Export of internal Abseil changes

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9beb68204986a015c9cb065b9fae4f9a8879a788 by Abseil Team <absl-team@google.com>:

Move Base64EscapeInternal and CalculateBase64EscapedLenInternal to an internal header.

PiperOrigin-RevId: 288917378

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90acfbe03b3f9f6de3ffa49c39343dfaa2c5d38c by Greg Falcon <gfalcon@google.com>:

Update macos CI script to support the ALTERNATE_OPTIONS environment variable.

PiperOrigin-RevId: 288913564

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f1572e870678cdcda6b48cb39780d1ad984e4c1b by Derek Mauro <dmauro@google.com>:

Makes absl::NullSafeStringView constexpr
Fixes https://github.com/abseil/abseil-cpp/issues/583

PiperOrigin-RevId: 288906940

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d28a8471e32c10caa64bfffe6d6d4d0a8d144013 by Abseil Team <absl-team@google.com>:

absl::GetFlag is lock free for small trivially copyable types.

PiperOrigin-RevId: 288768172

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2643b8ed1a1dc836b38ab9e46538a1af129ffd67 by Gennadiy Rozental <rogeeff@google.com>:

Eliminate call to callback from flag initialization.

We do not need to have this invocation inside FlagImpl::Init since SetCallback performs invocation anyways. Calling InitCallback from inside of Init complicates separation of value initialization from data guard initialization, which is about to happen.

PiperOrigin-RevId: 288732526

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22caa880b7a4cb6da34e16a2e064a473c99e880b by Abseil Team <absl-team@google.com>:

Fix the documentation on how to create a null string_view.

PiperOrigin-RevId: 288727968

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10727c5cadc561837141176f4c9b9717cec9233a by Greg Falcon <gfalcon@google.com>:

Change CI scripts for gcc to use the ALTERNATE_OPTIONS file as well.

PiperOrigin-RevId: 288718855

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5d1e2dd6c7fb12af8aa4337a0f61872f5f0c5992 by Greg Falcon <gfalcon@google.com>:

Add an option for using inline namespaces in Abseil.

PiperOrigin-RevId: 288614491
GitOrigin-RevId: 9beb68204986a015c9cb065b9fae4f9a8879a788
Change-Id: If9acd46301e3df8cb231b4c16f7ed651bf4fb3c3

1 files changed, 13 insertions, 175 deletions

diff --git a/absl/strings/escaping.cc b/absl/strings/escaping.cc
index d2fcd9c111bc..7adc1b657168 100644
--- a/absl/strings/escaping.cc
+++ b/absl/strings/escaping.cc
@@ -26,6 +26,7 @@
 #include "absl/base/internal/raw_logging.h"
 #include "absl/base/internal/unaligned_access.h"
 #include "absl/strings/internal/char_map.h"
+#include "absl/strings/internal/escaping.h"
 #include "absl/strings/internal/resize_uninitialized.h"
 #include "absl/strings/internal/utf8.h"
 #include "absl/strings/str_cat.h"
@@ -764,177 +765,10 @@ constexpr signed char kUnWebSafeBase64[] = {
 };
 /* clang-format on */
 
