/* SPDX-License-Identifier: MIT */
/* SPDX-FileCopyrightText: (c) Copyright 2024,2025 Andrew Bower <andrew@bower.uk> */

#include <assert.h>
#include <ctype.h>
#include <getopt.h>
#include <errno.h>
#include <fcntl.h>
#include <sched.h>
#include <stdint.h>
#include <stdio.h>
#include <stdbool.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/types.h>

#include "options.h"

struct options opt;
struct runtime runtime = { 0 };

static const char HIDE = (char) -1;

const struct option_info options_info[] = {
  { C_R, OPT_SETUIDGID,   'u',  NULL,       required_argument, "set uid, gid and supplementary groups", "[:]USER[:GROUP]*", },
  { C_R, OPT_ENVUIDGID,   'U',  NULL,       required_argument, "set UID, GID and GIDLIST vars", "[:]USER[:GROUP]*", },
  { C_R, OPT_ARGV0,       'b',  NULL,       required_argument, "launch program with ARGV0 as the argv[0]", "ARGV0" },
  { C_R, OPT_ENVDIR,      'e',  NULL,       required_argument, "populate environment from directory", "DIR" },
  { C_R, OPT_CHROOT,      '/',  NULL,       required_argument, "change root directory", "DIR" },
  { C_R, OPT_CHDIR,       'C',  NULL,       required_argument, "change directory", "DIR" },
  { C_R, OPT_NICE,        'n',  NULL,       required_argument, "adjust niceness", "INC" },
  { C_R, OPT_LOCK_WAIT,   'l',  NULL,       required_argument, "wait for lock", "FILE" },
  { C_R, OPT_LOCK,        'L',  NULL,       required_argument, "obtain lock; fail fast", "FILE" },
  { C_L, OPT_LOCKOPT_WAIT,'N',  NULL,       no_argument,       "wait for lock (default)", NULL },
  { C_L, OPT_LOCKOPT_TRY, 'n',  NULL,       no_argument,       "don't wait for lock", NULL },
  { C_L, OPT_LOCKOPT_NOISY,'X', NULL,       no_argument,       "fail noisily (default)", NULL },
  { C_L, OPT_LOCKOPT_QUIET,'x', NULL,       no_argument,       "fail silently", NULL },
  { C_RS,OPT_LIMIT_MEM,   'm',  NULL,       required_argument, "set soft DATA, STACK, MEMLOCK and AS limits", "BYTES" },
  { C_RS,OPT_RLIMIT_DATA, 'd',  NULL,       required_argument, "set RLIMIT_DATA", "BYTES" },
  { C_S, OPT_RLIMIT_MEMLOCK,'l',NULL,       required_argument, "set RLIMIT_MEMLOCK", "BYTES" },
  { C_RS,OPT_RLIMIT_NOFILE,'o', NULL,       required_argument, "set RLIMIT_NOFILE", "FILES" },
  { C_RS,OPT_RLIMIT_NPROC,'p',  NULL,       required_argument, "set RLIMIT_NPROC", "PROCS" },
  { C_RS,OPT_RLIMIT_FSIZE,'f',  NULL,       required_argument, "set RLIMIT_FSIZE", "BYTES" },
  { C_RS,OPT_RLIMIT_CORE, 'c',  NULL,       required_argument, "set RLIMIT_CORE", "BYTES" },
  { C_RS,OPT_RLIMIT_CPU,  't',  NULL,       required_argument, "set RLIMIT_CPU", "SECONDS" },
  { C_XS,OPT_RLIMIT_AS,   'a',  "limit-as",             required_argument, "set RLIMIT_AS", "BYTES" },
  { C_XS,OPT_RLIMIT_RSS,  'r',  "limit-rss",            required_argument, "set RLIMIT_RSS", "BYTES" },
  { C_XS,OPT_RLIMIT_STACK,'s',  "limit-stack",          required_argument, "set RLIMIT_STACK", "BYTES" },
  { C_X, OPT_RLIMIT_MEMLOCK,   '\0', "limit-memlock",   required_argument, "set RLIMIT_MEMLOCK", "BYTES" },
  { C_X, OPT_RLIMIT_MSGQUEUE,  '\0', "limit-msgqueue",  required_argument, "set RLIMIT_MSGQUEUE", "BYTES" },
  { C_X, OPT_RLIMIT_NICE,      '\0', "limit-nice",      required_argument, "set RLIMIT_NICE", "NICENESS" },
  { C_X, OPT_RLIMIT_RTPRIO,    '\0', "limit-rtprio",    required_argument, "set RLIMIT_RTPRIO", "PRIO" },
  { C_X, OPT_RLIMIT_RTTIME,    '\0', "limit-rttime",    required_argument, "set RLIMIT_RTTIME", "MS" },
  { C_X, OPT_RLIMIT_SIGPENDING,'\0', "limit-sigpending",required_argument, "set RLIMIT_SIGPENDING", "NUM" },
  { C_X, OPT_RLIMIT_LOCKS,     '\0', "limit-locks",     required_argument, "set RLIMIT_LOCKS", "NUM" },
  { C_ALL,OPT_VERBOSE,    'v',  "verbose",  no_argument,       "be verbose", NULL },
  { C_R, OPT_VERSION,     'V',  "version",  no_argument,       "show " NAME_STR " version", NULL },
  { C_R, OPT_PGRPHACK,    'P',  NULL,       no_argument,       "run in new process group", NULL },
  { C_R, OPT_FGHACK,      '\0', "fghack",   no_argument,       "wait for all spawned processes to terminate", NULL },
  { C_R, OPT_CLOSE_STDIN, '0',  NULL,       no_argument,       "close stdin", NULL },
  { C_R, OPT_CLOSE_STDOUT,'1',  NULL,       no_argument,       "close stdout", NULL },
  { C_R, OPT_CLOSE_STDERR,'2',  NULL,       no_argument,       "close stderr", NULL },
  { C_X, OPT_LEGACY,      '@',  NULL,       no_argument,       "restricts following options to chpst(8) ones", NULL },
  { C_X, OPT_OPT_START,   HIDE, "opt[",     no_argument,       "starts a group of optional options", NULL },
  { C_X, OPT_OPT_END,     HIDE, "opt]",     no_argument,       "ends a group of optional options", NULL },
