From: Glenn Strauss <gstrauss@gluelogic.com>
Date: Thu, 2 Mar 2017 22:53:42 +0000 (-0500)
Subject: libopkg/opkg_cmd.c: more robust PATH handling
X-Git-Url: https://git.librecmc.org/?p=oweals%2Fopkg-lede.git;a=commitdiff_plain;h=1ff24753478ceea81ec6c8e90bb1a59d57cc0501

libopkg/opkg_cmd.c: more robust PATH handling

preserve semantics of PATH when PATH is not set in environment

error and undefined behavior reported in
  https://github.com/openwrt/packages/issues/1922
when PATH not set in environment
(lighttpd executes CGI with empty base env, plus standard CGI env vars)

Signed-off-by: Glenn Strauss <gstrauss@gluelogic.com>
[Jo-Philipp Wich: avoid free() on NULL, use default from cmake cache string]
Signed-off-by: Jo-Philipp Wich <jo@mein.io>
---

diff --git a/libopkg/opkg_cmd.c b/libopkg/opkg_cmd.c
index d52bcb1..2ef2ff4 100644
--- a/libopkg/opkg_cmd.c
+++ b/libopkg/opkg_cmd.c
@@ -214,13 +214,19 @@ static opkg_intercept_t opkg_prep_intercepts(void)
 
 	ctx = xcalloc(1, sizeof(*ctx));
 	ctx->oldpath = xstrdup(getenv("PATH"));
-	sprintf_alloc(&newpath, "%s/opkg/intercept:%s", DATADIR, ctx->oldpath);
+
+	sprintf_alloc(&newpath, "%s/opkg/intercept:%s", DATADIR,
+	              ctx->oldpath ? ctx->oldpath : PATH_SPEC);
+
 	sprintf_alloc(&ctx->statedir, "%s/opkg-intercept-XXXXXX",
-		      conf->tmp_dir);
+	              conf->tmp_dir);
 
 	if (mkdtemp(ctx->statedir) == NULL) {
 		opkg_perror(ERROR, "Failed to make temp dir %s", ctx->statedir);
-		free(ctx->oldpath);
+
+		if (ctx->oldpath)
+			free(ctx->oldpath);
+
 		free(ctx->statedir);
 		free(newpath);
 		free(ctx);
@@ -239,8 +245,13 @@ static int opkg_finalize_intercepts(opkg_intercept_t ctx)
 	DIR *dir;
 	int err = 0;
 
-	setenv("PATH", ctx->oldpath, 1);
-	free(ctx->oldpath);
+	if (ctx->oldpath) {
+		setenv("PATH", ctx->oldpath, 1);
+		free(ctx->oldpath);
+	}
+	else {
+		unsetenv("PATH");
+	}
 
 	dir = opendir(ctx->statedir);
 	if (dir) {