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external/cache/sources/hcitools/monitor/display.c

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+/*
+ *
+ *  BlueZ - Bluetooth protocol stack for Linux
+ *
+ *  Copyright (C) 2011-2012  Intel Corporation
+ *  Copyright (C) 2004-2010  Marcel Holtmann <marcel@holtmann.org>
+ *
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <stdio.h>
+#include <errno.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <string.h>
+#include <signal.h>
+#include <sys/wait.h>
+#include <sys/prctl.h>
+#include <sys/ioctl.h>
+#include <termios.h>
+
+#include "display.h"
+
+static pid_t pager_pid = 0;
+
+bool use_color(void)
+{
+	static int cached_use_color = -1;
+
+	if (__builtin_expect(!!(cached_use_color < 0), 0))
+		cached_use_color = isatty(STDOUT_FILENO) > 0 || pager_pid > 0;
+
+	return cached_use_color;
+}
+
+int num_columns(void)
+{
+	static int cached_num_columns = -1;
+
+	if (__builtin_expect(!!(cached_num_columns < 0), 0)) {
+		struct winsize ws;
+
+		if (ioctl(STDOUT_FILENO, TIOCGWINSZ, &ws) < 0)
+			return -1;
+
+		if (ws.ws_col > 0)
+			cached_num_columns = ws.ws_col;
+	}
+
+	return cached_num_columns;
+}
+
+static void close_pipe(int p[])
+{
+	if (p[0] >= 0)
+		close(p[0]);
+	if (p[1] >= 0)
+		close(p[1]);
+}
+
+static void wait_for_terminate(pid_t pid)
+{
+	siginfo_t dummy;
+
+	for (;;) {
+		memset(&dummy, 0, sizeof(dummy));
+
+		if (waitid(P_PID, pid, &dummy, WEXITED) < 0) {
+			if (errno == EINTR)
+				continue;
+			return;
+		}
+
+		return;
+	}
+}
+
+void open_pager(void)
+{
+	const char *pager;
+	pid_t parent_pid;
+	int fd[2];
+
+	if (pager_pid > 0)
+		return;
+
+	pager = getenv("PAGER");
+	if (pager) {
+		if (!*pager || strcmp(pager, "cat") == 0)
+			return;
+	}
+
+	if (!(isatty(STDOUT_FILENO) > 0))
+		return;
+
+	num_columns();
+
+	if (pipe(fd) < 0) {
+		perror("Failed to create pager pipe");
+		return;
+	}
+
+	parent_pid = getpid();
+
+	pager_pid = fork();
+	if (pager_pid < 0) {
+		perror("Failed to fork pager");
+		close_pipe(fd);
+		return;
+	}
+
+	if (pager_pid == 0) {
+		dup2(fd[0], STDIN_FILENO);
+		close_pipe(fd);
+
+		setenv("LESS", "FRSX", 0);
+
+		if (prctl(PR_SET_PDEATHSIG, SIGTERM) < 0)
+			_exit(EXIT_FAILURE);
+
+		if (getppid() != parent_pid)
+			_exit(EXIT_SUCCESS);
+
+		if (pager) {
+			execlp(pager, pager, NULL);
+			execl("/bin/sh", "sh", "-c", pager, NULL);
+		}
+
+		execlp("pager", "pager", NULL);
+		execlp("less", "less", NULL);
+		execlp("more", "more", NULL);
+
+		_exit(EXIT_FAILURE);
+	}
+
+	if (dup2(fd[1], STDOUT_FILENO) < 0) {
+		perror("Failed to duplicate pager pipe");
+		return;
+	}
+
+	close_pipe(fd);
+}
+
+void close_pager(void)
+{
+	if (pager_pid <= 0)
+		return;
+
+	fclose(stdout);
+	kill(pager_pid, SIGCONT);
+	wait_for_terminate(pager_pid);
+	pager_pid = 0;
+}