From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Alastair D'Silva" Date: Fri, 12 Apr 2019 23:28:03 +0000 Subject: RE: [PATCH 2/4] lib/hexdump.c: Optionally suppress lines of filler bytes Message-Id: <093101d4f187$612f0f20$238d2d60$@d-silva.org> List-Id: References: <20190410031720.11067-1-alastair@au1.ibm.com> <20190410031720.11067-3-alastair@au1.ibm.com> <20190412140353.mgvksn3yk6n65hbk@pathway.suse.cz> In-Reply-To: <20190412140353.mgvksn3yk6n65hbk@pathway.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: 'Petr Mladek' , 'Alastair D'Silva' Cc: linux-fbdev@vger.kernel.org, 'Stanislaw Gruszka' , 'David Airlie' , 'Joonas Lahtinen' , dri-devel@lists.freedesktop.org, devel@driverdev.osuosl.org, linux-scsi@vger.kernel.org, 'Jassi Brar' , ath10k@lists.infradead.org, intel-gfx@lists.freedesktop.org, 'Jose Abreu' , 'Tom Lendacky' , "'James E.J. Bottomley'" , 'Jani Nikula' , linux-fsdevel@vger.kernel.org, 'Steven Rostedt' , 'Rodrigo Vivi' , 'Benson Leung' , 'Kalle Valo' , 'Karsten Keil' , "'Martin K. Petersen'" , 'Greg Kroah-Hartman' , linux-wireless@vger.kernel. > -----Original Message----- > From: Petr Mladek > Sent: Saturday, 13 April 2019 12:04 AM > To: Alastair D'Silva > Cc: alastair@d-silva.org; Jani Nikula ; Joonas > Lahtinen ; Rodrigo Vivi > ; David Airlie ; Daniel Vetter > ; Karsten Keil ; Jassi Brar > ; Tom Lendacky ; > David S. Miller ; Jose Abreu > ; Kalle Valo ; > Stanislaw Gruszka ; Benson Leung > ; Enric Balletbo i Serra > ; James E.J. Bottomley > ; Martin K. Petersen ; > Greg Kroah-Hartman ; Alexander Viro > ; Sergey Senozhatsky > ; Steven Rostedt ; > Andrew Morton ; intel- > gfx@lists.freedesktop.org; dri-devel@lists.freedesktop.org; linux- > kernel@vger.kernel.org; netdev@vger.kernel.org; > ath10k@lists.infradead.org; linux-wireless@vger.kernel.org; linux- > scsi@vger.kernel.org; linux-fbdev@vger.kernel.org; > devel@driverdev.osuosl.org; linux-fsdevel@vger.kernel.org > Subject: Re: [PATCH 2/4] lib/hexdump.c: Optionally suppress lines of filler > bytes > > On Wed 2019-04-10 13:17:18, Alastair D'Silva wrote: > > From: Alastair D'Silva > > > > Some buffers may only be partially filled with useful data, while the > > rest is padded (typically with 0x00 or 0xff). > > > > This patch introduces flags which allow lines of padding bytes to be > > suppressed, making the output easier to interpret: > > HEXDUMP_SUPPRESS_0X00, HEXDUMP_SUPPRESS_0XFF > > > > The first and last lines are not suppressed by default, so the > > function always outputs something. This behaviour can be further > > controlled with the HEXDUMP_SUPPRESS_FIRST & > HEXDUMP_SUPPRESS_LAST flags. > > > > An inline wrapper function is provided for backwards compatibility > > with existing code, which maintains the original behaviour. > > > > > diff --git a/lib/hexdump.c b/lib/hexdump.c index > > b8a164814744..2f3bafb55a44 100644 > > --- a/lib/hexdump.c > > +++ b/lib/hexdump.c > > +void print_hex_dump_ext(const char *level, const char *prefix_str, > > + int prefix_type, int rowsize, int groupsize, > > + const void *buf, size_t len, u64 flags) > > { > > const u8 *ptr = buf; > > - int i, linelen, remaining = len; > > + int i, remaining = len; > > unsigned char linebuf[64 * 3 + 2 + 64 + 1]; > > + bool first_line = true; > > > > if (rowsize != 16 && rowsize != 32 && rowsize != 64) > > rowsize = 16; > > > > for (i = 0; i < len; i += rowsize) { > > - linelen = min(remaining, rowsize); > > + bool skip = false; > > + int linelen = min(remaining, rowsize); > > + > > remaining -= rowsize; > > > > + if (flags & HEXDUMP_SUPPRESS_0X00) > > + skip = buf_is_all(ptr + i, linelen, 0x00); > > + > > + if (!skip && (flags & HEXDUMP_SUPPRESS_0XFF)) > > + skip = buf_is_all(ptr + i, linelen, 0xff); > > + > > + if (first_line && !(flags & HEXDUMP_SUPPRESS_FIRST)) > > + skip = false; > > + > > + if (remaining <= 0 && !(flags & HEXDUMP_SUPPRESS_LAST)) > > + skip = false; > > + > > + if (skip) > > + continue; > > IMHO, quietly skipping lines could cause a lot of confusion, espcially when > the address is not printed. > It's up to the caller to decide how they want it displayed. > I wonder how it would look like when we print something like: > > --- skipped XX lines full of 0x00 --- This could be added as a later enhancement, with a new flag (eg. HEXDUMP_SUPPRESS_VERBOSE). > > Then we might even remove the SUPPRESS_FIRST, SUPPRESS_LAST and the > ambiguous QUIET flags. > > > + > > + first_line = false; > > This should be above the if (skip). > > > + > > hex_dump_to_buffer(ptr + i, linelen, rowsize, groupsize, > > - linebuf, sizeof(linebuf), ascii); > > + linebuf, sizeof(linebuf), > > + flags & HEXDUMP_ASCII); > > > > switch (prefix_type) { > > case DUMP_PREFIX_ADDRESS: > > @@ -272,7 +316,7 @@ void print_hex_dump(const char *level, const char > *prefix_str, int prefix_type, > > } > > } > > } > > -EXPORT_SYMBOL(print_hex_dump); > > +EXPORT_SYMBOL(print_hex_dump_ext); > > We should still export even the original function that is still used everywhere. It's replaced with an inline wrapper function, there's no need to export it. -- Alastair D'Silva mob: 0423 762 819 skype: alastair_dsilva msn: alastair@d-silva.org blog: http://alastair.d-silva.org Twitter: @EvilDeece