fastfetch/src/common/impl/FFstrbuf.c

#include "common/FFstrbuf.h"
#include "common/mallocHelper.h"
#include "common/strutil.h"
#include "common/debug.h"

#include <ctype.h>
#include <inttypes.h>
#include <math.h>

char* CHAR_NULL_PTR = "";

void ffStrbufInitA(FFstrbuf* strbuf, uint32_t allocate) {
    strbuf->allocated = allocate;

    if (strbuf->allocated > 0) {
        strbuf->chars = (char*) malloc(sizeof(char) * strbuf->allocated);
    }

    // This will set the length to zero and the null byte.
    ffStrbufClear(strbuf);
}

void ffStrbufInitVF(FFstrbuf* strbuf, const char* format, va_list arguments) {
    char* buffer = nullptr;
    int len = vasprintf(&buffer, format, arguments);
    assert(len >= 0);

    ffStrbufInitMoveNS(strbuf, (uint32_t) len, buffer);
}

// Takes ownership of `heapStr`. The caller must not free `heapStr` after calling this
// function; the memory will be managed and freed via the associated FFstrbuf.
void ffStrbufInitMoveNS(FFstrbuf* strbuf, uint32_t length, char* heapStr) {
    strbuf->length = length;
    size_t allocSize = ffMallocUsableSize(heapStr);
    if (allocSize == 0) {
        allocSize = length + 1;
    } else if (allocSize > UINT32_MAX) {
        allocSize = UINT32_MAX;
    }
    strbuf->allocated = (uint32_t) allocSize;
    strbuf->chars = heapStr;
}

void ffStrbufInitF(FFstrbuf* strbuf, const char* format, ...) {
    va_list arguments;
    va_start(arguments, format);
    ffStrbufInitVF(strbuf, format, arguments);
    va_end(arguments);
}

FFstrbuf ffStrbufCreateF(const char* format, ...) {
    FFstrbuf strbuf;

    va_list arguments;
    va_start(arguments, format);
    ffStrbufInitVF(&strbuf, format, arguments);
    va_end(arguments);

    return strbuf;
}

void ffStrbufEnsureFreeNoCheck(FFstrbuf* strbuf, uint32_t free) {
    uint32_t allocate;
    if (__builtin_expect(__builtin_uadd_overflow(strbuf->length, free, &allocate), false)) {
        FF_DEBUG("Error: Integer overflow when calculating allocation size. Aborting");
        abort();
    }

    if (allocate < FASTFETCH_STRBUF_DEFAULT_ALLOC) { // `<` for null terminator
        allocate = FASTFETCH_STRBUF_DEFAULT_ALLOC;
    } else {
        if (__builtin_expect(allocate > (UINT32_MAX >> 1), false)) {
            // User tried to allocate more than 2GB of memory, which exceeds the maximum size supported by FFstrbuf.
            // This is likely an error or an attempt to exploit the program. Abort to prevent potential issues.
            FF_DEBUG("Error: Attempted to allocate %" PRIu32 " bytes more than 2GB of memory in FFstrbuf. Aborting", allocate);
            abort();
        }

        // Round up to the next power of 2.
        // If the value is already a power of 2, it will be rounded up to the next power of 2.
        // allocate = __builtin_stdc_bit_ceil(allocate + 1); // Currently generates worse asm code
        allocate = 1U << (32 - __builtin_clz(allocate));
    }

    if (strbuf->allocated == 0) {
        char* newbuf = malloc(sizeof(*strbuf->chars) * allocate);
        if (strbuf->length == 0) {
            *newbuf = '\0';
        } else {
            memcpy(newbuf, strbuf->chars, strbuf->length + 1);
        }
        strbuf->chars = newbuf;
    } else {
        strbuf->chars = realloc(strbuf->chars, sizeof(*strbuf->chars) * allocate);
    }

    strbuf->allocated = allocate;
}

// Ensure that at least `free` bytes are available in the buffer besides the current length
// for an empty buffer, free + 1 length memory will be allocated(+1 for the NUL)
// This function ensures a dynamic buffer is allocated even if free == 0
void ffStrbufEnsureFixedLengthFree(FFstrbuf* strbuf, uint32_t free) {
    uint32_t newCap;

