From caf39c26827f355c4e107f55c5c51f67c484bfd7 Mon Sep 17 00:00:00 2001
From: Rob Landley <rob@landley.net>
Date: Fri, 16 Nov 2012 00:35:46 -0600
Subject: Add rebound support to intercept error_exit() and longjmp instead.

---
 lib/lib.c          | 8 ++++++--
 main.c             | 4 ++--
 toys.h             | 2 ++
 toys/lsb/killall.c | 2 +-
 toys/posix/sh.c    | 9 +++++++--
 5 files changed, 18 insertions(+), 7 deletions(-)

diff --git a/lib/lib.c b/lib/lib.c
index 06828a40..18578815 100644
--- a/lib/lib.c
+++ b/lib/lib.c
@@ -61,7 +61,9 @@ void error_exit(char *msg, ...)
   verror_msg(msg, 0, va);
   va_end(va);
 
-  exit(!toys.exitval ? 1 : toys.exitval);
+  if (!toys.exitval) toys.exitval++;
+  if (toys.rebound) longjmp(*toys.rebound, 1);
+  else exit(toys.exitval);
 }
 
 
@@ -74,7 +76,9 @@ void perror_exit(char *msg, ...)
   verror_msg(msg, errno, va);
   va_end(va);
 
-  exit(!toys.exitval ? 1 : toys.exitval);
+  if (!toys.exitval) toys.exitval++;
+  if (toys.rebound) longjmp(*toys.rebound, 1);
+  else exit(toys.exitval);
 }
 
 // Die unless we can allocate memory.
diff --git a/main.c b/main.c
index c705d645..7fb543ab 100644
--- a/main.c
+++ b/main.c
@@ -76,10 +76,10 @@ void toy_init(struct toy_list *which, char *argv[])
     if ((which->flags & TOYFLAG_NEEDROOT) && euid) error_exit("Not root");
   }
 
-  // Free old toys contents (to be reentrant)
+  // Free old toys contents (to be reentrant), but leave rebound if any
 
   if (toys.optargs != toys.argv+1) free(toys.optargs);
-  memset(&toys, 0, sizeof(struct toy_context));
+  memset(&toys, 0, offsetof(struct toy_context, rebound));
 
   toys.which = which;
   toys.argv = argv;
diff --git a/toys.h b/toys.h
index 72670cd7..55256efe 100644
--- a/toys.h
+++ b/toys.h
@@ -24,6 +24,7 @@
 #include <sched.h>
 #include <shadow.h>
 #include <stdarg.h>
+#include <stddef.h>
 #include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -103,6 +104,7 @@ extern struct toy_context {
   int optc;                // Count of optargs
   int exithelp;            // Should error_exit print a usage message first?
   int old_umask;           // Old umask preserved by TOYFLAG_UMASK
+  jmp_buf *rebound;        // longjmp here instead of exit when do_rebound set
 } toys;
 
 // One big temporary buffer, for use by commands (not library functions).
diff --git a/toys/lsb/killall.c b/toys/lsb/killall.c
index 7883c53d..debc3dfc 100644
--- a/toys/lsb/killall.c
+++ b/toys/lsb/killall.c
@@ -48,7 +48,7 @@ void killall_main(void)
   toys.exitval++;
 
   if (!*toys.optargs) {
-    toys.exithelp = 1;
+    toys.exithelp++;
     error_exit("Process name missing!");
   }
 
diff --git a/toys/posix/sh.c b/toys/posix/sh.c
index 30900b30..32d05ec2 100644
--- a/toys/posix/sh.c
+++ b/toys/posix/sh.c
@@ -293,12 +293,17 @@ static void run_pipeline(struct pipeline *line)
   // Is this command a builtin that should run in this process?
   if (tl && (tl->flags & TOYFLAG_NOFORK)) {
     struct toy_context temp;
+    jmp_buf rebound;
 
     // This fakes lots of what toybox_main() does.
     memcpy(&temp, &toys, sizeof(struct toy_context));
     memset(&toys, 0, sizeof(struct toy_context));
-    toy_init(tl, cmd->argv);
-    tl->toy_main();
+
+    if (!setjmp(rebound)) {
+      toys.rebound = rebound;
+      toy_init(tl, cmd->argv);
+      tl->toy_main();
+    }
     cmd->pid = toys.exitval;
     free(toys.optargs);
     if (toys.old_umask) umask(toys.old_umask);
-- 
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