Rework oversizing of CharBufs Don't call Memory_oversize, but oversize by custom amount of 25%.
Check for integer overflow. This should only matter on exotic platforms, but it doesn't cost much. Project: http://git-wip-us.apache.org/repos/asf/lucy-clownfish/repo Commit: http://git-wip-us.apache.org/repos/asf/lucy-clownfish/commit/6e1d5fd1 Tree: http://git-wip-us.apache.org/repos/asf/lucy-clownfish/tree/6e1d5fd1 Diff: http://git-wip-us.apache.org/repos/asf/lucy-clownfish/diff/6e1d5fd1 Branch: refs/heads/master Commit: 6e1d5fd1a687eae61dc0609806c5269ba1e045fb Parents: 641250d Author: Nick Wellnhofer <wellnho...@aevum.de> Authored: Thu Nov 12 15:35:33 2015 +0100 Committer: Nick Wellnhofer <wellnho...@aevum.de> Committed: Thu Nov 12 16:09:44 2015 +0100 ---------------------------------------------------------------------- runtime/core/Clownfish/CharBuf.c | 69 +++++++++++++++++++++++++++++------ 1 file changed, 57 insertions(+), 12 deletions(-) ---------------------------------------------------------------------- http://git-wip-us.apache.org/repos/asf/lucy-clownfish/blob/6e1d5fd1/runtime/core/Clownfish/CharBuf.c ---------------------------------------------------------------------- diff --git a/runtime/core/Clownfish/CharBuf.c b/runtime/core/Clownfish/CharBuf.c index 0f1b7c3..fa7a2b3 100644 --- a/runtime/core/Clownfish/CharBuf.c +++ b/runtime/core/Clownfish/CharBuf.c @@ -33,6 +33,22 @@ #include "Clownfish/Util/StringHelper.h" #include "Clownfish/Class.h" +// Ensure that the CharBuf's capacity is at least (size + extra). +// If the buffer must be grown, oversize the allocation. +static CFISH_INLINE void +SI_add_grow_and_oversize(CharBuf *self, size_t size, size_t extra); + +// Compilers tend to inline this function although this is the unlikely +// slow path. If we ever add cross-platform support for the noinline +// attribute, it should be marked as such to reduce code size. +static void +S_grow_and_oversize(CharBuf *self, size_t min_size); + +// Not inlining the THROW macro reduces code size and complexity of +// SI_add_grow_and_oversize. +static void +S_overflow_error(); + // Helper function for throwing invalid UTF-8 error. Since THROW uses // a String internally, calling THROW with invalid UTF-8 would create an // infinite loop -- so we fwrite some of the bogus text to stderr and @@ -261,11 +277,9 @@ CB_Yield_String_IMP(CharBuf *self) { void CB_Cat_Char_IMP(CharBuf *self, int32_t code_point) { const size_t MAX_UTF8_BYTES = 4; - if (self->size + MAX_UTF8_BYTES > self->cap) { - CB_Grow(self, Memory_oversize(self->size + MAX_UTF8_BYTES, - sizeof(char))); - } - char *end = self->ptr + self->size; + size_t old_size = self->size; + SI_add_grow_and_oversize(self, old_size, MAX_UTF8_BYTES); + char *end = self->ptr + old_size; size_t count = StrHelp_encode_utf8_char(code_point, (uint8_t*)end); self->size += count; } @@ -283,13 +297,10 @@ CB_Clone_IMP(CharBuf *self) { static CFISH_INLINE void SI_cat_utf8(CharBuf *self, const char* ptr, size_t size) { - const size_t new_size = self->size + size; - if (new_size > self->cap) { - size_t amount = Memory_oversize(new_size, sizeof(char)); - CB_Grow(self, amount); - } - memcpy(self->ptr + self->size, ptr, size); - self->size = new_size; + size_t old_size = self->size; + SI_add_grow_and_oversize(self, old_size, size); + memcpy(self->ptr + old_size, ptr, size); + self->size = old_size + size; } void @@ -320,4 +331,38 @@ CB_Get_Size_IMP(CharBuf *self) { return self->size; } +static CFISH_INLINE void +SI_add_grow_and_oversize(CharBuf *self, size_t size, size_t extra) { + size_t min_size = size + extra; + if (min_size < size) { + S_overflow_error(); + return; + } + + if (min_size > self->cap) { + S_grow_and_oversize(self, min_size); + } +} + +static void +S_grow_and_oversize(CharBuf *self, size_t min_size) { + // Oversize by 25%, but at least eight bytes. + size_t extra = min_size / 4; + // Round up to next multiple of eight. + extra = (extra + 7) & ~7; + + size_t capacity = min_size + extra; + if (capacity < min_size) { + capacity = SIZE_MAX; + } + + self->cap = capacity; + self->ptr = (char*)REALLOCATE(self->ptr, capacity); +} + +static void +S_overflow_error() { + THROW(ERR, "CharBuf buffer overflow"); +} +
