string.hpp

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//    OpenVPN -- An application to securely tunnel IP networks
//               over a single port, with support for SSL/TLS-based
//               session authentication and key exchange,
//               packet encryption, packet authentication, and
//               packet compression.
//
//    Copyright (C) 2012- OpenVPN Inc.
//
//    SPDX-License-Identifier: MPL-2.0 OR AGPL-3.0-only WITH openvpn3-openssl-exception
//
 
// General purpose string-manipulation functions.
 
#ifndef OPENVPN_COMMON_STRING_H
#define OPENVPN_COMMON_STRING_H
 
#include <string>
#include <string_view>
#include <vector>
#include <cstring>
#include <locale>
#include <algorithm>
#include <optional>
 
#include <fmt/core.h>
 
#include <openvpn/common/platform.hpp>
#include <openvpn/common/size.hpp>
 
namespace openvpn::string {
// case insensitive compare functions
 
inline int strcasecmp(const char *s1, const char *s2)
{
#ifdef OPENVPN_PLATFORM_WIN
    return ::_stricmp(s1, s2);
#else
    return ::strcasecmp(s1, s2);
#endif
}
 
inline int strcasecmp(const std::string &s1, const char *s2)
{
    return strcasecmp(s1.c_str(), s2);
}
 
inline int strcasecmp(const char *s1, const std::string &s2)
{
    return strcasecmp(s1, s2.c_str());
}
 
inline int strcasecmp(const std::string &s1, const std::string &s2)
{
    return strcasecmp(s1.c_str(), s2.c_str());
}
 
// Like strncpy but makes sure dest is always null terminated
inline void strncpynt(char *dest, const char *src, size_t maxlen)
{
    strncpy(dest, src, maxlen);
    if (maxlen > 0)
        dest[maxlen - 1] = 0;
}
 
// Copy string to dest, make sure dest is always null terminated,
// and fill out trailing chars in dest with '\0' up to dest_size.
inline void copy_fill(void *dest, const std::string &src, const size_t dest_size)
{
    if (dest_size > 0)
    {
        const size_t ncopy = std::min(dest_size - 1, src.length());
        std::memcpy(dest, src.c_str(), ncopy);
        std::memset(static_cast<unsigned char *>(dest) + ncopy, 0, dest_size - ncopy);
    }
}
 
inline bool is_true(const std::string &str)
{
    return str == "1" || !strcasecmp(str.c_str(), "true");
}
 
// Return true if str == prefix or if str starts with prefix + delim
template <typename STRING>
inline bool starts_with_delim(const STRING &str, const std::string &prefix, const char delim)
{
    if (prefix.length() < str.length())
        return str[prefix.length()] == delim && str.starts_with(prefix);
    return prefix == str;
}
 
// return true if string ends with a newline
template <typename STRING>
inline bool ends_with_newline(const STRING &str)
{
    return str.ends_with('\n');
}
 
// return true if string ends with a CR or LF
template <typename STRING>
inline bool ends_with_crlf(const STRING &str)
{
    if (str.length())
    {
        const char c = str.back();
        return c == '\n' || c == '\r';
    }
    return false;
}
 
// Prepend leading characters (c) to str to obtain a minimum string length (min_len).
// Useful for adding leading zeros to numeric values or formatting tables.
inline std::string add_leading(const std::string &str, const size_t min_len, const char c)
{
    if (min_len <= str.length())
        return str;
    size_t len = min_len - str.length();
    std::string ret;
    ret.reserve(min_len);
    while (len--)
        ret += c;
    ret += str;
    return ret;
}
 
// make sure that string ends with char c, if not append it
inline std::string add_trailing_copy(const std::string &str, const char c)
{
    if (str.ends_with(c))
        return str;
    return str + c;
}
 
// make sure that string ends with char c, if not append it
inline void add_trailing(std::string &str, const char c)
{
    if (!str.ends_with(c))
        str += c;
}
 
