deletePath(): Succeed if path doesn't exist

Also makes it robust against concurrent deletions.

src/libstore/build.cc

@@ -1310,7 +1310,6 @@ void DerivationGoal::tryToBuild()
     for (auto & i : drv->outputs) {
         Path path = i.second.path;
         if (worker.store.isValidPath(path)) continue;
-        if (!pathExists(path)) continue;
         debug(format("removing invalid path ‘%1%’") % path);
         deletePath(path);
     }
@@ -1390,7 +1389,6 @@ void replaceValidPath(const Path & storePath, const Path tmpPath)
         rename(storePath.c_str(), oldPath.c_str());
     if (rename(tmpPath.c_str(), storePath.c_str()) == -1)
         throw SysError(format("moving ‘%1%’ to ‘%2%’") % tmpPath % storePath);
-    if (pathExists(oldPath))
     deletePath(oldPath);
 }
 
@@ -1490,7 +1488,7 @@ void DerivationGoal::buildDone()
 
         /* Delete unused redirected outputs (when doing hash rewriting). */
         for (auto & i : redirectedOutputs)
-            if (pathExists(i.second)) deletePath(i.second);
+            deletePath(i.second);
 
         /* Delete the chroot (if we were using one). */
         autoDelChroot.reset(); /* this runs the destructor */
@@ -1939,7 +1937,7 @@ void DerivationGoal::startBuilder()
            to ensure that we can create hard-links to non-directory
            inputs in the fake Nix store in the chroot (see below). */
         chrootRootDir = drvPath + ".chroot";
-        if (pathExists(chrootRootDir)) deletePath(chrootRootDir);
+        deletePath(chrootRootDir);
 
         /* Clean up the chroot directory automatically. */
         autoDelChroot = std::make_shared<AutoDelete>(chrootRootDir);
@@ -2514,7 +2512,7 @@ void DerivationGoal::runChild()
             debug(sandboxProfile);
 
             Path sandboxFile = drvPath + ".sb";
-            if (pathExists(sandboxFile)) deletePath(sandboxFile);
+            deletePath(sandboxFile);
             autoDelSandbox.reset(sandboxFile, false);
 
             writeFile(sandboxFile, sandboxProfile);
@@ -2706,7 +2704,6 @@ void DerivationGoal::registerOutputs()
                     return;
                 if (actualPath != dest) {
                     PathLocks outputLocks({dest});
-                    if (pathExists(dest))
                     deletePath(dest);
                     if (rename(actualPath.c_str(), dest.c_str()) == -1)
                         throw SysError(format("moving ‘%1%’ to ‘%2%’") % actualPath % dest);
@@ -2738,7 +2735,7 @@ void DerivationGoal::registerOutputs()
             if (hash.first != info.narHash) {
                 if (settings.keepFailed) {
                     Path dst = path + checkSuffix;
-                    if (pathExists(dst)) deletePath(dst);
+                    deletePath(dst);
                     if (rename(actualPath.c_str(), dst.c_str()))
                         throw SysError(format("renaming ‘%1%’ to ‘%2%’") % actualPath % dst);
                     throw Error(format("derivation ‘%1%’ may not be deterministic: output ‘%2%’ differs from ‘%3%’")
@@ -2830,7 +2827,7 @@ void DerivationGoal::registerOutputs()
     if (settings.keepFailed) {
         for (auto & i : drv->outputs) {
             Path prev = i.second.path + checkSuffix;
-            if (pathExists(prev)) deletePath(prev);
+            deletePath(prev);
             if (curRound < nrRounds) {
                 Path dst = i.second.path + checkSuffix;
                 if (rename(i.second.path.c_str(), dst.c_str()))
@@ -2998,7 +2995,7 @@ Path DerivationGoal::addHashRewrite(const Path & path)
     string h1 = string(path, settings.nixStore.size() + 1, 32);
     string h2 = string(printHash32(hashString(htSHA256, "rewrite:" + drvPath + ":" + path)), 0, 32);
     Path p = settings.nixStore + "/" + h2 + string(path, settings.nixStore.size() + 33);
-    if (pathExists(p)) deletePath(p);
+    deletePath(p);
     assert(path.size() == p.size());
     rewritesToTmp[h1] = h2;
     rewritesFromTmp[h2] = h1;
@@ -3259,7 +3256,6 @@ void SubstitutionGoal::tryToRun()
     destPath = repair ? storePath + ".tmp" : storePath;
 
     /* Remove the (stale) output path if it exists. */
-    if (pathExists(destPath))
     deletePath(destPath);
 
     worker.store.setSubstituterEnv();

src/libstore/gc.cc

@@ -608,7 +608,7 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
 
     state.shouldDelete = options.action == GCOptions::gcDeleteDead || options.action == GCOptions::gcDeleteSpecific;
 
-    if (state.shouldDelete && pathExists(reservedPath))
+    if (state.shouldDelete)
         deletePath(reservedPath);
 
     /* Acquire the global GC root.  This prevents

src/libstore/local-store.cc

@@ -1365,7 +1365,7 @@ Path LocalStore::addToStoreFromDump(const string & dump, const string & name,
 
         if (repair || !isValidPath(dstPath)) {
 
-            if (pathExists(dstPath)) deletePath(dstPath);
+            deletePath(dstPath);
 
             if (recursive) {
                 StringSource source(dump);
@@ -1434,7 +1434,7 @@ Path LocalStore::addTextToStore(const string & name, const string & s,
 
         if (repair || !isValidPath(dstPath)) {
 
-            if (pathExists(dstPath)) deletePath(dstPath);
+            deletePath(dstPath);
 
             writeFile(dstPath, s);
 
@@ -1659,7 +1659,7 @@ Path LocalStore::importPath(bool requireSignature, Source & source)
 
         if (!isValidPath(dstPath)) {
 
-            if (pathExists(dstPath)) deletePath(dstPath);
+            deletePath(dstPath);
 
             if (rename(unpacked.c_str(), dstPath.c_str()) == -1)
                 throw SysError(format("cannot move ‘%1%’ to ‘%2%’")

src/libutil/util.cc

@@ -320,9 +320,11 @@ static void _deletePath(const Path & path, unsigned long long & bytesFreed)
 {
     checkInterrupt();
 
-    printMsg(lvlVomit, format("%1%") % path);
+    struct stat st;
-
+    if (lstat(path.c_str(), &st) == -1) {
-    struct stat st = lstat(path);
+        if (errno == ENOENT) return;
+        throw SysError(format("getting status of ‘%1%’") % path);
+    }
 
     if (!S_ISDIR(st.st_mode) && st.st_nlink == 1)
         bytesFreed += st.st_blocks * 512;
@@ -338,9 +340,11 @@ static void _deletePath(const Path & path, unsigned long long & bytesFreed)
             _deletePath(path + "/" + i.name, bytesFreed);
     }
 
-    if (remove(path.c_str()) == -1)
+    if (remove(path.c_str()) == -1) {
+        if (errno == ENOENT) return;
         throw SysError(format("cannot unlink ‘%1%’") % path);
     }
+}
 
 
 void deletePath(const Path & path)

src/libutil/util.hh

@@ -92,8 +92,8 @@ string readLine(int fd);
 void writeLine(int fd, string s);
 
 /* Delete a path; i.e., in the case of a directory, it is deleted
-   recursively.  Don't use this at home, kids.  The second variant
+   recursively. It's not an error if the path does not exist. The
-   returns the number of bytes and blocks freed. */
+   second variant returns the number of bytes and blocks freed. */
 void deletePath(const Path & path);
 
 void deletePath(const Path & path, unsigned long long & bytesFreed);