[PATCH] Fix POSIX compliance in pgwin32_unsetenv()

[Bryan Green]

I noticed that pgwin32_unsetenv() in src/port/win32env.c lacks the input 
validation that its sibling function pgwin32_setenv() has (lines 126-132).

Without these checks, the function will crash on NULL input via 
strlen(NULL), and will accept empty strings or strings containing '=' in 
violation of POSIX.1-2008.

The attached patch adds the same validation that pgwin32_setenv already 
does, making the two functions consistent.  This is purely defensive - 
it only affects callers passing invalid arguments.

regards,

Bryan Green

From dda02bef12a725eff5e38367f2a525b2355c29d0 Mon Sep 17 00:00:00 2001
From: Bryan Green <dbryan.gr...@gmail.com>
Date: Sat, 18 Oct 2025 13:04:04 -0500
Subject: [PATCH] Fix POSIX compliance in pgwin32_unsetenv()

pgwin32_unsetenv() lacks the input validation that its sibling
pgwin32_setenv() has.  Add the same checks for NULL, empty string,
and '=' in the name parameter, per POSIX requirements.

Without these checks, unsetenv(NULL) crashes, and invalid names
are accepted when they should fail with EINVAL.
---
 src/port/win32env.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/port/win32env.c b/src/port/win32env.c
index b22fbafde4..e1cee683db 100644
--- a/src/port/win32env.c
+++ b/src/port/win32env.c
@@ -152,6 +152,13 @@ pgwin32_unsetenv(const char *name)
        int                     res;
        char       *envbuf;
 
+       /* Error conditions, per POSIX */
+       if (name == NULL || name[0] == '\0' || strchr(name, '=') != NULL)
+       {
+               errno = EINVAL;
+               return -1;
+       }
+
        envbuf = (char *) malloc(strlen(name) + 2);
        if (!envbuf)
                return -1;
-- 
2.49.0