Commit Graph

2 Commits

Author SHA1 Message Date
Dandan Bi dc9b2a5740 MdePkg/BaseSafeIntLib: Fix VS2015 IA32 NOOPT build failure
v2: Add [LibraryClasses] section in INF file and refine coding style.

There are VS2015 NOOPT IA32 build failure like below in BaseSafeIntLib.
XXX.lib(XXX.obj): error LNK2001: unresolved external symbol __allmul
XXX.lib(XXX.obj): error LNK2001: unresolved external symbol __allshl
XXX.lib(XXX.obj): error LNK2001: unresolved external symbol __aullshr

This patch replaces direct shift/multiplication of 64-bit integer
with related function call to fix these failure.

Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Liming Gao <liming.gao@intel.com>
Cc: Michael Kinney <michael.d.kinney@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Dandan Bi <dandan.bi@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
2018-02-28 11:44:14 +08:00
Sean Brogan d7a09cb86a MdePkg/BaseSafeIntLib: Add SafeIntLib class and instance
https://bugzilla.tianocore.org/show_bug.cgi?id=798

SafeIntLib provides helper functions to prevent integer overflow
during type conversion, addition, subtraction, and multiplication.

Conversion Functions
====================
* Converting from a signed type to an unsigned type of the same
  size, or vice-versa.
* Converting to a smaller type that could possibly overflow.
* Converting from a signed type to a larger unsigned type.

Unsigned Addition, Subtraction, Multiplication
===============================================
* Unsigned integer math functions protect from overflow and
  underflow (in case of subtraction).

Signed Addition, Subtraction, Multiplication
============================================
* Strongly consider using unsigned numbers.
* Signed numbers are often used where unsigned numbers should
  be used. For example file sizes and array indices should always
  be unsigned. Subtracting a larger positive signed number from a
  smaller positive signed number with SafeInt32Sub() will succeed,
  producing a negative number, that then must not be used as an
  array index (but can occasionally be used as a pointer index.)
  Similarly for adding a larger magnitude negative number to a
  smaller magnitude positive number.
* SafeIntLib does not protect you from such errors. It tells you
  if your integer operations overflowed, not if you are doing the
  right thing with your non-overflowed integers.
* Likewise you can overflow a buffer with a non-overflowed
  unsigned index.

Based on content from the following branch/commits:
https://github.com/Microsoft/MS_UEFI/tree/share/MsCapsuleSupport
21ef3a321c
ca516b1a61
33bab4031a

Cc: Sean Brogan <sean.brogan@microsoft.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Michael D Kinney <michael.d.kinney@intel.com>
Reviewed-by: Sean Brogan <sean.brogan@microsoft.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>
2018-01-25 09:42:20 -08:00