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/*
* libdpkg - Debian packaging suite library routines
* pager.c - pager execution support
*
* Copyright © 2018 Guillem Jover <guillem@debian.org>
*
* This 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 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, see <https://www.gnu.org/licenses/>.
*/
#include <config.h>
#include <compat.h>
#include <sys/types.h>
#include <stdbool.h>
#include <stdlib.h>
#include <string.h>
#include <signal.h>
#include <unistd.h>
#include <dpkg/dpkg.h>
#include <dpkg/i18n.h>
#include <dpkg/string.h>
#include <dpkg/subproc.h>
#include <dpkg/command.h>
#include <dpkg/pager.h>
static bool pager_enabled = true;
void
pager_enable(bool enable)
{
pager_enabled = enable;
}
/**
* Get a suitable pager.
*
* @return A string representing a pager.
*/
const char *
pager_get_exec(void)
{
const char *pager;
if (!isatty(0) || !isatty(1))
return CAT;
pager = getenv("DPKG_PAGER");
if (str_is_unset(pager))
pager = getenv("PAGER");
if (str_is_unset(pager))
pager = DEFAULTPAGER;
return pager;
}
struct pager {
bool used;
const char *desc;
pid_t pid;
struct sigaction sigpipe;
int stdout_old;
int pipe[2];
};
struct pager *
pager_spawn(const char *desc)
{
struct sigaction sa;
struct pager *pager;
const char *exec;
pager = m_calloc(1, sizeof(*pager));
pager->used = isatty(0) && isatty(1);
pager->desc = desc;
exec = pager_get_exec();
if (strcmp(exec, CAT) == 0)
pager->used = false;
if (!pager_enabled)
pager->used = false;
if (!pager->used)
return pager;
m_pipe(pager->pipe);
memset(&sa, 0, sizeof(sa));
sigemptyset(&sa.sa_mask);
sa.sa_handler = SIG_IGN;
sa.sa_flags = 0;
sigaction(SIGPIPE, &sa, &pager->sigpipe);
pager->pid = subproc_fork();
if (pager->pid == 0) {
/* Set better defaults for less if not already set. */
setenv("LESS", "-FRSXMQ", 0);
m_dup2(pager->pipe[0], 0);
close(pager->pipe[0]);
close(pager->pipe[1]);
command_shell(exec, desc);
}
pager->stdout_old = m_dup(1);
m_dup2(pager->pipe[1], 1);
close(pager->pipe[0]);
close(pager->pipe[1]);
/* Force the output to fully buffered, because originally stdout was
* a tty, so it was set as line buffered. This way we send as much as
* possible to the pager, which will handle the output by itself. */
setvbuf(stdout, NULL, _IOFBF, 0);
return pager;
}
void
pager_reap(struct pager *pager)
{
if (!pager->used)
return;
m_dup2(pager->stdout_old, 1);
subproc_reap(pager->pid, pager->desc, SUBPROC_NOPIPE);
sigaction(SIGPIPE, &pager->sigpipe, NULL);
free(pager);
}
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