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-rw-r--r--libio/fileops.c20
-rw-r--r--libio/iosetvbuf.c3
2 files changed, 15 insertions, 8 deletions
diff --git a/libio/fileops.c b/libio/fileops.c
index 1851d9a1fa..d3f4831e2d 100644
--- a/libio/fileops.c
+++ b/libio/fileops.c
@@ -45,21 +45,27 @@ extern int errno;
is that of gptr(); in put mode that of pptr().
The position in the buffer that corresponds to the position
- in external file system is file_ptr().
- This is normally _IO_read_end, except in putback mode,
+ in external file system is normally _IO_read_end, except in putback
+ mode, when it is _IO_save_end.
when it is _IO_save_end.
If the field _fb._offset is >= 0, it gives the offset in
the file as a whole corresponding to eGptr(). (?)
PUT MODE:
- If a filebuf is in put mode, pbase() is non-NULL and equal to base().
- Also, epptr() == ebuf().
- Also, eback() == gptr() && gptr() == egptr().
- The un-flushed character are those between pbase() and pptr().
+ If a filebuf is in put mode, then all of _IO_read_ptr, _IO_read_end,
+ and _IO_read_base are equal to each other. These are usually equal
+ to _IO_buf_base, though not necessarily if we have switched from
+ get mode to put mode. (The reason is to maintain the invariant
+ that _IO_read_end corresponds to the external file position.)
+ _IO_write_base is non-NULL and usually equal to _IO_base_base.
+ We also have _IO_write_end == _IO_buf_end, but only in fully buffered mode.
+ The un-flushed character are those between _IO_write_base and _IO_write_ptr.
+
GET MODE:
If a filebuf is in get or putback mode, eback() != egptr().
In get mode, the unread characters are between gptr() and egptr().
The OS file position corresponds to that of egptr().
+
PUTBACK MODE:
Putback mode is used to remember "excess" characters that have
been sputbackc'd in a separate putback buffer.
@@ -72,7 +78,7 @@ extern int errno;
The OS position corresponds to that of save_egptr().
LINE BUFFERED OUTPUT:
- During line buffered output, pbase()==base() && epptr()==base().
+ During line buffered output, _IO_write_base==base() && epptr()==base().
However, ptr() may be anywhere between base() and ebuf().
This forces a call to filebuf::overflow(int C) on every put.
If there is more space in the buffer, and C is not a '\n',
diff --git a/libio/iosetvbuf.c b/libio/iosetvbuf.c
index 3776330a88..8ba9753efc 100644
--- a/libio/iosetvbuf.c
+++ b/libio/iosetvbuf.c
@@ -42,7 +42,7 @@ _IO_setvbuf (fp, buf, mode, size)
switch (mode)
{
case _IOFBF:
- fp->_IO_file_flags &= ~_IO_LINE_BUF;
+ fp->_IO_file_flags &= ~_IO_LINE_BUF|_IO_UNBUFFERED;
if (buf == NULL)
{
if (fp->_IO_buf_base == NULL)
@@ -72,6 +72,7 @@ _IO_setvbuf (fp, buf, mode, size)
}
break;
case _IOLBF:
+ fp->_IO_file_flags &= ~_IO_UNBUFFERED;
fp->_IO_file_flags |= _IO_LINE_BUF;
if (buf == NULL)
{