-size_t CalculateBase64EscapedLenInternal(size_t input_len, bool do_padding) {
-  // Base64 encodes three bytes of input at a time. If the input is not
-  // divisible by three, we pad as appropriate.
-  //
-  // (from https://tools.ietf.org/html/rfc3548)
-  // Special processing is performed if fewer than 24 bits are available
-  // at the end of the data being encoded.  A full encoding quantum is
-  // always completed at the end of a quantity.  When fewer than 24 input
-  // bits are available in an input group, zero bits are added (on the
-  // right) to form an integral number of 6-bit groups.  Padding at the
-  // end of the data is performed using the '=' character.  Since all base
-  // 64 input is an integral number of octets, only the following cases
-  // can arise:
-
-  // Base64 encodes each three bytes of input into four bytes of output.
-  size_t len = (input_len / 3) * 4;
-
-  if (input_len % 3 == 0) {
-    // (from https://tools.ietf.org/html/rfc3548)
-    // (1) the final quantum of encoding input is an integral multiple of 24
-    // bits; here, the final unit of encoded output will be an integral
-    // multiple of 4 characters with no "=" padding,
-  } else if (input_len % 3 == 1) {
-    // (from https://tools.ietf.org/html/rfc3548)
-    // (2) the final quantum of encoding input is exactly 8 bits; here, the
-    // final unit of encoded output will be two characters followed by two
-    // "=" padding characters, or
-    len += 2;
-    if (do_padding) {
-      len += 2;
-    }
-  } else {  // (input_len % 3 == 2)
-    // (from https://tools.ietf.org/html/rfc3548)
-    // (3) the final quantum of encoding input is exactly 16 bits; here, the
-    // final unit of encoded output will be three characters followed by one
-    // "=" padding character.
-    len += 3;
-    if (do_padding) {
-      len += 1;
-    }
-  }
-
-  assert(len >= input_len);  // make sure we didn't overflow
-  return len;
-}
-
-size_t Base64EscapeInternal(const unsigned char* src, size_t szsrc, char* dest,
-                            size_t szdest, const char* base64,
-                            bool do_padding) {
-  static const char kPad64 = '=';
-
-  if (szsrc * 4 > szdest * 3) return 0;
-
-  char* cur_dest = dest;
-  const unsigned char* cur_src = src;
-
-  char* const limit_dest = dest + szdest;
-  const unsigned char* const limit_src = src + szsrc;
-
-  // Three bytes of data encodes to four characters of cyphertext.
-  // So we can pump through three-byte chunks atomically.
-  if (szsrc >= 3) {  // "limit_src - 3" is UB if szsrc < 3.
-    while (cur_src < limit_src - 3) {  // While we have >= 32 bits.
-      uint32_t in = absl::big_endian::Load32(cur_src) >> 8;
-
-      cur_dest[0] = base64[in >> 18];
-      in &= 0x3FFFF;
-      cur_dest[1] = base64[in >> 12];
-      in &= 0xFFF;
-      cur_dest[2] = base64[in >> 6];
-      in &= 0x3F;
-      cur_dest[3] = base64[in];
-
-      cur_dest += 4;
-      cur_src += 3;
-    }
-  }
-  // To save time, we didn't update szdest or szsrc in the loop.  So do it now.
-  szdest = limit_dest - cur_dest;
-  szsrc = limit_src - cur_src;
-
-  /* now deal with the tail (<=3 bytes) */
-  switch (szsrc) {
-    case 0:
-      // Nothing left; nothing more to do.
-      break;
-    case 1: {
-      // One byte left: this encodes to two characters, and (optionally)
-      // two pad characters to round out the four-character cypherblock.
-      if (szdest < 2) return 0;
-      uint32_t in = cur_src[0];
-      cur_dest[0] = base64[in >> 2];
-      in &= 0x3;
-      cur_dest[1] = base64[in << 4];
-      cur_dest += 2;
-      szdest -= 2;
-      if (do_padding) {
-        if (szdest < 2) return 0;
-        cur_dest[0] = kPad64;
-        cur_dest[1] = kPad64;
-        cur_dest += 2;
-        szdest -= 2;
-      }
-      break;
-    }
-    case 2: {
-      // Two bytes left: this encodes to three characters, and (optionally)
-      // one pad character to round out the four-character cypherblock.
-      if (szdest < 3) return 0;
-      uint32_t in = absl::big_endian::Load16(cur_src);
-      cur_dest[0] = base64[in >> 10];
-      in &= 0x3FF;
-      cur_dest[1] = base64[in >> 4];
-      in &= 0x00F;
-      cur_dest[2] = base64[in << 2];
-      cur_dest += 3;
-      szdest -= 3;
-      if (do_padding) {
-        if (szdest < 1) return 0;
-        cur_dest[0] = kPad64;
-        cur_dest += 1;
-        szdest -= 1;
-      }
-      break;
-    }
-    case 3: {
-      // Three bytes left: same as in the big loop above.  We can't do this in
-      // the loop because the loop above always reads 4 bytes, and the fourth
-      // byte is past the end of the input.
-      if (szdest < 4) return 0;
-      uint32_t in = (cur_src[0] << 16) + absl::big_endian::Load16(cur_src + 1);
-      cur_dest[0] = base64[in >> 18];
-      in &= 0x3FFFF;
-      cur_dest[1] = base64[in >> 12];
-      in &= 0xFFF;
-      cur_dest[2] = base64[in >> 6];
-      in &= 0x3F;
-      cur_dest[3] = base64[in];
-      cur_dest += 4;
-      szdest -= 4;
-      break;
-    }
-    default:
-      // Should not be reached: blocks of 4 bytes are handled
-      // in the while loop before this switch statement.
-      ABSL_RAW_LOG(FATAL, "Logic problem? szsrc = %zu", szsrc);
-      break;
-  }
-  return (cur_dest - dest);
-}
-
-constexpr char kBase64Chars[] =
-    "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
-
 constexpr char kWebSafeBase64Chars[] =
     "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_";
 
