Export of internal Abseil changes

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1801102e11205861bc063e067e9fd4754b625c5a by Derek Mauro <dmauro@google.com>:

Internal change

PiperOrigin-RevId: 398562681

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485008445725d4013f60f4b2876f84b6b47932ec by Jorg Brown <jorg@google.com>:

Replace calls to std::isinf with comparison against max().

PiperOrigin-RevId: 398534255

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9b99d074d39ad677cf92f99549d22bb73f504f8f by Saleem Abdulrasool <abdulras@google.com>:

debugging: add support for non-glibc targets for debugging

This relaxes the ELF mem_image handling and subsequently enables the VDSO
support for non-glibc targets.  The primary need for the restriction was the
use of the `__GLIBC_PREREQ` macro.  If it is undefined, assume that the glibc
pre-requisite is unavailable.  This allows building the debugging_internal
target on musl targets.

PiperOrigin-RevId: 398499050

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3cc3630ef2226ae1981a944573f0f9c27a527ebf by Abseil Team <absl-team@google.com>:

Replace usages of `auto` with proper typedefs.

PiperOrigin-RevId: 398479551
GitOrigin-RevId: 1801102e11205861bc063e067e9fd4754b625c5a
Change-Id: Ib13e8612d1b263b9c1ae7f56a9f394b24c3add2e

1 files changed, 16 insertions, 3 deletions

diff --git a/absl/debugging/internal/vdso_support.cc b/absl/debugging/internal/vdso_support.cc
index 6be16d9..0dfe9ca 100644
--- a/absl/debugging/internal/vdso_support.cc
+++ b/absl/debugging/internal/vdso_support.cc
@@ -20,12 +20,25 @@
 
 #ifdef ABSL_HAVE_VDSO_SUPPORT     // defined in vdso_support.h
 
+#if !defined(__has_include)
+#define __has_include(header) 0
+#endif
+
 #include <errno.h>
 #include <fcntl.h>
+#if __has_include(<syscall.h>)
+#include <syscall.h>
+#elif __has_include(<sys/syscall.h>)
 #include <sys/syscall.h>
+#endif
 #include <unistd.h>
 
-#if __GLIBC_PREREQ(2, 16)  // GLIBC-2.16 implements getauxval.
+#if defined(__GLIBC__) && \
+    (__GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 16))
+#define ABSL_HAVE_GETAUXVAL
+#endif
+
+#ifdef ABSL_HAVE_GETAUXVAL
 #include <sys/auxv.h>
 #endif
 
@@ -65,7 +78,7 @@ VDSOSupport::VDSOSupport()
 // the operation should be idempotent.
 const void *VDSOSupport::Init() {
   const auto kInvalidBase = debugging_internal::ElfMemImage::kInvalidBase;
-#if __GLIBC_PREREQ(2, 16)
+#ifdef ABSL_HAVE_GETAUXVAL
   if (vdso_base_.load(std::memory_order_relaxed) == kInvalidBase) {
     errno = 0;
     const void *const sysinfo_ehdr =
@@ -74,7 +87,7 @@ const void *VDSOSupport::Init() {
       vdso_base_.store(sysinfo_ehdr, std::memory_order_relaxed);
     }
   }
-#endif  // __GLIBC_PREREQ(2, 16)
+#endif  // ABSL_HAVE_GETAUXVAL
   if (vdso_base_.load(std::memory_order_relaxed) == kInvalidBase) {
     int fd = open("/proc/self/auxv", O_RDONLY);
     if (fd == -1) {