glibc printf

Version

• glibc v2.35

Definition

// stdio-common/printf.c
int
__printf (const char *format, ...)
{
  va_list arg;
  int done;

  va_start (arg, format);
  done = __vfprintf_internal (stdout, format, arg, 0);
  va_end (arg);

  return done;
}

#undef _IO_printf
ldbl_strong_alias (__printf, printf);
ldbl_strong_alias (__printf, _IO_printf);

// stdio-common/vfprintf-internal.c
# define vfprintf	__vfprintf_internal
...
int
vfprintf (FILE *s, const CHAR_T *format, va_list ap, unsigned int mode_flags)
{
  ...
  /* Hand off processing for positional parameters.  */
do_positional:
  done = printf_positional (s, format, readonly_format, ap, &ap_save,
			    done, nspecs_done, lead_str_end, work_buffer,
			    save_errno, grouping, thousands_sep, mode_flags);

all_done:
  /* Unlock the stream.  */
  _IO_funlockfile (s);
  _IO_cleanup_region_end (0);

  return done;
}

// stdio-common/vfprintf-internal.c
static int
printf_positional (FILE *s, const CHAR_T *format, int readonly_format,
		   va_list ap, va_list *ap_savep, int done, int nspecs_done,
		   const UCHAR_T *lead_str_end,
		   CHAR_T *work_buffer, int save_errno,
		   const char *grouping, THOUSANDS_SEP_T thousands_sep,
		   unsigned int mode_flags)

// stdio-common/vfprintf-internal.c
# define PUT(F, S, N)	_IO_sputn ((F), (S), (N))
...
static inline int
outstring_func (FILE *s, const UCHAR_T *string, size_t length, int done)
{
  assert ((size_t) done <= (size_t) INT_MAX);
  if ((size_t) PUT (s, string, length) != (size_t) (length))
    return -1;
  return done_add_func (length, done);
}

#define outstring(String, Len)						\
  do									\
    {									\
      const void *string_ = (String);					\
      done = outstring_func (s, string_, (Len), done);			\
      if (done < 0)							\
	goto all_done;							\
    }									\
   while (0)