tools/lib/subcmd/pager.c

Source file repositories/reference/linux-study-clean/tools/lib/subcmd/pager.c

File Facts

System
Linux kernel
Corpus path
tools/lib/subcmd/pager.c
Extension
.c
Size
2536 bytes
Lines
130
Domain
Support Tooling And Documentation
Bucket
tools
Inferred role
Support Tooling And Documentation: implementation source
Status
source implementation candidate

Why This File Exists

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

Dependency Surface

Detected Declarations

Annotated Snippet

// SPDX-License-Identifier: GPL-2.0
#include <sys/select.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <signal.h>
#include <sys/ioctl.h>
#include "pager.h"
#include "run-command.h"
#include "sigchain.h"
#include "subcmd-config.h"

/*
 * This is split up from the rest of git so that we can do
 * something different on Windows.
 */

static int spawned_pager;
static int pager_columns;

void pager_init(const char *pager_env)
{
	subcmd_config.pager_env = pager_env;
}

static const char *forced_pager;

void force_pager(const char *pager)
{
	forced_pager = pager;
}

static void pager_preexec(void)
{
	/*
	 * Work around bug in "less" by not starting it until we
	 * have real input
	 */
	fd_set in;
	fd_set exception;

	FD_ZERO(&in);
	FD_ZERO(&exception);
	FD_SET(0, &in);
	FD_SET(0, &exception);
	select(1, &in, NULL, &exception, NULL);

	setenv("LESS", "FRSX", 0);
}

static const char *pager_argv[] = { "sh", "-c", NULL, NULL };
static struct child_process pager_process;

static void wait_for_pager(void)
{
	fflush(stdout);
	fflush(stderr);
	/* signal EOF to pager */
	close(1);
	close(2);
	finish_command(&pager_process);
}

static void wait_for_pager_signal(int signo)
{
	wait_for_pager();
	sigchain_pop(signo);
	raise(signo);
}

void setup_pager(void)
{
	const char *pager = getenv(subcmd_config.pager_env);
	struct winsize sz;

	if (forced_pager)
		pager = forced_pager;
	if (!isatty(1) && !forced_pager)
		return;
	if (ioctl(1, TIOCGWINSZ, &sz) == 0)
		pager_columns = sz.ws_col;
	if (!pager)
		pager = getenv("PAGER");
	if (!(pager || access("/usr/bin/pager", X_OK)))
		pager = "/usr/bin/pager";
	if (!(pager || access("/usr/bin/less", X_OK)))
		pager = "/usr/bin/less";
	if (!pager)
		pager = "cat";
	if (!*pager || !strcmp(pager, "cat"))

Annotation

Implementation Notes