cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
Log | Files | Refs | README | LICENSE | sfeed.txt

pager.c (2536B)

      1// SPDX-License-Identifier: GPL-2.0
      2#include <sys/select.h>
      3#include <stdlib.h>
      4#include <stdio.h>
      5#include <string.h>
      6#include <signal.h>
      7#include <sys/ioctl.h>
      8#include "pager.h"
      9#include "run-command.h"
     10#include "sigchain.h"
     11#include "subcmd-config.h"
     12
     13/*
     14 * This is split up from the rest of git so that we can do
     15 * something different on Windows.
     16 */
     17
     18static int spawned_pager;
     19static int pager_columns;
     20
     21void pager_init(const char *pager_env)
     22{
     23	subcmd_config.pager_env = pager_env;
     24}
     25
     26static const char *forced_pager;
     27
     28void force_pager(const char *pager)
     29{
     30	forced_pager = pager;
     31}
     32
     33static void pager_preexec(void)
     34{
     35	/*
     36	 * Work around bug in "less" by not starting it until we
     37	 * have real input
     38	 */
     39	fd_set in;
     40	fd_set exception;
     41
     42	FD_ZERO(&in);
     43	FD_ZERO(&exception);
     44	FD_SET(0, &in);
     45	FD_SET(0, &exception);
     46	select(1, &in, NULL, &exception, NULL);
     47
     48	setenv("LESS", "FRSX", 0);
     49}
     50
     51static const char *pager_argv[] = { "sh", "-c", NULL, NULL };
     52static struct child_process pager_process;
     53
     54static void wait_for_pager(void)
     55{
     56	fflush(stdout);
     57	fflush(stderr);
     58	/* signal EOF to pager */
     59	close(1);
     60	close(2);
     61	finish_command(&pager_process);
     62}
     63
     64static void wait_for_pager_signal(int signo)
     65{
     66	wait_for_pager();
     67	sigchain_pop(signo);
     68	raise(signo);
     69}
     70
     71void setup_pager(void)
     72{
     73	const char *pager = getenv(subcmd_config.pager_env);
     74	struct winsize sz;
     75
     76	if (forced_pager)
     77		pager = forced_pager;
     78	if (!isatty(1) && !forced_pager)
     79		return;
     80	if (ioctl(1, TIOCGWINSZ, &sz) == 0)
     81		pager_columns = sz.ws_col;
     82	if (!pager)
     83		pager = getenv("PAGER");
     84	if (!(pager || access("/usr/bin/pager", X_OK)))
     85		pager = "/usr/bin/pager";
     86	if (!(pager || access("/usr/bin/less", X_OK)))
     87		pager = "/usr/bin/less";
     88	if (!pager)
     89		pager = "cat";
     90	if (!*pager || !strcmp(pager, "cat"))
     91		return;
     92
     93	spawned_pager = 1; /* means we are emitting to terminal */
     94
     95	/* spawn the pager */
     96	pager_argv[2] = pager;
     97	pager_process.argv = pager_argv;
     98	pager_process.in = -1;
     99	pager_process.preexec_cb = pager_preexec;
    100
    101	if (start_command(&pager_process))
    102		return;
    103
    104	/* original process continues, but writes to the pipe */
    105	dup2(pager_process.in, 1);
    106	if (isatty(2))
    107		dup2(pager_process.in, 2);
    108	close(pager_process.in);
    109
    110	/* this makes sure that the parent terminates after the pager */
    111	sigchain_push_common(wait_for_pager_signal);
    112	atexit(wait_for_pager);
    113}
    114
    115int pager_in_use(void)
    116{
    117	return spawned_pager;
    118}
    119
    120int pager_get_columns(void)
    121{
    122	char *s;
    123
    124	s = getenv("COLUMNS");
    125	if (s)
    126		return atoi(s);
    127
    128	return (pager_columns ? pager_columns : 80) - 2;
    129}