  { C_X, OPT_HELP,        'h',  "help",     no_argument,       "show help", NULL },
  { C_X, OPT_FILE,        '\0', "file",     required_argument, "read options from file", "FILE" },
  { C_X, OPT_EXIT,        '\0', "exit",     optional_argument, "exit (with optional RETCODE)", "RETCODE" },
  { C_X, OPT_MOUNT_NS,    '\0', "mount-ns", no_argument,       "create mount namespace", NULL },
  { C_X, OPT_NET_NS,      '\0', "net-ns",   no_argument,       "create net namespace", NULL },
  { C_X, OPT_USER_NS,     '\0', "user-ns",  no_argument,       "create user namespace", NULL },
  { COMPAT_FGHACK,
         OPT_PID_NS,      'I',  "pid-ns",   no_argument,       "create pid namespace", NULL },
  { C_R, OPT_PID_NS,      '\0', "pid-ns",   no_argument,       "create pid namespace", NULL },
  { C_X, OPT_UTS_NS,      '\0', "uts-ns",   no_argument,       "create uts namespace", NULL },
  { C_X, OPT_NET_ADOPT,   '\0', "adopt-net",required_argument, "adopt net namespace", "NS-PATH" },
  { C_X, OPT_PRIVATE_RUN, '\0', "private-run",  no_argument,    "create private /run", NULL },
  { C_X, OPT_PRIVATE_TMP, '\0', "private-tmp",  no_argument,    "create private /tmp", NULL },
  { C_X, OPT_PROTECT_HOME,'\0', "protect-home", no_argument,    "hide home directories", NULL },
  { C_X, OPT_RO_HOME,     '\0', "ro-home",      no_argument,    "make home directories read only", NULL },
  { C_X, OPT_RO_SYS,      '\0', "ro-sys",       no_argument,    "create read only system", NULL },
  { C_X, OPT_RO_ETC,      '\0', "ro-etc",       no_argument,    "make config files read only", NULL },
#ifndef NO_CAP
  { C_X, OPT_CAPBS_KEEP,  '\0', "cap-bs-keep",  required_argument, "restrict capabilities bounding set", "CAP[,...]" },
  { C_X, OPT_CAPBS_DROP,  '\0', "cap-bs-drop",  required_argument, "drop from capabilities bounding set", "CAP[,...]" },
  { C_X, OPT_CAPS_KEEP,   '\0', "caps-keep",    required_argument, "keep (only) these capabilities", "CAP[,...]" },
  { C_X, OPT_CAPS_DROP,   '\0', "caps-drop",    required_argument, "drop these capabilities", "CAP[,...]" },
#endif
  { C_X, OPT_FORK_JOIN,   '\0', "fork-join",    no_argument,   "fork and wait for process", NULL },
  { C_X, OPT_NEW_ROOT,    '\0', "new-root",     no_argument,   "create a new root fs", NULL },
  { C_X, OPT_NO_NEW_PRIVS,'\0', "no-new-privs", no_argument,   "no new privileges", NULL },
  { C_X, OPT_CPUS,        '\0', "cpus",         required_argument, "set CPU affinity", "AFFINITY" },
  { C_X, OPT_CPU_SCHED,   '\0', "cpu-scheduler",required_argument, "set CPU scheduler policy", "POLICY" },
  { C_X, OPT_IO_SCHED,    '\0', "io-scheduler", required_argument, "set I/O scheduling class", "rt|best-effort|idle[:PRIORITY]"},
  { C_X, OPT_UMASK,       '\0', "umask",     required_argument,"set umask", "MODE" },
  { C_X, OPT_APP,         '\0', "app",       required_argument,"define application name", "NAME"},
  { C_X, OPT_RUN_DIR,     '\0', "run-dir",   no_argument,      "create run dir", NULL },
  { C_X, OPT_STATE_DIR,   '\0', "state-dir", no_argument,      "create state dir", NULL },
  { C_X, OPT_CACHE_DIR,   '\0', "cache-dir", no_argument,      "create cache dir", NULL },
  { C_X, OPT_LOG_DIR,     '\0', "log-dir",   no_argument,      "create log dir", NULL },
  { C_X, OPT_LOGIN,       '\0', "login",     no_argument,      "simulate login environment", NULL },
  { C_X, OPT_OOM,         '\0', "oom",       required_argument,"set oom adjust value", "ADJ" },
  { C_X, OPT_HARDLIMIT,   '\0', "hardlimit", no_argument,      "set hard limits with soft limits", NULL },
  { C_X, OPT_DEV_NULL,    '\0', "dev-null",  no_argument,      "open /dev/null instead of closing fds", NULL },
  { C_A, OPT_UIDNUM,      'u',  NULL,        required_argument,"set numerical uid", "UID" },
  { C_A, OPT_GIDNUM,      'g',  NULL,        required_argument,"set numerical gid", "GID" },
  { C_A, OPT_GIDSNUM,     'G',  NULL,        required_argument,"set numerical supplementary groups", "GID*" },
  { C_A, OPT_UGFROMENV,   'U',  NULL,              no_argument,"set numerical uid, gid and supplementary groups from env", NULL },
  { C_X, OPT_UGFROMENV,   '\0', "ugids-from-env",  no_argument,"set numerical uid, gid and supplementary groups from env", NULL },
  { C_A, OPT_UGCLEARENV,  'z',  NULL,              no_argument,"clear numerical uid, gid and supplementary groups in env", NULL },
  { C_X, OPT_UGCLEARENV,  '\0', "ugids-clear-env", no_argument,"clear numerical uid, gid and supplementary groups in env", NULL },
  { C_X, OPT_IDMAP,       '\0', "id-map",    required_argument,"define uid/gid mapping to use for user namespace", "self|identity|full" },
};
#define max_options ((ssize_t) ((sizeof options_info / sizeof *options_info)))

