[msan] strsignal interceptor

[vitalybuka]

undo removed line

[vitalybuka]

reorder code

[kstoimenov]

LGTM

compiler-rt/lib/msan/msan_interceptors.cpp

#define COMMON_SYSCALL_PRE_WRITE_RANGE(p, s) \
   } while (false)
 #define COMMON_SYSCALL_POST_READ_RANGE(p, s) \
   do {                                       \
   } while (false)
 #define COMMON_SYSCALL_POST_WRITE_RANGE(p, s) __msan_unpoison(p, s)
 #include "sanitizer_common/sanitizer_common_syscalls.inc"
 #include "sanitizer_common/sanitizer_syscalls_netbsd.inc"
 
+INTERCEPTOR(const char *, strsignal, int sig) {
+  void *ctx;
+  COMMON_INTERCEPTOR_ENTER(ctx, strsignal, sig);
+  const char *res = REAL(strsignal)(sig);
+  if (res)
+    __msan_unpoison(res, internal_strlen(res) + 1);
+  return res;
+}
+
 struct dlinfo {
   char *dli_fname;
   void *dli_fbase;
   char *dli_sname;
   void *dli_saddr;
 };
 
 INTERCEPTOR(int, dladdr, void *addr, dlinfo *info) {
#endif
   INTERCEPT_FUNCTION(getrlimit);
   MSAN_MAYBE_INTERCEPT___GETRLIMIT;
   MSAN_MAYBE_INTERCEPT_GETRLIMIT64;
   MSAN_MAYBE_INTERCEPT_PRLIMIT;
   MSAN_MAYBE_INTERCEPT_PRLIMIT64;
   INTERCEPT_FUNCTION(gethostname);
   MSAN_MAYBE_INTERCEPT_EPOLL_WAIT;
   MSAN_MAYBE_INTERCEPT_EPOLL_PWAIT;
+  INTERCEPT_FUNCTION(strsignal);
   INTERCEPT_FUNCTION(dladdr);
   INTERCEPT_FUNCTION(dlerror);
   INTERCEPT_FUNCTION(dl_iterate_phdr);
   INTERCEPT_FUNCTION(getrusage);
 #if defined(__mips__)
   INTERCEPT_FUNCTION_VER(pthread_create, "GLIBC_2.2");
 #else
   INTERCEPT_FUNCTION(pthread_create);

compiler-rt/test/msan/strsignal.cpp

+// RUN: %clangxx_msan -O0 %s -o %t && %run %t
+
+#include <assert.h>
+#include <signal.h>
+#include <stdio.h>
+#include <string.h>
+
+int main(void) {
+  const char *p = strsignal(SIGSEGV);
+  assert(p);
+  printf("%s %zu\n", p, strlen(p));
+  return 0;
+}