Add an option to limit the log output of builders

This is mostly useful for Hydra to deal with builders that get stuck
in an infinite loop writing data to stdout/stderr.

1 files changed, 13 insertions, 0 deletions

diff --git a/src/libstore/build.cc b/src/libstore/build.cc
index b5d064e8c60d..25bf848ca697 100644
--- a/src/libstore/build.cc
+++ b/src/libstore/build.cc
@@ -813,6 +813,9 @@ private:
     BZFILE * bzLogFile;
     AutoCloseFD fdLogFile;
 
+    /* Number of bytes received from the builder's stdout/stderr. */
+    unsigned long logSize;
+
     /* Pipe for the builder's standard output/error. */
     Pipe builderOut;
 
@@ -2403,6 +2406,8 @@ string drvsLogDir = "drvs";
 
 Path DerivationGoal::openLogFile()
 {
+    logSize = 0;
+
     if (!settings.keepLog) return "";
 
     string baseName = baseNameOf(drvPath);
@@ -2478,6 +2483,14 @@ void DerivationGoal::handleChildOutput(int fd, const string & data)
     if ((hook && fd == hook->builderOut.readSide) ||
         (!hook && fd == builderOut.readSide))
     {
+        logSize += data.size();
+        if (settings.maxLogSize && logSize > settings.maxLogSize) {
+            printMsg(lvlError,
+                format("%1% killed after writing more than %2% bytes of log output")
+                % getName() % settings.maxLogSize);
+            cancel(true); // not really a timeout, but close enough
+            return;
+        }
         if (verbosity >= settings.buildVerbosity)
             writeToStderr(data);
         if (bzLogFile) {