Quelle  tracing_path.c   Sprache: C

// SPDX-License-Identifier: GPL-2.0
#ifndef _GNU_SOURCE
# define _GNU_SOURCE
#endif

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <linux/string.h>
#include <errno.h>
#include <unistd.h>
#include "fs.h"

#include "tracing_path.h"

static char tracing_path[PATH_MAX]        = "/sys/kernel/tracing";

static void __tracing_path_set(const char *tracing, const char *mountpoint)
{
 snprintf(tracing_path, sizeof(tracing_path), "%s/%s",
   mountpoint, tracing);
}

static const char *tracing_path_tracefs_mount(void)
{
 const char *mnt;

 mnt = tracefs__mount();
 if (!mnt)
  return NULL;

 __tracing_path_set("", mnt);

 return tracing_path;
}

static const char *tracing_path_debugfs_mount(void)
{
 const char *mnt;

 mnt = debugfs__mount();
 if (!mnt)
  return NULL;

 __tracing_path_set("tracing/", mnt);

 return tracing_path;
}

const char *tracing_path_mount(void)
{
 const char *mnt;

 mnt = tracing_path_tracefs_mount();
 if (mnt)
  return mnt;

 mnt = tracing_path_debugfs_mount();

 return mnt;
}

void tracing_path_set(const char *mntpt)
{
 __tracing_path_set("tracing/", mntpt);
}

char *get_tracing_file(const char *name)
{
 char *file;

 if (asprintf(&file, "%s%s", tracing_path_mount(), name) < 0)
  return NULL;

 return file;
}

void put_tracing_file(char *file)
{
 free(file);
}

char *get_events_file(const char *name)
{
 char *file;

 if (asprintf(&file, "%s/events/%s", tracing_path_mount(), name) < 0)
  return NULL;

 return file;
}

void put_events_file(char *file)
{
 free(file);
}

DIR *tracing_events__opendir(void)
{
 DIR *dir = NULL;
 char *path = get_tracing_file("events");

 if (path) {
  dir = opendir(path);
  put_events_file(path);
 }

 return dir;
}

int tracing_events__scandir_alphasort(struct dirent ***namelist)
{
 char *path = get_tracing_file("events");
 int ret;

 if (!path) {
  *namelist = NULL;
  return 0;
 }

 ret = scandir(path, namelist, NULL, alphasort);
 put_events_file(path);

 return ret;
}

int tracing_path__strerror_open_tp(int err, char *buf, size_t size,
       const char *sys, const char *name)
{
 char sbuf[128];
 char filename[PATH_MAX];

 snprintf(filename, PATH_MAX, "%s/%s", sys, name ?: "*");

 switch (err) {
 case ENOENT:
  /*
 * We will get here if we can't find the tracepoint, but one of
 * debugfs or tracefs is configured, which means you probably
 * want some tracepoint which wasn't compiled in your kernel.
 * - jirka
 */
  if (debugfs__configured() || tracefs__configured()) {
   /* sdt markers */
   if (!strncmp(filename, "sdt_", 4)) {
    snprintf(buf, size,
     "Error:\tFile %s/events/%s not found.\n"
     "Hint:\tSDT event cannot be directly recorded on.\n"
     "\tPlease first use 'perf probe %s:%s' before recording it.\n",
     tracing_path, filename, sys, name);
   } else {
    snprintf(buf, size,
      "Error:\tFile %s/events/%s not found.\n"
      "Hint:\tPerhaps this kernel misses some CONFIG_ setting to enable this feature?.\n",
      tracing_path, filename);
   }
   break;
  }
  snprintf(buf, size, "%s",
    "Error:\tUnable to find debugfs/tracefs\n"
    "Hint:\tWas your kernel compiled with debugfs/tracefs support?\n"
    "Hint:\tIs the debugfs/tracefs filesystem mounted?\n"
    "Hint:\tTry 'sudo mount -t debugfs nodev /sys/kernel/debug'");
  break;
 case EACCES: {
  snprintf(buf, size,
    "Error:\tNo permissions to read %s/events/%s\n"
    "Hint:\tTry 'sudo mount -o remount,mode=755 %s'\n",
    tracing_path, filename, tracing_path_mount());
 }
  break;
 default:
  snprintf(buf, size, "%s", str_error_r(err, sbuf, sizeof(sbuf)));
  break;
 }

 return 0;
}