Add test to verify that TMPDIR has no (known) security implications

Author: vmcj

example_problems/fltcmp/submissions/accepted/fltcmp-test-write-files-between-submissions.R

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+fltcmp-test-write-files-between-testcases.R

example_problems/fltcmp/submissions/accepted/fltcmp-test-write-files-between-testcases.R

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+# This checks if we can write extra files
+# between different testcase runs. R uses
+# a temporary directory which DOMjudge should
+# make unavailable between runs and in case this
+# is forgotten teams can precalculate extra files for later
+# testcases. We need a working solution to make sure
+# we get to all testcases.
+#
+# This submission is symlinked to make sure we submit it twice
+# to verify that we can't see the TMPDIR of the earlier submission.
+#
+# The script will be WRONG-ANSWER if any of the assumptions
+# are wrong.
+# The script will be NO-OUTPUT if there is a security violation.
+# The verdict RUN-ERROR is expected if we correctly detect the
+# violation and would be the correct verdict if we don't need a
+# TMPDIR.
+#
+# @EXPECTED_RESULTS@: CORRECT
+
+# For R the TMPDIR needs to be set, if it's not
+# we can skip this whole test.
+tmpdir<-Sys.getenv(c("TMPDIR"))
+if (tmpdir == '') {
+  print("TMPDIR not set, update installation instructions.")
+  quit()
+}
+
+# We had 3 testcases in the past, try with double for when new testcases get added.
+testcaseIds<-rep(1:6)
+possibleTempDirs <- (function (x) sprintf("/testcase%05d/write_tmp", x))(testcaseIds)
+if (!(tmpdir %in% possibleTempDirs)) {	
+  print("Either TMPDIR format has changed, or too many testcases.")
+  print(sprintf("Current TMPDIR: %s", tmpdir))
+  quit()
+}
+
+for (possibleTempDir in possibleTempDirs) {
+  teamFile<-sprintf("%s/fileFromTeam.txt", possibleTempDir)
+  if (file.exists(teamFile)) {
+    # File should not be here
+    quit()
+  }
+}
+
+# Try to write to our TMPDIR to read it in the next testcase.
+currentTeamFile<-sprintf("%s/fileFromTeam.txt", tmpdir)
+fileConn<-file(currentTeamFile)
+writeLines(c("Calculate","all","floats"), fileConn)
+close(fileConn)
+# Make sure our test from earlier does work for this testcase
+if (!(file.exists(currentTeamFile))) {
+  # File should be here
+  quit()
+}
+
+# Now try the actual problem to advance to the next testcase.
+input<-file("stdin")
+lines<-readLines(input)
+
+# https://evolutionarygenetics.github.io/Chapter10.html
+# a simple reciprocal example
+reciprocal <- function(x){
+  # calculate the reciprocal
+  y <- 1/x
+  return(y)
+}
+
+for (l in lines[-1]) {
+  l<-as.numeric(l)
+  r<-reciprocal(l)
+  cat(r,"\n")
+}