refactor(3p/nix): Remove custom base64 implementation r/1462

Replace the custom, rather questionable base64 implementation with
absl::Base64{Une,E}scape. To make sure that the custom implementation
was doing the same thing I've also added a test covering
nix::Hash::to_string, which was one function that used it - the test
passed prior to the replacement, and continued to pass afterwards.

The previous base64Decode function threw an exception on failure - to
avoid going too far down the rabbit hole I've replicated that
functionality at all call sites, but this should be replaced with more
sensible error handling such as StatusOr eventually.

Also, before this change:

    ❯ nix eval -f . users.tazjin.emacs.outPath
    "/nix/store/g6ri2q8nra96ix20bcsc734r1yyaylb1-tazjins-emacs"

And after:

    ❯ ./result/bin/nix eval -f . users.tazjin.emacs.outPath
    "/nix/store/g6ri2q8nra96ix20bcsc734r1yyaylb1-tazjins-emacs"

Change-Id: Id292ffbb82fe808f3f1b34670afbe7b8c13ad615
Reviewed-on: https://cl.tvl.fyi/c/depot/+/1385
Reviewed-by: tazjin <mail@tazj.in>
Tested-by: BuildkiteCI

1 files changed, 0 insertions, 67 deletions

diff --git a/third_party/nix/src/libutil/util.cc b/third_party/nix/src/libutil/util.cc
index b97624e58dbb..f69c341c2c59 100644
--- a/third_party/nix/src/libutil/util.cc
+++ b/third_party/nix/src/libutil/util.cc
@@ -1321,73 +1321,6 @@ std::string filterANSIEscapes(const std::string& s, bool filterAll,
   return t;
 }
 
-static char base64Chars[] =
-    "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
-
-std::string base64Encode(const std::string& s) {
-  std::string res;
-  int data = 0;
-  int nbits = 0;
-
-  for (char c : s) {
-    data = data << 8 | (unsigned char)c;
-    nbits += 8;
-    while (nbits >= 6) {
-      nbits -= 6;
-      res.push_back(base64Chars[data >> nbits & 0x3f]);
-    }
-  }
-
-  if (nbits != 0) {
-    res.push_back(base64Chars[data << (6 - nbits) & 0x3f]);
-  }
-  while ((res.size() % 4) != 0u) {
-    res.push_back('=');
-  }
-
-  return res;
-}
-
-std::string base64Decode(const std::string& s) {
-  bool init = false;
-  char decode[256];
-  if (!init) {
-    // FIXME: not thread-safe.
-    memset(decode, -1, sizeof(decode));
-    for (int i = 0; i < 64; i++) {
-      decode[(int)base64Chars[i]] = i;
-    }
-    init = true;
-  }
-
-  std::string res;
-  unsigned int d = 0;
-  unsigned int bits = 0;
-
-  for (char c : s) {
-    if (c == '=') {
-      break;
-    }
-    if (c == '\n') {
-      continue;
-    }
-
-    char digit = decode[(unsigned char)c];
-    if (digit == -1) {
-      throw Error("invalid character in Base64 string");
-    }
-
-    bits += 6;
-    d = d << 6 | digit;
-    if (bits >= 8) {
-      res.push_back(d >> (bits - 8) & 0xff);
-      bits -= 8;
-    }
-  }
-
-  return res;
-}
-
 void callFailure(const std::function<void(std::exception_ptr exc)>& failure,
                  const std::exception_ptr& exc) {
   try {