280 lines
7.8 KiB
C
280 lines
7.8 KiB
C
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/*
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* inplace.c - Provide support for in-place editing.
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*/
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/*
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* Copyright (C) 2013-2015, 2017, 2018, the Free Software Foundation, Inc.
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*
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* This file is part of GAWK, the GNU implementation of the
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* AWK Programming Language.
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*
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* GAWK is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 3 of the License, or
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* (at your option) any later version.
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*
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* GAWK is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
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*/
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#ifdef HAVE_CONFIG_H
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#include <config.h>
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#endif
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#ifndef _XOPEN_SOURCE
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# define _XOPEN_SOURCE 1
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#endif
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#ifndef _XOPEN_SOURCE_EXTENDED
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# define _XOPEN_SOURCE_EXTENDED 1
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#endif
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#include <stdio.h>
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#include <assert.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include "gawkapi.h"
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#include "gettext.h"
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#define _(msgid) gettext(msgid)
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#define N_(msgid) msgid
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#if ! defined(S_ISREG) && defined(S_IFREG)
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#define S_ISREG(m) (((m) & S_IFMT) == S_IFREG)
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#endif
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#ifdef __MINGW32__
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# define chown(x,y,z) (0)
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# define link(f1,f2) rename(f1,f2)
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int
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mkstemp (char *template)
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{
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char *tmp_fname = _mktemp (template);
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if (tmp_fname)
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return _open (tmp_fname, O_RDWR | O_CREAT | O_EXCL, S_IREAD | S_IWRITE);
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return -1;
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}
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#endif
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static const gawk_api_t *api; /* for convenience macros to work */
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static awk_ext_id_t ext_id;
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static const char *ext_version = "inplace extension: version 1.0";
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int plugin_is_GPL_compatible;
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static struct {
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char *tname;
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int default_stdout;
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int posrc; /* return code from fgetpos */
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fpos_t pos;
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} state = { NULL, -1 };
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/*
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* XXX Known problems:
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* 1. Should copy ACL.
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* 2. Not reentrant, so will not work if multiple files are open at
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* the same time. I'm not sure this is a meaningful problem in practice.
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*/
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static void
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at_exit(void *data, int exit_status)
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{
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(void) data; /* silence warnings */
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(void) exit_status; /* silence warnings */
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if (state.tname) {
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unlink(state.tname);
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gawk_free(state.tname);
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state.tname = NULL;
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}
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}
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/*
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* N.B. Almost everything is a fatal error because this feature is typically
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* used for one-liners where the user is not going to be worrying about
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* checking errors. If anything unexpected occurs, we want to abort
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* immediately!
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*/
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static int
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invalid_filename(const awk_string_t *filename)
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{
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return filename->len == 0 ||
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(filename->len == 1 && *filename->str == '-');
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}
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/* do_inplace_begin --- start in-place editing */
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static awk_value_t *
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do_inplace_begin(int nargs, awk_value_t *result, struct awk_ext_func *unused)
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{
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awk_value_t filename;
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struct stat sbuf;
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int fd;
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assert(result != NULL);
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fflush(stdout);
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if (state.tname)
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fatal(ext_id, _("inplace::begin: in-place editing already active"));
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if (nargs != 2)
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fatal(ext_id, _("inplace::begin: expects 2 arguments but called with %d"), nargs);
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if (! get_argument(0, AWK_STRING, &filename))
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fatal(ext_id, _("inplace::begin: cannot retrieve 1st argument as a string filename"));
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/*
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* N.B. In the current implementation, the 2nd suffix arg is not used
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* in this function. It is used only in the inplace_end function.
