From 3d55b9b277ced49a7f13a1080049cbf326ba70fc Mon Sep 17 00:00:00 2001
From: haotuo <380743811@qq.com>
Date: Tue, 16 May 2023 19:23:55 +0800
Subject: [PATCH] Optimize getenv performance by using self str cmp
 implementation

Issue: #I73MBP

Test: libc test & benchmark test

Signed-off-by: haotuo <haotuo@huawei.com>
Change-Id: Ibf8667e46c5199e5b7c3039029efb5b9daacc836
---
 musl_src.gni                        |  1 +
 porting/linux/user/src/env/getenv.c | 24 ++++++++++++++++++++++++
 2 files changed, 25 insertions(+)
 create mode 100644 porting/linux/user/src/env/getenv.c

diff --git a/musl_src.gni b/musl_src.gni
index 07b5e05e..50d5da0e 100644
--- a/musl_src.gni
+++ b/musl_src.gni
@@ -2180,6 +2180,7 @@ musl_src_porting_file = [
   "src/sigchain/sigchain.c",
   "src/conf/legacy.c",
   "src/conf/sysconf.c",
+  "src/env/getenv.c",
 ]
 
 musl_inc_hook_files = [
diff --git a/porting/linux/user/src/env/getenv.c b/porting/linux/user/src/env/getenv.c
new file mode 100644
index 00000000..d5fa6710
--- /dev/null
+++ b/porting/linux/user/src/env/getenv.c
@@ -0,0 +1,24 @@
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+char *getenv(const char *name)
+{
+	if (name == NULL || __environ == NULL)
+		return 0;
+	size_t i, l = 0;
+	const char *np;
+	char **p, *ep;
+	for (; *(name + l) && *(name + l) != '='; ++l);
+	for (p = __environ; (ep = *p) != NULL; ++p) {
+		for (np = name, i = l; i && *ep; i--) {
+			if (*ep++ != *np++) {
+				break;
+			}
+		}
+		if (i == 0 && *ep++ == '=') {
+			return (ep);
+		}
+	}
+	return 0;
+}
-- 
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