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[libc] Make the bump pointer explicitly return null on buffer oveerrun

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We use a simple bump ptr in the `libc` tests. If we run out of data we
can currently return other static memory and have weird failure cases.
We should fail more explicitly here by returning a null pointer instead.

Reviewed By: sivachandra

Differential Revision: https://reviews.llvm.org/D150529
This commit is contained in:
Joseph Huber 2023-04-24 14:35:38 -05:00
parent 1a42f79558
commit 9417d9fc38
2 changed files with 6 additions and 4 deletions
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5
libc/test/IntegrationTest/test.cpp
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@ -57,7 +57,8 @@ int atexit(void (*func)(void)) { return __llvm_libc::atexit(func); }
// which just hands out continuous blocks from a statically allocated chunk of // which just hands out continuous blocks from a statically allocated chunk of
// memory. // memory.
static uint8_t memory[16384]; static constexpr uint64_t MEMORY_SIZE = 16384;
static uint8_t memory[MEMORY_SIZE];
static uint8_t *ptr = memory; static uint8_t *ptr = memory;
extern "C" { extern "C" {
@ -65,7 +66,7 @@ extern "C" {
void *malloc(size_t s) { void *malloc(size_t s) {
void *mem = ptr; void *mem = ptr;
ptr += s; ptr += s;
return mem; return static_cast<uint64_t>(ptr - memory) >= MEMORY_SIZE ? nullptr : mem;
} }
void free(void *) {} void free(void *) {}

5
libc/test/UnitTest/HermeticTestUtils.cpp
View File

@ -29,7 +29,8 @@ namespace {
// requires. Hence, as a work around for this problem, we use a simple allocator // requires. Hence, as a work around for this problem, we use a simple allocator
// which just hands out continuous blocks from a statically allocated chunk of // which just hands out continuous blocks from a statically allocated chunk of
// memory. // memory.
static uint8_t memory[16384]; static constexpr uint64_t MEMORY_SIZE = 16384;
static uint8_t memory[MEMORY_SIZE];
static uint8_t *ptr = memory; static uint8_t *ptr = memory;
} // anonymous namespace } // anonymous namespace
@ -68,7 +69,7 @@ void *malloc(size_t s) {
s = ((s + ALIGNMENT - 1) / ALIGNMENT) * ALIGNMENT; s = ((s + ALIGNMENT - 1) / ALIGNMENT) * ALIGNMENT;
void *mem = ptr; void *mem = ptr;
ptr += s; ptr += s;
return mem; return static_cast<uint64_t>(ptr - memory) >= MEMORY_SIZE ? nullptr : mem;
} }
void free(void *) {} void free(void *) {}