static struct option options[max_options + 1];
static char optstr[max_options * 2];

static void handle_option(enum compat_level *compat,
                          const struct option_info *optdef,
                          char *optarg);

void options_print(FILE *out) {
  const struct option_info *optdef;
  int i = 0;

  for (optdef = options_info; optdef - options_info < max_options; optdef++) {
    if (is_compatible(optdef) && optdef->short_name != HIDE) {
      if (i++ == 0)
        fprintf(out, "\n OPTIONS\n");
      fprintf(out, "  %c%c%s%s%s%c%-*s %s\n",
             optdef->short_name ? '-' : ' ',
             optdef->short_name ? optdef->short_name : ' ',
             opt.app->long_opts && optdef->long_name ? (optdef->short_name ? "," : " ") : "",
             opt.app->long_opts && optdef->long_name ? " --" : "",
             opt.app->long_opts && optdef->long_name ? optdef->long_name : "",
             optdef->has_arg == optional_argument ? '=' : ' ',
             opt.app->long_opts && optdef->long_name ? 20 - (int) strlen(optdef->long_name) : 24,
             optdef->arg ? optdef->arg : " ",
             optdef->help ? optdef->help : "");
    }
  }
}

void options_print_positional(FILE *out) {
  int i;

  for (i = 0; i < opt.app->takes_positional_opts; i++) {
    const struct option_info *optdef;
    enum opt option = opt.app->positional_opts[i];

    /* Look up option definition */
    for (optdef = options_info;
         optdef - options_info < max_options && option != optdef->option;
         optdef++);
    if (optdef->has_arg != no_argument)
      fprintf(out, " %s", optdef->arg);
  }
}

void options_explain_positional(FILE *out) {
  int i;

  if (opt.app->takes_positional_opts)
    fprintf(out, "\n");

  for (i = 0; i < opt.app->takes_positional_opts; i++) {
    const struct option_info *optdef;
    enum opt option = opt.app->positional_opts[i];

    /* Look up option definition */
    for (optdef = options_info;
         optdef - options_info < max_options && option != optdef->option;
         optdef++);
    fprintf(out, " %-10s %s\n",
            optdef->has_arg != no_argument ? optdef->arg : "",
            optdef->help);
  }
}

bool options_init(void) {
  const struct option_info *optdef;
  size_t optstr_sz = 1;
  size_t optstr_len;
  int i = 0;

  for (optdef = options_info; optdef - options_info < max_options; optdef++) {
    if (is_compatible(optdef) && optdef->short_name != HIDE) {

      /* Populate long option list */
      if (optdef->long_name) {
        struct option option = {
          .name = optdef->long_name,
          .has_arg = optdef->has_arg,
          .flag = 0,
          .val = optdef->option
        };
        options[i++] = option;
      }

