[asan, myriad] Support environment variables

[alekseyshl]

compiler-rt/lib/sanitizer_common/sanitizer_rtems.cc

252

What if name_len > env_len - 2?

256

name == "" and env="=x\0" will work and return "x", but maybe it's not that a bad thing.

[vitalybuka]

compiler-rt/lib/sanitizer_common/sanitizer_rtems.cc

39

why?

41

Howe about making it static and add __sanitizer::SetEnvForTest()

248

how this can happen?

254

for (uptr i = 0; i <= end; i += internal_strlen(env) + 1)

[waltl]

Sorry for the overly complicated initial patch. We've decided to get
setenv() to work in our test enviroment (using similar approach to the
initial patch here), so now the sanitizer run-time can just call that.

compiler-rt/lib/sanitizer_common/sanitizer_rtems.cc

 
 // There is no mmap on RTEMS.  Use memalign, etc.
 #define __mmap_alloc_aligned posix_memalign
 #define __mmap_free free
 #define __mmap_memset memset
 
 namespace __sanitizer {
 
 #include "sanitizer_syscall_generic.inc"
 
 void NORETURN internal__exit(int exitcode) {
   _exit(exitcode);
 }
 
 uptr internal_sched_yield() {
   return sched_yield();
 }
 
 uptr internal_getpid() {

 void ReleaseMemoryPagesToOS(uptr beg, uptr end) {}
 void DumpProcessMap() {}
 
 // There is no page protection so everything is "accessible."
 bool IsAccessibleMemoryRange(uptr beg, uptr size) {
   return true;
 }
 
-char **GetArgv() { return NULL; }
-const char *GetEnv(const char *name) { return NULL; }
+char **GetArgv() { return nullptr; }
+
+const char *GetEnv(const char *name) {
+  return getenv(name);
+}
 
 uptr ReadBinaryName(/*out*/char *buf, uptr buf_len) {
   internal_strncpy(buf, "StubBinaryName", buf_len);
   return internal_strlen(buf);
 }
 
 uptr ReadLongProcessName(/*out*/ char *buf, uptr buf_len) {
   internal_strncpy(buf, "StubProcessName", buf_len);
   return internal_strlen(buf);
 }
 
 bool IsPathSeparator(const char c) {
   return c == '/';
 }
 
 bool IsAbsolutePath(const char *path) {
   return path != nullptr && IsPathSeparator(path[0]);
 }