From 06b6fb0c33aa37fdb7ad123d6111c85032fe82a9 Mon Sep 17 00:00:00 2001
From: topjohnwu <topjohnwu@gmail.com>
Date: Sat, 24 Feb 2024 03:27:09 -0800
Subject: [PATCH] Add setenv

---
 native/src/crt0/misc.c | 90 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 90 insertions(+)

diff --git a/native/src/crt0/misc.c b/native/src/crt0/misc.c
index 2199641a4..649c74109 100644
--- a/native/src/crt0/misc.c
+++ b/native/src/crt0/misc.c
@@ -2,6 +2,96 @@
 #include <string.h>
 #include <libgen.h>
 #include <errno.h>
+#include <unistd.h>
+
+// Source: bionic/libc/upstream-openbsd/lib/libc/stdlib/getenv.c
+static char *__findenv(const char *name, int len, int *offset) {
+    int i;
+    const char *np;
+    char **p, *cp;
+
+    if (name == NULL || environ == NULL)
+        return (NULL);
+    for (p = environ + *offset; (cp = *p) != NULL; ++p) {
+        for (np = name, i = len; i && *cp; i--)
+            if (*cp++ != *np++)
+                break;
+        if (i == 0 && *cp++ == '=') {
+            *offset = p - environ;
+            return (cp);
+        }
+    }
+    return (NULL);
+}
+
+// Source: bionic/libc/upstream-openbsd/lib/libc/stdlib/setenv.c
+int setenv(const char *name, const char *value, int rewrite) {
+    static char **lastenv;
+
+    char *C, **P;
+    const char *np;
+    int l_value, offset = 0;
+
+    if (!name || !*name) {
+        errno = EINVAL;
+        return (-1);
+    }
+    for (np = name; *np && *np != '='; ++np)
+        ;
+    if (*np) {
+        errno = EINVAL;
+        return (-1);			/* has `=' in name */
+    }
+
+    l_value = strlen(value);
+    if ((C = __findenv(name, (int)(np - name), &offset)) != NULL) {
+        int tmpoff = offset + 1;
+        if (!rewrite)
+            return (0);
+#if 0 /* XXX - existing entry may not be writable */
+        if (strlen(C) >= l_value) {	/* old larger; copy over */
+			while ((*C++ = *value++))
+				;
+			return (0);
+		}
+#endif
+        /* could be set multiple times */
+        while (__findenv(name, (int)(np - name), &tmpoff)) {
+            for (P = &environ[tmpoff];; ++P)
+                if (!(*P = *(P + 1)))
+                    break;
+        }
+    } else {					/* create new slot */
+        size_t cnt = 0;
+
+        if (environ != NULL) {
+            for (P = environ; *P != NULL; P++)
+                ;
+            cnt = P - environ;
+        }
+        size_t new_size;
+        if (__builtin_mul_overflow(cnt + 2, sizeof(char *), &new_size)) {
+            errno = ENOMEM;
+            return (-1);
+        }
+        P = realloc(lastenv, new_size);
+        if (!P)
+            return (-1);
+        if (lastenv != environ && environ != NULL)
+            memcpy(P, environ, cnt * sizeof(char *));
+        lastenv = environ = P;
+        offset = cnt;
+        environ[cnt + 1] = NULL;
+    }
+    if (!(environ[offset] =			/* name + `=' + value */
+                  malloc((int)(np - name) + l_value + 2)))
+        return (-1);
+    for (C = environ[offset]; (*C = *name++) && *C != '='; ++C)
+        ;
+    for (*C++ = '='; (*C++ = *value++); )
+        ;
+    return (0);
+}
 
 // Source: bionic/libc/bionic/libgen.cpp
 static int __basename_r(const char *path, char* buffer, size_t buffer_size) {