On Wed, Jun 14, 2017 at 12:13:26PM +0200, Greg Kroah-Hartman wrote:
> On Tue, Jun 13, 2017 at 11:37:03PM +0100, okash.khawaja@xxxxxxxxx wrote:
> > The function converts strings like ttyS0 and ttyUSB0 to dev_t like
> > (4, 64) and (188, 0). Subsequent patch in this set will call it to
> > convert user-supplied device into device number. The function does
> > some basic sanity checks on the string passed in. It currently supports
> > ttyS*, ttyUSB* and, for selected synths, lp*.
> >
> > In order to do this, the patch also introduces a string member variable
> > named 'dev' to struct spk_synth. 'dev' represents the device name -
> > ttyUSB0 etc - which needs conversion to dev_t.
> >
> > Signed-off-by: Okash Khawaja <okash.khawaja@xxxxxxxxx>
> > Reviewed-by: Samuel Thibault <samuel.thibault@xxxxxxxxxxxx>
> >
> > ---
> > drivers/staging/speakup/spk_priv.h | 2
> > drivers/staging/speakup/spk_ttyio.c | 105 ++++++++++++++++++++++++++++++++++++
> > drivers/staging/speakup/spk_types.h | 1
> > 3 files changed, 108 insertions(+)
> >
> > --- a/drivers/staging/speakup/spk_priv.h
> > +++ b/drivers/staging/speakup/spk_priv.h
> > @@ -40,6 +40,8 @@
> >
> > #define KT_SPKUP 15
> > #define SPK_SYNTH_TIMEOUT 100000 /* in micro-seconds */
> > +#define SYNTH_DEFAULT_DEV "ttyS0"
> > +#define SYNTH_DEFAULT_SER 0
> >
> > const struct old_serial_port *spk_serial_init(int index);
> > void spk_stop_serial_interrupt(void);
> > --- a/drivers/staging/speakup/spk_ttyio.c
> > +++ b/drivers/staging/speakup/spk_ttyio.c
> > @@ -7,6 +7,13 @@
> > #include "spk_types.h"
> > #include "spk_priv.h"
> >
> > +/* Supported device types */
> > +#define DEV_PREFIX_TTYS "ttyS"
> > +#define DEV_PREFIX_TTYUSB "ttyUSB"
> > +#define DEV_PREFIX_LP "lp"
> > +
> > +const char *lp_supported[] = { "acntsa", "bns", "dummy", "txprt" };
> > +
> > struct spk_ldisc_data {
> > char buf;
> > struct semaphore sem;
> > @@ -16,6 +23,104 @@ struct spk_ldisc_data {
> > static struct spk_synth *spk_ttyio_synth;
> > static struct tty_struct *speakup_tty;
> >
> > +static int name_to_dev(const char *name, dev_t *dev_no)
> > +{
> > + int maj = -1, min = -1;
> > +
> > + if (strncmp(name, DEV_PREFIX_TTYS, strlen(DEV_PREFIX_TTYS)) == 0) {
> > + if (kstrtoint(name + strlen(DEV_PREFIX_TTYS), 10, &min)) {
> > + pr_err("speakup: Invalid ser param. Must be \
> > + between 0 and 191 inclusive.\n");
> > + return -EINVAL;
> > + }
> > + maj = 4;
> > +
> > + if (min < 0 || min > 191) {
> > + pr_err("speakup: Invalid ser param. Must be \
> > + between 0 and 191 inclusive.\n");
> > + return -EINVAL;
> > + }
> > + min = min + 64;
> > + } else if (strncmp(name, DEV_PREFIX_TTYUSB, strlen(DEV_PREFIX_TTYUSB))
> > + == 0) {
> > + if (kstrtoint(name + strlen(DEV_PREFIX_TTYUSB), 10, &min)) {
> > + pr_err("speakup: Invalid ttyUSB number. \
> > + Must be a number from 0 onwards\n");
> > + return -EINVAL;
> > + }
> > + maj = 188;
> > +
> > + if (min < 0) {
> > + pr_err("speakup: Invalid ttyUSB number. \
> > + Must be a number from 0 onwards\n");
> > + return -EINVAL;
> > + }
> > + } else if (strncmp(name, DEV_PREFIX_LP, strlen(DEV_PREFIX_LP)) == 0) {
> > + if (kstrtoint(name + strlen(DEV_PREFIX_LP), 10, &min)) {
> > + pr_warn("speakup: Invalid lp number. \
> > + Must be a number from 0 onwards\n");
> > + return -EINVAL;
> > + }
> > + maj = 6;
> > +
> > + if (min < 0) {
> > + pr_warn("speakup: Invalid lp number. \
> > + Must be a number from 0 onwards\n");
> > + return -EINVAL;
> > + }
> > + }
> > +
> > + if (maj == -1 || min == -1)
> > + return -EINVAL;
> > +
> > + /* if here, maj and min must be valid */
> > + *dev_no = MKDEV(maj, min);
> > +
> > + return 0;
> > +}
>
> Eeek, no, let's never try to parse strings like this and "figure out"
> what major/minor number it is. That's madness and will break if we ever
> make all char majors dynamic (there's a thread on lkml about that.)
>
> Why would the kernel need to know major/minor? Is it going to open a
> device node? If so, again, crazy stuff, that's not good...
Ah, no, nevermind, you just need the major/minor. So why not just take
that as the input here, and not a string?
thanks,
greg k-h
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