    if (strbuf->allocated == 0) {
        assert(strbuf->length < UINT32_MAX - 1); // We don't use static strings with length >= UINT32_MAX - 1, so this should never happen
        if (__builtin_expect(__builtin_uadd_overflow(strbuf->length + 1, free, &newCap), false)) {
            FF_DEBUG("Error: Integer overflow when calculating new capacity. Aborting");
            abort();
        }

        char* newbuf = malloc(sizeof(*strbuf->chars) * newCap);
        if (strbuf->length == 0) {
            *newbuf = '\0';
        } else {
            memcpy(newbuf, strbuf->chars, strbuf->length + 1);
        }
        strbuf->chars = newbuf;
    } else {
        uint32_t oldFree = ffStrbufGetFree(strbuf);
        if (oldFree >= free) {
            return;
        }

        if (__builtin_expect(__builtin_uadd_overflow(strbuf->allocated, free - oldFree, &newCap), false)) {
            FF_DEBUG("Error: Integer overflow when calculating new capacity. Aborting");
            abort();
        }
        strbuf->chars = realloc(strbuf->chars, sizeof(*strbuf->chars) * newCap);
    }

    strbuf->allocated = newCap;
}

void ffStrbufAppendTransformS(FFstrbuf* strbuf, const char* value, int (*transformFunc)(int)) {
    if (value == nullptr) {
        return;
    }

    // Ensure capacity > 0 or the modification below will fail
    uint32_t length = (uint32_t) strlen(value);
    if (length == 0) {
        return;
    }

    ffStrbufEnsureFree(strbuf, length);
    for (uint32_t i = 0; value[i] != '\0'; i++) {
        strbuf->chars[strbuf->length++] = (char) transformFunc(value[i]);
    }
    strbuf->chars[strbuf->length] = '\0';
}

void ffStrbufAppendVF(FFstrbuf* strbuf, const char* format, va_list arguments) {
    va_list copy;
    va_copy(copy, arguments);

    uint32_t free = ffStrbufGetFree(strbuf);
    int written = vsnprintf(strbuf->chars + strbuf->length, strbuf->allocated > 0 ? free + 1 : 0, format, arguments);

    if (written > 0 && (uint32_t) written > free) {
        ffStrbufEnsureFreeNoCheck(strbuf, (uint32_t) written);
        written = vsnprintf(strbuf->chars + strbuf->length, (uint32_t) written + 1, format, copy);
    }

    va_end(copy);

    if (written > 0) {
        strbuf->length += (uint32_t) written;
    }
}

const char* ffStrbufAppendSUntilC(FFstrbuf* strbuf, const char* value, char until) {
    if (value == nullptr) {
        return nullptr;
    }

    const char* end = strchr(value, until);
    if (end == nullptr) {
        ffStrbufAppendS(strbuf, value);
    } else {
        ffStrbufAppendNS(strbuf, (uint32_t) (end - value), value);
    }
    return end;
}

void ffStrbufSetF(FFstrbuf* strbuf, const char* format, ...) {
    va_list arguments;
    va_start(arguments, format);

    if (strbuf->allocated == 0) {
        ffStrbufInitVF(strbuf, format, arguments);
        va_end(arguments);
        return;
    }

    ffStrbufClear(strbuf);
    ffStrbufAppendVF(strbuf, format, arguments);
    va_end(arguments);
}

void ffStrbufAppendF(FFstrbuf* strbuf, const char* format, ...) {
    va_list arguments;
    va_start(arguments, format);
    ffStrbufAppendVF(strbuf, format, arguments);
    va_end(arguments);
}

void ffStrbufPrependNS(FFstrbuf* strbuf, uint32_t length, const char* value) {
    if (value == nullptr || length == 0) {
        return;
    }

    ffStrbufEnsureFree(strbuf, length);
    memmove(strbuf->chars + length, strbuf->chars, strbuf->length + 1); // + 1 for the null byte
    memcpy(strbuf->chars, value, length);
    strbuf->length += length;
}

void ffStrbufPrependC(FFstrbuf* strbuf, char c) {
    ffStrbufEnsureFree(strbuf, 1);
    memmove(strbuf->chars + 1, strbuf->chars, strbuf->length + 1); // + 1 for the null byte
    strbuf->chars[0] = c;
    strbuf->length += 1;
}

