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>
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index ba3cd0a..ec337f64 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -33,6 +33,7 @@
#include <asm/page.h> /* for PAGE_SIZE */
#include <asm/sections.h> /* for dereference_function_descriptor() */
+#include <linux/string_helpers.h>
#include "kstrtox.h"
/**
@@ -1101,6 +1102,62 @@
}
static noinline_for_stack
+char *escaped_string(char *buf, char *end, u8 *addr, struct printf_spec spec,
+ const char *fmt)
+{
+ bool found = true;
+ int count = 1;
+ unsigned int flags = 0;
+ int len;
+
+ if (spec.field_width == 0)
+ return buf; /* nothing to print */
+
+ if (ZERO_OR_NULL_PTR(addr))
+ return string(buf, end, NULL, spec); /* NULL pointer */
+
+
+ do {
+ switch (fmt[count++]) {
+ case 'a':
+ flags |= ESCAPE_ANY;
+ break;
+ case 'c':
+ flags |= ESCAPE_SPECIAL;
+ break;
+ case 'h':
+ flags |= ESCAPE_HEX;
+ break;
+ case 'n':
+ flags |= ESCAPE_NULL;
+ break;
+ case 'o':
+ flags |= ESCAPE_OCTAL;
+ break;
+ case 'p':
+ flags |= ESCAPE_NP;
+ break;
+ case 's':
+ flags |= ESCAPE_SPACE;
+ break;
+ default:
+ found = false;
+ break;
+ }
+ } while (found);
+
+ if (!flags)
+ flags = ESCAPE_ANY_NP;
+
+ len = spec.field_width < 0 ? 1 : spec.field_width;
+
+ /* Ignore the error. We print as many characters as we can */
+ string_escape_mem(addr, len, &buf, end - buf, flags, NULL);
+
+ return buf;
+}
+
+static noinline_for_stack
char *uuid_string(char *buf, char *end, const u8 *addr,
struct printf_spec spec, const char *fmt)
{
@@ -1221,6 +1278,17 @@
* - '[Ii][4S][hnbl]' IPv4 addresses in host, network, big or little endian order
* - 'I[6S]c' for IPv6 addresses printed as specified by
* http://tools.ietf.org/html/rfc5952
+ * - 'E[achnops]' For an escaped buffer, where rules are defined by combination
+ * of the following flags (see string_escape_mem() 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.
* - 'U' For a 16 byte UUID/GUID, it prints the UUID/GUID in the form
* "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx"
* Options for %pU are:
@@ -1321,6 +1389,8 @@
}}
}
break;
+ case 'E':
+ return escaped_string(buf, end, ptr, spec, fmt);
case 'U':
return uuid_string(buf, end, ptr, spec, fmt);
case 'V':
@@ -1633,6 +1703,7 @@
* %piS depending on sa_family of 'struct sockaddr *' print IPv4/IPv6 address
* %pU[bBlL] print a UUID/GUID in big or little endian using lower or upper
* case.
+ * %*pE[achnops] print an escaped buffer
* %*ph[CDN] a variable-length hex string with a separator (supports up to 64
* bytes of the input)
* %n is ignored