#include <stdio.h>

#include <string.h>

#include <stdlib.h>

#include <stdarg.h>

#define MAX_PATH 4096

#define _STR(x) #x

#define STR(x) _STR(x)

static const char *find_debugfs(void)

{

static char debugfs[MAX_PATH+1];

static int debugfs_found;

char type[100];

FILE *fp;

if (debugfs_found)

return debugfs;

if ((fp = fopen("/proc/mounts","r")) == NULL)

return NULL;

while (fscanf(fp, "%*s %"STR(MAX_PATH)"s %99s %*s %*d %*d\n", debugfs, type) == 2)

if (strcmp(type, "debugfs") == 0)

break;

fclose(fp);

if (strcmp(type, "debugfs") != 0)

return NULL;

debugfs_found = 1;

return debugfs;

}

static const char *find_trace(void)

{

static char t[MAX_PATH + 1];

if (t[0] != '\0')

return t;

const char *mt = getenv("T");

if (mt)

strcpy(t, mt);

if (t[0] != '\0')

return t;

const char *d = find_debugfs();

if (!d)

return NULL;

strcpy(t, d);

strcat(t, "/trace/trace");

return t;

}

static void die(const char *fmt, ...)

{

va_list va;

va_start(va, fmt);

vfprintf(stderr, fmt, va);

va_end(va);

putc('\n', stderr);

exit(EXIT_FAILURE);

}

int main(int argc, char **argv)

{

const char *dfs = find_debugfs();

if (!dfs)

die("could not find debugfs");

return 0;

}