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202 lines
5.4 KiB
202 lines
5.4 KiB
commit 123eaff0d5d1aebe128295959435b9ca5909c26d |
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Author: Andreas Gruenbacher <agruen@gnu.org> |
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Date: Fri Apr 6 12:14:49 2018 +0200 |
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Fix arbitrary command execution in ed-style patches (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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diff --git a/src/pch.c b/src/pch.c |
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index 0c5cc26..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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@@ -2389,24 +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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- 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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- 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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@@ -2417,14 +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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@@ -2437,13 +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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