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*/
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if (invalid_filename(&filename.str_value)) {
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warning(ext_id, _("inplace::begin: disabling in-place editing for invalid FILENAME `%s'"),
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filename.str_value.str);
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unset_ERRNO();
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return make_number(-1, result);
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}
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if (stat(filename.str_value.str, & sbuf) < 0) {
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warning(ext_id, _("inplace::begin: Cannot stat `%s' (%s)"),
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filename.str_value.str, strerror(errno));
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update_ERRNO_int(errno);
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return make_number(-1, result);
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}
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if (! S_ISREG(sbuf.st_mode)) {
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warning(ext_id, _("inplace::begin: `%s' is not a regular file"),
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filename.str_value.str);
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unset_ERRNO();
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return make_number(-1, result);
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}
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/* create a temporary file to which to redirect stdout */
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emalloc(state.tname, char *, filename.str_value.len+14, "do_inplace_begin");
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sprintf(state.tname, "%s.gawk.XXXXXX", filename.str_value.str);
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if ((fd = mkstemp(state.tname)) < 0)
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fatal(ext_id, _("inplace::begin: mkstemp(`%s') failed (%s)"),
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state.tname, strerror(errno));
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/* N.B. chown/chmod should be more portable than fchown/fchmod */
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if (chown(state.tname, sbuf.st_uid, sbuf.st_gid) < 0) {
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/* jumping through hoops to silence gcc and clang. :-( */
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int junk;
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junk = chown(state.tname, -1, sbuf.st_gid);
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++junk;
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}
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if (chmod(state.tname, sbuf.st_mode) < 0)
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fatal(ext_id, _("inplace::begin: chmod failed (%s)"),
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strerror(errno));
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fflush(stdout);
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/* N.B. fgetpos fails when stdout is a tty */
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state.posrc = fgetpos(stdout, &state.pos);
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if ((state.default_stdout = dup(STDOUT_FILENO)) < 0)
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fatal(ext_id, _("inplace::begin: dup(stdout) failed (%s)"),
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strerror(errno));
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if (dup2(fd, STDOUT_FILENO) < 0)
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fatal(ext_id, _("inplace::begin: dup2(%d, stdout) failed (%s)"),
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fd, strerror(errno));
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if (close(fd) < 0)
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fatal(ext_id, _("inplace::begin: close(%d) failed (%s)"),
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fd, strerror(errno));
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rewind(stdout);
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return make_number(0, result);
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}
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/* do_inplace_end --- finish in-place editing */
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static awk_value_t *
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do_inplace_end(int nargs, awk_value_t *result, struct awk_ext_func *unused)
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{
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awk_value_t filename, suffix;
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assert(result != NULL);
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if (nargs != 2)
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fatal(ext_id, _("inplace::end: expects 2 arguments but called with %d"), nargs);
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if (! get_argument(0, AWK_STRING, &filename))
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fatal(ext_id, _("inplace::end: cannot retrieve 1st argument as a string filename"));
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if (! get_argument(1, AWK_STRING, &suffix))
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suffix.str_value.str = NULL;
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if (! state.tname) {
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if (! invalid_filename(&filename.str_value))
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warning(ext_id, _("inplace::end: in-place editing not active"));
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return make_number(0, result);
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}
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fflush(stdout);
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if (dup2(state.default_stdout, STDOUT_FILENO) < 0)
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fatal(ext_id, _("inplace::end: dup2(%d, stdout) failed (%s)"),
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state.default_stdout, strerror(errno));
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if (close(state.default_stdout) < 0)
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fatal(ext_id, _("inplace::end: close(%d) failed (%s)"),
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state.default_stdout, strerror(errno));
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state.default_stdout = -1;
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if (state.posrc == 0 && fsetpos(stdout, &state.pos) < 0)
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fatal(ext_id, _("inplace::end: fsetpos(stdout) failed (%s)"),
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strerror(errno));
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if (suffix.str_value.str && suffix.str_value.str[0]) {
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/* backup requested */
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char *bakname;
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emalloc(bakname, char *, filename.str_value.len+suffix.str_value.len+1,
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"do_inplace_end");
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sprintf(bakname, "%s%s",
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filename.str_value.str, suffix.str_value.str);
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unlink(bakname); /* if backup file exists already, remove it */
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if (link(filename.str_value.str, bakname) < 0)
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fatal(ext_id, _("inplace::end: link(`%s', `%s') failed (%s)"),
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filename.str_value.str, bakname, strerror(errno));
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gawk_free(bakname);
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}
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#ifdef __MINGW32__
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unlink(filename.str_value.str);
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#endif
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if (rename(state.tname, filename.str_value.str) < 0)
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fatal(ext_id, _("inplace::end: rename(`%s', `%s') failed (%s)"),
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state.tname, filename.str_value.str, strerror(errno));
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gawk_free(state.tname);
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state.tname = NULL;
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return make_number(0, result);
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}
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static awk_ext_func_t func_table[] = {
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{ "begin", do_inplace_begin, 2, 2, awk_false, NULL },
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{ "end", do_inplace_end, 2, 2, awk_false, NULL },
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};
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static awk_bool_t init_inplace(void)
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{
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awk_atexit(at_exit, NULL);
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return awk_true;
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}
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static awk_bool_t (*init_func)(void) = init_inplace;
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/* define the dl_load function using the boilerplate macro */
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dl_load_func(func_table, inplace, "inplace")
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