Add the filesystem collector.

1 files changed, 76 insertions, 0 deletions

diff --git a/filesystem.c b/filesystem.c
new file mode 100644
index 0000000..84f6805
--- /dev/null
+++ b/filesystem.c
@@ -0,0 +1,76 @@
+#define _POSIX_C_SOURCE 200809L
+
+#include <string.h>
+#include <sys/statvfs.h>
+
+#include "filesystem.h"
+#include "util.h"
+
+// size of input buffer for paths and lines
+#define BUF_SIZE 256
+
+static void filesystem_collect(scrape_req *req, void *ctx);
+
+const struct collector filesystem_collector = {
+  .name = "filesystem",
+  .collect = filesystem_collect,
+};
+
+static void filesystem_collect(scrape_req *req, void *ctx) {
+  // buffers
+
+  const char *labels[][2] = {  // all filled by code
+    { "device", 0 },
+    { "fstype", 0 },
+    { "mountpoint", 0 },
+    { 0, 0 },
+  };
+  const char **dev = &labels[0][1];
+  const char **fstype = &labels[1][1];
+  const char **mount = &labels[2][1];
+
+  char buf[BUF_SIZE];
+
+  FILE *f;
+  struct statvfs fs;
+
+  // loop over /proc/mounts to get visible mounts
+
+  f = fopen("/proc/mounts", "r");
+  if (!f)
+    return;
+
+  while (fgets_line(buf, sizeof buf, f)) {
+    // extract device, mountpoint and filesystem type
+
+    char *p;
+    *dev = strtok_r(buf, " ", &p);
+    if (!*dev)
+      continue;
+    *mount = strtok_r(0, " ", &p);
+    if (!*mount)
+      continue;
+    *fstype = strtok_r(0, " ", &p);
+    if (!*fstype)
+      continue;
+
+    if (**dev != '/')
+      continue;
+    // TODO: device, mountpoint, filesystem exclude lists
+
+    // report metrics from statfs
+
+    if (statvfs(*mount, &fs) != 0)
+      continue;
+
+    double bs = fs.f_frsize;
+    scrape_write(req, "node_filesystem_avail_bytes", labels, fs.f_bavail * bs);
+    scrape_write(req, "node_filesystem_files", labels, fs.f_files);
+    scrape_write(req, "node_filesystem_files_free", labels, fs.f_ffree);
+    scrape_write(req, "node_filesystem_free_bytes", labels, fs.f_bfree * bs);
+    scrape_write(req, "node_filesystem_readonly", labels, fs.f_flag & ST_RDONLY ? 1.0 : 0.0);
+    scrape_write(req, "node_filesystem_size_bytes", labels, fs.f_blocks * bs);
+  }
+
+  fclose(f);
+}