[sanitizer] Fix build for new GLIBC msghdr/cmsghdr definition

[zatrazz]

Summary

GLIBC now follows POSIX [1] for both msghdr and cmsghdr definitions,
which means that msg_iovlen, msg_controllen, and cmsg_len are no
longer size_t but sockelen_t for 64-bits architectures. The final struct
size does not change, since paddings were added.

This patch fixes the build issue against GLIBC 2.24 socket.h header by
using the same definition for internal sanitizer_msghdr and
sanitizer_cmsghdr.

[1] http://pubs.opengroup.org/onlinepubs/9699919799/

[eugenis]

lib/sanitizer_common/sanitizer_platform_limits_posix.cc

1023 ↗

(On Diff #59760)

You are disabling the test on older glibc. Why? It used to work just fine.

lib/sanitizer_common/sanitizer_platform_limits_posix.h

465

This is too confusing. Please provide the entire msghdr & cmsghdr definitions for the three cases (be, le, pre-2.24) w/o conditional macros inside.

[zatrazz]

lib/sanitizer_common/sanitizer_platform_limits_posix.cc

1023 ↗

(On Diff #59760)

That's not its intention, __GLIBC_PREREQ will only set to 0 if is not yet defined (mainly when it is built using interposed features.h that do not define it).

lib/sanitizer_common/sanitizer_platform_limits_posix.h

465

Right, I will change it.

[eugenis]

lib/sanitizer_common/sanitizer_platform_limits_posix.cc

1023 ↗

(On Diff #59760)

Could you elaborate? What is this "interposed features.h" configuration, and why does it fail this test? This indicates that the struct definition does not match the system, which means certain interceptors are broken. Can it be fixed?

[zatrazz]

lib/sanitizer_common/sanitizer_platform_limits_posix.cc

1023 ↗

(On Diff #59760)

And now I realize my mistake here, I will fix it.

[zatrazz]

lib/sanitizer_common/sanitizer_platform_limits_posix.cc

1023 ↗

(On Diff #59760)

Sorry if I was not clear enough, this part is trying to 'fix' a build for gcc libsanitizer build (where it does not define __GLIBC_PREREQ due the interposed features.h header). Now I realize this piece is should be in llvm compiler-rt and I will remove it.

[zatrazz]

Update patch based on previous comments.

[eugenis]

LGTM

lib/sanitizer_common/sanitizer_platform_limits_posix.h

475

&& defined(_LP64

[zatrazz]

lib/sanitizer_common/sanitizer_platform_limits_posix.h

475

Right, I will fix it on commit.

lib/sanitizer_common/sanitizer_platform_limits_posix.h

struct __sanitizer_msghdr {
     int msg_flags;
   };
   struct __sanitizer_cmsghdr {
     unsigned cmsg_len;
     int cmsg_level;
     int cmsg_type;
   };
 #else
+# ifndef __GLIBC_PREREQ
+# define __GLIBC_PREREQ(x, y) 0
+# endif
+// GLIBC 2.24 follows msghdr and cmsghdr POSIX definition for internal
+// member size and adds padding where required.
+# if __GLIBC_PREREQ(2, 24) && defined(_LP64)
+#  if __BYTE_ORDER == __BIG_ENDIAN
+  struct __sanitizer_msghdr {
+    void *msg_name;
+    unsigned msg_namelen;
+    struct __sanitizer_iovec *msg_iov;
+    int __padding1;
+    unsigned msg_iovlen;
+    void *msg_control;
+    int __padding2;
+    unsigned msg_controllen;
+    int msg_flags;
+  };
+  struct __sanitizer_cmsghdr {
+    uptr cmsg_len;
+    int cmsg_level;
+    int cmsg_type;
+  };
+#  else
+  struct __sanitizer_msghdr {
+    void *msg_name;
+    unsigned msg_namelen;
+    struct __sanitizer_iovec *msg_iov;
+    int msg_iovlen;
+    int __padding1;
+    void *msg_control;
+    int msg_controllen;
+    int __padding2;
+    int msg_flags;
+  };
+  struct __sanitizer_cmsghdr {
+    unsigned cmsg_len;
+    int __padding1;
+    int cmsg_level;
+    int cmsg_type;
+  };
+#  endif // __BYTE_ORDER == __BIG_ENDIAN
+# else
   struct __sanitizer_msghdr {
     void *msg_name;
     unsigned msg_namelen;
     struct __sanitizer_iovec *msg_iov;
     uptr msg_iovlen;
     void *msg_control;
     uptr msg_controllen;
     int msg_flags;
   };
   struct __sanitizer_cmsghdr {
     uptr cmsg_len;
     int cmsg_level;
     int cmsg_type;
   };
+# endif // __GLIBC_PREREQ (2, 24) && __WORDSIZE == 64
 #endif
 
 #if SANITIZER_MAC
   struct __sanitizer_dirent {
     unsigned long long d_ino;
     unsigned long long d_seekoff;
     unsigned short d_reclen;
     // more fields that we don't care about