/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8                                :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2021 Justine Alexandra Roberts Tunney                              │
│                                                                              │
│ Permission to use, copy, modify, and/or distribute this software for         │
│ any purpose with or without fee is hereby granted, provided that the         │
│ above copyright notice and this permission notice appear in all copies.      │
│                                                                              │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL                │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED                │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE             │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL         │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR        │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER               │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
│ PERFORMANCE OF THIS SOFTWARE.                                                │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/runtime/runtime.h"
#include "libc/str/str.h"

/**
 * Enables plaintext function tracing if `--ftrace` flag is passed.
 *
 * The `--ftrace` CLI arg is removed before main() is called. This code
 * is intended for diagnostic purposes and assumes binaries are
 * trustworthy and stack isn't corrupted. Logging plain text allows
 * program structure to easily be visualized and hotspots identified w/
 * `sed | sort | uniq -c | sort`. A compressed trace can be made by
 * appending `--ftrace 2>&1 | gzip -4 >trace.gz` to the CLI arguments.
 *
 * @see libc/runtime/_init.S for documentation
 */
textstartup int ftrace_init(int argc, char *argv[]) {
  int i;
  bool foundflag;
  foundflag = false;
  for (i = 1; i <= argc; ++i) {
    if (!foundflag) {
      if (argv[i]) {
        if (strcmp(argv[i], "--ftrace") == 0) {
          foundflag = true;
        } else if (strcmp(argv[i], "----ftrace") == 0) {
          strcpy(argv[i], "--ftrace");
        }
      }
    } else {
      argv[i - 1] = argv[i];
    }
  }
  if (foundflag) {
    --argc;
    ftrace_install();
  }
  return argc;
}