use dynamic buffer for getmntent

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@alpinelinux.org>
This commit is contained in:
Natanael Copa 2016-09-08 19:07:31 +02:00 committed by Rich Felker
parent 167dfe9672
commit 05973dc3bb

View File

@ -3,6 +3,11 @@
#include <mntent.h>
#include <errno.h>
static char *internal_buf;
static size_t internal_bufsize;
#define SENTINEL (char *)&internal_buf
FILE *setmntent(const char *name, const char *mode)
{
return fopen(name, mode);
@ -16,13 +21,18 @@ 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 (feof(f) || ferror(f)) return 0;
if (!strchr(linebuf, '\n')) {
fscanf(f, "%*[^\n]%*[\n]");
@ -49,9 +59,8 @@ struct mntent *getmntent_r(FILE *f, struct mntent *mnt, char *linebuf, int bufle
struct mntent *getmntent(FILE *f)
{
static char linebuf[256];
static struct mntent mnt;
return getmntent_r(f, &mnt, linebuf, sizeof linebuf);
return getmntent_r(f, &mnt, SENTINEL, 0);
}
int addmntent(FILE *f, const struct mntent *mnt)