The patch titled
Subject: lib/vsprintf.c: update documentation
has been added to the -mm tree. Its filename is
lib-vsprintfc-update-documentation.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/lib-vsprintfc-update-documentation.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/lib-vsprintfc-update-documentation.patch
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*** Remember to use Documentation/SubmitChecklist when testing your code ***
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------------------------------------------------------
From: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx>
Subject: lib/vsprintf.c: update documentation
%n is no longer just ignored; it results in early return from vsnprintf.
Also add a request to add test cases for future %p extensions.
Signed-off-by: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx>
Reviewed-by: Martin Kletzander <mkletzan@xxxxxxxxxx>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Cc: Jonathan Corbet <corbet@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/printk-formats.txt | 12 ++++++------
lib/vsprintf.c | 7 ++++---
2 files changed, 10 insertions(+), 9 deletions(-)
diff -puN Documentation/printk-formats.txt~lib-vsprintfc-update-documentation Documentation/printk-formats.txt
--- a/Documentation/printk-formats.txt~lib-vsprintfc-update-documentation
+++ a/Documentation/printk-formats.txt
@@ -23,6 +23,10 @@ Example:
Reminder: sizeof() result is of type size_t.
+The kernel's printf does not support %n. For obvious reasons, floating
+point formats (%e, %f, %g, %a) are also not recognized. Use of any
+unsupported specifier or length qualifier results in a WARN and early
+return from vsnprintf.
Raw pointer value SHOULD be printed with %p. The kernel supports
the following extended format specifiers for pointer types:
@@ -305,13 +309,9 @@ Command from struct task_struct
Passed by reference.
-Ignored argument:
+If you add other %p extensions, please extend lib/test_printf.c with
+one or more test cases, if at all feasible.
- %n %n
-
- The argument passed will be ignored. In other words, literal "%n" will
- be in the output and the argument will be considered for next format
- specifier.
Thank you for your cooperation and attention.
diff -puN lib/vsprintf.c~lib-vsprintfc-update-documentation lib/vsprintf.c
--- a/lib/vsprintf.c~lib-vsprintfc-update-documentation
+++ a/lib/vsprintf.c
@@ -1448,7 +1448,6 @@ int kptr_restrict __read_mostly;
* - 'Cn' For a clock, it prints the name (Common Clock Framework) or address
* (legacy clock framework) of the clock
* - 'Cr' For a clock, it prints the current rate of the clock
- * - 'n' For ignored argument
*
* ** Please update also Documentation/printk-formats.txt when making changes **
*
@@ -1814,8 +1813,10 @@ qualifier:
* @fmt: The format string to use
* @args: Arguments for the format string
*
- * This function follows C99 vsnprintf, but has some extensions:
- * %n is ignored
+ * This function generally follows C99 vsnprintf, but has some
+ * extensions and a few limitations:
+ *
+ * %n is unsupported
* %p* is handled by pointer()
*
* See pointer() or Documentation/printk-formats.txt for more
_
Patches currently in -mm which might be from linux@xxxxxxxxxxxxxxxxxx are
compilerh-add-support-for-function-attribute-assume_aligned.patch
slabh-sprinkle-__assume_aligned-attributes.patch
lib-dynamic_debugc-use-kstrdup_const.patch
lib-vsprintfc-handle-invalid-format-specifiers-more-robustly.patch
lib-vsprintfc-also-improve-sanity-check-in-bstr_printf.patch
lib-vsprintfc-remove-special-handling-in-pointer.patch
test_printf-test-printf-family-at-runtime.patch
lib-vsprintfc-update-documentation.patch
lib-introduce-kvasprintf_const.patch
kobject-use-kvasprintf_const-for-formatting-name.patch
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