diff options
Diffstat (limited to 'apps/nshlib/nsh_builtin.c')
| -rw-r--r-- | apps/nshlib/nsh_builtin.c | 63 |
1 files changed, 49 insertions, 14 deletions
diff --git a/apps/nshlib/nsh_builtin.c b/apps/nshlib/nsh_builtin.c index ba39e8dfe..0d5a0231c 100644 --- a/apps/nshlib/nsh_builtin.c +++ b/apps/nshlib/nsh_builtin.c @@ -116,8 +116,8 @@ int nsh_builtin(FAR struct nsh_vtbl_s *vtbl, FAR const char *cmd, { int ret = OK; - /* Lock the scheduler to prevent the application from running until the - * waitpid() has been called. + /* Lock the scheduler in an attempt to prevent the application from + * running until waitpid() has been called. */ sched_lock(); @@ -129,16 +129,20 @@ int nsh_builtin(FAR struct nsh_vtbl_s *vtbl, FAR const char *cmd, ret = exec_builtin(cmd, (FAR const char **)argv, redirfile, oflags); if (ret >= 0) { - /* The application was successfully started (but still blocked because - * the scheduler is locked). If the application was not backgrounded, - * then we need to wait here for the application to exit. These really - * only works works with the following options: + /* The application was successfully started with pre-emption disabled. + * In the simplest cases, the application will not have run because the + * the scheduler is locked. But in the case where I/O was redirected, a + * proxy task ran and broke our lock. As result, the application may + * have aso ran if its priority was higher than than the priority of + * this thread. + * + * If the application did not run to completion and if the application + * was not backgrounded, then we need to wait here for the application + * to exit. This only works works with the following options: * * - CONFIG_NSH_DISABLEBG - Do not run commands in background * - CONFIG_SCHED_WAITPID - Required to run external commands in * foreground - * - * These concepts do not apply cleanly to the external applications. */ #ifdef CONFIG_SCHED_WAITPID @@ -154,15 +158,46 @@ int nsh_builtin(FAR struct nsh_vtbl_s *vtbl, FAR const char *cmd, { int rc = 0; - /* Wait for the application to exit. Since we have locked the - * scheduler above, we know that the application has not yet - * started and there is no possibility that it has already exited. - * The scheduler will be unlocked while waitpid is waiting and the - * application will be able to run. + /* Wait for the application to exit. We did lock the scheduler + * above, but that does not guarantee that the application did not + * already run to completion in the case where I/O was redirected. + * Here the scheduler will be unlocked while waitpid is waiting + * and if the application has not yet run, it will now be able to + * do so. + * + * Also, if CONFIG_SCHED_HAVE_PARENT is defined waitpid() might fail + * even if task is still active: If the I/O was re-directed by a + * proxy task, then the ask is a child of the proxy, and not this + * task. waitpid() fails with ECHILD in either case. */ ret = waitpid(ret, &rc, 0); - if (ret >= 0) + if (ret < 0) + { + /* If the child thread does not exist, waitpid() will return + * the error ECHLD. Since we know that the task was successfully + * started, this must be one of the cases described above; we + * have to assume that the task already exit'ed. In this case, + * we have no idea if the application ran successfully or not + * (because NuttX does not retain exit status of child tasks). + * Let's assume that is did run successfully. + */ + + int errcode = errno; + if (errcode == ECHILD) + { + ret = OK; + } + else + { + nsh_output(vtbl, g_fmtcmdfailed, cmd, "waitpid", + NSH_ERRNO_OF(errcode)); + } + } + + /* Waitpid completed the wait successfully */ + + else { /* We can't return the exact status (nsh has nowhere to put it) * so just pass back zero/nonzero in a fashion that doesn't look |