V3 [PATCH] Add "%d" support to _dl_debug_vdprintf
Commit Message
On Tue, Jun 9, 2020 at 9:19 AM Adhemerval Zanella
<adhemerval.zanella@linaro.org> wrote:
>
>
>
> On 09/06/2020 11:46, H.J. Lu wrote:
> > On Tue, Jun 9, 2020 at 7:39 AM Adhemerval Zanella
> > <adhemerval.zanella@linaro.org> wrote:
> >>
> >>
> >>
> >> On 09/06/2020 11:18, Adhemerval Zanella wrote:
> >>>
> >>>
> >>> On 05/06/2020 12:03, H.J. Lu via Libc-alpha wrote:
> >>>> "%d" will be used to print out signed value.
> >>>
> >>> LGTM with some smalls nits below.
> >>>
> >>>> ---
> >>>> elf/dl-misc.c | 31 +++++++++++++++++++++++++++++--
> >>>> 1 file changed, 29 insertions(+), 2 deletions(-)
> >>>>
> >>>> diff --git a/elf/dl-misc.c b/elf/dl-misc.c
> >>>> index ab70481fda..c82c8ae6fa 100644
> >>>> --- a/elf/dl-misc.c
> >>>> +++ b/elf/dl-misc.c
> >>>> @@ -167,6 +167,7 @@ _dl_debug_vdprintf (int fd, int tag_p, const char *fmt, va_list arg)
> >>>> switch (*fmt)
> >>>> {
> >>>> /* Integer formatting. */
> >>>> + case 'd':
> >>>> case 'u':
> >>>> case 'x':
> >>>> {
> >>>
> >>> Ok.
> >>>
> >>>> @@ -179,11 +180,34 @@ _dl_debug_vdprintf (int fd, int tag_p, const char *fmt, va_list arg)
> >>>> #else
> >>>> unsigned long int num = va_arg (arg, unsigned int);
> >>>> #endif
> >>>> + bool negative = false;
> >>>> + if (*fmt == 'd')
> >>>> + {
> >>>> +#if LONG_MAX != INT_MAX
> >>>> + if (long_mod)
> >>>> + {
> >>>> + if ((long) num < 0)
> >>>
> >>> Full type specify on cast.
> >>>
> >>>> + negative = true;
> >>>> + }
> >>>> + else
> >>>> + {
> >>>> + if ((int) num < 0)> + {
> >>>> + num = (unsigned int) num;
> >>>> + negative = true;
> >>>> + }
> >>>> + }
> >>>> +#else
> >>>> + if ((int) num < 0)
> >>>> + negative = true;
> >>>> +#endif
> >>>> + }
> >>>> +
> >>>> /* We use alloca() to allocate the buffer with the most
> >>>> pessimistic guess for the size. Using alloca() allows
> >>>> having more than one integer formatting in a call. */
> >>>> - char *buf = (char *) alloca (3 * sizeof (unsigned long int));
> >>>> - char *endp = &buf[3 * sizeof (unsigned long int)];
> >>>> + char *buf = (char *) alloca (1 + 3 * sizeof (unsigned long int));
> >>>> + char *endp = &buf[1 + 3 * sizeof (unsigned long int)];
> >>>
> >>> I think we can remove alloca here and use INT_STRLEN_BOUND (since the
> >>> string is not '\0' bounded due the writev usage). Something like:
> >>
> >> Sigh, you can't actually remove the alloca here.
> >
> > Why not? It seems to work:
> >
>
> Because the iov uses the allocated buffer on the _dl_writev and it will
> an invalid pointer if we allocate on the stack without alloca.
Here is the updated patch with alloca. I am checking it in.
From 561064eb588c0ca9caffc92c1c6af9cb7964d68b Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Fri, 5 Jun 2020 07:59:25 -0700
Subject: [PATCH] Add "%d" support to _dl_debug_vdprintf
"%d" will be used to print out signed value.
---
elf/dl-misc.c | 31 +++++++++++++++++++++++++++++--
1 file changed, 29 insertions(+), 2 deletions(-)
@@ -167,6 +167,7 @@ _dl_debug_vdprintf (int fd, int tag_p, const char *fmt, va_list arg)
switch (*fmt)
{
/* Integer formatting. */
+ case 'd':
case 'u':
case 'x':
{
@@ -179,11 +180,34 @@ _dl_debug_vdprintf (int fd, int tag_p, const char *fmt, va_list arg)
#else
unsigned long int num = va_arg (arg, unsigned int);
#endif
+ bool negative = false;
+ if (*fmt == 'd')
+ {
+#if LONG_MAX != INT_MAX
+ if (long_mod)
+ {
+ if ((long int) num < 0)
+ negative = true;
+ }
+ else
+ {
+ if ((int) num < 0)
+ {
+ num = (unsigned int) num;
+ negative = true;
+ }
+ }
+#else
+ if ((int) num < 0)
+ negative = true;
+#endif
+ }
+
/* We use alloca() to allocate the buffer with the most
pessimistic guess for the size. Using alloca() allows
having more than one integer formatting in a call. */
- char *buf = (char *) alloca (3 * sizeof (unsigned long int));
- char *endp = &buf[3 * sizeof (unsigned long int)];
+ char *buf = (char *) alloca (1 + 3 * sizeof (unsigned long int));
+ char *endp = &buf[1 + 3 * sizeof (unsigned long int)];
char *cp = _itoa (num, endp, *fmt == 'x' ? 16 : 10, 0);
/* Pad to the width the user specified. */
@@ -191,6 +215,9 @@ _dl_debug_vdprintf (int fd, int tag_p, const char *fmt, va_list arg)
while (endp - cp < width)
*--cp = fill;
+ if (negative)
+ *--cp = '-';
+
iov[niov].iov_base = cp;
iov[niov].iov_len = endp - cp;
++niov;
--
2.26.2