image manager: add inotify watch

Add an inotify watch to the known software image location.

Hook the inotify fd with sd-event, so that on callback, version d-bus
objects can be created based on the newly added software image.

Resolves openbmc/openbmc#1444.

Change-Id: I5c460f820c8d3a851b8ddc969f26d38870c36991
Signed-off-by: Deepak Kodihalli <dkodihal@in.ibm.com>

1 files changed, 104 insertions, 0 deletions

diff --git a/watch.cpp b/watch.cpp
new file mode 100644
index 0000000..a520dd2
--- /dev/null
+++ b/watch.cpp
@@ -0,0 +1,104 @@
+#include <stdexcept>
+#include <cstddef>
+#include <cstring>
+#include <string>
+#include <sys/inotify.h>
+#include <unistd.h>
+#include <phosphor-logging/log.hpp>
+#include "config.h"
+#include "watch.hpp"
+
+namespace phosphor
+{
+namespace software
+{
+namespace manager
+{
+
+using namespace std::string_literals;
+
+Watch::Watch(sd_event* loop)
+{
+    fd = inotify_init1(IN_NONBLOCK);
+    if (-1 == fd)
+    {
+        // Store a copy of errno, because the string creation below will
+        // invalidate errno due to one more system calls.
+        auto error = errno;
+        throw std::runtime_error(
+            "inotify_init1 failed, errno="s + std::strerror(error));
+    }
+
+    wd = inotify_add_watch(fd, IMG_UPLOAD_DIR, IN_CREATE);
+    if (-1 == wd)
+    {
+        auto error = errno;
+        close(fd);
+        throw std::runtime_error(
+            "inotify_add_watch failed, errno="s + std::strerror(error));
+    }
+
+    auto rc = sd_event_add_io(loop,
+                              nullptr,
+                              fd,
+                              EPOLLIN,
+                              callback,
+                              this);
+    if (0 > rc)
+    {
+        throw std::runtime_error(
+            "failed to add to event loop, rc="s + std::strerror(-rc));
+    }
+}
+
+Watch::~Watch()
+{
+    if ((-1 != fd) && (-1 != wd))
+    {
+        inotify_rm_watch(fd, wd);
+        close(fd);
+    }
+}
+
+int Watch::callback(sd_event_source* s,
+                    int fd,
+                    uint32_t revents,
+                    void* userdata)
+{
+    if (!(revents & EPOLLIN))
+    {
+        return 0;
+    }
+
+    constexpr auto maxBytes = 1024;
+    uint8_t buffer[maxBytes];
+    auto bytes = read(fd, buffer, maxBytes);
+    if (0 > bytes)
+    {
+        auto error = errno;
+        throw std::runtime_error(
+            "failed to read inotify event, errno="s + std::strerror(error));
+    }
+
+    auto offset = 0;
+    while (offset < bytes)
+    {
+        auto event = reinterpret_cast<inotify_event*>(&buffer[offset]);
+        if ((event->mask & IN_CREATE) && !(event->mask & IN_ISDIR))
+        {
+            // TODO: openbmc/openbmc#1352 - invoke method (which takes uploaded
+            // filepath) to construct software version d-bus objects.
+            // For now, log the image filename.
+            using namespace phosphor::logging;
+            log<level::INFO>(event->name);
+        }
+
+        offset += offsetof(inotify_event, name) + event->len;
+    }
+
+    return 0;
+}
+
+} // namespace manager
+} // namespace software
+} // namespace phosphor