 template <typename String>
-void Base64EscapeInternal(const unsigned char* src, size_t szsrc, String* dest,
-                          bool do_padding, const char* base64_chars) {
-  const size_t calc_escaped_size =
-      CalculateBase64EscapedLenInternal(szsrc, do_padding);
-  strings_internal::STLStringResizeUninitialized(dest, calc_escaped_size);
-
-  const size_t escaped_len = Base64EscapeInternal(
-      src, szsrc, &(*dest)[0], dest->size(), base64_chars, do_padding);
-  assert(calc_escaped_size == escaped_len);
-  dest->erase(escaped_len);
-}
-
-template <typename String>
 bool Base64UnescapeInternal(const char* src, size_t slen, String* dest,
                             const signed char* unbase64) {
   // Determine the size of the output std::string.  Base64 encodes every 3 bytes into
@@ -1068,26 +902,30 @@ bool WebSafeBase64Unescape(absl::string_view src, std::string* dest) {
 }
 
 void Base64Escape(absl::string_view src, std::string* dest) {
-  Base64EscapeInternal(reinterpret_cast<const unsigned char*>(src.data()),
-                       src.size(), dest, true, kBase64Chars);
+  strings_internal::Base64EscapeInternal(
+      reinterpret_cast<const unsigned char*>(src.data()), src.size(), dest,
+      true, strings_internal::kBase64Chars);
 }
 
 void WebSafeBase64Escape(absl::string_view src, std::string* dest) {
-  Base64EscapeInternal(reinterpret_cast<const unsigned char*>(src.data()),
-                       src.size(), dest, false, kWebSafeBase64Chars);
+  strings_internal::Base64EscapeInternal(
+      reinterpret_cast<const unsigned char*>(src.data()), src.size(), dest,
+      false, kWebSafeBase64Chars);
 }
 
 std::string Base64Escape(absl::string_view src) {
   std::string dest;
-  Base64EscapeInternal(reinterpret_cast<const unsigned char*>(src.data()),
-                       src.size(), &dest, true, kBase64Chars);
+  strings_internal::Base64EscapeInternal(
+      reinterpret_cast<const unsigned char*>(src.data()), src.size(), &dest,
+      true, strings_internal::kBase64Chars);
   return dest;
 }
 
 std::string WebSafeBase64Escape(absl::string_view src) {
   std::string dest;
-  Base64EscapeInternal(reinterpret_cast<const unsigned char*>(src.data()),
-                       src.size(), &dest, false, kWebSafeBase64Chars);
+  strings_internal::Base64EscapeInternal(
+      reinterpret_cast<const unsigned char*>(src.data()), src.size(), &dest,
+      false, kWebSafeBase64Chars);
   return dest;
 }