void ffStrbufSetNS(FFstrbuf* strbuf, uint32_t length, const char* value) {
    if (length == 0) {
        ffStrbufClear(strbuf);
        return;
    }

    if (strbuf->allocated <= length) {
        char* newBuf = malloc(sizeof(char) * (length + 1));
        memcpy(newBuf, value, length);
        if (strbuf->allocated > 0) {
            free(strbuf->chars);
        }
        strbuf->chars = newBuf;
        strbuf->allocated = length + 1;
    } else {
        memmove(strbuf->chars, value, length);
    }

    strbuf->length = length;
    strbuf->chars[length] = '\0';
}

void ffStrbufSet(FFstrbuf* strbuf, const FFstrbuf* value) {
    // `value` is non-null per the `nonnull(2)` contract; the aliasing check cannot be expressed by an attribute
    assert(value != strbuf);

    if (value->length == 0) {
        ffStrbufClear(strbuf);
        return;
    }

    if (value->allocated == 0) // static string
    {
        if (strbuf->allocated != 0) {
            free(strbuf->chars);
            strbuf->allocated = 0;
        }
        strbuf->chars = value->chars;
        strbuf->length = value->length;
        return;
    }
    ffStrbufSetNS(strbuf, value->length, value->chars);
}

void ffStrbufTrimLeft(FFstrbuf* strbuf, char c) {
    if (strbuf->length == 0) {
        return;
    }

    uint32_t index = 0;
    while (index < strbuf->length && strbuf->chars[index] == c) {
        ++index;
    }

    if (index == 0) {
        return;
    }

    if (strbuf->allocated == 0) {
        // static string
        strbuf->length -= index;
        strbuf->chars += index;
        return;
    }

    memmove(strbuf->chars, strbuf->chars + index, strbuf->length - index);
    strbuf->length -= index;
    strbuf->chars[strbuf->length] = '\0';
}

void ffStrbufTrimRight(FFstrbuf* strbuf, char c) {
    if (strbuf->length == 0) {
        return;
    }

    if (!ffStrbufEndsWithC(strbuf, c)) {
        return;
    }

    do {
        --strbuf->length;
    } while (ffStrbufEndsWithC(strbuf, c));

    if (strbuf->allocated == 0) {
        // static string
        ffStrbufInitNS(strbuf, strbuf->length, strbuf->chars);
        return;
    }

    strbuf->chars[strbuf->length] = '\0';
}

void ffStrbufTrimLeftSpace(FFstrbuf* strbuf) {
    if (strbuf->length == 0) {
        return;
    }

    uint32_t index = 0;
    while (index < strbuf->length && isspace(strbuf->chars[index])) {
        ++index;
    }

    if (index == 0) {
        return;
    }

    if (strbuf->allocated == 0) {
        // static string
        strbuf->length -= index;
        strbuf->chars += index;
        return;
    }

    memmove(strbuf->chars, strbuf->chars + index, strbuf->length - index);
    strbuf->length -= index;
    strbuf->chars[strbuf->length] = '\0';
}

void ffStrbufTrimRightSpace(FFstrbuf* strbuf) {
    if (strbuf->length == 0) {
        return;
    }

    if (!ffStrbufEndsWithFn(strbuf, isspace)) {
        return;
    }

    do {
        --strbuf->length;
    } while (ffStrbufEndsWithFn(strbuf, isspace));

    if (strbuf->allocated == 0) {
        // static string
        ffStrbufInitNS(strbuf, strbuf->length, strbuf->chars);
        return;
    }

    strbuf->chars[strbuf->length] = '\0';
}

bool ffStrbufRemoveSubstr(FFstrbuf* strbuf, uint32_t startIndex, uint32_t endIndex) {
    if (startIndex > strbuf->length || startIndex >= endIndex) {
        return false;
    }

    if (endIndex > strbuf->length) {
        ffStrbufSubstrBefore(strbuf, startIndex);
        return true;
    }

    ffStrbufEnsureFree(strbuf, 0);
    memmove(strbuf->chars + startIndex, strbuf->chars + endIndex, strbuf->length - endIndex);
    strbuf->length -= (endIndex - startIndex);
    strbuf->chars[strbuf->length] = '\0';
    return true;
}