// make sure that string ends with CRLF, if not append it
inline void add_trailing_crlf(std::string &str)
{
    if (str.ends_with("\r\n"))
        ;
    else if (str.ends_with('\r'))
        str += '\n';
    else if (str.ends_with('\n'))
    {
        str.pop_back();
        str += "\r\n";
    }
    else
        str += "\r\n";
}
 
// make sure that string ends with CRLF, if not append it
inline std::string add_trailing_crlf_copy(std::string str)
{
    add_trailing_crlf(str);
    return str;
}
 
// make sure that string ends with char c, if not append it (unless the string is empty)
inline std::string add_trailing_unless_empty_copy(const std::string &str, const char c)
{
    if (str.empty() || str.ends_with(c))
        return str;
    return str + c;
}
 
// remove trailing \r or \n chars
template <typename STRING>
inline void trim_crlf(STRING &str)
{
    while (ends_with_crlf(str))
        str.pop_back();
}
 
// remove trailing \r or \n chars
inline std::string trim_crlf_copy(std::string str)
{
    trim_crlf(str);
    return str;
}
 
// return true if str of size len contains an embedded null
inline bool embedded_null(const char *str, size_t len)
{
    while (len--)
        if (!*str++)
            return true;
    return false;
}
 
// return the length of a string, omitting trailing nulls
inline size_t len_without_trailing_nulls(const char *str, size_t len)
{
    while (len > 0 && str[len - 1] == '\0')
        --len;
    return len;
}
 
// return true if string contains at least one newline
inline bool is_multiline(const std::string &str)
{
    return str.find_first_of('\n') != std::string::npos;
}
 
// Return string up to a delimiter (without the delimiter).
// Returns the entire string if no delimiter is found.
inline std::string to_delim(const std::string &str, const char delim)
{
    const size_t pos = str.find_first_of(delim);
    if (pos != std::string::npos)
        return str.substr(0, pos);
    return str;
}
 
// return the first line (without newline) of a multi-line string
inline std::string first_line(const std::string &str)
{
    return to_delim(str, '\n');
}
 
inline bool is_space(const char c)
{
    return std::isspace(static_cast<unsigned char>(c)) != 0;
}
 
inline bool is_digit(const char c)
{
    return std::isdigit(static_cast<unsigned char>(c)) != 0;
}
 
inline bool is_alpha(const char c)
{
    return std::isalpha(static_cast<unsigned char>(c)) != 0;
}
 
inline bool is_alphanumeric(const char c)
{
    return std::isalnum(static_cast<unsigned char>(c)) != 0;
}
 
inline bool is_printable(const char c)
{
    return std::isprint(static_cast<unsigned char>(c)) != 0;
}
 
inline bool is_printable(const unsigned char c)
{
    return std::isprint(c) != 0;
}
 
inline bool is_ctrl(const char c)
{
    return std::iscntrl(static_cast<unsigned char>(c)) != 0;
}
 
inline bool is_ctrl(const unsigned char c)
{
    return std::iscntrl(c) != 0;
}
 
// return true if string conforms to regex \w*
inline bool is_word(const std::string &str)
{
    for (auto &c : str)
        if (!(is_alphanumeric(c) || c == '_'))
            return false;
    return true;
}
 
// return true if all string characters are printable (or if string is empty)
inline bool is_printable(const std::string &str)
{
    for (auto &c : str)
        if (!is_printable(c))
            return false;
    return true;
}
 
// return true if str contains at least one non-space control char
inline bool contains_non_space_ctrl(const std::string &str)
{
    for (auto &c : str)
        if ((!is_space(c) && is_ctrl(c)) || c == 127)
            return true;
    return false;
}
 
// return true if str contains at least one space char
inline bool contains_space(const std::string &str)
{
    for (std::string::const_iterator i = str.begin(); i != str.end(); ++i)
        if (is_space(*i))
            return true;
    return false;
}
 
// remove all spaces in string
inline std::string remove_spaces(const std::string &str)
{
    std::string ret;
    for (std::string::const_iterator i = str.begin(); i != str.end(); ++i)
    {
        char c = *i;
        if (!is_space(c))
            ret += c;
    }
    return ret;
}
 
