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Diffstat (limited to 'libio')
-rw-r--r--libio/vsnprintf.c87
1 files changed, 80 insertions, 7 deletions
diff --git a/libio/vsnprintf.c b/libio/vsnprintf.c
index af901bf3e6..5ada74215c 100644
--- a/libio/vsnprintf.c
+++ b/libio/vsnprintf.c
@@ -1,5 +1,5 @@
/*
-Copyright (C) 1994 Free Software Foundation
+Copyright (C) 1994, 1997 Free Software Foundation, Inc.
This file is part of the GNU IO Library. This library is free
software; you can redistribute it and/or modify it under the
@@ -25,6 +25,73 @@ the executable file might be covered by the GNU General Public License. */
#include "libioP.h"
#include "strfile.h"
+
+typedef struct
+{
+ _IO_strfile f;
+ /* This is used for the characters which do not fit in the buffer
+ provided by the user. */
+ char overflow_buf[64];
+} _IO_strnfile;
+
+
+static int
+_IO_strn_overflow (_IO_FILE* fp, int c)
+{
+ /* When we come to here this means the user supplied buffer is
+ filled. But since we must return the number of characters which
+ would have been written in total we must provide a buffer for
+ further use. We can do this by writing on and on in the overflow
+ buffer in the _IO_strnfile structure. */
+ _IO_strnfile *snf = (_IO_strnfile *) fp;
+
+ if (fp->_IO_buf_base != snf->overflow_buf)
+ {
+ /* Terminate the string. We know that there is room for at
+ least one more character since we initialized the stream with
+ a size to make this possible. */
+ *fp->_IO_write_ptr = '\0';
+
+ _IO_setb (fp, snf->overflow_buf,
+ snf->overflow_buf + sizeof (snf->overflow_buf), 0);
+
+ fp->_IO_write_base = snf->overflow_buf;
+ fp->_IO_read_base = snf->overflow_buf;
+ fp->_IO_read_ptr = snf->overflow_buf;
+ fp->_IO_read_end = snf->overflow_buf + sizeof (snf->overflow_buf);
+ }
+
+ fp->_IO_write_ptr = snf->overflow_buf;
+ fp->_IO_write_end = snf->overflow_buf;
+
+ /* Since we are not really interested in storing the characters
+ which do not fit in the buffer we simply ignore it. */
+ return c;
+}
+
+
+static struct _IO_jump_t _IO_strn_jumps = {
+ JUMP_INIT_DUMMY,
+ JUMP_INIT(finish, _IO_str_finish),
+ JUMP_INIT(overflow, _IO_strn_overflow),
+ JUMP_INIT(underflow, _IO_str_underflow),
+ JUMP_INIT(uflow, _IO_default_uflow),
+ JUMP_INIT(pbackfail, _IO_str_pbackfail),
+ JUMP_INIT(xsputn, _IO_default_xsputn),
+ JUMP_INIT(xsgetn, _IO_default_xsgetn),
+ JUMP_INIT(seekoff, _IO_str_seekoff),
+ JUMP_INIT(seekpos, _IO_default_seekpos),
+ JUMP_INIT(setbuf, _IO_default_setbuf),
+ JUMP_INIT(sync, _IO_default_sync),
+ JUMP_INIT(doallocate, _IO_default_doallocate),
+ JUMP_INIT(read, _IO_default_read),
+ JUMP_INIT(write, _IO_default_write),
+ JUMP_INIT(seek, _IO_default_seek),
+ JUMP_INIT(close, _IO_default_close),
+ JUMP_INIT(stat, _IO_default_stat)
+};
+
+
int
_IO_vsnprintf (string, maxlen, format, args)
char *string;
@@ -32,22 +99,28 @@ _IO_vsnprintf (string, maxlen, format, args)
const char *format;
_IO_va_list args;
{
- _IO_strfile sf;
+ _IO_strnfile sf;
int ret;
#ifdef _IO_MTSAFE_IO
_IO_lock_t lock;
- sf._sbf._f._lock = &lock;
+ sf.f._sbf._f._lock = &lock;
#endif
- /* We need to handle the special case where MAXLEN is 0. */
+ /* We need to handle the special case where MAXLEN is 0. Use the
+ overflow buffer right from the start. */
if (maxlen == 0)
- return 0;
+ {
+ string = sf.overflow_buf;
+ maxlen = sizeof (sf.overflow_buf);
+ }
_IO_init ((_IO_FILE *) &sf, 0);
- _IO_JUMPS ((_IO_FILE *) &sf) = &_IO_str_jumps;
+ _IO_JUMPS ((_IO_FILE *) &sf) = &_IO_strn_jumps;
_IO_str_init_static ((_IO_FILE *) &sf, string, maxlen - 1, string);
ret = _IO_vfprintf ((_IO_FILE *) &sf, format, args);
- *((_IO_FILE *) &sf)->_IO_write_ptr = '\0';
+
+ if (sf.f._sbf._f._IO_buf_base != sf.overflow_buf)
+ *sf.f._sbf._f._IO_write_ptr = '\0';
return ret;
}
weak_alias (_IO_vsnprintf, __vsnprintf)