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kernel/linux-imx6_3.14.28/tools/perf/util/pager.c 1.9 KB
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  #include "cache.h"
  #include "run-command.h"
  #include "sigchain.h"
  
  /*
   * This is split up from the rest of git so that we can do
   * something different on Windows.
   */
  
  static int spawned_pager;
  
  static void pager_preexec(void)
  {
  	/*
  	 * Work around bug in "less" by not starting it until we
  	 * have real input
  	 */
  	fd_set in;
  
  	FD_ZERO(&in);
  	FD_SET(0, &in);
  	select(1, &in, NULL, &in, 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("PERF_PAGER");
  
  	if (!isatty(1))
  		return;
  	if (!pager) {
  		if (!pager_program)
  			perf_config(perf_default_config, NULL);
  		pager = pager_program;
  	}
  	if (!pager)
  		pager = getenv("PAGER");
  	if (!pager) {
  		if (!access("/usr/bin/pager", X_OK))
  			pager = "/usr/bin/pager";
  	}
  	if (!pager)
  		pager = "less";
  	else if (!*pager || !strcmp(pager, "cat"))
  		return;
  
  	spawned_pager = 1; /* means we are emitting to terminal */
  
  	/* spawn the pager */
  	pager_argv[2] = pager;
  	pager_process.argv = pager_argv;
  	pager_process.in = -1;
  	pager_process.preexec_cb = pager_preexec;
  
  	if (start_command(&pager_process))
  		return;
  
  	/* original process continues, but writes to the pipe */
  	dup2(pager_process.in, 1);
  	if (isatty(2))
  		dup2(pager_process.in, 2);
  	close(pager_process.in);
  
  	/* this makes sure that the parent terminates after the pager */
  	sigchain_push_common(wait_for_pager_signal);
  	atexit(wait_for_pager);
  }
  
  int pager_in_use(void)
  {
  	const char *env;
  
  	if (spawned_pager)
  		return 1;
  
  	env = getenv("PERF_PAGER_IN_USE");
  	return env ? perf_config_bool("PERF_PAGER_IN_USE", env) : 0;
  }