tools/lib/api/fs/tracing_path.c

   1 #ifndef _GNU_SOURCE
   2 # define _GNU_SOURCE
   3 #endif
   4
   5 #include <stdio.h>
   6 #include <stdlib.h>
   7 #include <string.h>
   8 #include <errno.h>
   9 #include <unistd.h>
  10 #include "fs.h"
  11
  12 #include "tracing_path.h"
  13
  14
  15 char tracing_mnt[PATH_MAX]         = "/sys/kernel/debug";
  16 char tracing_path[PATH_MAX]        = "/sys/kernel/debug/tracing";
  17 char tracing_events_path[PATH_MAX] = "/sys/kernel/debug/tracing/events";
  18
  19
  20 static void __tracing_path_set(const char *tracing, const char *mountpoint)
  21 {
  22         snprintf(tracing_mnt, sizeof(tracing_mnt), "%s", mountpoint);
  23         snprintf(tracing_path, sizeof(tracing_path), "%s/%s",
  24                  mountpoint, tracing);
  25         snprintf(tracing_events_path, sizeof(tracing_events_path), "%s/%s%s",
  26                  mountpoint, tracing, "events");
  27 }
  28
  29 static const char *tracing_path_tracefs_mount(void)
  30 {
  31         const char *mnt;
  32
  33         mnt = tracefs__mount();
  34         if (!mnt)
  35                 return NULL;
  36
  37         __tracing_path_set("", mnt);
  38
  39         return mnt;
  40 }
  41
  42 static const char *tracing_path_debugfs_mount(void)
  43 {
  44         const char *mnt;
  45
  46         mnt = debugfs__mount();
  47         if (!mnt)
  48                 return NULL;
  49
  50         __tracing_path_set("tracing/", mnt);
  51
  52         return mnt;
  53 }
  54
  55 const char *tracing_path_mount(void)
  56 {
  57         const char *mnt;
  58
  59         mnt = tracing_path_tracefs_mount();
  60         if (mnt)
  61                 return mnt;
  62
  63         mnt = tracing_path_debugfs_mount();
  64
  65         return mnt;
  66 }
  67
  68 void tracing_path_set(const char *mntpt)
  69 {
  70         __tracing_path_set("tracing/", mntpt);
  71 }
  72
  73 char *get_tracing_file(const char *name)
  74 {
  75         char *file;
  76
  77         if (asprintf(&file, "%s/%s", tracing_path, name) < 0)
  78                 return NULL;
  79
  80         return file;
  81 }
  82
  83 void put_tracing_file(char *file)
  84 {
  85         free(file);
  86 }
  87
  88 static int strerror_open(int err, char *buf, size_t size, const char *filename)
  89 {
  90         char sbuf[128];
  91
  92         switch (err) {
  93         case ENOENT:
  94                 /*
  95                  * We will get here if we can't find the tracepoint, but one of
  96                  * debugfs or tracefs is configured, which means you probably
  97                  * want some tracepoint which wasn't compiled in your kernel.
  98                  * - jirka
  99                  */
 100                 if (debugfs__configured() || tracefs__configured()) {
 101                         snprintf(buf, size,
 102                                  "Error:\tFile %s/%s not found.\n"
 103                                  "Hint:\tPerhaps this kernel misses some CONFIG_ setting to enable this feature?.\n",
 104                                  tracing_events_path, filename);
 105                         break;
 106                 }
 107                 snprintf(buf, size, "%s",
 108                          "Error:\tUnable to find debugfs/tracefs\n"
 109                          "Hint:\tWas your kernel compiled with debugfs/tracefs support?\n"
 110                          "Hint:\tIs the debugfs/tracefs filesystem mounted?\n"
 111                          "Hint:\tTry 'sudo mount -t debugfs nodev /sys/kernel/debug'");
 112                 break;
 113         case EACCES: {
 114                 snprintf(buf, size,
 115                          "Error:\tNo permissions to read %s/%s\n"
 116                          "Hint:\tTry 'sudo mount -o remount,mode=755 %s'\n",
 117                          tracing_events_path, filename, tracing_mnt);
 118         }
 119                 break;
 120         default:
 121                 snprintf(buf, size, "%s", strerror_r(err, sbuf, sizeof(sbuf)));
 122                 break;
 123         }
 124
 125         return 0;
 126 }
 127
 128 int tracing_path__strerror_open_tp(int err, char *buf, size_t size, const char *sys, const char *name)
 129 {
 130         char path[PATH_MAX];
 131
 132         snprintf(path, PATH_MAX, "%s/%s", sys, name ?: "*");
 133
 134         return strerror_open(err, buf, size, path);
 135 }