[Findutils-patches] [PATCH] xargs: Don't leak file descriptors over an exec boundary.

[James Youngman]

This fixes a bug reported by Kyle Sallee (by email, so there is no
Savannah bug number for it).
* xargs/xargs.c (fopen_cloexec_for_read_only): New function; like
fopen (..., "r") but sets the resulting file to be closed on exec.
(main): Remember any non-O_CLOEXEC file desciptors that were open
on startup so that we don't get false positives later.
(prep_child_for_exec): Call complain_about_leaky_fds.
(main): Any file opened to support the -a option is marked
close-on-exec.  If we open /dev/tty to support the -p option, mark
that file close-on-exec, too.
* NEWS: mention this bugfix.
---
 NEWS          |  5 +++++
 xargs/xargs.c | 13 +++++++++++--
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/NEWS b/NEWS
index e04ac9b..5c429b3 100644
--- a/NEWS
+++ b/NEWS
@@ -2,6 +2,11 @@ GNU findutils NEWS - User visible changes.      -*- outline 
-*- (allout)
 
 * Major changes in release 4.5.17-git, 2015-12-DD
 
+** Bug Fixes:
+
+When the -a option of xargs is used, xargs no longer leaks a file
+descriptor (fixing a bug reported by Kyle Sallee).
+
 ** Translations
 
 Updated the Brazilian Portuguese and Serbian translations.
diff --git a/xargs/xargs.c b/xargs/xargs.c
index 2b0f8f2..bf130e0 100644
--- a/xargs/xargs.c
+++ b/xargs/xargs.c
@@ -65,6 +65,7 @@
 
 /* find headers. */
 #include "buildcmd.h"
+#include "fdleak.h"
 #include "findutils-version.h"
 
 #if ENABLE_NLS
@@ -366,6 +367,11 @@ smaller_of (size_t a, size_t b)
 }
 
 
+static FILE* fopen_cloexec_for_read_only (const char *file_name) {
+  int fd = open_cloexec (file_name, O_RDONLY);
+  return (fd < 0) ? NULL : fdopen (fd, "r");
+}
+
 
 int
 main (int argc, char **argv)
@@ -387,6 +393,7 @@ main (int argc, char **argv)
   else
     set_program_name ("xargs");
 
+  remember_non_cloexec_fds ();
   parent = getpid ();
   original_exit_value = EXIT_SUCCESS;
 
@@ -678,7 +685,7 @@ main (int argc, char **argv)
   else
     {
       keep_stdin = 1;          /* see prep_child_for_exec () */
-      input_stream = fopen (input_file, "r");
+      input_stream = fopen_cloexec_for_read_only (input_file);
       if (NULL == input_stream)
        {
          error (EXIT_FAILURE, errno,
@@ -1075,7 +1082,7 @@ print_args (bool ask)
 
       if (!tty_stream)
        {
-         tty_stream = fopen ("/dev/tty", "r");
+         tty_stream = fopen_cloexec_for_read_only ("/dev/tty");
          if (!tty_stream)
            error (EXIT_FAILURE, errno,
                   _("failed to open /dev/tty for reading"));
@@ -1154,6 +1161,8 @@ set_slot_var (unsigned int n)
 static void
 prep_child_for_exec (void)
 {
+  complain_about_leaky_fds ();
+
   /* The parent will call add_proc to allocate a slot.  We do the same in the
      child to make sure we get the same value.
 
-- 
2.1.4