Man page 9 : bstr_printf

bstr_printf - Format a string from binary arguments and place it in a buffer

int bstr_printf(char *  buf , size_t  size , const char *  fmt , const u32 *  bin_buf );

buf
    The buffer to place the result into

size
    The size of the buffer, including the trailing null space

fmt
    The format string to use

bin_buf
    Binary arguments for the format string

This function like C99 vsnprintf, but the difference is that vsnprintf gets arguments from stack, and bstr_printf gets arguments from bin_buf which is a binary buffer that generated by vbin_printf.

The format follows C99 vsnprintf, but has some extensions: see vsnprintf comment for details.

The return value is the number of characters which would be generated for the given input, excluding the trailing Aq\0Aq, as per ISO C99. If you want to have the exact number of characters written into buf as return value (not including the trailing Aq\0Aq), use vscnprintf. If the return is greater than or equal to size, the resulting string is truncated.