// replace all spaces in string with rep
inline std::string replace_spaces(const std::string &str, const char rep)
{
    std::string ret;
    for (std::string::const_iterator i = str.begin(); i != str.end(); ++i)
    {
        char c = *i;
        if (is_space(c))
            c = rep;
        ret += c;
    }
    return ret;
}
 
// replace all spaces in string with rep, reducing instances of multiple
// consecutive spaces to a single instance of rep and removing leading
// and trailing spaces
inline std::string reduce_spaces(const std::string &str, const char rep)
{
    std::string ret;
    bool last_space = true;
    for (std::string::const_iterator i = str.begin(); i != str.end(); ++i)
    {
        char c = *i;
        const bool space = is_space(c);
        if (is_space(c))
            c = rep;
        if (!(space && last_space))
            ret += c;
        last_space = space;
    }
    if (last_space && !ret.empty())
        ret.pop_back();
    return ret;
}
 
// generate a string with n instances of char c
inline std::string repeat(const char c, size_t n)
{
    std::string ret;
    ret.reserve(n);
    while (n-- > 0)
        ret += c;
    return ret;
}
 
// generate a string with spaces
inline std::string spaces(size_t n)
{
    return repeat(' ', n);
}
 
// indent a multiline string
inline std::string indent(const std::string &str, const int first, const int remaining)
{
    std::string ret;
    int n_spaces = first;
    for (auto &c : str)
    {
        if (n_spaces)
            ret += spaces(n_spaces);
        n_spaces = 0;
        ret += c;
        if (c == '\n')
            n_spaces = remaining;
    }
    return ret;
}
 
// replace instances of char 'from' in string with char 'to'
inline std::string replace_copy(const std::string &str, const char from, const char to)
{
    std::string ret;
    ret.reserve(str.length());
    for (auto &c : str)
        ret.push_back(c == from ? to : c);
    return ret;
}
 
// return true if str is empty or contains only space chars
inline bool is_empty(const std::string &str)
{
    for (const auto &c : str)
        if (!is_space(c))
            return false;
    return true;
}
 
// return true if str is empty or contains only space chars
inline bool is_empty(const char *str)
{
    if (!str)
        return true;
    char c;
    while ((c = *str++) != '\0')
        if (!is_space(c))
            return false;
    return true;
}
 
// convert \n to \r\n
inline std::string unix2dos(const std::string &str, const bool force_eol = false)
{
    std::string ret;
    bool last_char_was_cr = false;
 
    ret.reserve(str.length() + str.length() / 8);
    for (std::string::const_iterator i = str.begin(); i != str.end(); ++i)
    {
        const char c = *i;
        if (c == '\n' && !last_char_was_cr)
            ret += '\r';
        ret += c;
        last_char_was_cr = (c == '\r');
    }
    if (force_eol)
        add_trailing_crlf(ret);
    return ret;
}
 
// Split a string on sep delimiter.  The size of the
// returned string vector will be at least 1 and at
// most maxsplit + 1 (unless maxsplit is passed as -1).
template <typename T>
inline std::vector<T> split(const T &str,
                            const typename T::value_type sep,
                            const int maxsplit = -1)
{
    /* ensure we have a string as type */
    static_assert(std::is_same_v<T, std::string> || std::is_same_v<T, std::wstring>);
    std::vector<T> ret;
    int nterms = 0;
    T term;
 
    if (maxsplit >= 0)
        ret.reserve(maxsplit + 1);
 
    for (const auto c : str)
    {
        if (c == sep && (maxsplit < 0 || nterms < maxsplit))
        {
            ret.push_back(std::move(term));
            ++nterms;
            term.clear();
        }
        else
            term += c;
    }
    ret.push_back(std::move(term));
    return ret;
}
 
