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Subject[RFC PATCHv2] printk: add the %pM, %p4, %p6 format specifiers
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Date
Add format specifiers for printing out colon-separated bytes:

MAC addresses (%pM):
xx:xx:xx:xx:xx:xx

IPv4 addresses (%p4):
xx:xx:xx:xx

IPv6 addresses (%p6):
xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx

%#pM, %#p4, %#p6 are also supported and print without the colon
separators.

[Based on Johannes Berg's initial patch]
Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
---
This one without the embarrassing index typos in ip6_address and mac_address.

lib/vsprintf.c | 64 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 64 insertions(+), 0 deletions(-)

diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index a013bbc..eec3879 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -581,6 +581,58 @@ static char *resource_string(char *buf, char *end, struct resource *res, int fie
return string(buf, end, sym, field_width, precision, flags);
}

+static char *ip4_address(char *buf, char *end, u8 *addr, int field_width,
+ int precision, int flags)
+{
+ char ip4_addr[4 * 3]; /* (4 * 2 hex digits), 3 colons and trailing zero */
+ char *p = ip4_addr;
+ int i;
+
+ for (i = 0; i < 4; i++) {
+ p = pack_hex_byte(p, addr[i]);
+ if (!(flags & SPECIAL) && i != 3)
+ *p++ = ':';
+ }
+ *p = '\0';
+
+ return string(buf, end, ip4_addr, field_width, precision, flags & ~SPECIAL);
+}
+
+static char *ip6_address(char *buf, char *end, u8 *addr, int field_width,
+ int precision, int flags)
+{
+ char ip6_addr[8 * 5]; /* (8 * 4 hex digits), 7 colons and trailing zero */
+ char *p = ip6_addr;
+ int i;
+
+ for (i = 0; i < 8; i++) {
+ p = pack_hex_byte(p, addr[2 * i]);
+ p = pack_hex_byte(p, addr[2 * i + 1]);
+ if (!(flags & SPECIAL) && i != 7)
+ *p++ = ':';
+ }
+ *p = '\0';
+
+ return string(buf, end, ip6_addr, field_width, precision, flags & ~SPECIAL);
+}
+
+static char *mac_address(char *buf, char *end, u8 *addr, int field_width,
+ int precision, int flags)
+{
+ char mac_addr[6 * 3]; /* (6 * 2 hex digits), 5 colons and trailing zero */
+ char *p = mac_addr;
+ int i;
+
+ for (i = 0; i < 6; i++) {
+ p = pack_hex_byte(p, addr[i]);
+ if (!(flags & SPECIAL) && i != 5)
+ *p++ = ':';
+ }
+ *p = '\0';
+
+ return string(buf, end, mac_addr, field_width, precision, flags & ~SPECIAL);
+}
+
/*
* Show a '%p' thing. A kernel extension is that the '%p' is followed
* by an extra set of alphanumeric characters that are extended format
@@ -592,6 +644,12 @@ static char *resource_string(char *buf, char *end, struct resource *res, int fie
* - 'S' For symbolic direct pointers
* - 'R' For a struct resource pointer, it prints the range of
* addresses (not the name nor the flags)
+ * - 'M' For a 6-byte MAC address, it prints the address in the
+ * usual colon-separated hex notation
+ * - '4' For a 4-byte IPv4 address, it prints the address in the
+ * usual colon-separated hex notation
+ * - 'M' For a 16-byte IPv6 address, it prints the address in colon separated
+ * big-endian 16 bit hex notation
*
* Note: The difference between 'S' and 'F' is that on ia64 and ppc64
* function pointers are really function descriptors, which contain a
@@ -607,6 +665,12 @@ static char *pointer(const char *fmt, char *buf, char *end, void *ptr, int field
return symbol_string(buf, end, ptr, field_width, precision, flags);
case 'R':
return resource_string(buf, end, ptr, field_width, precision, flags);
+ case 'M':
+ return mac_address(buf, end, ptr, field_width, precision, flags);
+ case '4':
+ return ip4_address(buf, end, ptr, field_width, precision, flags);
+ case '6':
+ return ip6_address(buf, end, ptr, field_width, precision, flags);
}
flags |= SMALL;
if (field_width == -1) {
--
1.6.0.3.729.g6ea410




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