void ffStrbufRemoveS(FFstrbuf* strbuf, const char* str) {
    uint32_t stringLength = (uint32_t) strlen(str);

    for (uint32_t i = ffStrbufNextIndexS(strbuf, 0, str); i < strbuf->length; i = ffStrbufNextIndexS(strbuf, i, str)) {
        ffStrbufRemoveSubstr(strbuf, i, i + stringLength);
    }
}

void ffStrbufRemoveStrings(FFstrbuf* strbuf, uint32_t numStrings, const char* strings[]) {
    for (uint32_t i = 0; i < numStrings; i++) {
        ffStrbufRemoveS(strbuf, strings[i]);
    }
}

void ffStrbufReplaceAllC(FFstrbuf* strbuf, char find, char replace) {
    if (strbuf->length == 0) {
        return;
    }

    ffStrbufEnsureFree(strbuf, 0);
    for (
        char* current_pos = memchr(strbuf->chars, find, strbuf->length);
        current_pos;
        current_pos = memchr(
            current_pos + 1,
            find,
            strbuf->length - (uint32_t) (current_pos + 1 - strbuf->chars))) {
        *current_pos = replace;
    }
}

bool ffStrbufSubstrBefore(FFstrbuf* strbuf, uint32_t index) {
    if (strbuf->length <= index) {
        return false;
    }

    if (strbuf->allocated == 0) {
        // static string
        ffStrbufInitNS(strbuf, index, strbuf->chars);
        return true;
    }

    strbuf->length = index;
    strbuf->chars[strbuf->length] = '\0';
    return true;
}

bool ffStrbufSubstrAfter(FFstrbuf* strbuf, uint32_t index) {
    if (index >= strbuf->length) {
        ffStrbufClear(strbuf);
        return true;
    }

    if (strbuf->allocated == 0) {
        // static string
        strbuf->length -= index + 1;
        strbuf->chars += index + 1;
        return true;
    }

    memmove(strbuf->chars, strbuf->chars + index + 1, strbuf->length - index - 1);
    strbuf->length -= (index + 1);
    strbuf->chars[strbuf->length] = '\0';
    return true;
}

bool ffStrbufSubstrAfterFirstC(FFstrbuf* strbuf, char c) {
    uint32_t index = ffStrbufFirstIndexC(strbuf, c);
    if (index >= strbuf->length) {
        return false;
    }
    ffStrbufSubstrAfter(strbuf, index);
    return true;
}

bool ffStrbufSubstrAfterFirstS(FFstrbuf* strbuf, const char* str) {
    if (*str == '\0') {
        return false;
    }

    uint32_t index = ffStrbufFirstIndexS(strbuf, str) + (uint32_t) strlen(str) - 1; // -1, because firstIndexS is already pointing to str[0], we want to add only the remaining length
    if (index >= strbuf->length) {
        return false;
    }

    ffStrbufSubstrAfter(strbuf, index);
    return true;
}

bool ffStrbufSubstrAfterLastC(FFstrbuf* strbuf, char c) {
    uint32_t index = ffStrbufLastIndexC(strbuf, c);
    if (index >= strbuf->length) {
        return false;
    }

    ffStrbufSubstrAfter(strbuf, index);
    return true;
}

bool ffStrbufSubstr(FFstrbuf* strbuf, uint32_t start, uint32_t end) {
    if (__builtin_expect(start >= end, false)) {
        ffStrbufClear(strbuf);
        return false;
    }

    if (__builtin_expect(start == 0, false)) {
        return ffStrbufSubstrBefore(strbuf, end);
    }
    if (__builtin_expect(end >= strbuf->length, false)) {
        return ffStrbufSubstrAfter(strbuf, start - 1);
    }

    uint32_t len = end - start;
    ffStrbufEnsureFixedLengthFree(strbuf, len); // In case of static string
    memmove(strbuf->chars, strbuf->chars + start, len);

    strbuf->length = len;
    strbuf->chars[len] = '\0';
    return true;
}

uint32_t ffStrbufCountC(const FFstrbuf* strbuf, char c) {
    uint32_t result = 0;
    for (uint32_t i = 0; i < strbuf->length; i++) {
        if (strbuf->chars[i] == c) {
            result++;
        }
    }

