diff -r b7e2e1d7ed22 -r 85859399a0cc src/cx/printf.h
--- a/src/cx/printf.h	Tue Jan 16 23:12:43 2024 +0100
+++ b/src/cx/printf.h	Tue Jan 16 23:13:01 2024 +0100
@@ -164,6 +164,170 @@
 #define cx_bprintf(buffer, fmt, ...) cx_fprintf((CxBuffer*)buffer, \
     (cx_write_func) cxBufferWrite, fmt, __VA_ARGS__)
 
+
+/**
+ * An \c sprintf like function which reallocates the string when the buffer is not large enough.
+ *
+ * \note The resulting string is guaranteed to be zero-terminated.
+ * That means, when the buffer needed to be reallocated, the new size of the buffer will be
+ * the length returned by this function plus one.
+ *
+ * @param str a pointer to the string buffer
+ * @param len the current length of the buffer
+ * @param fmt the format string
+ * @param ... additional arguments
+ * @return the length of produced string
+ */
+#define cx_sprintf(str, len, fmt, ...) cx_sprintf_a(cxDefaultAllocator, str, len, fmt, __VA_ARGS__)
+
+/**
+ * An \c sprintf like function which reallocates the string when the buffer is not large enough.
+ *
+ * \note The resulting string is guaranteed to be zero-terminated.
+ * That means, when the buffer needed to be reallocated, the new size of the buffer will be
+ * the length returned by this function plus one.
+ *
+ * \attention The original buffer MUST have been allocated with the same allocator!
+ *
+ * @param alloc the allocator to use
+ * @param str a pointer to the string buffer
+ * @param len the current length of the buffer
+ * @param fmt the format string
+ * @param ... additional arguments
+ * @return the length of produced string
+ */
+__attribute__((__nonnull__(1, 2, 4), __format__(printf, 4, 5)))
+int cx_sprintf_a(CxAllocator *alloc, char **str, size_t len, const char *fmt, ... );
+
+
+/**
+ * An \c sprintf like function which reallocates the string when the buffer is not large enough.
+ *
+ * \note The resulting string is guaranteed to be zero-terminated.
+ * That means, when the buffer needed to be reallocated, the new size of the buffer will be
+ * the length returned by this function plus one.
+ *
+ * @param str a pointer to the string buffer
+ * @param len the current length of the buffer
+ * @param fmt the format string
+ * @param ap argument list
+ * @return the length of produced string
+ */
+#define cx_vsprintf(str, len, fmt, ap) cx_vsprintf_a(cxDefaultAllocator, str, len, fmt, ap)
+
+/**
+ * An \c sprintf like function which reallocates the string when the buffer is not large enough.
+ *
+ * \note The resulting string is guaranteed to be zero-terminated.
+ * That means, when the buffer needed to be reallocated, the new size of the buffer will be
+ * the length returned by this function plus one.
+ *
+ * \attention The original buffer MUST have been allocated with the same allocator!
+ *
+ * @param alloc the allocator to use
+ * @param str a pointer to the string buffer
+ * @param len the current length of the buffer
+ * @param fmt the format string
+ * @param ap argument list
+ * @return the length of produced string
+ */
+__attribute__((__nonnull__))
+int cx_vsprintf_a(CxAllocator *alloc, char **str, size_t len, const char *fmt, va_list ap);
+
+
+/**
+ * An \c sprintf like function which allocates a new string when the buffer is not large enough.
+ *
+ * The location of the resulting string will \em always be stored to \p str. When the buffer
+ * was sufficiently large, \p buf itself will be stored to the location of \p str.
+ *
+ * \note The resulting string is guaranteed to be zero-terminated.
+ * That means, when the buffer needed to be reallocated, the new size of the buffer will be
+ * the length returned by this function plus one.
+ * 
+ * \remark When a new string needed to be allocated, the contents of \p buf will be
+ * poisoned after the call, because this function tries to produce the string in \p buf, first.
+ *
+ * @param buf a pointer to the buffer
+ * @param len the length of the buffer
+ * @param str a pointer to the location
+ * @param fmt the format string
+ * @param ... additional arguments
+ * @return the length of produced string
+ */
+#define cx_sprintf_s(buf, len, str, fmt, ...) cx_sprintf_sa(cxDefaultAllocator, buf, len, str, fmt, __VA_ARGS__)
+
+/**
+ * An \c sprintf like function which allocates a new string when the buffer is not large enough.
+ *
+ * The location of the resulting string will \em always be stored to \p str. When the buffer
+ * was sufficiently large, \p buf itself will be stored to the location of \p str.
+ *
+ * \note The resulting string is guaranteed to be zero-terminated.
+ * That means, when the buffer needed to be reallocated, the new size of the buffer will be
+ * the length returned by this function plus one.
+ *
+ * \remark When a new string needed to be allocated, the contents of \p buf will be
+ * poisoned after the call, because this function tries to produce the string in \p buf, first.
+ *
+ * @param alloc the allocator to use
+ * @param buf a pointer to the buffer
+ * @param len the length of the buffer
+ * @param str a pointer to the location
+ * @param fmt the format string
+ * @param ... additional arguments
+ * @return the length of produced string
+ */
+__attribute__((__nonnull__(1, 2, 4, 5), __format__(printf, 5, 6)))
+int cx_sprintf_sa(CxAllocator *alloc, char *buf, size_t len, char **str, const char *fmt, ... );
+
+/**
+ * An \c sprintf like function which allocates a new string when the buffer is not large enough.
+ *
+ * The location of the resulting string will \em always be stored to \p str. When the buffer
+ * was sufficiently large, \p buf itself will be stored to the location of \p str.
+ *
+ * \note The resulting string is guaranteed to be zero-terminated.
+ * That means, when the buffer needed to be reallocated, the new size of the buffer will be
+ * the length returned by this function plus one.
+ *
+ * \remark When a new string needed to be allocated, the contents of \p buf will be
+ * poisoned after the call, because this function tries to produce the string in \p buf, first.
+ *
+ * @param buf a pointer to the buffer
+ * @param len the length of the buffer
+ * @param str a pointer to the location
+ * @param fmt the format string
+ * @param ap argument list
+ * @return the length of produced string
+ */
+#define cx_vsprintf_s(buf, len, str, fmt, ap) cx_vsprintf_sa(cxDefaultAllocator, buf, len, str, fmt, ap)
+
+/**
+ * An \c sprintf like function which allocates a new string when the buffer is not large enough.
+ *
+ * The location of the resulting string will \em always be stored to \p str. When the buffer
+ * was sufficiently large, \p buf itself will be stored to the location of \p str.
+ *
+ * \note The resulting string is guaranteed to be zero-terminated.
+ * That means, when the buffer needed to be reallocated, the new size of the buffer will be
+ * the length returned by this function plus one.
+ *
+ * \remark When a new string needed to be allocated, the contents of \p buf will be
+ * poisoned after the call, because this function tries to produce the string in \p buf, first.
+ *
+ * @param alloc the allocator to use
+ * @param buf a pointer to the buffer
+ * @param len the length of the buffer
+ * @param str a pointer to the location
+ * @param fmt the format string
+ * @param ap argument list
+ * @return the length of produced string
+ */
+__attribute__((__nonnull__))
+int cx_vsprintf_sa(CxAllocator *alloc, char *buf, size_t len, char **str, const char *fmt, va_list ap);
+
+
 #ifdef __cplusplus
 } // extern "C"
 #endif