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Date: Thu, 20 Oct 2016 01:25:27 -0400
From: Rich Felker <dalias@...c.org>
To: musl@...ts.openwall.com
Subject: Re: [PATCH] use dynamic buffer for getmntent
On Thu, Sep 08, 2016 at 07:07:31PM +0200, Natanael Copa wrote:
> overlayfs may have fairly long lines so we use getline to allocate a
> buffer dynamically. The buffer will be allocated on first use, expand as
> needed, but will never be free'ed.
>
> Downstream bug: http://bugs.alpinelinux.org/issues/5703
>
> Signed-off-by: Natanael Copa <ncopa@...inelinux.org>
Thanks! Sorry for the delay. Committed with minor style fixes:
> ---
> src/misc/mntent.c | 16 ++++++++++++----
> 1 file changed, 12 insertions(+), 4 deletions(-)
>
> diff --git a/src/misc/mntent.c b/src/misc/mntent.c
> index a16d652..722a030 100644
> --- a/src/misc/mntent.c
> +++ b/src/misc/mntent.c
> @@ -3,6 +3,11 @@
> #include <mntent.h>
> #include <errno.h>
>
> +static char *internal_buf = NULL;
> +static size_t internal_bufsize = 0;
Explicit zero initialization is not needed, and current/going-forward
style in musl is not to use the NULL macro but rather 0 or (T*)0 if
needed (e.g. for variadic args).
> +
> +#define SENTINEL (char *)&internal_buf
> +
> FILE *setmntent(const char *name, const char *mode)
> {
> return fopen(name, mode);
> @@ -16,13 +21,17 @@ int endmntent(FILE *f)
>
> struct mntent *getmntent_r(FILE *f, struct mntent *mnt, char *linebuf, int buflen)
> {
> - int cnt, n[8];
> + int cnt, n[8], use_internal = (linebuf == SENTINEL);
>
> mnt->mnt_freq = 0;
> mnt->mnt_passno = 0;
>
> do {
> - fgets(linebuf, buflen, f);
> + if (use_internal) {
> + getline(&internal_buf, &internal_bufsize, f);
> + linebuf = internal_buf;
> + } else
> + fgets(linebuf, buflen, f);
If if clause uses braces, else should too. There might be some
existing violations but I'm trying to make this consistent.
Rich
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