[bug-inetutils] [PATCH 2/2] ftpd: add daemon (-D) nommu support

[Mike Frysinger]

The current daemon design of ftpd is to:
        - loop in server_mode() waiting for a connection
        - fork a child and return to main() to process like inetd
        - have parent continue looping in server_mode()

On a nommu system where we can only vfork(), the child returning
from server_mode() corrupts the stack and messes up the the parent.
So rather than having the child return, exec a new ftpd process in
the normal inetd mode.  This also fixes the problem in nommu where
a vfork-ed child pauses the parent until it either exits or execs
something.

Signed-off-by: Mike Frysinger <address@hidden>
---
 ftpd/extern.h      |    3 ++-
 ftpd/ftpd.c        |   17 ++++++++++++++---
 ftpd/server_mode.c |    9 ++++++++-
 3 files changed, 24 insertions(+), 5 deletions(-)

diff --git a/ftpd/extern.h b/ftpd/extern.h
index b1580c2..2aaea27 100644
--- a/ftpd/extern.h
+++ b/ftpd/extern.h
@@ -110,7 +110,8 @@ extern char tmpline[];
 extern off_t restart_point;
 
 /* Exported from server_mode.c.  */
-extern int server_mode (const char *pidfile, struct sockaddr_in *phis_addr);
+extern int server_mode (const char *pidfile, struct sockaddr_in *phis_addr,
+                       char *argv[]);
 
 /* Credential for the request.  */
 struct credentials
diff --git a/ftpd/ftpd.c b/ftpd/ftpd.c
index 22500bb..b4bf1c7 100644
--- a/ftpd/ftpd.c
+++ b/ftpd/ftpd.c
@@ -424,8 +424,7 @@ main (int argc, char *argv[], char **envp)
   argp_parse (&argp, argc, argv, 0, &index, NULL);
 
   /* Bail out, wrong usage */
-  argc -= index;
-  if (argc != 0)
+  if (argc - index != 0)
     error (EXIT_FAILURE, 0, "surplus arguments; try `%s --help' for more info",
           program_name);
 
@@ -438,7 +437,19 @@ main (int argc, char *argv[], char **envp)
      fd = accept(). tcpd is check if compile with the support  */
   if (daemon_mode)
     {
-      if (server_mode (pid_file, &his_addr) < 0)
+#ifndef HAVE_FORK
+      /* Shift out the daemon option in subforks  */
+      int i;
+      for (i = 0; i < argc; ++i)
+       if (strcmp (argv[i], "-D") == 0)
+         {
+           int j;
+           for (j = i; j < argc; ++j)
+             argv[j] = argv[j + 1];
+           argv[--argc] = NULL;
+         }
+#endif
+      if (server_mode (pid_file, &his_addr, argv) < 0)
        exit (EXIT_FAILURE);
     }
   else
diff --git a/ftpd/server_mode.c b/ftpd/server_mode.c
index 8e39ffd..b6673b1 100644
--- a/ftpd/server_mode.c
+++ b/ftpd/server_mode.c
@@ -37,6 +37,8 @@
 # include <tcpd.h>
 #endif
 
+#include <libinetutils.h>
+
 static void reapchild (int);
 
 #define DEFPORT 21
@@ -92,7 +94,7 @@ reapchild (int signo ARG_UNUSED)
 }
 
 int
-server_mode (const char *pidfile, struct sockaddr_in *phis_addr)
+server_mode (const char *pidfile, struct sockaddr_in *phis_addr, char *argv[])
 {
   int ctl_sock, fd;
   struct servent *sv;
@@ -176,5 +178,10 @@ server_mode (const char *pidfile, struct sockaddr_in 
*phis_addr)
   if (!check_host ((struct sockaddr *) phis_addr))
     return -1;
 #endif
+
+#ifndef HAVE_FORK
+  _exit(execvp(argv[0], argv));
+#endif
+
   return fd;
 }
-- 
1.7.4.1