[Libguestfs] [libnbd PATCH v3 22/29] CONNECT_COMMAND.START: check syscalls for errors in the child process

[Laszlo Ersek]

It's bad hygiene to just assume dup2(), close() and signal() will succeed.
Check all return values.

Signed-off-by: Laszlo Ersek <lersek at redhat.com>
---

Notes:
    context:-U10

 generator/states-connect.c | 22 +++++++++++++++-----
 1 file changed, 17 insertions(+), 5 deletions(-)

diff --git a/generator/states-connect.c b/generator/states-connect.c
index e08608336fd6..d2476dc11c60 100644
--- a/generator/states-connect.c
+++ b/generator/states-connect.c
@@ -262,29 +262,41 @@  CONNECT_COMMAND.START:
 
   pid = fork ();
   if (pid == -1) {
     SET_NEXT_STATE (%.DEAD);
     set_error (errno, "fork");
     close (sv[0]);
     close (sv[1]);
     return 0;
   }
   if (pid == 0) {         /* child - run command */
-    close (sv[0]);
-    dup2 (sv[1], STDIN_FILENO);
-    dup2 (sv[1], STDOUT_FILENO);
+    if (close (sv[0]) == -1) {
+      nbd_internal_fork_safe_perror ("close");
+      _exit (126);
+    }
+    if (dup2 (sv[1], STDIN_FILENO) == -1 ||
+        dup2 (sv[1], STDOUT_FILENO) == -1) {
+      nbd_internal_fork_safe_perror ("dup2");
+      _exit (126);
+    }
     NBD_INTERNAL_FORK_SAFE_ASSERT (sv[1] != STDIN_FILENO);
     NBD_INTERNAL_FORK_SAFE_ASSERT (sv[1] != STDOUT_FILENO);
-    close (sv[1]);
+    if (close (sv[1]) == -1) {
+      nbd_internal_fork_safe_perror ("close");
+      _exit (126);
+    }
 
     /* Restore SIGPIPE back to SIG_DFL. */
-    signal (SIGPIPE, SIG_DFL);
+    if (signal (SIGPIPE, SIG_DFL) == SIG_ERR) {
+      nbd_internal_fork_safe_perror ("signal");
+      _exit (126);
+    }
 
     execvp (h->argv.ptr[0], h->argv.ptr);
     nbd_internal_fork_safe_perror (h->argv.ptr[0]);
     if (errno == ENOENT)
       _exit (127);
     else
       _exit (126);
   }
 
   /* Parent. */