Hi, Cyril
> Hi!
> > > Using sscanf() to fill string buffer is potentialy dangerous. You
> > > could
> > > either to use GNU extension to hardcode maximal buffer length into
> > > the
> > > format string or to go trough the string while you find whitespace
> > > (see
> > > isspace()).
> > I'm not sure how to changed it, could you give me more details about
> > how to avoid
> > Using sscanf(). and always I think Using sscanf() can solve this
> > question.
>
> Well, the problem with sscanf("%s", buf) is that the sscanf() don't
> know
> how long is the buffer and that may lead to buffer overflow and
> strange
> and unexpected behavior.
Hmm,
+long long read_meminfo(char *item)
+{
+ FILE *fp;
+ char line[BUFSIZ], buf[BUFSIZ];
+ long long val;
+
+ fp = fopen(PATH_MEMINFO, "r");
+ if (fp == NULL)
+ tst_brkm(TBROK|TERRNO, cleanup, "fopen %s", PATH_MEMINFO);
+ while (fgets(line, BUFSIZ, fp) != NULL) {
+ if (sscanf(line, "%s %lld", buf, &val) == 2)
+ if (strcmp(buf, item) == 0) {
+ fclose(fp);
+ return val;
in this case, read_meminfo can only read /proc/meminfo,
fgets() read a line from /proc/meminfo one time, and the content of
the line would always be like as this:
MemTotal: 8080956 kB
and sscanf(line, "%s %lld", buf, &val) can match the item.
so I think it is enough safe to get it.
PTY: it's a little hard for me to use GNU extension to hardcode the maximal
length.
>
> Generally there are two ways how to fix it. Either use GNU extension
> to
> hardcode the maximal length of the buffer into the string, eg.
> sscanf("%64s, buf); would say sscanf to use at most 64 bytes of the
> buffer. Or go trough the string with while cycle till you find first
> occurence of whitespace.
>
> --
> Cyril Hrubis
> [email protected]
--
Thanks,
Zhouping Liu
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