libostd/ostd/environ.hh

/* Environment handling.
 *
 * This file is part of OctaSTD. See COPYING.md for futher information.
 */

#ifndef OSTD_ENVIRON_HH
#define OSTD_ENVIRON_HH

#include "ostd/platform.hh"
#include "ostd/internal/win32.hh"

#include <stdlib.h>
#include <string.h>

#include "ostd/maybe.hh"
#include "ostd/string.hh"

/* TODO: make POSIX version thread safe, the Windows version is... */

namespace ostd {
namespace envvar {

inline Maybe<String> get(ConstCharRange name) {
    char buf[256];
    auto tbuf = to_temp_cstr(name, buf, sizeof(buf));
#ifndef OSTD_PLATFORM_WIN32
    char const *ret = getenv(tbuf.get());
    if (!ret) return ostd::nothing;
    return ostd::move(String(ret));
#else
    String rbuf;
    for (;;) {
        auto ret = GetEnvironmentVariable(tbuf.get(), rbuf.data(),
                                          rbuf.capacity() + 1);
        if (!ret) return ostd::nothing;
        if (ret <= rbuf.capacity()) {
            rbuf.advance(ret);
            break;
        }
        rbuf.reserve(ret - 1);
    }
    return ostd::move(rbuf);
#endif
}

inline bool set(ConstCharRange name, ConstCharRange value,
                bool update = true) {
    char sbuf[2048];
    char *buf = sbuf;
    bool alloc = (name.size() + value.size() + 2) > sizeof(sbuf);
    if (alloc)
        buf = new char[name.size() + value.size() + 2];
    memcpy(buf, name.data(), name.size());
    buf[name.size()] = '\0';
    memcpy(&buf[name.size() + 1], value.data(), value.size());
    buf[name.size() + value.size() + 1] = '\0';
#ifndef OSTD_PLATFORM_WIN32
    bool ret = !setenv(buf, &buf[name.size() + 1], update);
#else
    if (!update && GetEnvironmentVariable(buf, nullptr, 0))
        return true;
    bool ret = !!SetEnvironmentVariable(buf, &buf[name.size() + 1]);
#endif
    if (alloc)
        delete[] buf;
    return ret;
}

inline bool unset(ConstCharRange name) {
    char buf[256];
    if (name.size() < sizeof(buf)) {
        memcpy(buf, name.data(), name.size());
        buf[name.size()] = '\0';
#ifndef OSTD_PLATFORM_WIN32
        return !unsetenv(buf);
#else
        return !!SetEnvironmentVariable(buf, nullptr);
#endif
    }
#ifndef OSTD_PLATFORM_WIN32
    return !unsetenv(String(name).data());
#else
        return !!SetEnvironmentVariable(String(name).data(), nullptr);
#endif
}

} /* namespace envvar */
} /* namespace ostd */

#endif