    return result;
}

bool ffStrbufRemoveIgnCaseEndS(FFstrbuf* strbuf, const char* end) {
    uint32_t endLength = (uint32_t) strlen(end);
    if (ffStrbufEndsWithIgnCaseNS(strbuf, endLength, end)) {
        ffStrbufSubstrBefore(strbuf, strbuf->length - endLength);
        return true;
    }

    return false;
}

bool ffStrbufEnsureEndsWithC(FFstrbuf* strbuf, char c) {
    if (ffStrbufEndsWithC(strbuf, c)) {
        return false;
    }

    ffStrbufAppendC(strbuf, c);
    return true;
}

void ffStrbufAppendSInt(FFstrbuf* strbuf, int64_t value) {
    ffStrbufEnsureFree(strbuf, 21); // Required by yyjson_write_number
    char* start = strbuf->chars + strbuf->length;

    yyjson_val val = {};
    unsafe_yyjson_set_sint(&val, value);
    char* end = yyjson_write_number(&val, start);

    assert(end != nullptr);

    strbuf->length += (uint32_t) (end - start);
}

void ffStrbufAppendUInt(FFstrbuf* strbuf, uint64_t value) {
    ffStrbufEnsureFree(strbuf, 21); // Required by yyjson_write_number
    char* start = strbuf->chars + strbuf->length;

    yyjson_val val = {};
    unsafe_yyjson_set_uint(&val, value);
    char* end = yyjson_write_number(&val, start);

    assert(end != nullptr);

    strbuf->length += (uint32_t) (end - start);
}

void ffStrbufAppendDouble(FFstrbuf* strbuf, double value, int8_t precision, bool trailingZeros) {
    assert(precision <= 15); // yyjson_write_number supports up to 15 digits after the decimal point

    ffStrbufEnsureFree(strbuf, 40); // Required by yyjson_write_number
    char* start = strbuf->chars + strbuf->length;

    if (precision == 0) {
        value = round(value);
    }
    yyjson_val val = {};
    unsafe_yyjson_set_double(&val, value);
    if (precision > 0) {
        unsafe_yyjson_set_fp_to_fixed(&val, precision);
    }

    // Write at most <precision> digits after the decimal point; doesn't append trailing zeros
    char* end = yyjson_write_number(&val, start);

    assert(end > start);

    strbuf->length += (uint32_t) (end - start);

    if (__builtin_expect(value > 1e21 || value < -1e21, false)) {
        // If the value is too large, yyjson_write_number will write it in scientific notation
        return;
    }

    if (trailingZeros) {
        if (precision > 1) {
            for (char* p = end - 1; *p != '.' && p > start; --p) {
                --precision;
            }
            if (precision > 0) {
                ffStrbufAppendNC(strbuf, (uint32_t) precision, '0');
            }
        } else if (precision == 0 || (precision < 0 && end[-1] == '0')) {
            goto removeDecimalPoint;
        }
    } else {
        if (end[-1] == '0') {
        removeDecimalPoint:
            // yyjson always appends ".0" to make it a float point number. We need to remove it
            strbuf->length -= 2;
            strbuf->chars[strbuf->length] = '\0';
        }
    }
}

void ffStrbufUpperCase(FFstrbuf* strbuf) {
    for (uint32_t i = 0; i < strbuf->length; ++i) {
        strbuf->chars[i] = (char) toupper(strbuf->chars[i]);
    }
}

void ffStrbufLowerCase(FFstrbuf* strbuf) {
    for (uint32_t i = 0; i < strbuf->length; ++i) {
        strbuf->chars[i] = (char) tolower(strbuf->chars[i]);
    }
}

void ffStrbufInsertNC(FFstrbuf* strbuf, uint32_t index, uint32_t num, char c) {
    if (num == 0) {
        return;
    }
    if (index >= strbuf->length) {
        index = strbuf->length;
    }

    ffStrbufEnsureFree(strbuf, num);
    memmove(strbuf->chars + index + num, strbuf->chars + index, strbuf->length - index + 1);
    memset(&strbuf->chars[index], c, num);
    strbuf->length += num;
}

bool ffStrbufGetdelim(char** lineptr, size_t* n, char delimiter, FFstrbuf* buffer) {
    assert(buffer->allocated > 0 || (buffer->allocated == 0 && buffer->length == 0));
    assert(!*lineptr || (*lineptr >= buffer->chars && *lineptr <= buffer->chars + buffer->length));

