lib/vsprintf.c: "%#o",0 becomes '0' instead of '00'

number()'s behaviour is slighly changed: 0 becomes "0" instead of "00"
when using the flag SPECIAL and base 8.

Before:
Number\Format  %o    %#o  %x    %#x
            0     0   00    0   0x0
            1     1   01    1   0x1
           16    20  020   10  0x10

After:
Number\Format  %o    %#o  %x    %#x
            0     0    0    0   0x0
            1     1   01    1   0x1
           16    20  020   10  0x10

Signed-off-by: Pierre Carrier <pierre@spotify.com>
Acked-by: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 8 insertions, 4 deletions

diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index f5dfe0ca34f6..5391299c1e78 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -284,6 +284,7 @@ char *number(char *buf, char *end, unsigned long long num,
         char locase;
         int need_pfx = ((spec.flags & SPECIAL) && spec.base != 10);
         int i;
+        bool is_zero = num == 0LL;
 
         /* locase = 0 or 0x20. ORing digits or letters with 'locase'
          * produces same digits or (maybe lowercased) letters */
@@ -305,8 +306,9 @@ char *number(char *buf, char *end, unsigned long long num,
                 }
         }
         if (need_pfx) {
-                spec.field_width--;
                 if (spec.base == 16)
+                        spec.field_width -= 2;
+                else if (!is_zero)
                         spec.field_width--;
         }
 
@@ -353,9 +355,11 @@ char *number(char *buf, char *end, unsigned long long num,
         }
         /* "0x" / "0" prefix */
         if (need_pfx) {
-                if (buf < end)
-                        *buf = '0';
-                ++buf;
+                if (spec.base == 16 || !is_zero) {
+                        if (buf < end)
+                                *buf = '0';
+                        ++buf;
+                }
                 if (spec.base == 16) {
                         if (buf < end)
                                 *buf = ('X' | locase);