diff options
Diffstat (limited to 'libc/manual/stdio.texi')
| -rw-r--r-- | libc/manual/stdio.texi | 35 |
1 files changed, 27 insertions, 8 deletions
diff --git a/libc/manual/stdio.texi b/libc/manual/stdio.texi index 0d23daae2..c58ca22b2 100644 --- a/libc/manual/stdio.texi +++ b/libc/manual/stdio.texi @@ -196,13 +196,31 @@ Additional characters may appear after these to specify flags for the call. Always put the mode (@samp{r}, @samp{w+}, etc.) first; that is the only part you are guaranteed will be understood by all systems. -@Theglibc{} defines one additional character for use in -@var{opentype}: the character @samp{x} insists on creating a new -file---if a file @var{filename} already exists, @code{fopen} fails -rather than opening it. If you use @samp{x} you are guaranteed that -you will not clobber an existing file. This is equivalent to the -@code{O_EXCL} option to the @code{open} function (@pxref{Opening and -Closing Files}). +@Theglibc{} defines additional characters for use in @var{opentype}: + +@table @samp +@item c +The file is opened with cancellation in the I/O functions disabled. + +@item e +The underlying file descriptor will be closed if you use any of the +@code{exec@dots{}} functions (@pxref{Executing a File}). (This is +equivalent to having set @code{FD_CLOEXEC} on that descriptor. +@xref{Descriptor Flags}.) + +@item m +The file is opened and accessed using @code{mmap}. This is only +supported with files opened for reading. + +@item x +Insist on creating a new file---if a file @var{filename} already +exists, @code{fopen} fails rather than opening it. If you use +@samp{x} you are guaranteed that you will not clobber an existing +file. This is equivalent to the @code{O_EXCL} option to the +@code{open} function (@pxref{Opening and Closing Files}). + +The @samp{x} modifier is part of @w{ISO C11}. +@end table The character @samp{b} in @var{opentype} has a standard meaning; it requests a binary stream rather than a text stream. But this makes no @@ -5003,7 +5021,8 @@ ssize_t @var{writer} (void *@var{cookie}, const char *@var{buffer}, size_t @var{ This is very similar to the @code{write} function; see @ref{I/O Primitives}. Your function should transfer up to @var{size} bytes from the buffer, and return the number of bytes written. You can return a -value of @code{-1} to indicate an error. +value of @code{0} to indicate an error. You must not return any +negative value. You should define the function to perform seek operations on the cookie as: |