template <class T>
inline auto join(const T &strings,
                 const typename T::value_type &delim,
                 const bool tail = false)
{
    /* ensure we have a container with strings as values */
    static_assert(std::is_same_v<typename T::value_type, std::string> || std::is_same_v<typename T::value_type, std::wstring>);
    typename T::value_type ret;
    bool first = true;
    for (const auto &s : strings)
    {
        if (!first)
            ret += delim;
        ret += s;
        first = false;
    }
    if (tail && !ret.empty())
        ret += delim;
    return ret;
}
 
inline std::vector<std::string> from_argv(int argc, char *argv[], const bool skip_first)
{
    std::vector<std::string> ret;
    for (int i = (skip_first ? 1 : 0); i < argc; ++i)
        ret.emplace_back(argv[i]);
    return ret;
}
 
inline std::string trim_left_copy(const std::string &str)
{
    for (size_t i = 0; i < str.length(); ++i)
    {
        if (!is_space(str[i]))
            return str.substr(i);
    }
    return std::string();
}
 
inline std::string trim_copy(const std::string &str)
{
    for (size_t i = 0; i < str.length(); ++i)
    {
        if (!is_space(str[i]))
        {
            size_t last_nonspace = i;
            for (size_t j = i + 1; j < str.length(); ++j)
            {
                if (!is_space(str[j]))
                    last_nonspace = j;
            }
            return str.substr(i, last_nonspace - i + 1);
        }
    }
    return std::string();
}
 
inline std::string to_upper_copy(const std::string &str)
{
    std::string ret;
    std::locale loc;
    ret.reserve(str.length());
    for (const auto &c : str)
        ret.push_back(std::toupper(c, loc));
    return ret;
}
 
inline std::string to_lower_copy(const std::string &str)
{
    std::string ret;
    std::locale loc;
    ret.reserve(str.length());
    for (const auto &c : str)
        ret.push_back(std::tolower(c, loc));
    return ret;
}
 
inline void trim(std::string &str)
{
    str = trim_copy(str);
}
 
inline void trim_left(std::string &str)
{
    str = trim_left_copy(str);
}
 
inline void to_lower(std::string &str)
{
    str = to_lower_copy(str);
}
 
inline void to_upper(std::string &str)
{
    str = to_upper_copy(str);
}
 
// Replace any subsequence of consecutive space chars containing
// at least one newline with a single newline char.  If string
// is non-empty and doesn't include a trailing newline, add one.
inline std::string remove_blanks(const std::string &str)
{
    std::string ret;
    ret.reserve(str.length() + 1);
 
    std::string spaces;
    bool in_space = false;
    bool has_nl = false;
 
    for (auto &c : str)
    {
        const bool s = is_space(c);
    reprocess:
        if (in_space)
        {
            if (s)
            {
                if (c == '\n')
                    has_nl = true;
                spaces += c;
            }
            else
            {
                if (has_nl)
                    ret += '\n';
                else
                    ret += spaces;
                in_space = false;
                has_nl = false;
                spaces.clear();
                goto reprocess;
            }
        }
        else
        {
            if (s)
            {
                in_space = true;
                goto reprocess;
            }
            else
                ret += c;
        }
    }
    if (!ret.empty() && !ends_with_newline(ret))
        ret += '\n';
    return ret;
}
 
// copy str to the return value, removing all instances of
// chars that match remove
inline std::string remove_char(const std::string &str, const char remove)
{
    std::string ret;
    ret.reserve(str.length());
    for (const auto c : str)
    {
        if (c != remove)
            ret.push_back(c);
    }
    return ret;
}
 
template <typename... ArgsT>
inline auto args_to_string(std::string_view delim, ArgsT &&...args) -> std::string
{
    std::string result;
    ((result += std::string(result.empty() ? "" : delim) + fmt::format("{}", args)), ...);
    return result;
}
 
template <typename... ArgsT>
inline auto format_safe(std::string format, ArgsT &&...args) noexcept -> std::optional<std::string>
{
    try
    {
        return fmt::vformat(format, fmt::make_format_args(args...));
    }
    catch (...)
    {
        return std::nullopt;
    }
}
 
} // namespace openvpn::string
 
#endif // OPENVPN_COMMON_STRING_H