forked from lix-project/lix
Check for and repair bad .links entries
A corrupt entry in .links prevents adding a fixed version of that file to the store in any path. The user experience is that corruption present in the store 'spreads' to new paths added to the store: (With store optimisation enabled) 1. A file in the store gets corrupted somehow (eg: filesystem bug). 2. The user tries to add a thing to the store which contains a good copy of the corrupted file. 3. The file being added to the store is hashed, found to match the bad .links entry, and is replaced by a link to the bad .links entry. (The .links entry's hash is not verified during add -- this would impose a substantial performance burden.) 4. The user observes that the thing in the store that is supposed to be a copy of what they were trying to add is not a correct copy -- some files have different contents! Running "nix-store --verify --check-contents --repair" does not fix the problem. This change makes "nix-store --verify --check-contents --repair" fix this problem. Bad .links entries are simply removed, allowing future attempts to insert a good copy of the file to succeed.
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@ -1238,7 +1238,35 @@ bool LocalStore::verifyStore(bool checkContents, RepairFlag repair)
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/* Optionally, check the content hashes (slow). */
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if (checkContents) {
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printInfo("checking hashes...");
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printInfo("checking link hashes...");
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AutoCloseDir dir(opendir(linksDir.c_str()));
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if (!dir) throw SysError(format("opening directory '%1%'") % linksDir);
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struct dirent * dirent;
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while (errno = 0, dirent = readdir(dir.get())) { /* sic */
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checkInterrupt();
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if (strcmp(dirent->d_name, ".") == 0 || strcmp(dirent->d_name, "..") == 0) continue;
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Path linkPath = linksDir + "/" + dirent->d_name;
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string hash = hashPath(htSHA256, linkPath).first.to_string(Base32, false);
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if (hash != dirent->d_name) {
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printError(format("link '%1%' was modified! "
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"expected hash '%2%', got '%3%'")
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% linkPath % dirent->d_name % hash);
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if (repair) {
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if (unlink(linkPath.c_str()) == 0)
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printError(format("Removed link '%1%'") % linkPath);
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else
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throw SysError(format("removing corrupt link '%1%'") % linkPath);
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} else {
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errors = true;
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}
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}
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}
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if (errno) throw SysError(format("reading directory '%1%'") % linksDir);
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printInfo("checking store hashes...");
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Hash nullHash(htSHA256);
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