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transmission/libtransmission/tr-getopt.cc

252 lines
6.5 KiB
C++

// This file Copyright © Mnemosyne LLC.
// It may be used under GPLv2 (SPDX: GPL-2.0-only), GPLv3 (SPDX: GPL-3.0-only),
// or any future license endorsed by Mnemosyne LLC.
// License text can be found in the licenses/ folder.
#include <algorithm>
#include <cstdio>
#include <cstdlib> /* exit() */
#include <cstring>
#include <string>
#include <string_view>
#include <fmt/core.h>
#include "libtransmission/tr-getopt.h"
#include "libtransmission/utils.h"
using namespace std::literals;
int tr_optind = 1;
namespace
{
[[nodiscard]] constexpr std::string_view getArgName(tr_option const* opt)
{
if (!opt->has_arg)
{
return ""sv;
}
if (opt->argName != nullptr)
{
return opt->argName;
}
return "<args>"sv;
}
[[nodiscard]] constexpr size_t get_next_line_len(std::string_view description, size_t maxlen)
{
auto len = std::size(description);
if (len > maxlen)
{
description.remove_suffix(len - maxlen);
auto const pos = description.rfind(' ');
len = pos != std::string_view::npos ? pos : maxlen;
}
return len;
}
void getopts_usage_line(tr_option const* const opt, size_t long_width, size_t short_width, size_t arg_width)
{
auto const long_name = std::string_view{ opt->longName != nullptr ? opt->longName : "" };
auto const short_name = std::string_view{ opt->shortName != nullptr ? opt->shortName : "" };
auto const arg = getArgName(opt);
fmt::print(
FMT_STRING(" {:s}{:<{}s} {:s}{:<{}s} {:<{}s} "),
std::empty(short_name) ? " "sv : "-"sv,
short_name,
short_width,
std::empty(long_name) ? " "sv : "--"sv,
long_name,
long_width,
arg,
arg_width);
auto const d_indent = short_width + long_width + arg_width + 7U;
auto const d_width = 80U - d_indent;
auto description = std::string_view{ opt->description };
auto len = get_next_line_len(description, d_width);
fmt::print(FMT_STRING("{:s}\n"), description.substr(0, len));
description.remove_prefix(len);
description = tr_strv_strip(description);
auto const indent = std::string(d_indent, ' ');
while ((len = get_next_line_len(description, d_width)) != 0)
{
fmt::print(FMT_STRING("{:s}{:s}\n"), indent, description.substr(0, len));
description.remove_prefix(len);
description = tr_strv_strip(description);
}
}
void maxWidth(struct tr_option const* o, size_t& long_width, size_t& short_width, size_t& arg_width)
{
if (o->longName != nullptr)
{
long_width = std::max(long_width, strlen(o->longName));
}
if (o->shortName != nullptr)
{
short_width = std::max(short_width, strlen(o->shortName));
}
if (auto const arg = getArgName(o); !std::empty(arg))
{
arg_width = std::max(arg_width, std::size(arg));
}
}
tr_option const* findOption(tr_option const* opts, char const* str, char const** setme_arg)
{
size_t matchlen = 0;
char const* arg = nullptr;
tr_option const* match = nullptr;
/* find the longest matching option */
for (tr_option const* o = opts; o->val != 0; ++o)
{
size_t len = o->longName != nullptr ? strlen(o->longName) : 0;
if (matchlen < len && str[0] == '-' && str[1] == '-' && strncmp(str + 2, o->longName, len) == 0 &&
(str[len + 2] == '\0' || (o->has_arg && str[len + 2] == '=')))
{
matchlen = len;
match = o;
arg = str[len + 2] == '=' ? str + len + 3 : nullptr;
}
len = o->shortName != nullptr ? strlen(o->shortName) : 0;
if (matchlen < len && str[0] == '-' && strncmp(str + 1, o->shortName, len) == 0 && (str[len + 1] == '\0' || o->has_arg))
{
matchlen = len;
match = o;
switch (str[len + 1])
{
case '\0':
arg = nullptr;
break;
case '=':
arg = str + len + 2;
break;
default:
arg = str + len + 1;
break;
}
}
}
if (setme_arg != nullptr)
{
*setme_arg = arg;
}
return match;
}
} // namespace
void tr_getopt_usage(char const* app_name, char const* description, struct tr_option const* opts)
{
auto long_width = size_t{ 0 };
auto short_width = size_t{ 0 };
auto arg_width = size_t{ 0 };
for (tr_option const* o = opts; o->val != 0; ++o)
{
maxWidth(o, long_width, short_width, arg_width);
}
auto const help = tr_option{ -1, "help", "Display this help page and exit", "h", false, nullptr };
maxWidth(&help, long_width, short_width, arg_width);
if (description == nullptr)
{
description = "Usage: %s [options]";
}
printf(description, app_name);
printf("\n\nOptions:\n");
getopts_usage_line(&help, long_width, short_width, arg_width);
for (tr_option const* o = opts; o->val != 0; ++o)
{
getopts_usage_line(o, long_width, short_width, arg_width);
}
}
int tr_getopt(char const* usage, int argc, char const* const* argv, tr_option const* opts, char const** setme_optarg)
{
char const* arg = nullptr;
tr_option const* o = nullptr;
*setme_optarg = nullptr;
/* handle the builtin 'help' option */
for (int i = 1; i < argc; ++i)
{
if (strcmp(argv[i], "-h") == 0 || strcmp(argv[i], "--help") == 0)
{
tr_getopt_usage(argv[0], usage, opts);
exit(0);
}
}
/* out of options? */
if (argc == 1 || tr_optind >= argc)
{
return TR_OPT_DONE;
}
o = findOption(opts, argv[tr_optind], &arg);
if (o == nullptr)
{
/* let the user know we got an unknown option... */
*setme_optarg = argv[tr_optind++];
return TR_OPT_UNK;
}
if (!o->has_arg)
{
/* no argument needed for this option, so we're done */
if (arg != nullptr)
{
return TR_OPT_ERR;
}
*setme_optarg = nullptr;
++tr_optind;
return o->val;
}
/* option needed an argument, and it was embedded in this string */
if (arg != nullptr)
{
*setme_optarg = arg;
++tr_optind;
return o->val;
}
/* throw an error if the option needed an argument but didn't get one */
if (++tr_optind >= argc)
{
return TR_OPT_ERR;
}
if (findOption(opts, argv[tr_optind], nullptr) != nullptr)
{
return TR_OPT_ERR;
}
*setme_optarg = argv[tr_optind++];
return o->val;
}