efi/printf: Refactor code to consolidate padding and output

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Consolidate the actual output of the formatted text into one place.

Fix a couple of edge cases:
1. If 0 is printed with a precision of 0, the printf specification says
   that nothing should be output, with one exception (2b).
2. The specification for octal alternate format (%#o) adds the leading
   zero not as a prefix as the 0x for hexadecimal is, but by increasing
   the precision if necessary to add the zero. This means that
   a. %#.2o turns 8 into "010", but 1 into "01" rather than "001".
   b. %#.o prints 0 as "0" rather than "", unlike the situation for
      decimal, hexadecimal and regular octal format, which all output an
      empty string.

Reduce the space allocated for printing a number to the maximum actually
required (22 bytes for a 64-bit number in octal), instead of the 66
bytes previously allocated.

Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Link: https://lore.kernel.org/r/20200518190716.751506-15-nivedita@alum.mit.edu
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

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Arvind Sankar 2020-05-18 15:07:06 -04:00 • committed by Ard Biesheuvel

parent fb031937a8

commit 6c4bcd8a46

1 changed files with 148 additions and 126 deletions

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drivers/firmware/efi/libstub/vsprintf.c

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