From 625d3d275a4a92fff2408a3e0a7bae6db0dbb200 Mon Sep 17 00:00:00 2001
From: Farzin Monsef <monseffarzin@gmail.com>
Date: Sat, 2 Mar 2024 13:54:57 +0330
Subject: [PATCH] cygwin: implement uv_resident_set_memory (#4333)

According to the documentation for Cygwin, the penultimate field
of /proc/pid/stat corresponds to the RSS, so the method is basically
the same as in the Linux version. The only difference is that getpagesize()
will return wincap.allocation_granularity(), but in this mapping, RSS is
calculated using wincap.page_size(), which can be accessed by sysinfo.mem_unit.
---
 src/unix/cygwin.c | 40 ++++++++++++++++++++++++++++++++++++++--
 1 file changed, 38 insertions(+), 2 deletions(-)

diff --git a/src/unix/cygwin.c b/src/unix/cygwin.c
index 4e541396..49131082 100644
--- a/src/unix/cygwin.c
+++ b/src/unix/cygwin.c
@@ -36,9 +36,45 @@ int uv_uptime(double* uptime) {
 }
 
 int uv_resident_set_memory(size_t* rss) {
-  /* FIXME: read /proc/meminfo? */
-  *rss = 0;
+  char buf[1024];
+  const char* s;
+  long val;
+  int rc;
+  int i;
+  struct sysinfo si;
+
+  /* rss: 24th element */
+  rc = uv__slurp("/proc/self/stat", buf, sizeof(buf));
+  if (rc < 0)
+    return rc;
+
+  /* find the last ')' */
+  s = strrchr(buf, ')');
+  if (s == NULL)
+    goto err;
+
+  for (i = 1; i <= 22; i++) {
+    s = strchr(s + 1, ' ');
+    if (s == NULL)
+      goto err;
+  }
+
+  errno = 0;
+  val = strtol(s, NULL, 10);
+  if (val < 0 || errno != 0)
+    goto err;
+
+  do
+    rc = sysinfo(&si);
+  while (rc == -1 && errno == EINTR);
+  if (rc == -1)
+    return UV__ERR(errno);
+
+  *rss = val * si.mem_unit;
   return 0;
+
+err:
+  return UV_EINVAL;
 }
 
 int uv_cpu_info(uv_cpu_info_t** cpu_infos, int* count) {