[compiler-rt] [sanitizer_common] Implement address sanitizer on AIX: process memory mapping (PR #138537)

[Hubert Tong via llvm-commits]

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@@ -0,0 +1,132 @@
+//===-- sanitizer_procmaps_aix.cpp ----------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// Information about the process mappings (AIX-specific parts).
+//===----------------------------------------------------------------------===//
+
+#include "sanitizer_platform.h"
+
+#if SANITIZER_AIX
+#  include <assert.h>
+#  include <stdio.h>
+#  include <stdlib.h>
+#  include <sys/procfs.h>
+
+#  include "sanitizer_common.h"
+#  include "sanitizer_file.h"
+#  include "sanitizer_procmaps.h"
+
+namespace __sanitizer {
+
+static int qsort_comp(const void *va, const void *vb) {
+  const prmap_t *a = (const prmap_t *)va;
+  const prmap_t *b = (const prmap_t *)vb;
+
+  if (a->pr_vaddr < b->pr_vaddr)
+    return -1;
+
+  if (a->pr_vaddr > b->pr_vaddr)
+    return 1;
+
+  return 0;
+}
+
+static prmap_t *SortProcMapEntries(char *buffer) {
+  prmap_t *begin = (prmap_t *)buffer;
+  prmap_t *mapIter = begin;
+  // The AIX procmap utility detects the end of the array of `prmap`s by finding
+  // an entry where pr_size and pr_vaddr are both zero.
+  while (mapIter->pr_size != 0 || mapIter->pr_vaddr != 0) ++mapIter;
+  prmap_t *end = mapIter;
+
+  size_t count = end - begin;
+  size_t elemSize = sizeof(prmap_t);
+  qsort(begin, count, elemSize, qsort_comp);
+
+  return end;
+}
+
+void ReadProcMaps(ProcSelfMapsBuff *proc_maps) {
+  uptr pid = internal_getpid();
+  constexpr unsigned BUFFER_SIZE = 128;
+  char filenameBuf[BUFFER_SIZE] = {};
+  internal_snprintf(filenameBuf, BUFFER_SIZE, "/proc/%d/map", pid);
+  if (!ReadFileToBuffer(filenameBuf, &proc_maps->data, &proc_maps->mmaped_size,
+                        &proc_maps->len)) {
+    proc_maps->data = nullptr;
+    proc_maps->mmaped_size = 0;
+    proc_maps->len = 0;
+    proc_maps->mapEnd = nullptr;
+    return;
+  }
+
+  proc_maps->mapEnd = SortProcMapEntries(proc_maps->data);
+}
+
+bool MemoryMappingLayout::Next(MemoryMappedSegment *segment) {
+  if (Error())
+    return false;  // simulate empty maps
+
+  const prmap_t *mapIter = (const prmap_t *)data_.current;
+
+  if (mapIter >= data_.proc_self_maps.mapEnd)
+    return false;
+
+  // Skip the kernel segment.
+  if ((mapIter->pr_mflags & MA_TYPE_MASK) == MA_KERNTEXT)
+    ++mapIter;
+
+  if (mapIter >= data_.proc_self_maps.mapEnd)
+    return false;
+
+  segment->start = (uptr)mapIter->pr_vaddr;
+  segment->end = segment->start + mapIter->pr_size;
+
+  segment->protection = 0;
+  uint32_t flags = mapIter->pr_mflags;
+  if (flags & MA_READ)
+    segment->protection |= kProtectionRead;
+  if (flags & MA_WRITE)
+    segment->protection |= kProtectionWrite;
+  if (flags & MA_EXEC)
+    segment->protection |= kProtectionExecute;
+
+  uint32_t type = mapIter->pr_mflags & MA_TYPE_MASK;
+  if (type == MA_SLIBTEXT || type == MA_PLIBDATA)
+    segment->protection |= kProtectionShared;
+
+  if (segment->filename && mapIter->pr_pathoff) {
+    uptr len;
+    constexpr unsigned BUFFER_SIZE = 128;
+    char objPath[BUFFER_SIZE] = {};
----------------
hubert-reinterpretcast wrote:

No need for an extra copy.
```suggestion
```

https://github.com/llvm/llvm-project/pull/138537