      /* Size up short option string */
      if (optdef->short_name) {
        switch (optdef->has_arg) {
        case optional_argument:
          optstr_sz++;
          [[fallthrough]];
        case required_argument:
          optstr_sz++;
          [[fallthrough]];
        default:
          optstr_sz++;
        }
      }
    }
  }

  /* Populate short option string */
  if (optstr_sz + 1 > sizeof optstr) {
    fprintf(stderr, "short option string too long\n");
    return false;
  }
  optstr_len = 0;
  optstr[optstr_len++] = '+'; /* Stop accepting options after prog name */
  for (optdef = options_info; optdef - options_info < max_options; optdef++) {
    if (is_compatible(optdef) && optdef->short_name != 0 && optdef->short_name != HIDE) {
      optstr[optstr_len++] = optdef->short_name;
      switch (optdef->has_arg) {
      case optional_argument:
        optstr[optstr_len++] = ':';
        [[fallthrough]];
      case required_argument:
        optstr[optstr_len++] = ':';
      default:
      }
    }
  }
  assert(optstr_len == optstr_sz);
  optstr[optstr_len++] = '\0';
  return true;
}

bool parse_limit(rlim_t *lim, const char *arg) {
  int toks = 0;
  long long val;

  if (!strcmp(arg, "unlimited") ||
      !strcmp(arg, "infinity") ||
      !strcmp(arg, "=")) {
    *lim = RLIM_INFINITY;
    toks = 1;
  } else {
    toks = sscanf(arg, "%lld", &val);
    if (toks == 1) {
      if (val == -1LL) {
        *lim = RLIM_INFINITY;
      } else if (val >= 0LL) {
        *lim = val;
      } else {
        fprintf(stderr, "invalid limit: %lld\n", val);
        toks = 0;
      }
    }
  }
  return toks == 1 ? true : false;
}

/* SUPPORTED FORMATS
 *   soft    (this differs from prlimit to match chpst)
 *   soft:
 *   soft:hard
 *   :hard
 *   +both   (this is unique to xchpst)
 */
bool parse_limits(struct limit *limit, const char *arg) {
  char *sep;
  bool both = *arg == '+';

  if (both)
    arg++;

  sep = strchr(arg, ':');
  if (sep != NULL) {
    *sep++ = '\0';
    limit->hard_specified = parse_limit(&limit->limits.rlim_max, sep);
  } else if (set(OPT_HARDLIMIT)) {
    both = true;
  }
  if (arg != sep) {
    limit->soft_specified = parse_limit(&limit->limits.rlim_cur, arg);
  }
  if (both) {
    limit->limits.rlim_max = limit->limits.rlim_cur;
    limit->hard_specified = limit->soft_specified;
  }
  return limit->soft_specified || limit->hard_specified;
}

#ifndef NO_CAP
bool parse_caps(cap_bits_t *caps, char *names) {
  cap_bits_t set = 0;
  cap_value_t val;
  cap_value_t max_cap = cap_max_bits();
  bool good = true;
  char *tok;
  int rc;

  if (max_cap < 0) {
    /* Record that we don't have capabilities but don't fail option */
    runtime.absent.caps = true;
    return true;
  }

  assert(8 * sizeof set >= (unsigned) max_cap);

  while (names && *names && (tok = strsep(&names, ","))) {
    rc = cap_from_name(tok, &val);
    if (rc != 0) {
      fprintf(stderr, "cannot interpret capability \"%s\"\n", tok);
      good = false;
    }
    set |= (1ull << val);
    if (is_debug())
      fprintf(stderr, "  added capability %d(%s) to a set\n", val, cap_to_name(val));
  }
  *caps = set;
  if (is_debug())
    fprintf(stderr, "  set is: %llx\n", (long long) *caps);

  return good;
}
#endif

bool parse_cpu_range(const char *str, int range[3], int *max) {
  int field = 0;
  int val = 0;
  char c = -1;

  while (field < 3 && c) {
    if (isdigit(c = *str++)) {
      val = val * 10 + c - '0';
    } else if ((c == '-' && field == 0) ||
               (c == ':' && field == 1) ||
               c == '\0') {
      range[field++] = val;
      val = 0;
    } else {
      return false;
    }
  }

  /* Default stride is 1 */
  if (field < 3)
    range[2] = 1;

  /* Singleton */
  if (field < 2)
    range[1] = range[0];

