cosmopolitan/libc/log/commandvenv.c

/*-*- 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 2020 Justine Alexandra Roberts Tunney                              │
│                                                                              │
│ This program is free software; you can redistribute it and/or modify         │
│ it under the terms of the GNU General Public License as published by         │
│ the Free Software Foundation; version 2 of the License.                      │
│                                                                              │
│ This program is distributed in the hope that it will be useful, but          │
│ WITHOUT ANY WARRANTY; without even the implied warranty of                   │
│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU             │
│ General Public License for more details.                                     │
│                                                                              │
│ You should have received a copy of the GNU General Public License            │
│ along with this program; if not, write to the Free Software                  │
│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA                │
│ 02110-1301 USA                                                               │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/bits/safemacros.h"
#include "libc/calls/calls.h"
#include "libc/log/log.h"
#include "libc/mem/mem.h"
#include "libc/runtime/runtime.h"
#include "libc/sysv/consts/ok.h"

/**
 * Finds full executable path in overridable way.
 */
nodiscard char *commandvenv(const char *var, const char *cmd) {
  const char *exepath;
  char pathbuf[PATH_MAX];
  if ((exepath = getenv(var))) {
    if (!isempty(exepath) && access(exepath, X_OK) != -1) {
      return strdup(exepath);
    } else {
      return NULL;
    }
  } else if ((exepath = commandv(cmd, pathbuf))) {
    return strdup(exepath);
  } else {
    return NULL;
  }
}