From 2a01fe0325524f7745f60a528d1f3076c098d89d Mon Sep 17 00:00:00 2001
From: Ron Yorston <rmy@pobox.com>
Date: Thu, 16 May 2024 12:42:46 +0100
Subject: win32: ensure PIDs are read early in procps_scan()

Recent changes to allow orphaned processes to report a parent PID
of 1 rely on the assumption that Process32First/Process32Next
return parents before children.  This isn't guaranteed by the API.

Obtain all known PIDs on the first call to procps_scan() so that
dead parents can be detected reliably.

Costs 48 bytes.
---
 include/libbb.h |  3 +--
 win32/process.c | 25 +++++++++++++++----------
 2 files changed, 16 insertions(+), 12 deletions(-)

diff --git a/include/libbb.h b/include/libbb.h
index 8d5537114..d37d4e64c 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -2148,9 +2148,8 @@ typedef struct procps_status_t {
 	DIR *dir;
 #else
 	HANDLE snapshot;
-	unsigned *pids;
+	DWORD *pids;
 	int npids;
-	int maxpids;
 #endif
 	IF_FEATURE_SHOW_THREADS(DIR *task_dir;)
 	uint8_t shift_pages_to_bytes;
diff --git a/win32/process.c b/win32/process.c
index 9dd4bc1db..bbb04678f 100644
--- a/win32/process.c
+++ b/win32/process.c
@@ -605,6 +605,16 @@ UNUSED_PARAM
 			free(sp);
 			return NULL;
 		}
+		if (Process32First(sp->snapshot, &pe)) {
+			int maxpids = 0;
+			do {
+				if (sp->npids == maxpids) {
+					maxpids += NPIDS;
+					sp->pids = xrealloc(sp->pids, sizeof(DWORD) * maxpids);
+				}
+				sp->pids[sp->npids++] = pe.th32ProcessID;
+			} while (Process32Next(sp->snapshot, &pe));
+		}
 		ret = Process32First(sp->snapshot, &pe);
 	}
 	else {
@@ -665,12 +675,7 @@ UNUSED_PARAM
 			break;
 		}
 	}
-
-	if (sp->npids == sp->maxpids) {
-		sp->maxpids += NPIDS;
-		sp->pids = xrealloc(sp->pids, sizeof(unsigned) * sp->maxpids);
-	}
-	sp->pids[sp->npids++] = sp->pid = pe.th32ProcessID;
+	sp->pid = pe.th32ProcessID;
 
 	if (sp->pid == getpid()) {
 		comm = applet_name;
@@ -787,10 +792,10 @@ static int kill_signal(pid_t pid, int sig)
 }
 
 /**
- * If the process ID is positive invoke the callback for that process
- * only.  If negative or zero invoke the callback for all descendants
- * of the indicated process.  Zero indicates the current process; negative
- * indicates the process with process ID -pid.
+ * If the process ID is positive signal that process only.  If negative
+ * or zero signal all descendants of the indicated process.  Zero
+ * indicates the current process; negative indicates the process with
+ * process ID -pid.
  */
 static int kill_pids(pid_t pid, int sig)
 {
-- 
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