  /* No CPUs listed */
  if (field < 1)
    return false;

  if (max != NULL && range[1] > *max)
    *max = range[1];

  return true;
}

void parse_cpus(char *spec) {
  char *rest = spec;
  char *tok;
  char *end = spec;
  int range[3];
  int cpu;
  int max = 0;

  while((tok = strsep(&rest, ","))) {
    if (!parse_cpu_range(tok, range, &max))
      goto fail;
    end = tok;
  }
  opt.cpu_affinity.size = CPU_ALLOC_SIZE(max);
  opt.cpu_affinity.mask = CPU_ALLOC(max + 1);
  if (opt.cpu_affinity.mask == NULL) {
    perror("CPU_ALLOC");
    goto fail;
  }
  CPU_ZERO_S(opt.cpu_affinity.size, opt.cpu_affinity.mask);

  for (tok = spec; tok <= end; tok += strlen(tok) + 1) {
    parse_cpu_range(tok, range, NULL);
    for (cpu = range[0]; cpu <= range[1]; cpu += range[2])
      CPU_SET_S(cpu, opt.cpu_affinity.size, opt.cpu_affinity.mask);
  }
  return;

fail:
  opt.error = true;
  fprintf(stderr, "error in CPU list (at %s)\n", tok);
}

void parse_ionice(char *spec) {
  const char *classes[] = {
    "rt", "best-effort", "idle", NULL
  };
  long n;
  int data;
  char *s = strchrnul(spec, ':');
  char *end;

  for (n = 0; classes[n] && strncmp(spec, classes[n], s - spec); n++);
  if (classes[n++] == NULL) {
    n = strtol(spec, &end, 10);
    if (end == spec || (*end != '\0' && *end != ':')) {
      *end = '\0';
      opt.error = true;
      fprintf(stderr, "invalid ionice class: %s\n", spec);
    }
  }
  if (*s)
    s++;
  data = strtol(s, NULL, 10);
  opt.ionice_prio = IOPRIO_PRIO_VALUE(n, data);
}

enum idmap parse_idmap(char *spec) {
  const char *classes[] = {
    [IDMAP_SELF] = "self",
    [IDMAP_IDENTITY] = "identity",
    [IDMAP_FULL] = "full",
    NULL
  };
  enum idmap n;

  for (n = 0; classes[n] && strcmp(spec, classes[n]); n++);
  if (classes[n] == NULL) {
    opt.error = true;
    fprintf(stderr, "invalid idmap: %s\n", spec);
    n = 0;
  }
  return n;
}

int sched_policy_from_name(const char *name) {
  if (!strcmp(name, "batch"))
    return SCHED_BATCH;
  else if (!strcmp(name, "idle"))
    return SCHED_IDLE;
  else if (strcmp(name, "other"))
    fprintf(stderr, "ignoring unknown scheduler policy: %s\n", name);

  return SCHED_OTHER;
}

const struct option_info *find_option(int by_code,
                                      const char *by_name) {
  const struct option_info *optdef;
  const struct option_info *incompatible_option = NULL;
  bool is_short = (by_code && isascii(by_code)) ||
                  (by_name && *by_name && by_name[1] == '\0');

  /* Look up option definition */
  for (optdef = options_info;
       optdef - options_info < max_options;
       optdef++) {

    if ((by_code && by_code == (is_short ? optdef->short_name : (int) optdef->option)) ||
        (by_name && (is_short ? *by_name == optdef->short_name : optdef->long_name && !strcmp(by_name, optdef->long_name)))) {
      if (!is_compatible(optdef)) {
        /* Tentatively found an incompatible option but there may be
         * another one that is compatible later in the list. */
        incompatible_option = optdef;
      } else {
        incompatible_option = NULL;
        break;
      }
    }
  }

  if (optdef - options_info == max_options)
    return incompatible_option;
  else
    return optdef;
}

static void read_options_file(const char *path) {
  struct options_file *opt_file;
  struct stat statbuf;
  int fd;
  int rc;
  off_t offset;
  char *ptr;
  char *option_name = NULL;
  char *option_name_end = NULL;
  char *option_value = NULL;
  char *option_value_end = NULL;
  ssize_t len;
  const struct option_info *optdef;
  enum compat_level compat = opt.app->compat_level;
  enum {
    S_LEADING_WSP,
    S_COMMENT,
    /* No states above are actionable on EOF */
    /* All states below are actionable on EOF */
    S_KEY,
    S_DELIM_WSP,
    S_VALUE,
    S_POSSIBLY_TRAILING_WSP,
  } state = S_LEADING_WSP;

  fd = open(path, O_RDONLY);
  if (fd == -1) {
    fprintf(stderr, "error opening options file %s: %s\n", path, strerror(errno));
    goto fail;
  }

  rc = fstat(fd, &statbuf);
  if (rc == -1) {
    close(fd);
    goto fail;
  }

  /* We allocate the space for the file permanently, just as the argv array
     remains allocated. Option processing modifies argument values.
     Add one for NUL-terminating last element if not a newline. */
  opt_file = malloc(sizeof *opt_file + statbuf.st_size + 1);
  if (opt_file == NULL) {
    close(fd);
    goto fail;
  }

  opt_file->next = opt.opt_files;
  opt.opt_files = opt_file;

  offset = 0;
  do {
    len = read(fd, opt_file->content + offset, statbuf.st_size - offset);
    if (len == -1) {
      close(fd);
      goto fail;
    }
    offset += len;
  } while (offset < statbuf.st_size);
  close(fd);

  ptr = opt_file->content;
  for (ptr = opt_file->content; ptr - opt_file->content < statbuf.st_size; ptr++) {
    char c = *ptr;

