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Improve content address parsing

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- Ensure hash is in form <algo>-<prefix> and not SRI.

 - Better errors if something goes wrong

 - string_view for no coppying
This commit is contained in:
John Ericson 2020-06-22 18:08:27 +00:00
parent 965b80347e
commit 55d4bd6e0e
3 changed files with 50 additions and 35 deletions
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77
src/libstore/content-address.cc
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@ -1,3 +1,4 @@
#include "args.hh"
#include "content-address.hh"
namespace nix {
@ -40,38 +41,52 @@ std::string renderContentAddress(ContentAddress ca) {
}
ContentAddress parseContentAddress(std::string_view rawCa) {
auto prefixSeparator = rawCa.find(':');
if (prefixSeparator != string::npos) {
auto prefix = string(rawCa, 0, prefixSeparator);
if (prefix == "text") {
auto hashTypeAndHash = rawCa.substr(prefixSeparator+1, string::npos);
Hash hash = Hash(string(hashTypeAndHash));
if (*hash.type != htSHA256) {
throw Error("parseContentAddress: the text hash should have type SHA256");
}
return TextHash { hash };
} else if (prefix == "fixed") {
// This has to be an inverse of makeFixedOutputCA
auto methodAndHash = rawCa.substr(prefixSeparator+1, string::npos);
if (methodAndHash.substr(0,2) == "r:") {
std::string_view hashRaw = methodAndHash.substr(2,string::npos);
return FixedOutputHash {
.method = FileIngestionMethod::Recursive,
.hash = Hash(string(hashRaw)),
};
} else {
std::string_view hashRaw = methodAndHash;
return FixedOutputHash {
.method = FileIngestionMethod::Flat,
.hash = Hash(string(hashRaw)),
};
}
} else {
throw Error("parseContentAddress: format not recognized; has to be text or fixed");
auto rest = rawCa;
// Ensure prefix
const auto prefixSeparator = rawCa.find(':');
if (prefixSeparator == string::npos)
throw UsageError("not a content address because it is not in the form \"<prefix>:<rest>\": %s", rawCa);
auto prefix = rest.substr(0, prefixSeparator);
rest = rest.substr(prefixSeparator + 1);
auto parseHashType_ = [&](){
// Parse hash type
auto algoSeparator = rest.find(':');
HashType hashType;
if (algoSeparator == string::npos)
throw UsageError("content address hash must be in form \"<algo>:<hash>\", but found: %s", rest);
hashType = parseHashType(rest.substr(0, algoSeparator));
rest = rest.substr(algoSeparator + 1);
return std::move(hashType);
};
// Switch on prefix
if (prefix == "text") {
// No parsing of the method, "text" only support flat.
HashType hashType = parseHashType_();
if (hashType != htSHA256)
throw Error("text content address hash should use %s, but instead uses %s",
printHashType(htSHA256), printHashType(hashType));
return TextHash {
.hash = Hash { rest, std::move(hashType) },
};
} else if (prefix == "fixed") {
// Parse method
auto method = FileIngestionMethod::Flat;
if (rest.substr(0, 2) == "r:") {
method = FileIngestionMethod::Recursive;
rest = rest.substr(2);
}
} else {
throw Error("Not a content address because it lacks an appropriate prefix");
}
HashType hashType = parseHashType_();
return FixedOutputHash {
.method = method,
.hash = Hash { rest, std::move(hashType) },
};
} else
throw UsageError("content address prefix \"%s\" is unrecognized. Recogonized prefixes are \"text\" or \"fixed\"", prefix);
};
std::optional<ContentAddress> parseContentAddressOpt(std::string_view rawCaOpt) {