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| author | Andy Shevchenko <andriy.shevchenko@linux.intel.com> | 2014-10-13 15:55:18 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2014-10-14 02:18:26 +0200 |
| commit | 71dca95d5cf5ece6c1bee8e625e23c16025952c7 (patch) | |
| tree | 098b1a20867ef6d1b38f549f162c160610b3cbff /Documentation | |
| parent | c8250381c8272a9828fdd353171727b154fbd296 (diff) | |
| download | lwn-71dca95d5cf5ece6c1bee8e625e23c16025952c7.tar.gz lwn-71dca95d5cf5ece6c1bee8e625e23c16025952c7.zip | |
lib/vsprintf: add %*pE[achnops] format specifier
This allows user to print a given buffer as an escaped string. The
rules are applied according to an optional mix of flags provided by
additional format letters.
For example, if the given buffer is:
1b 62 20 5c 43 07 22 90 0d 5d
The result strings would be:
%*pE "\eb \C\a"\220\r]"
%*pEhp "\x1bb \C\x07"\x90\x0d]"
%*pEa "\e\142\040\\\103\a\042\220\r\135"
Please, read Documentation/printk-formats.txt and lib/string_helpers.c
kernel documentation to get further information.
[akpm@linux-foundation.org: tidy up comment layout, per Joe]
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Suggested-by: Joe Perches <joe@perches.com>
Cc: "John W . Linville" <linville@tuxdriver.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/printk-formats.txt | 32 |
1 files changed, 32 insertions, 0 deletions
diff --git a/Documentation/printk-formats.txt b/Documentation/printk-formats.txt index b4498218c474..5a615c14f75d 100644 --- a/Documentation/printk-formats.txt +++ b/Documentation/printk-formats.txt @@ -70,6 +70,38 @@ DMA addresses types dma_addr_t: For printing a dma_addr_t type which can vary based on build options, regardless of the width of the CPU data path. Passed by reference. +Raw buffer as an escaped string: + + %*pE[achnops] + + For printing raw buffer as an escaped string. For the following buffer + + 1b 62 20 5c 43 07 22 90 0d 5d + + few examples show how the conversion would be done (the result string + without surrounding quotes): + + %*pE "\eb \C\a"\220\r]" + %*pEhp "\x1bb \C\x07"\x90\x0d]" + %*pEa "\e\142\040\\\103\a\042\220\r\135" + + The conversion rules are applied according to an optional combination + of flags (see string_escape_mem() kernel documentation for the + details): + a - ESCAPE_ANY + c - ESCAPE_SPECIAL + h - ESCAPE_HEX + n - ESCAPE_NULL + o - ESCAPE_OCTAL + p - ESCAPE_NP + s - ESCAPE_SPACE + By default ESCAPE_ANY_NP is used. + + ESCAPE_ANY_NP is the sane choice for many cases, in particularly for + printing SSIDs. + + If field width is omitted the 1 byte only will be escaped. + Raw buffer as a hex string: %*ph 00 01 02 ... 3f %*phC 00:01:02: ... :3f |