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209 lines
5.6 KiB
209 lines
5.6 KiB
From b56779aed483f0036a32a65e62ab7b5e461b07cc Mon Sep 17 00:00:00 2001
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From: Andreas Gruenbacher <agruen@gnu.org>
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Date: Fri, 6 Apr 2018 12:14:49 +0200
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Subject: [PATCH] Fix arbitrary command execution in ed-style patches
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(CVE-2018-1000156)
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* src/pch.c (do_ed_script): Write ed script to a temporary file instead
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of piping it to ed: this will cause ed to abort on invalid commands
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instead of rejecting them and carrying on.
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* tests/ed-style: New test case.
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* tests/Makefile.am (TESTS): Add test case.
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---
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src/pch.c | 89 +++++++++++++++++++++++++++++++++++------------
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tests/Makefile.am | 1 +
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tests/ed-style | 41 ++++++++++++++++++++++
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3 files changed, 108 insertions(+), 23 deletions(-)
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create mode 100644 tests/ed-style
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diff --git a/src/pch.c b/src/pch.c
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index bc6278c..4fd5a05 100644
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--- a/src/pch.c
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+++ b/src/pch.c
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@@ -33,6 +33,7 @@
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# include <io.h>
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#endif
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#include <safe.h>
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+#include <sys/wait.h>
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#define INITHUNKMAX 125 /* initial dynamic allocation size */
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@@ -2389,22 +2390,28 @@ do_ed_script (char const *inname, char const *outname,
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static char const editor_program[] = EDITOR_PROGRAM;
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file_offset beginning_of_this_line;
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- FILE *pipefp = 0;
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size_t chars_read;
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+ FILE *tmpfp = 0;
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+ char const *tmpname;
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+ int tmpfd;
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+ pid_t pid;
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+
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+ if (! dry_run && ! skip_rest_of_patch)
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+ {
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+ /* Write ed script to a temporary file. This causes ed to abort on
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+ invalid commands such as when line numbers or ranges exceed the
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+ number of available lines. When ed reads from a pipe, it rejects
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+ invalid commands and treats the next line as a new command, which
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+ can lead to arbitrary command execution. */
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+
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+ tmpfd = make_tempfile (&tmpname, 'e', NULL, O_RDWR | O_BINARY, 0);
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+ if (tmpfd == -1)
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+ pfatal ("Can't create temporary file %s", quotearg (tmpname));
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+ tmpfp = fdopen (tmpfd, "w+b");
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+ if (! tmpfp)
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+ pfatal ("Can't open stream for file %s", quotearg (tmpname));
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+ }
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- if (! dry_run && ! skip_rest_of_patch) {
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- int exclusive = *outname_needs_removal ? 0 : O_EXCL;
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- assert (! inerrno);
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- *outname_needs_removal = true;
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- copy_file (inname, outname, 0, exclusive, instat.st_mode, true);
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- sprintf (buf, "%s %s%s", editor_program,
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- verbosity == VERBOSE ? "" : "- ",
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- outname);
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- fflush (stdout);
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- pipefp = popen(buf, binary_transput ? "wb" : "w");
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- if (!pipefp)
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- pfatal ("Can't open pipe to %s", quotearg (buf));
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- }
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for (;;) {
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char ed_command_letter;
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beginning_of_this_line = file_tell (pfp);
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@@ -2415,14 +2422,14 @@ do_ed_script (char const *inname, char const *outname,
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}
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ed_command_letter = get_ed_command_letter (buf);
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if (ed_command_letter) {
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- if (pipefp)
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- if (! fwrite (buf, sizeof *buf, chars_read, pipefp))
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+ if (tmpfp)
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+ if (! fwrite (buf, sizeof *buf, chars_read, tmpfp))
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write_fatal ();
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if (ed_command_letter != 'd' && ed_command_letter != 's') {
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p_pass_comments_through = true;
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while ((chars_read = get_line ()) != 0) {
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- if (pipefp)
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- if (! fwrite (buf, sizeof *buf, chars_read, pipefp))
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+ if (tmpfp)
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+ if (! fwrite (buf, sizeof *buf, chars_read, tmpfp))
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write_fatal ();
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if (chars_read == 2 && strEQ (buf, ".\n"))
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break;
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@@ -2435,13 +2442,49 @@ do_ed_script (char const *inname, char const *outname,
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break;
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}
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}
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- if (!pipefp)
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+ if (!tmpfp)
