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Because pledge(2) does not allow us to pass directory file descriptors
around, we can't use file descriptors for the working directory because
we will be unable to pass it to a privileged process to tell it where to
read or write files or spawn children. So move tmux back to using
strings for the current working directory. We try to check it exists
with access() when it is set but ultimately fall back to ~ if it fails
at time of use (or / if that fails too).

/* $OpenBSD: cmd-save-buffer.c,v 1.31 2015/10/31 08:13:58 nicm Exp $ */

/*
 * Copyright (c) 2009 Tiago Cunha <me@tiagocunha.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF MIND, USE, DATA OR PROFITS, WHETHER
 * IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
 * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/types.h>
#include <sys/stat.h>

#include <errno.h>
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <vis.h>

#include "tmux.h"

/*
 * Saves a paste buffer to a file.
 */

enum cmd_retval	 cmd_save_buffer_exec(struct cmd *, struct cmd_q *);

const struct cmd_entry cmd_save_buffer_entry = {
	"save-buffer", "saveb",
	"ab:", 1, 1,
	"[-a] " CMD_BUFFER_USAGE " path",
	0,
	cmd_save_buffer_exec
};

const struct cmd_entry cmd_show_buffer_entry = {
	"show-buffer", "showb",
	"b:", 0, 0,
	CMD_BUFFER_USAGE,
	0,
	cmd_save_buffer_exec
};

enum cmd_retval
cmd_save_buffer_exec(struct cmd *self, struct cmd_q *cmdq)
{
	struct args		*args = self->args;
	struct client		*c = cmdq->client;
	struct session          *s;
	struct paste_buffer	*pb;
	const char		*path, *bufname, *bufdata, *start, *end, *cwd;
	const char		*flags;
	char			*msg, *file, resolved[PATH_MAX];
	size_t			 size, used, msglen, bufsize;
	FILE			*f;

	if (!args_has(args, 'b')) {
		if ((pb = paste_get_top(NULL)) == NULL) {
			cmdq_error(cmdq, "no buffers");
			return (CMD_RETURN_ERROR);
		}
	} else {
		bufname = args_get(args, 'b');
		pb = paste_get_name(bufname);
		if (pb == NULL) {
			cmdq_error(cmdq, "no buffer %s", bufname);
			return (CMD_RETURN_ERROR);
		}
	}
	bufdata = paste_buffer_data(pb, &bufsize);

	if (self->entry == &cmd_show_buffer_entry)
		path = "-";
	else
		path = args->argv[0];
	if (strcmp(path, "-") == 0) {
		if (c == NULL) {
			cmdq_error(cmdq, "can't write to stdout");
			return (CMD_RETURN_ERROR);
		}
		if (c->session == NULL || (c->flags & CLIENT_CONTROL))
			goto do_stdout;
		goto do_print;
	}

	if (c != NULL && c->session == NULL)
		cwd = c->cwd;
	else if ((s = cmd_find_current(cmdq)) != NULL)
		cwd = s->cwd;
	else
		cwd = ".";

	flags = "wb";
	if (args_has(self->args, 'a'))
		flags = "ab";

	xasprintf(&file, "%s/%s", cwd, path);
	if (realpath(file, resolved) == NULL)
		f = NULL;
	else
		f = fopen(resolved, flags);
	free(file);
	if (f == NULL) {
		cmdq_error(cmdq, "%s: %s", resolved, strerror(errno));
		return (CMD_RETURN_ERROR);
	}

	if (fwrite(bufdata, 1, bufsize, f) != bufsize) {
		cmdq_error(cmdq, "%s: write error", resolved);
		fclose(f);
		return (CMD_RETURN_ERROR);
	}
	fclose(f);

	return (CMD_RETURN_NORMAL);

do_stdout:
	evbuffer_add(c->stdout_data, bufdata, bufsize);
	server_push_stdout(c);
	return (CMD_RETURN_NORMAL);

do_print:
	if (bufsize > (INT_MAX / 4) - 1) {
		cmdq_error(cmdq, "buffer too big");
		return (CMD_RETURN_ERROR);
	}
	msg = NULL;

	used = 0;
	while (used != bufsize) {
		start = bufdata + used;
		end = memchr(start, '\n', bufsize - used);
		if (end != NULL)
			size = end - start;
		else
			size = bufsize - used;

		msglen = size * 4 + 1;
		msg = xrealloc(msg, msglen);

		strvisx(msg, start, size, VIS_OCTAL|VIS_TAB);
		cmdq_print(cmdq, "%s", msg);

		used += size + (end != NULL);
	}

	free(msg);
	return (CMD_RETURN_NORMAL);
}