From 4e0359ce93c4b0185c5340d03be505b609417b04 Mon Sep 17 00:00:00 2001
From: Ron Yorston <rmy@pobox.com>
Date: Tue, 14 May 2024 14:03:25 +0100
Subject: ps: report unknown parent PID as 1

If the parent PID doesn't appear in the process table, report it
as 1.  This more closely matches how orphaned children are handled
on UNIX.

Adds 96-128 bytes.

(GitHub issue #416)
---
 include/libbb.h |  3 +++
 win32/process.c | 22 ++++++++++++++++++++--
 2 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/include/libbb.h b/include/libbb.h
index a7d31ed0c..8d5537114 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -2148,6 +2148,9 @@ typedef struct procps_status_t {
 	DIR *dir;
 #else
 	HANDLE snapshot;
+	unsigned *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 b993bb2be..8931eae2e 100644
--- a/win32/process.c
+++ b/win32/process.c
@@ -583,6 +583,8 @@ static char *get_bb_string(DWORD pid, const char *exe, char *string)
 	return name;
 }
 
+#define NPIDS 128
+
 /* POSIX version in libbb/procps.c */
 procps_status_t* FAST_FUNC procps_scan(procps_status_t* sp, int flags
 #if !ENABLE_FEATURE_PS_TIME && !ENABLE_FEATURE_PS_LONG
@@ -603,6 +605,8 @@ UNUSED_PARAM
 			free(sp);
 			return NULL;
 		}
+		sp->pids = xmalloc(sizeof(unsigned) * NPIDS);
+		sp->maxpids = NPIDS;
 		ret = Process32First(sp->snapshot, &pe);
 	}
 	else {
@@ -611,6 +615,7 @@ UNUSED_PARAM
 
 	if (!ret) {
 		CloseHandle(sp->snapshot);
+		free(sp->pids);
 		free(sp);
 		return NULL;
 	}
@@ -653,8 +658,21 @@ UNUSED_PARAM
 		}
 	}
 
-	sp->pid = pe.th32ProcessID;
-	sp->ppid = pe.th32ParentProcessID;
+	/* The parent of PID 0 is 0.  If the parent is a PID we haven't
+	 * seen set PPID to 1. */
+	sp->ppid = pe.th32ProcessID != 0;
+	for (int i = 0; i < sp->npids; ++i) {
+		if (sp->pids[i] == pe.th32ParentProcessID) {
+			sp->ppid = pe.th32ParentProcessID;
+			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;
 
 	if (sp->pid == getpid()) {
 		comm = applet_name;
-- 
cgit v1.2.3-55-g6feb