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 <linux/string.h>
   9 #include <errno.h>
  10 #include <unistd.h>
  11 #include "fs.h"
  12
  13 #include "tracing_path.h"
  14
  15
  16 char tracing_mnt[PATH_MAX]         = "/sys/kernel/debug";
  17 char tracing_path[PATH_MAX]        = "/sys/kernel/debug/tracing";
  18 char tracing_events_path[PATH_MAX] = "/sys/kernel/debug/tracing/events";
  19
  20
  21 static void __tracing_path_set(const char *tracing, const char *mountpoint)
  22 {
  23         snprintf(tracing_mnt, sizeof(tracing_mnt), "%s", mountpoint);
  24         snprintf(tracing_path, sizeof(tracing_path), "%s/%s",
  25                  mountpoint, tracing);
  26         snprintf(tracing_events_path, sizeof(tracing_events_path), "%s/%s%s",
  27                  mountpoint, tracing, "events");
  28 }
  29
  30 static const char *tracing_path_tracefs_mount(void)
  31 {
  32         const char *mnt;
  33
  34         mnt = tracefs__mount();
  35         if (!mnt)
  36                 return NULL;
  37
  38         __tracing_path_set("", mnt);
  39
  40         return mnt;
  41 }
  42
  43 static const char *tracing_path_debugfs_mount(void)
  44 {
  45         const char *mnt;
  46
  47         mnt = debugfs__mount();
  48         if (!mnt)
  49                 return NULL;
  50
  51         __tracing_path_set("tracing/", mnt);
  52
  53         return mnt;
  54 }
  55
  56 const char *tracing_path_mount(void)
  57 {
  58         const char *mnt;
  59
  60         mnt = tracing_path_tracefs_mount();
  61         if (mnt)
  62                 return mnt;
  63
  64         mnt = tracing_path_debugfs_mount();
  65
  66         return mnt;
  67 }
  68
  69 void tracing_path_set(const char *mntpt)
  70 {
  71         __tracing_path_set("tracing/", mntpt);
  72 }
  73
  74 char *get_tracing_file(const char *name)
  75 {
  76         char *file;
  77
  78         if (asprintf(&file, "%s/%s", tracing_path, name) < 0)
  79                 return NULL;
  80
  81         return file;
  82 }
  83
  84 void put_tracing_file(char *file)
  85 {
  86         free(file);
  87 }
  88
  89 static int strerror_open(int err, char *buf, size_t size, const char *filename)
  90 {
  91         char sbuf[128];
  92
  93         switch (err) {
  94         case ENOENT:
  95                 /*
  96                  * We will get here if we can't find the tracepoint, but one of
  97                  * debugfs or tracefs is configured, which means you probably
  98                  * want some tracepoint which wasn't compiled in your kernel.
  99                  * - jirka
 100                  */
 101                 if (debugfs__configured() || tracefs__configured()) {
 102                         snprintf(buf, size,
 103                                  "Error:\tFile %s/%s not found.\n"
 104                                  "Hint:\tPerhaps this kernel misses some CONFIG_ setting to enable this feature?.\n",
 105                                  tracing_events_path, filename);
 106                         break;
 107                 }
 108                 snprintf(buf, size, "%s",
 109                          "Error:\tUnable to find debugfs/tracefs\n"
 110                          "Hint:\tWas your kernel compiled with debugfs/tracefs support?\n"
 111                          "Hint:\tIs the debugfs/tracefs filesystem mounted?\n"
 112                          "Hint:\tTry 'sudo mount -t debugfs nodev /sys/kernel/debug'");
 113                 break;
 114         case EACCES: {
 115                 snprintf(buf, size,
 116                          "Error:\tNo permissions to read %s/%s\n"
 117                          "Hint:\tTry 'sudo mount -o remount,mode=755 %s'\n",
 118                          tracing_events_path, filename, tracing_mnt);
 119         }
 120                 break;
 121         default:
 122                 snprintf(buf, size, "%s", str_error_r(err, sbuf, sizeof(sbuf)));
 123                 break;
 124         }
 125
 126         return 0;
 127 }
 128
 129 int tracing_path__strerror_open_tp(int err, char *buf, size_t size, const char *sys, const char *name)
 130 {
 131         char path[PATH_MAX];
 132
 133         snprintf(path, PATH_MAX, "%s/%s", sys, name ?: "*");
 134
 135         return strerror_open(err, buf, size, path);
 136 }