Add glibc back compat code

To ensure that the binaries compiled by gitian run across many linux
distributions, enforce 2.17 as the minimum libc version supported.

2 files changed, 102 insertions, 0 deletions

diff --git a/src/common/CMakeLists.txt b/src/common/CMakeLists.txt
index aed9bfee7..1aaab555d 100644
--- a/src/common/CMakeLists.txt
+++ b/src/common/CMakeLists.txt
@@ -49,6 +49,10 @@ if (STACK_TRACE)
   list(APPEND common_sources stack_trace.cpp)
 endif()
 
+if (BACKCOMPAT)
+  list(APPEND common_sources compat/glibc_compat.cpp)
+endif()
+
 set(common_headers)
 
 set(common_private_headers
diff --git a/src/common/compat/glibc_compat.cpp b/src/common/compat/glibc_compat.cpp
new file mode 100644
index 000000000..bf567987d
--- /dev/null
+++ b/src/common/compat/glibc_compat.cpp
@@ -0,0 +1,98 @@
+#include <cstddef>
+#include <cstdint>
+#include <strings.h>
+#include <string.h>
+#include <glob.h>
+#include <unistd.h>
+#include <fnmatch.h>
+
+#if defined(HAVE_SYS_SELECT_H)
+#include <sys/select.h>
+#endif
+
+// Prior to GLIBC_2.14, memcpy was aliased to memmove.
+extern "C" void* memmove(void* a, const void* b, size_t c);
+//extern "C" void* memset(void* a, int b, long unsigned int c);
+extern "C" void* memcpy(void* a, const void* b, size_t c)
+{
+    return memmove(a, b, c);
+}
+
+extern "C" void __chk_fail(void) __attribute__((__noreturn__));
+
+#if defined(__i386__) || defined(__arm__)
+
+extern "C" int64_t __udivmoddi4(uint64_t u, uint64_t v, uint64_t* rp);
+
+extern "C" int64_t __wrap___divmoddi4(int64_t u, int64_t v, int64_t* rp)
+{
+    int32_t c1 = 0, c2 = 0;
+    int64_t uu = u, vv = v;
+    int64_t w;
+    int64_t r;
+
+    if (uu < 0) {
+        c1 = ~c1, c2 = ~c2, uu = -uu;
+    }
+    if (vv < 0) {
+        c1 = ~c1, vv = -vv;
+    }
+
+    w = __udivmoddi4(uu, vv, (uint64_t*)&r);
+    if (c1)
+        w = -w;
+    if (c2)
+        r = -r;
+
+    *rp = r;
+    return w;
+}
+#endif
+
+/* glibc-internal users use __explicit_bzero_chk, and explicit_bzero
+   redirects to that.  */
+#undef explicit_bzero
+/* Set LEN bytes of S to 0.  The compiler will not delete a call to
+   this function, even if S is dead after the call.  */
+void
+explicit_bzero (void *s, size_t len)
+{
+  memset (s, '\0', len);
+  /* Compiler barrier.  */
+  asm volatile ("" ::: "memory");
+}
+
+// Redefine explicit_bzero_chk
+void
+__explicit_bzero_chk (void *dst, size_t len, size_t dstlen)
+{
+  /* Inline __memset_chk to avoid a PLT reference to __memset_chk.  */
+  if (__glibc_unlikely (dstlen < len))
+    __chk_fail ();
+  memset (dst, '\0', len);
+  /* Compiler barrier.  */
+  asm volatile ("" ::: "memory");
+}
+/* libc-internal references use the hidden
+   __explicit_bzero_chk_internal symbol.  This is necessary if
+   __explicit_bzero_chk is implemented as an IFUNC because some
+   targets do not support hidden references to IFUNC symbols.  */
+#define strong_alias (__explicit_bzero_chk, __explicit_bzero_chk_internal)
+
+#undef glob
+extern "C" int glob_old(const char * pattern, int flags, int (*errfunc) (const char *epath, int eerrno), glob_t *pglob);
+#ifdef __i386__
+__asm__(".symver glob_old,glob@GLIBC_2.1");
+#elif defined(__amd64__)
+__asm__(".symver glob_old,glob@GLIBC_2.2.5");
+#elif defined(__arm__)
+__asm(".symver glob_old,glob@GLIBC_2.4");
+#elif defined(__aarch64__)
+__asm__(".symver glob_old,glob@GLIBC_2.17");
+#endif
+
+extern "C" int __wrap_glob(const char * pattern, int flags, int (*errfunc) (const char *epath, int eerrno), glob_t *pglob)
+{
+    return glob_old(pattern, flags, errfunc, pglob);
+}
+