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return;
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- if (fwrite ("w\nq\n", sizeof (char), (size_t) 4, pipefp) == 0
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- || fflush (pipefp) != 0)
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+ if (fwrite ("w\nq\n", sizeof (char), (size_t) 4, tmpfp) == 0
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+ || fflush (tmpfp) != 0)
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write_fatal ();
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- if (pclose (pipefp) != 0)
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- fatal ("%s FAILED", editor_program);
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+
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+ if (lseek (tmpfd, 0, SEEK_SET) == -1)
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+ pfatal ("Can't rewind to the beginning of file %s", quotearg (tmpname));
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+
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+ if (! dry_run && ! skip_rest_of_patch) {
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+ int exclusive = *outname_needs_removal ? 0 : O_EXCL;
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+ *outname_needs_removal = true;
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+ if (inerrno != ENOENT)
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+ {
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+ *outname_needs_removal = true;
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+ copy_file (inname, outname, 0, exclusive, instat.st_mode, true);
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+ }
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+ sprintf (buf, "%s %s%s", editor_program,
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+ verbosity == VERBOSE ? "" : "- ",
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+ outname);
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+ fflush (stdout);
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+
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+ pid = fork();
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+ if (pid == -1)
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+ pfatal ("Can't fork");
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+ else if (pid == 0)
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+ {
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+ dup2 (tmpfd, 0);
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+ execl ("/bin/sh", "sh", "-c", buf, (char *) 0);
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+ _exit (2);
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+ }
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+ else
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+ {
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+ int wstatus;
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+ if (waitpid (pid, &wstatus, 0) == -1
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+ || ! WIFEXITED (wstatus)
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+ || WEXITSTATUS (wstatus) != 0)
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+ fatal ("%s FAILED", editor_program);
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+ }
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+ }
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+
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+ fclose (tmpfp);
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+ safe_unlink (tmpname);
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if (ofp)
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{
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diff --git a/tests/Makefile.am b/tests/Makefile.am
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index 6b6df63..16f8693 100644
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--- a/tests/Makefile.am
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+++ b/tests/Makefile.am
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@@ -32,6 +32,7 @@ TESTS = \
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crlf-handling \
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dash-o-append \
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deep-directories \
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+ ed-style \
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empty-files \
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false-match \
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fifo \
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diff --git a/tests/ed-style b/tests/ed-style
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new file mode 100644
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index 0000000..d8c0689
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--- /dev/null
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+++ b/tests/ed-style
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@@ -0,0 +1,41 @@
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+# Copyright (C) 2018 Free Software Foundation, Inc.
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+#
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+# Copying and distribution of this file, with or without modification,
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+# in any medium, are permitted without royalty provided the copyright
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+# notice and this notice are preserved.
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+
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+. $srcdir/test-lib.sh
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+
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+require cat
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+use_local_patch
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+use_tmpdir
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+
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+# ==============================================================
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+
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+cat > ed1.diff <<EOF
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+0a
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+foo
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+.
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+EOF
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+
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+check 'patch -e foo -i ed1.diff' <<EOF
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+EOF
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+
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+check 'cat foo' <<EOF
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+foo
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+EOF
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+
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+cat > ed2.diff <<EOF
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+1337a
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+r !echo bar
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+,p
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+EOF
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+
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+check 'patch -e foo -i ed2.diff 2> /dev/null || echo "Status: $?"' <<EOF
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+?
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+Status: 2
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+EOF
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+
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+check 'cat foo' <<EOF
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+foo
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+EOF
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--
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2.19.1
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