    /* Whether a key and value are now completely specified */
    bool action = false;

    switch (state) {
    case S_LEADING_WSP:
      if (c == '#') {
        state = S_COMMENT;
      } else if (!isspace(c)) {
        option_name = ptr;
        state = S_KEY;
      }
      break;
    case S_KEY:
      if (c == '\n') {
        action = true;
      } else if (isspace(c)) {
        state = S_DELIM_WSP;
      }
      option_name_end = ptr;
      break;
    case S_DELIM_WSP:
      if (c == '\n') {
        action = true;
      } else if (!isspace(c)) {
        option_value = ptr;
        state = S_VALUE;
      }
      break;
    case S_VALUE:
      if (c == '\n') {
        action = true;
      } else if (isspace(c)) {
        state = S_POSSIBLY_TRAILING_WSP;
      }
      option_value_end = ptr;
      break;
    case S_POSSIBLY_TRAILING_WSP:
      if (c == '\n') {
        action = true;
      } else if (!isspace(c)) {
        state = S_VALUE;
        option_value_end = ptr;
      }
      break;
    case S_COMMENT:
      if (c == '\n') {
        state = S_LEADING_WSP;
      }
      break;
    }

    if (action /* EOL */ ||
        (ptr + 1 == opt_file->content + statbuf.st_size /* EOF */ &&
         state >= S_KEY /* An actionable state */)) {
      if (!action) {
        /* If EOF then there is no EOL character to overwrite */
        if (option_value)
          option_value_end = ptr + 1;
        else
          option_name_end = ptr + 1;
      }
      *option_name_end = '\0';
      if (option_value)
        *option_value_end = '\0';

      state = S_LEADING_WSP;
    } else {
      continue;
    }

    optdef = find_option(0, option_name);

    if (optdef && !is_compatible(optdef)) {
      char short_name[2] = { optdef->short_name, 0};
      fprintf(stderr, "illegal option (%s) at this compat level\n",
              optdef->long_name ? optdef->long_name : short_name);
      opt.error = true;
      continue;
    } else if (!optdef) {
      if (opt.optionality > 0) {
        if (is_verbose())
          fprintf(stderr, "ignoring unknown optional option: %s\n", option_name);
      } else {
        fprintf(stderr, "unknown option in config file: %s\n", option_name);
        opt.error = true;
      }
      continue;
    }

    if (is_verbose())
      fprintf(stderr, "handling file option '%s' with value '%s'\n", option_name, option_value);

    enable(optdef->option);

    /* For now, throw away the value end pointer. In future we could use
       this to enable arguments containing NUL bytes to be handled.
       (Of course, this format cannot handle newline characters, which would
       probably be more useful to embed!) */
    handle_option(&compat, optdef,
                  optdef->has_arg == no_argument ? NULL : option_value);
    option_value = NULL;
  }

  if (errno != 0) {
    fprintf(stderr, "error reading options file %s: %s\n", path, strerror(errno));
    goto fail;
  }

  return;
fail:
   opt.error = true;
}

static void handle_option(enum compat_level *compat,
                          const struct option_info *optdef,
                          char *optarg) {
  char *end;

