#include "common/FFstrbuf.h" #include "common/mallocHelper.h" #include "common/strutil.h" #include #include #include 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) { assert(format != NULL); char* buffer = NULL; 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) { assert(heapStr != NULL); 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 ffStrbufEnsureFree(FFstrbuf* strbuf, uint32_t free) { if (ffStrbufGetFree(strbuf) >= free && !(strbuf->allocated == 0 && strbuf->length > 0)) { return; } uint32_t allocate = strbuf->allocated; if (allocate < FASTFETCH_STRBUF_DEFAULT_ALLOC) { allocate = FASTFETCH_STRBUF_DEFAULT_ALLOC; } while ((strbuf->length + free + 1) > allocate) { // + 1 for the null byte allocate *= 2; } 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) void ffStrbufEnsureFixedLengthFree(FFstrbuf* strbuf, uint32_t free) { uint32_t oldFree = ffStrbufGetFree(strbuf); if (oldFree >= free && !(strbuf->allocated == 0 && strbuf->length > 0)) { return; } uint32_t newCap = strbuf->allocated + (free - oldFree); if (strbuf->allocated == 0) { newCap += strbuf->length + 1; 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 { strbuf->chars = realloc(strbuf->chars, sizeof(*strbuf->chars) * newCap); } strbuf->allocated = newCap; } void ffStrbufClear(FFstrbuf* strbuf) { assert(strbuf != NULL); if (strbuf->allocated == 0) { strbuf->chars = CHAR_NULL_PTR; } else { strbuf->chars[0] = '\0'; } strbuf->length = 0; } void ffStrbufAppendC(FFstrbuf* strbuf, char c) { ffStrbufEnsureFree(strbuf, 1); strbuf->chars[strbuf->length++] = c; strbuf->chars[strbuf->length] = '\0'; } void ffStrbufAppendNC(FFstrbuf* strbuf, uint32_t num, char c) { if (num == 0) { return; } ffStrbufEnsureFree(strbuf, num); memset(&strbuf->chars[strbuf->length], c, num); strbuf->length += num; strbuf->chars[strbuf->length] = '\0'; } void ffStrbufAppendNS(FFstrbuf* strbuf, uint32_t length, const char* value) { if (value == NULL || length == 0) { return; } ffStrbufEnsureFree(strbuf, length); memcpy(&strbuf->chars[strbuf->length], value, length); strbuf->length += length; strbuf->chars[strbuf->length] = '\0'; } void ffStrbufAppendTransformS(FFstrbuf* strbuf, const char* value, int (*transformFunc)(int)) { if (value == NULL) { 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) { assert(format != NULL); 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) { ffStrbufEnsureFree(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 == NULL) { return NULL; } const char* end = strchr(value, until); if (end == NULL) { ffStrbufAppendS(strbuf, value); } else { ffStrbufAppendNS(strbuf, (uint32_t) (end - value), value); } return end; } void ffStrbufSetF(FFstrbuf* strbuf, const char* format, ...) { assert(format != NULL); 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, ...) { assert(format != NULL); 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 == NULL || 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) { assert(strbuf != NULL); if (length == 0) { ffStrbufClear(strbuf); return; } assert(value != NULL); 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) { assert(value && 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 if (index < strbuf->length) { 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 ffStrbufWriteTo(const FFstrbuf* strbuf, FILE* file) { fwrite(strbuf->chars, sizeof(*strbuf->chars), strbuf->length, file); } void ffStrbufPutTo(const FFstrbuf* strbuf, FILE* file) { ffStrbufWriteTo(strbuf, file); fputc('\n', file); } double ffStrbufToDouble(const FFstrbuf* strbuf, double defaultValue) { char* str_end; double result = strtod(strbuf->chars, &str_end); return str_end == strbuf->chars ? defaultValue : result; } uint64_t ffStrbufToUInt(const FFstrbuf* strbuf, uint64_t defaultValue) { char* str_end; unsigned long long result = strtoull(strbuf->chars, &str_end, 10); return str_end == strbuf->chars ? defaultValue : (uint64_t) result; } int64_t ffStrbufToSInt(const FFstrbuf* strbuf, int64_t defaultValue) { char* str_end; long long result = strtoll(strbuf->chars, &str_end, 10); return str_end == strbuf->chars ? defaultValue : (int64_t) result; } 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 != NULL); 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 != NULL); 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 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(lineptr && n && 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 && lineptr && n); 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. bool ffStrbufMatchSeparatedNS(const FFstrbuf* strbuf, uint32_t compLength, const char* comp, char separator) { if (strbuf->length == 0) { return true; } if (compLength == 0) { return false; } for (const char* p = comp; p < comp + compLength;) { const char* colon = memchr(p, separator, (size_t) (comp + compLength - p)); if (colon == NULL) { 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 (strbuf->length == 0) { return true; } if (compLength == 0) { return false; } for (const char* p = comp; p < comp + compLength;) { const char* colon = memchr(p, separator, (size_t) (comp + compLength - p)); if (colon == NULL) { 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. bool ffStrbufSeparatedContainNS(const FFstrbuf* strbuf, uint32_t compLength, const char* comp, char separator) { uint32_t startIndex = 0; while (startIndex < strbuf->length) { 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) { uint32_t startIndex = 0; while (startIndex < strbuf->length) { 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) { assert(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; }