LXR linux/tools/perf/util/pager.c

   1#include "cache.h"
   2#include "run-command.h"
   3#include "sigchain.h"
   4
   5/*
   6 * This is split up from the rest of git so that we can do
   7 * something different on Windows.
   8 */
   9
  10static int spawned_pager;
  11
  12static void pager_preexec(void)
  13{
  14        /*
  15         * Work around bug in "less" by not starting it until we
  16         * have real input
  17         */
  18        fd_set in;
  19
  20        FD_ZERO(&in);
  21        FD_SET(0, &in);
  22        select(1, &in, NULL, &in, NULL);
  23
  24        setenv("LESS", "FRSX", 0);
  25}
  26
  27static const char *pager_argv[] = { "sh", "-c", NULL, NULL };
  28static struct child_process pager_process;
  29
  30static void wait_for_pager(void)
  31{
  32        fflush(stdout);
  33        fflush(stderr);
  34        /* signal EOF to pager */
  35        close(1);
  36        close(2);
  37        finish_command(&pager_process);
  38}
  39
  40static void wait_for_pager_signal(int signo)
  41{
  42        wait_for_pager();
  43        sigchain_pop(signo);
  44        raise(signo);
  45}
  46
  47void setup_pager(void)
  48{
  49        const char *pager = getenv("PERF_PAGER");
  50
  51        if (!isatty(1))
  52                return;
  53        if (!pager) {
  54                if (!pager_program)
  55                        perf_config(perf_default_config, NULL);
  56                pager = pager_program;
  57        }
  58        if (!pager)
  59                pager = getenv("PAGER");
  60        if (!pager) {
  61                if (!access("/usr/bin/pager", X_OK))
  62                        pager = "/usr/bin/pager";
  63        }
  64        if (!pager)
  65                pager = "less";
  66        else if (!*pager || !strcmp(pager, "cat"))
  67                return;
  68
  69        spawned_pager = 1; /* means we are emitting to terminal */
  70
  71        /* spawn the pager */
  72        pager_argv[2] = pager;
  73        pager_process.argv = pager_argv;
  74        pager_process.in = -1;
  75        pager_process.preexec_cb = pager_preexec;
  76
  77        if (start_command(&pager_process))
  78                return;
  79
  80        /* original process continues, but writes to the pipe */
  81        dup2(pager_process.in, 1);
  82        if (isatty(2))
  83                dup2(pager_process.in, 2);
  84        close(pager_process.in);
  85
  86        /* this makes sure that the parent terminates after the pager */
  87        sigchain_push_common(wait_for_pager_signal);
  88        atexit(wait_for_pager);
  89}
  90
  91int pager_in_use(void)
  92{
  93        const char *env;
  94
  95        if (spawned_pager)
  96                return 1;
  97
  98        env = getenv("PERF_PAGER_IN_USE");
  99        return env ? perf_config_bool("PERF_PAGER_IN_USE", env) : 0;
 100}
 101