text: // SPDX-License-Identifier: GPL-2.0-only
  /*
   * tools/testing/selftests/kvm/lib/assert.c
   *
   * Copyright (C) 2018, Google LLC.
   */
  
  #define _GNU_SOURCE /* for getline(3) and strchrnul(3)*/
  
  #include "test_util.h"
  
  #include <execinfo.h>
  #include <sys/syscall.h>
  
  #include "kselftest.h"
  
  /* Dumps the current stack trace to stderr. */
  static void __attribute__((noinline)) test_dump_stack(void);
  static void test_dump_stack(void)
  {
  	/*
  	 * Build and run this command:
  	 *
  	 *	addr2line -s -e /proc/$PPID/exe -fpai {backtrace addresses} | \
  	 *		grep -v test_dump_stack | cat -n 1>&2
  	 *
  	 * Note that the spacing is different and there's no newline.
  	 */
  	size_t i;
  	size_t n = 20;
  	void *stack[n];
  	const char *addr2line = "addr2line -s -e /proc/$PPID/exe -fpai";
  	const char *pipeline = "|cat -n 1>&2";
  	char cmd[strlen(addr2line) + strlen(pipeline) +
  		 /* N bytes per addr * 2 digits per byte + 1 space per addr: */
  		 n * (((sizeof(void *)) * 2) + 1) +
  		 /* Null terminator: */
  		 1];
  	char *c;
  
  	n = backtrace(stack, n);
  	c = &cmd[0];
  	c += sprintf(c, "%s", addr2line);
  	/*
  	 * Skip the first 3 frames: backtrace, test_dump_stack, and
  	 * test_assert. We hope that backtrace isn't inlined and the other two
  	 * we've declared noinline.
  	 */
  	for (i = 2; i < n; i++)
  		c += sprintf(c, " %lx", ((unsigned long) stack[i]) - 1);
  	c += sprintf(c, "%s", pipeline);
  #pragma GCC diagnostic push
  #pragma GCC diagnostic ignored "-Wunused-result"
  	system(cmd);
  #pragma GCC diagnostic pop
  }
  
  static pid_t _gettid(void)
  {
  	return syscall(SYS_gettid);
  }
  
  void __attribute__((noinline))
  test_assert(bool exp, const char *exp_str,
  	const char *file, unsigned int line, const char *fmt, ...)
  {
  	va_list ap;
  
  	if (!(exp)) {
  		va_start(ap, fmt);
  
  		fprintf(stderr, "==== Test Assertion Failure ====\n"
  			"  %s:%u: %s\n"
  			"  pid=%d tid=%d - %s\n",
  			file, line, exp_str, getpid(), _gettid(),
  			strerror(errno));
  		test_dump_stack();
  		if (fmt) {
  			fputs("  ", stderr);
  			vfprintf(stderr, fmt, ap);
  			fputs("\n", stderr);
  		}
  		va_end(ap);
  
  		if (errno == EACCES)
  			ksft_exit_skip("Access denied - Exiting.\n");
  		exit(254);
  	}
  
  	return;
  }
  