    const char* pBufferEnd = buffer->chars + buffer->length;
    if (!*lineptr) {
        *lineptr = buffer->chars;
    } else {
        *lineptr += *n;
        if (*lineptr >= pBufferEnd) { // non-empty last line
            return false;
        }
        **lineptr = delimiter;
        ++*lineptr;
    }
    if (*lineptr >= pBufferEnd) { // empty last line
        return false;
    }

    size_t remaining = (size_t) (pBufferEnd - *lineptr);
    char* ending = memchr(*lineptr, delimiter, remaining);
    if (ending) {
        *n = (size_t) (ending - *lineptr);
        *ending = '\0';
    } else {
        *n = remaining;
    }
    return true;
}

void ffStrbufGetdelimRestore(char** lineptr, size_t* n, char delimiter, FFstrbuf* buffer) {
    assert(buffer->allocated > 0 || (buffer->allocated == 0 && buffer->length == 0));
    assert(!*lineptr || (*lineptr >= buffer->chars && *lineptr <= buffer->chars + buffer->length));

    if (!*lineptr) {
        return;
    }

    *lineptr += *n;
    if (*lineptr < buffer->chars + buffer->length) {
        **lineptr = delimiter;
    }
}

bool ffStrbufRemoveDupWhitespaces(FFstrbuf* strbuf) {
    if (strbuf->allocated == 0) {
        return false; // Doesn't work with static strings
    }

    bool changed = false;
    for (uint32_t i = 0; i < strbuf->length; i++) {
        if (strbuf->chars[i] != ' ') {
            continue;
        }

        i++;
        uint32_t j = i;
        for (; j < strbuf->length && strbuf->chars[j] == ' '; j++);

        if (j == i) {
            continue;
        }
        memmove(&strbuf->chars[i], &strbuf->chars[j], strbuf->length - j + 1);
        strbuf->length -= j - i;
        changed = true;
    }

    return changed;
}

/// @brief Check if a separated string (comp) contains a substring (strbuf).
/// @param strbuf The substring to check.
/// @param compLength The length of the separated string to check.
/// @param comp The separated string to check.
/// @param separator The separator character.
///
/// Empty-string handling:
/// - If `strbuf` is empty, it matches only if `comp` contains an empty segment
///   (e.g. "abc::def", "abc:", ":abc") or `comp` itself is empty.
/// - If `comp` is empty (compLength == 0), it matches only if `strbuf` is also empty.
bool ffStrbufMatchSeparatedNS(const FFstrbuf* strbuf, uint32_t compLength, const char* comp, char separator) {
    if (__builtin_expect(compLength == 0, false)) {
        return strbuf->length == 0;
    }

    for (const char* p = comp; p <= comp + compLength;) {
        const char* colon = memchr(p, separator, (size_t) (comp + compLength - p));
        if (colon == nullptr) {
            uint32_t remainingLen = (uint32_t) (comp + compLength - p);
            return strbuf->length == remainingLen && memcmp(strbuf->chars, p, remainingLen) == 0;
        }

        uint32_t substrLength = (uint32_t) (colon - p);
        if (strbuf->length == substrLength && memcmp(strbuf->chars, p, substrLength) == 0) {
            return true;
        }

        p = colon + 1;
    }

    return false;
}

/// @brief Case insensitive version of ffStrbufMatchSeparatedNS.
bool ffStrbufMatchSeparatedIgnCaseNS(const FFstrbuf* strbuf, uint32_t compLength, const char* comp, char separator) {
    if (__builtin_expect(compLength == 0, false)) {
        return strbuf->length == 0;
    }

    for (const char* p = comp; p <= comp + compLength;) {
        const char* colon = memchr(p, separator, (size_t) (comp + compLength - p));
        if (colon == nullptr) {
            uint32_t remainingLen = (uint32_t) (comp + compLength - p);
            return strbuf->length == remainingLen && strncasecmp(strbuf->chars, p, remainingLen) == 0;
        }

        uint32_t substrLength = (uint32_t) (colon - p);
        if (strbuf->length == substrLength && strncasecmp(strbuf->chars, p, substrLength) == 0) {
            return true;
        }