  switch (optdef->option) {
  case OPT_LEGACY:
    *compat = COMPAT_CHPST;
    break;
  case OPT_OPT_START:
    opt.optionality++;
    break;
  case OPT_OPT_END:
    opt.optionality--;
    break;
  case OPT_VERSION:
    opt.version = true;
    break;
  case OPT_HELP:
    opt.help = true;
    break;
  case OPT_FILE:
    read_options_file(optarg);
    break;
  case OPT_EXIT:
    opt.exit = true;
    opt.retcode = optarg ? atoi(optarg) : CHPST_ERROR_EXIT;
    break;
  case OPT_VERBOSE:
    opt.verbosity++;
    break;
  case OPT_ARGV0:
    opt.argv0 = optarg;
    break;
  case OPT_ENVDIR:
    opt.env_dir = optarg;
    break;
  case OPT_CHROOT:
    opt.chroot = optarg;
    break;
  case OPT_CHDIR:
    opt.chdir = optarg;
    break;
  case OPT_NICE:
    opt.niceness = atoi(optarg);
    break;
  case OPT_LOCK_WAIT:
    opt.lock_wait = true;
    [[fallthrough]];
  case OPT_LOCK:
    opt.lock_file = optarg;
    break;
  case OPT_LOCKOPT_WAIT:
    opt.lock_wait = true;
    break;
  case OPT_LOCKOPT_TRY:
    opt.lock_wait = false;
    opt.lock_nowait_override = true;
    break;
  case OPT_LOCKOPT_NOISY:
    opt.lock_quiet = false;
    break;
  case OPT_LOCKOPT_QUIET:
    opt.lock_quiet = true;
    break;
  case OPT_MOUNT_NS:
    opt.new_ns |= CLONE_NEWNS;
    break;
  case OPT_NET_NS:
    opt.new_ns |= CLONE_NEWNET;
    break;
  case OPT_PID_NS:
    opt.new_ns |= CLONE_NEWPID;
    break;
  case OPT_USER_NS:
    opt.new_ns |= CLONE_NEWUSER;
    break;
  case OPT_UTS_NS:
    opt.new_ns |= CLONE_NEWUTS;
    break;
  case OPT_NET_ADOPT:
    opt.net_adopt = optarg;
    break;
  case OPT_IDMAP:
    opt.idmap = parse_idmap(optarg);
    break;
  case OPT_PRIVATE_RUN:
  case OPT_PRIVATE_TMP:
  case OPT_PROTECT_HOME:
  case OPT_RO_HOME:
  case OPT_RO_SYS:
  case OPT_RO_ETC:
  case OPT_PGRPHACK:
  case OPT_FGHACK:
  case OPT_FORK_JOIN:
  case OPT_NEW_ROOT:
  case OPT_NO_NEW_PRIVS:
  case OPT_RUN_DIR:
  case OPT_STATE_DIR:
  case OPT_CACHE_DIR:
  case OPT_LOG_DIR:
  case OPT_LOGIN:
  case OPT_HARDLIMIT:
  case OPT_DEV_NULL:
  case OPT_UGCLEARENV:
    /* Boolean options needing no further option processing */
    break;
#ifndef NO_CAP
  case OPT_CAPBS_KEEP:
  case OPT_CAPBS_DROP:
    if (!parse_caps(&opt.cap_bounds, optarg))
      opt.error = true;
    break;
  case OPT_CAPS_KEEP:
  case OPT_CAPS_DROP:
    if (!parse_caps(&opt.caps, optarg))
      opt.error = true;
    opt.caps_op = optdef->option == OPT_CAPS_KEEP ? CAP_OP_KEEP : CAP_OP_DROP;
    break;
#endif
  case OPT_CPU_SCHED:
    opt.sched_policy = sched_policy_from_name(optarg);
    break;
  case OPT_CPUS:
    parse_cpus(optarg);
    break;
  case OPT_IO_SCHED:
    parse_ionice(optarg);
    break;
  case OPT_UMASK:
    if (sscanf(optarg, "%o", &opt.umask) != 1)
      opt.error = true;
    break;
  case OPT_OOM:
    opt.oom_adjust = strtol(optarg, &end, 10);
    if (*optarg == '\0' || *end != '\0')
      opt.error = true;
    break;
  case OPT_APP:
    opt.app_name = optarg;
    break;
  case OPT_SETUIDGID:
    if (usrgrp_parse(&opt.users_groups, optarg))
      opt.error = true;
    else if (usrgrp_resolve(&opt.users_groups))
      opt.error = true;
    if (opt.verbosity > 1)
      usrgrp_print(stderr, "setuidgid", &opt.users_groups);
    break;
  case OPT_ENVUIDGID:
    if (usrgrp_parse(&opt.env_users_groups, optarg))
      opt.error = true;
    else if (usrgrp_resolve(&opt.env_users_groups))
      opt.error = true;
    if (opt.verbosity > 1)
      usrgrp_print(stderr, "envuidgid", &opt.env_users_groups);
    break;
  case OPT_UIDNUM:
    if (usrgrp_from_env(&opt.users_groups, optarg, NULL, NULL))
      opt.error = true;
    else
      enable(OPT_SETUIDGID);
    break;
  case OPT_GIDNUM:
    if (usrgrp_from_env(&opt.users_groups, NULL, optarg, NULL))
      opt.error = true;
    else
      enable(OPT_SETUIDGID);
    break;
  case OPT_GIDSNUM:
    if (usrgrp_from_env(&opt.users_groups, NULL, NULL, optarg))
      opt.error = true;
    else
      enable(OPT_SETUIDGID);
    break;
  case OPT_UGFROMENV:
    if (usrgrp_from_env(&opt.users_groups,
                        getenv("UID"), getenv("GID"), getenv("GIDLIST")))
      opt.error = true;
    else
      enable(OPT_SETUIDGID);
    if (opt.verbosity > 1)
      usrgrp_print(stderr, "ugfromenv", &opt.users_groups);
    break;
  case OPT_LIMIT_MEM:
    if (!parse_limits(&opt.rlimit_memlock, optarg)) {
      opt.error = true;
    } else {
      opt.rlimit_data = opt.rlimit_memlock;
      opt.rlimit_stack = opt.rlimit_memlock;
      opt.rlimit_as = opt.rlimit_as;
    }
    break;
   case OPT_RLIMIT_DATA:
    if (!parse_limits(&opt.rlimit_data, optarg))
      opt.error = true;
    break;
  case OPT_RLIMIT_MEMLOCK:
    if (!parse_limits(&opt.rlimit_memlock, optarg))
      opt.error = true;
    break;
  case OPT_RLIMIT_AS:
    if (!parse_limits(&opt.rlimit_as, optarg))
      opt.error = true;
    break;
  case OPT_RLIMIT_STACK:
    if (!parse_limits(&opt.rlimit_stack, optarg))
      opt.error = true;
    break;
  case OPT_RLIMIT_NOFILE:
    if (!parse_limits(&opt.rlimit_nofile, optarg))
      opt.error = true;
    break;
  case OPT_RLIMIT_RSS:
    if (!parse_limits(&opt.rlimit_rss, optarg))
      opt.error = true;
    break;
  case OPT_RLIMIT_NPROC:
    if (!parse_limits(&opt.rlimit_nproc, optarg))
      opt.error = true;
    break;
  case OPT_RLIMIT_FSIZE:
    if (!parse_limits(&opt.rlimit_fsize, optarg))
      opt.error = true;
    break;
  case OPT_RLIMIT_CPU:
    if (!parse_limits(&opt.rlimit_cpu, optarg))
      opt.error = true;
    break;
  case OPT_RLIMIT_CORE:
    if (!parse_limits(&opt.rlimit_core, optarg))
      opt.error = true;
    break;
  case OPT_RLIMIT_MSGQUEUE:
    if (!parse_limits(&opt.rlimit_msgqueue, optarg))
      opt.error = true;
    break;
  case OPT_RLIMIT_NICE:
    if (!parse_limits(&opt.rlimit_nice, optarg))
      opt.error = true;
    break;
  case OPT_RLIMIT_RTPRIO:
    if (!parse_limits(&opt.rlimit_rtprio, optarg))
      opt.error = true;
    break;
  case OPT_RLIMIT_RTTIME:
    if (!parse_limits(&opt.rlimit_rttime, optarg))
      opt.error = true;
    break;
  case OPT_RLIMIT_SIGPENDING:
    if (!parse_limits(&opt.rlimit_sigpending, optarg))
      opt.error = true;
    break;
  case OPT_RLIMIT_LOCKS:
    if (!parse_limits(&opt.rlimit_locks, optarg))
      opt.error = true;
    break;
  case OPT_CLOSE_STDIN:
  case OPT_CLOSE_STDOUT:
  case OPT_CLOSE_STDERR:
    if (set(OPT_DEV_NULL))
      opt.dev_null_fds |= 1 << (optdef->option - OPT_CLOSE_STDIN + STDIN_FILENO);
    else
      opt.close_fds |= 1 << (optdef->option - OPT_CLOSE_STDIN + STDIN_FILENO);
    break;
  /* Avoid default case to get useful compiler warnings instead.
  default:
    fprintf(stderr, "-%c%s not yet implemented\n",
                    optdef->long_name ? '-' : optdef->short_name,
                    optdef->long_name ? optdef->long_name : "");
    opt.error = true;
   */
  }
}

