add formats for dentry/file pathnames (4b6ccca7) · Commits · 戴 / test

Documentation/printk-formats.txt

+9 −0

Original line number	Diff line number	Diff line
		@@ -168,6 +168,15 @@ UUID/GUID addresses:
		Where no additional specifiers are used the default little endian
		order with lower case hex characters will be printed.

		dentry names:
		%pd{,2,3,4}
		%pD{,2,3,4}

		For printing dentry name; if we race with d_move(), the name might be
		a mix of old and new ones, but it won't oops. %pd dentry is a safer
		equivalent of %s dentry->d_name.name we used to use, %pd<n> prints
		n last components. %pD does the same thing for struct file.

		struct va_format:

		%pV

lib/vsprintf.c

+82 −0

Original line number	Diff line number	Diff line
		@@ -26,6 +26,7 @@
		#include <linux/math64.h>
		#include <linux/uaccess.h>
		#include <linux/ioport.h>
		#include <linux/dcache.h>
		#include <net/addrconf.h>

		#include <asm/page.h> /* for PAGE_SIZE */
		@@ -532,6 +533,81 @@ char string(char buf, char end, const char s, struct printf_spec spec)
		return buf;
		}

		static void widen(char buf, char end, unsigned len, unsigned spaces)
		{
		size_t size;
		if (buf >= end) /* nowhere to put anything */
		return;
		size = end - buf;
		if (size <= spaces) {
		memset(buf, ' ', size);
		return;
		}
		if (len) {
		if (len > size - spaces)
		len = size - spaces;
		memmove(buf + spaces, buf, len);
		}
		memset(buf, ' ', spaces);
		}

		static noinline_for_stack
		char dentry_name(char buf, char end, const struct dentry d, struct printf_spec spec,
		const char *fmt)
		{
		const char array[4], s;
		const struct dentry *p;
		int depth;
		int i, n;

		switch (fmt[1]) {
		case '2': case '3': case '4':
		depth = fmt[1] - '0';
		break;
		default:
		depth = 1;
		}

		rcu_read_lock();
		for (i = 0; i < depth; i++, d = p) {
		p = ACCESS_ONCE(d->d_parent);
		array[i] = ACCESS_ONCE(d->d_name.name);
		if (p == d) {
		if (i)
		array[i] = "";
		i++;
		break;
		}
		}
		s = array[--i];
		for (n = 0; n != spec.precision; n++, buf++) {
		char c = *s++;
		if (!c) {
		if (!i)
		break;
		c = '/';
		s = array[--i];
		}
		if (buf < end)
		*buf = c;
		}
		rcu_read_unlock();
		if (n < spec.field_width) {
		/* we want to pad the sucker */
		unsigned spaces = spec.field_width - n;
		if (!(spec.flags & LEFT)) {
		widen(buf - n, end, n, spaces);
		return buf + spaces;
		}
		while (spaces--) {
		if (buf < end)
		*buf = ' ';
		++buf;
		}
		}
		return buf;
		}

		static noinline_for_stack
		char symbol_string(char buf, char end, void ptr,
		struct printf_spec spec, const char *fmt)
		@@ -1253,6 +1329,12 @@ char pointer(const char fmt, char buf, char end, void *ptr,
		spec.base = 16;
		return number(buf, end,
		(unsigned long long) ((phys_addr_t )ptr), spec);
		case 'd':
		return dentry_name(buf, end, ptr, spec, fmt);
		case 'D':
		return dentry_name(buf, end,
		((const struct file *)ptr)->f_path.dentry,
		spec, fmt);
		}
		spec.flags \|= SMALL;
		if (spec.field_width == -1) {

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