proxmox-mirrors/libgit2
1
0
Fork 0
mirror of https://git.proxmox.com/git/libgit2 synced 2025-05-07 12:57:05 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity

integer overflow: use compiler intrinsics if supported

Browse Source 
gcc and clang support __builtin_add_overflow, use it whenever
possible, falling back to our naive routines.
This commit is contained in:
Edward Thomson 2015-02-12 17:36:48 -05:00
parent 8aab36a301
commit 16942c6fda
2 changed files with 20 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
src/common.h
View File

@ -17,6 +17,11 @@
# define GIT_INLINE(type) static inline type
#endif
/** Support for gcc/clang __has_builtin intrinsic */
#ifndef __has_builtin
# define __has_builtin(x) 0
#endif
#include <assert.h>
#include <errno.h>
#include <limits.h>

15
src/integer.h
View File

@ -54,6 +54,19 @@ GIT_INLINE(bool) git__add_uint64_overflow(uint64_t *out, uint64_t one, uint64_t
return false;
}
/* Use clang/gcc compiler intrinsics whenever possible */
#if (SIZE_MAX == UINT_MAX) && __has_builtin(__builtin_uadd_overflow)
# define git__add_sizet_overflow(out, one, two) \
__builtin_uadd_overflow(one, two, out)
# define git__multiply_sizet_overflow(out, one, two)
__builtin_umul_overflow(one, two, out)
#elif (SIZE_MAX == ULONG_MAX) && __has_builtin(__builtin_uaddl_overflow)
# define git__add_sizet_overflow(out, one, two) \
__builtin_uaddl_overflow(one, two, out)
# define git__multiply_sizet_overflow(out, one, two) \
__builtin_umull_overflow(one, two, out)
#else
/**
* Sets `one + two` into `out`, unless the arithmetic would overflow.
* @return true if the result fits in a `size_t`, false on overflow.
@ -78,4 +91,6 @@ GIT_INLINE(bool) git__multiply_sizet_overflow(size_t *out, size_t one, size_t tw
return false;
}
#endif
#endif /* INCLUDE_integer_h__ */