_spawn_file_actions_t *actions,
+                bool spawn)
 {
   FAR struct task_tcb_s *tcb;
 #if defined(CONFIG_ARCH_ADDRENV) && defined(CONFIG_BUILD_KERNEL)
@@ -285,10 +372,6 @@ int exec_module(FAR struct binary_s *binp,
     }
 #endif
 
-  /* Get the assigned pid before we start the task */
-
-  pid = tcb->cmn.pid;
-
 #ifdef CONFIG_SCHED_USER_IDENTITY
   if (binp->mode & S_ISUID)
     {
@@ -301,6 +384,15 @@ int exec_module(FAR struct binary_s *binp,
     }
 #endif
 
+  if (!spawn)
+    {
+      exec_swap(this_task(), (FAR struct tcb_s *)tcb);
+    }
+
+  /* Get the assigned pid before we start the task */
+
+  pid = tcb->cmn.pid;
+
   /* Then activate the task at the provided priority */
 
   nxtask_activate((FAR struct tcb_s *)tcb);

include/nuttx/binfmt/binfmt.h

@@ -270,7 +270,8 @@ int unload_module(FAR struct binary_s *bin);
 int exec_module(FAR struct binary_s *binp,
                 FAR const char *filename, FAR char * const *argv,
                 FAR char * const *envp,
-                FAR const posix_spawn_file_actions_t *actions);
+                FAR const posix_spawn_file_actions_t *actions,
+                bool spawn);
 
 /****************************************************************************
  * Name: exec