int options_parse(int argc, char *argv[]) {
  const struct option_info *optdef;
  enum compat_level compat = opt.app->compat_level;
  int c;

  /* Process options */
  while ((c = opt.app->long_opts ?
                getopt_long(argc, argv, optstr, options, NULL) :
                getopt(argc, argv, optstr)) != -1) {

    optdef = find_option(c, NULL);

    if (optdef && !is_compatible(optdef)) {
      char short_name[2] = { optdef->short_name, 0};
      fprintf(stderr, "illegal option (%s) at this compat level\n",
              optdef->long_name ? optdef->long_name : short_name);
      opt.error = true;
    } else if (optdef) {
      /* Set bitfield before calling handler in case the handler wishes
       * to reset the option based on argument value. */
      enable(optdef->option);
      handle_option(&compat, optdef, optarg);
    } else {
      opt.error = true;
    }
  }

  /* Process positional arguments */
  assert(opt.app->takes_positional_opts <= MAX_POSITIONAL_OPTS);
  for (int i = 0; i < opt.app->takes_positional_opts; i++) {
    enum opt option = opt.app->positional_opts[i];
    if (optind == argc) {
      opt.error = true;
      break;
    }

    /* Look up option definition */
    for (optdef = options_info;
         optdef - options_info < max_options && option != optdef->option;
         optdef++);
    assert(optdef);

    enable(optdef->option);
    handle_option(&compat, optdef,
                  optdef->has_arg == no_argument ? NULL : argv[optind++]);
  }
  return optind;
}

void options_free(void) {
  struct options_file *file, *next;

  if (opt.cpu_affinity.size)
    CPU_FREE(opt.cpu_affinity.mask);
  usrgrp_free(&opt.users_groups);
  usrgrp_free(&opt.env_users_groups);

  for (file = opt.opt_files; file; file = next) {
    next = file->next;
    free(file);
  }
}
