Make defconfig build for nommu.

Adds XVFORK() macro, teaches xpopen_both() to call /proc/self/exe with NULL
argv (and converts cpio -p to use that), adds TOYBOX_FORK guards to some
unconverted commands.

3 files changed, 10 insertions, 7 deletions

diff --git a/toys/posix/cpio.c b/toys/posix/cpio.c
index 312bb939..a442f0d1 100644
--- a/toys/posix/cpio.c
+++ b/toys/posix/cpio.c
@@ -82,12 +82,15 @@ void cpio_main(void)
   // In passthrough mode, parent stays in original dir and generates archive
   // to pipe, child does chdir to new dir and reads archive from stdin (pipe).
   if (TT.pass) {
-    if (!(pid = xpopen(0, &pipe, 0))) {
+    if (toys.stacktop) {
+      // xpopen() doesn't return from child due to vfork(), instead restarts
+      // with !toys.stacktop
+      pid = xpopen(0, &pipe, 0);
+      afd = pipe;
+    } else {
+      // child
       toys.optflags |= FLAG_i;
       xchdir(TT.pass);
-    } else {
-      toys.optflags |= FLAG_o;
-      afd = pipe;
     }
   }
 
diff --git a/toys/posix/time.c b/toys/posix/time.c
index b3cfd26b..2151826d 100644
--- a/toys/posix/time.c
+++ b/toys/posix/time.c
@@ -28,7 +28,7 @@ void time_main(void)
   struct timeval tv, tv2;
 
   gettimeofday(&tv, NULL);
-  if (!(pid = xvfork())) xexec(toys.optargs);
+  if (!(pid = XVFORK())) xexec(toys.optargs);
   else {
     int stat;
     struct rusage ru;
diff --git a/toys/posix/xargs.c b/toys/posix/xargs.c
index 50c42620..b4cb80a0 100644
--- a/toys/posix/xargs.c
+++ b/toys/posix/xargs.c
@@ -111,6 +111,7 @@ void xargs_main(void)
   struct double_list *dlist = NULL, *dtemp;
   int entries, bytes, done = 0, status;
   char *data = NULL, **out;
+  pid_t pid;
 
   if (!(toys.optflags & FLAG_0)) TT.delim = '\n';
 
@@ -168,8 +169,7 @@ void xargs_main(void)
     for (dtemp = dlist; dtemp; dtemp = dtemp->next)
       handle_entries(dtemp->data, out+entries);
 
-    pid_t pid=xvfork();
-    if (!pid) {
+    if (!(pid = XVFORK())) {
       xclose(0);
       open("/dev/null", O_RDONLY);
       xexec(out);