        p = colon + 1;
    }

    return false;
}

int ffStrbufAppendUtf32CodePoint(FFstrbuf* strbuf, uint32_t codepoint) {
    if (codepoint <= 0x7F) {
        ffStrbufAppendC(strbuf, (char) codepoint);
        return 1;
    } else if (codepoint <= 0x7FF) {
        ffStrbufAppendNS(strbuf, 2, (char[]) { (char) (0xC0 | (codepoint >> 6)), (char) (0x80 | (codepoint & 0x3F)) });
        return 2;
    } else if (codepoint <= 0xFFFF) {
        ffStrbufAppendNS(strbuf, 3, (char[]) { (char) (0xE0 | (codepoint >> 12)), (char) (0x80 | ((codepoint >> 6) & 0x3F)), (char) (0x80 | (codepoint & 0x3F)) });
        return 3;
    } else if (codepoint <= 0x10FFFF) {
        ffStrbufAppendNS(strbuf, 4, (char[]) { (char) (0xF0 | (codepoint >> 18)), (char) (0x80 | ((codepoint >> 12) & 0x3F)), (char) (0x80 | ((codepoint >> 6) & 0x3F)), (char) (0x80 | (codepoint & 0x3F)) });
        return 4;
    }

    ffStrbufAppendS(strbuf, "�"); // U+FFFD REPLACEMENT CHARACTER
    return 1;
}

/// @brief Check if a separated string (strbuf) contains a substring (comp).
/// @param strbuf The separated to check.
/// @param compLength The length of the separated string to check.
/// @param comp The substring to check.
/// @param separator The separator character.
///
/// Empty-string handling is symmetric to ffStrbufMatchSeparatedNS
bool ffStrbufSeparatedContainNS(const FFstrbuf* strbuf, uint32_t compLength, const char* comp, char separator) {
    if (__builtin_expect(strbuf->length == 0, false)) {
        return compLength == 0; // An empty list contains only the empty segment
    }

    uint32_t startIndex = 0;
    while (startIndex <= strbuf->length) { // `<=` so a trailing empty segment (e.g. "abc:") is checked
        uint32_t colonIndex = ffStrbufNextIndexC(strbuf, startIndex, separator);

        uint32_t folderLength = colonIndex - startIndex;
        if (folderLength == compLength && memcmp(strbuf->chars + startIndex, comp, compLength) == 0) {
            return true;
        }

        startIndex = colonIndex + 1;
    }

    return false;
}

bool ffStrbufSeparatedContainIgnCaseNS(const FFstrbuf* strbuf, uint32_t compLength, const char* comp, char separator) {
    if (__builtin_expect(strbuf->length == 0, false)) {
        return compLength == 0; // An empty list contains only the empty segment
    }

    uint32_t startIndex = 0;
    while (startIndex <= strbuf->length) { // `<=` so a trailing empty segment (e.g. "abc:") is checked
        uint32_t colonIndex = ffStrbufNextIndexC(strbuf, startIndex, separator);

        uint32_t folderLength = colonIndex - startIndex;
        if (folderLength == compLength && strncasecmp(strbuf->chars + startIndex, comp, compLength) == 0) {
            return true;
        }

        startIndex = colonIndex + 1;
    }

    return false;
}

bool ffStrbufDecodeHexEscapeSequences(FFstrbuf* strbuf) {
    if (strbuf->length < 4) {
        return false;
    }

    // Static string must be converted first.
    assert(strbuf->allocated > 0);

    bool changed = false;
    uint32_t read = 0;
    uint32_t write = 0;

    while (read < strbuf->length) {
        if (
            read + 3 < strbuf->length &&
            strbuf->chars[read] == '\\' &&
            strbuf->chars[read + 1] == 'x') {
            int8_t hi = ffHexCharToInt(strbuf->chars[read + 2]);
            int8_t lo = ffHexCharToInt(strbuf->chars[read + 3]);
            if (hi >= 0 && lo >= 0) {
                strbuf->chars[write++] = (char) ((hi << 4) | lo);
                read += 4;
                changed = true;
                continue;
            }
        }

        strbuf->chars[write++] = strbuf->chars[read++];
    }

    strbuf->length = write;
    strbuf->chars[write] = '\0';
    return changed;
}