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>
This commit is contained in:
Andy Shevchenko
Linus Torvalds
parent
c8250381c8
commit
71dca95d5c
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@ -70,6 +70,38 @@ DMA addresses types dma_addr_t:
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For printing a dma_addr_t type which can vary based on build options,
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regardless of the width of the CPU data path. Passed by reference.
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Raw buffer as an escaped string:
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%*pE[achnops]
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For printing raw buffer as an escaped string. For the following buffer
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1b 62 20 5c 43 07 22 90 0d 5d
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few examples show how the conversion would be done (the result string
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without surrounding quotes):
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%*pE "\eb \C\a"\220\r]"
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%*pEhp "\x1bb \C\x07"\x90\x0d]"
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%*pEa "\e\142\040\\\103\a\042\220\r\135"
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The conversion rules are applied according to an optional combination
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of flags (see string_escape_mem() kernel documentation for the
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details):
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a - ESCAPE_ANY
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c - ESCAPE_SPECIAL
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h - ESCAPE_HEX
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n - ESCAPE_NULL
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o - ESCAPE_OCTAL
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p - ESCAPE_NP
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s - ESCAPE_SPACE
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By default ESCAPE_ANY_NP is used.
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ESCAPE_ANY_NP is the sane choice for many cases, in particularly for
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printing SSIDs.
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If field width is omitted the 1 byte only will be escaped.
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Raw buffer as a hex string:
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%*ph 00 01 02 ... 3f
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%*phC 00:01:02: ... :3f
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@ -33,6 +33,7 @@
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#include <asm/page.h> /* for PAGE_SIZE */
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#include <asm/sections.h> /* for dereference_function_descriptor() */
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#include <linux/string_helpers.h>
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#include "kstrtox.h"
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/**
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@ -1100,6 +1101,62 @@ char *ip4_addr_string_sa(char *buf, char *end, const struct sockaddr_in *sa,
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return string(buf, end, ip4_addr, spec);
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}
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static noinline_for_stack
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char *escaped_string(char *buf, char *end, u8 *addr, struct printf_spec spec,
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const char *fmt)
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{
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bool found = true;
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int count = 1;
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unsigned int flags = 0;
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int len;
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if (spec.field_width == 0)
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return buf; /* nothing to print */
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if (ZERO_OR_NULL_PTR(addr))
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return string(buf, end, NULL, spec); /* NULL pointer */
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do {
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switch (fmt[count++]) {
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case 'a':
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flags |= ESCAPE_ANY;
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break;
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case 'c':
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flags |= ESCAPE_SPECIAL;
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break;
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case 'h':
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flags |= ESCAPE_HEX;
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break;
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case 'n':
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flags |= ESCAPE_NULL;
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break;
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case 'o':
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flags |= ESCAPE_OCTAL;
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break;
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case 'p':
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flags |= ESCAPE_NP;
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break;
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case 's':
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flags |= ESCAPE_SPACE;
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break;
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default:
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found = false;
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break;
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}
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} while (found);
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if (!flags)
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flags = ESCAPE_ANY_NP;
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len = spec.field_width < 0 ? 1 : spec.field_width;
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/* Ignore the error. We print as many characters as we can */
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string_escape_mem(addr, len, &buf, end - buf, flags, NULL);
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return buf;
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}
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static noinline_for_stack
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char *uuid_string(char *buf, char *end, const u8 *addr,
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struct printf_spec spec, const char *fmt)
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@ -1221,6 +1278,17 @@ int kptr_restrict __read_mostly;
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* - '[Ii][4S][hnbl]' IPv4 addresses in host, network, big or little endian order
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* - 'I[6S]c' for IPv6 addresses printed as specified by
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* http://tools.ietf.org/html/rfc5952
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* - 'E[achnops]' For an escaped buffer, where rules are defined by combination
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* of the following flags (see string_escape_mem() for the
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* details):
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* a - ESCAPE_ANY
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* c - ESCAPE_SPECIAL
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* h - ESCAPE_HEX
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* n - ESCAPE_NULL
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* o - ESCAPE_OCTAL
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* p - ESCAPE_NP
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* s - ESCAPE_SPACE
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* By default ESCAPE_ANY_NP is used.
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* - 'U' For a 16 byte UUID/GUID, it prints the UUID/GUID in the form
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* "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx"
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* Options for %pU are:
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@ -1321,6 +1389,8 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr,
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}}
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}
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break;
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case 'E':
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return escaped_string(buf, end, ptr, spec, fmt);
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case 'U':
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return uuid_string(buf, end, ptr, spec, fmt);
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case 'V':
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@ -1633,6 +1703,7 @@ qualifier:
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* %piS depending on sa_family of 'struct sockaddr *' print IPv4/IPv6 address
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* %pU[bBlL] print a UUID/GUID in big or little endian using lower or upper
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* case.
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* %*pE[achnops] print an escaped buffer
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* %*ph[CDN] a variable-length hex string with a separator (supports up to 64
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* bytes of the input)
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* %n is ignored
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