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Re: readlink null termination problem
On Mon, 5 Jan 2004, Christopher Faylor wrote:
> On Tue, Jan 06, 2004 at 08:17:14AM +0800, peter garrone wrote:
> >I was having a problem with mkcramfs on cygwin creating symbolic links
> >for the compressed linux filesystem.
> >
> >mkcramfs uses malloc to allocate a buffer that it sends to the readlink function in cygwin path.cc
> >That function uses memcpy to do a copy of the link into a buffer.
> >Neither mkcramfs or readlink is null-terminating the string representing the link.
> >
> >Probably both are at fault. I have fixed my problem by zeroing the buffer in mkcramfs
> > before calling readlink, but it would probably be beneficial if readlink terminates
> > the returned string, if there is room.
>
> NAME
> readlink - read value of a symbolic link
>
> SYNOPSIS
> #include <unistd.h>
>
> int readlink(const char *path, char *buf, size_t bufsiz);
>
> DESCRIPTION
> readlink places the contents of the symbolic link path in the buffer
> buf, which has size bufsiz. readlink does not append a NUL character
> to buf. It will truncate the contents (to a length of bufsiz charac-
> ters), in case the buffer is too small to hold all of the contents.
And, to ward off the obvious next question:
RETURN VALUES
The call returns the count of characters placed in the
buffer if it succeeds, or a -1 if an error occurs, placing
the error code in errno.
HTH,
Igor
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