5 files changed, 113 insertions, 0 deletions
diff --git a/images/default/Dockerfile b/images/default/Dockerfile
index 2d0bb5ba5..397082b02 100644
--- a/images/default/Dockerfile
+++ b/images/default/Dockerfile
@@ -1,11 +1,16 @@
 FROM fedora:31
+# Install bazel.
 RUN dnf install -y dnf-plugins-core && dnf copr enable -y vbatts/bazel
 RUN dnf install -y git gcc make golang gcc-c++ glibc-devel python3 which python3-pip python3-devel libffi-devel openssl-devel pkg-config glibc-static libstdc++-static patch
 RUN pip install pycparser
 RUN dnf install -y bazel3
+# Install gcloud.
 RUN curl https://dl.google.com/dl/cloudsdk/channels/rapid/downloads/google-cloud-sdk-289.0.0-linux-x86_64.tar.gz | \
     tar zxvf - google-cloud-sdk && \
     google-cloud-sdk/install.sh && \
     ln -s /google-cloud-sdk/bin/gcloud /usr/bin/gcloud
+# Install Docker client for the website build.
+RUN dnf config-manager --add-repo https://download.docker.com/linux/fedora/docker-ce.repo
+RUN dnf install -y docker-ce-cli
 WORKDIR /workspace
 ENTRYPOINT ["/usr/bin/bazel"]
diff --git a/images/hostoverlaytest/Dockerfile b/images/hostoverlaytest/Dockerfile
new file mode 100644
index 000000000..d83439e9c
--- /dev/null
+++ b/images/hostoverlaytest/Dockerfile
@@ -0,0 +1,7 @@
+FROM ubuntu:bionic
+
+WORKDIR /root
+COPY . .
+
+RUN apt-get update && apt-get install -y gcc
+RUN gcc -O2 -o test test.c
diff --git a/images/hostoverlaytest/test.c b/images/hostoverlaytest/test.c
new file mode 100644
index 000000000..088f90746
--- /dev/null
+++ b/images/hostoverlaytest/test.c
@@ -0,0 +1,88 @@
+#include <err.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/mman.h>
+#include <unistd.h>
+
+int main(int argc, char** argv) {
+  const char kTestFilePath[] = "testfile.txt";
+  const char kOldFileData[] = "old data\n";
+  const char kNewFileData[] = "new data\n";
+  const size_t kPageSize = sysconf(_SC_PAGE_SIZE);
+
+  // Open a file that already exists in a host overlayfs lower layer.
+  const int fd_rdonly = open(kTestFilePath, O_RDONLY);
+  if (fd_rdonly < 0) {
+    err(1, "open(%s, O_RDONLY)", kTestFilePath);
+  }
+
+  // Check that the file's initial contents are what we expect when read via
+  // syscall.
+  char oldbuf[sizeof(kOldFileData)] = {};
+  ssize_t n = pread(fd_rdonly, oldbuf, sizeof(oldbuf), 0);
+  if (n < 0) {
+    err(1, "initial pread");
+  }
+  if (n != strlen(kOldFileData)) {
+    errx(1, "short initial pread (%ld/%lu bytes)", n, strlen(kOldFileData));
+  }
+  if (strcmp(oldbuf, kOldFileData) != 0) {
+    errx(1, "initial pread returned wrong data: %s", oldbuf);
+  }
+
+  // Check that the file's initial contents are what we expect when read via
+  // memory mapping.
+  void* page = mmap(NULL, kPageSize, PROT_READ, MAP_SHARED, fd_rdonly, 0);
+  if (page == MAP_FAILED) {
+    err(1, "mmap");
+  }
+  if (strcmp(page, kOldFileData) != 0) {
+    errx(1, "mapping contains wrong initial data: %s", (const char*)page);
+  }
+
+  // Open the same file writably, causing host overlayfs to copy it up, and
+  // replace its contents.
+  const int fd_rdwr = open(kTestFilePath, O_RDWR);
+  if (fd_rdwr < 0) {
+    err(1, "open(%s, O_RDWR)", kTestFilePath);
+  }
+  n = write(fd_rdwr, kNewFileData, strlen(kNewFileData));
+  if (n < 0) {
+    err(1, "write");
+  }
+  if (n != strlen(kNewFileData)) {
+    errx(1, "short write (%ld/%lu bytes)", n, strlen(kNewFileData));
+  }
+  if (ftruncate(fd_rdwr, strlen(kNewFileData)) < 0) {
+    err(1, "truncate");
+  }
+
+  int failed = 0;
+
+  // Check that syscalls on the old FD return updated contents. (Before Linux
+  // 4.18, this requires that runsc use a post-copy-up FD to service the read.)
+  char newbuf[sizeof(kNewFileData)] = {};
+  n = pread(fd_rdonly, newbuf, sizeof(newbuf), 0);
+  if (n < 0) {
+    err(1, "final pread");
+  }
+  if (n != strlen(kNewFileData)) {
+    warnx("short final pread (%ld/%lu bytes)", n, strlen(kNewFileData));
+    failed = 1;
+  } else if (strcmp(newbuf, kNewFileData) != 0) {
+    warnx("final pread returned wrong data: %s", newbuf);
+    failed = 1;
+  }
+
+  // Check that the memory mapping of the old FD has been updated. (Linux
+  // overlayfs does not do this, so regardless of kernel version this requires
+  // that runsc replace existing memory mappings with mappings of a
+  // post-copy-up FD.)
+  if (strcmp(page, kNewFileData) != 0) {
+    warnx("mapping contains wrong final data: %s", (const char*)page);
+    failed = 1;
+  }
+
+  return failed;
+}
diff --git a/images/hostoverlaytest/testfile.txt b/images/hostoverlaytest/testfile.txt
new file mode 100644
index 000000000..e4188c841
--- /dev/null
+++ b/images/hostoverlaytest/testfile.txt
@@ -0,0 +1 @@
+old data
diff --git a/images/jekyll/Dockerfile b/images/jekyll/Dockerfile
new file mode 100644
index 000000000..cefd949a6
--- /dev/null
+++ b/images/jekyll/Dockerfile
@@ -0,0 +1,12 @@
+FROM jekyll/jekyll:4.0.0
+USER root
+RUN gem install \
+        html-proofer:3.10.2 \
+        nokogiri:1.10.1 \
+        jekyll-autoprefixer:1.0.2 \
+        jekyll-inline-svg:1.1.4 \
+        jekyll-paginate:1.1.0 \
+        kramdown-parser-gfm:1.1.0 \
+        jekyll-relative-links:0.6.1 \
+        jekyll-feed:0.13.0
+CMD ["/usr/gem/gems/jekyll-4.0.0/exe/jekyll", "build", "-t", "-s", "/input", "-d", "/output"]