vsprintf: correctly handle width when '#' flag used in %#p format (725fe002) · Commits · 戴 / test

The '%p' output of the kernel's vsprintf() uses spec.field_width to determine how many digits to output based on 2 * sizeof(void*) so that all digits of a pointer are shown. ie. a pointer will be output as "001A2B3C" instead of "1A2B3C". However, if the '#' flag is used in the format (%#p), then the code doesn't take into account the width of the '0x' prefix and will end up outputing "0x1A2B3C" instead of "0x001A2B3C". This patch reworks the "pointer()" format hook to include 2 characters for the '0x' prefix if the '#' flag is included. [akpm@linux-foundation.org: checkpatch fixes] Signed-off-by:

Grant Likely <grant.likely@secretlab.ca> Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

lib/vsprintf.c

+5 −3

Original line number	Diff line number	Diff line
		@@ -870,13 +870,15 @@ static noinline_for_stack
		char pointer(const char fmt, char buf, char end, void *ptr,
		struct printf_spec spec)
		{
		int default_width = 2 * sizeof(void *) + (spec.flags & SPECIAL ? 2 : 0);

		if (!ptr && *fmt != 'K') {
		/*
		* Print (null) with the same width as a pointer so it makes
		* tabular output look nice.
		*/
		if (spec.field_width == -1)
		spec.field_width = 2 * sizeof(void *);
		spec.field_width = default_width;
		return string(buf, end, "(null)", spec);
		}

		@@ -931,7 +933,7 @@ char pointer(const char fmt, char buf, char end, void *ptr,
		*/
		if (in_irq() \|\| in_serving_softirq() \|\| in_nmi()) {
		if (spec.field_width == -1)
		spec.field_width = 2 * sizeof(void *);
		spec.field_width = default_width;
		return string(buf, end, "pK-error", spec);
		}
		if (!((kptr_restrict == 0) \|\|
		@@ -948,7 +950,7 @@ char pointer(const char fmt, char buf, char end, void *ptr,
		}
		spec.flags \|= SMALL;
		if (spec.field_width == -1) {
		spec.field_width = 2 * sizeof(void *);
		spec.field_width = default_width;
		spec.flags \|= ZEROPAD;
		}
		spec.base = 16;

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