1 files changed, 99 insertions, 0 deletions
diff --git a/plugins/sudoers/exptilde.c b/plugins/sudoers/exptilde.c
new file mode 100644
index 0000000..03de3da
--- /dev/null
+++ b/plugins/sudoers/exptilde.c
@@ -0,0 +1,99 @@
+/*
+ * SPDX-License-Identifier: ISC
+ *
+ * Copyright (c) 2020 Todd C. Miller <Todd.Miller@sudo.ws>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+/*
+ * This is an open source non-commercial project. Dear PVS-Studio, please check it.
+ * PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com
+ */
+
+#include <config.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <grp.h>
+#include <pwd.h>
+
+#include <sudoers.h>
+#include <pwutil.h>
+
+/*
+ * Expand leading tilde in *path, which must be dynamically allocated.
+ * Replaces path with the expanded version as needed, freeing the old one.
+ * Returns true on success, false on failure.
+ */
+bool
+expand_tilde(char **path, const char *user)
+{
+    char *npath, *opath = *path;
+    char *slash = NULL;
+    struct passwd *pw;
+    int len;
+    debug_decl(expand_tilde, SUDOERS_DEBUG_UTIL);
+
+    switch (*opath++) {
+    case '/':
+	/* A fully-qualified path, nothing to do. */
+	debug_return_bool(true);
+    case '~':
+	/* See below. */
+	break;
+    default:
+	/* Not a fully-qualified path or one that starts with a tilde. */
+	debug_return_bool(false);
+    }
+
+    switch (*opath) {
+    case '\0':
+	/* format: ~ */
+	break;
+    case '/':
+	/* format: ~/foo */
+	opath++;
+	break;
+    default:
+	/* format: ~user/foo */
+	user = opath;
+	slash = strchr(opath, '/');
+	if (slash != NULL) {
+	    *slash = '\0';
+	    opath = slash + 1;
+	} else {
+	    opath = (char *)"";
+	}
+    }
+    pw = sudo_getpwnam(user);
+    if (slash != NULL)
+	*slash = '/';
+    if (pw == NULL) {
+	/* Unknown user. */
+	sudo_warnx(U_("unknown user %s"), user);
+	debug_return_bool(false);
+    }
+
+    len = asprintf(&npath, "%s%s%s", pw->pw_dir, *opath ? "/" : "", opath);
+    sudo_pw_delref(pw);
+    if (len == -1) {
+	sudo_warnx(U_("%s: %s"), __func__, U_("unable to allocate memory"));
+	debug_return_bool(false);
+    }
+
+    free(*path);
+    *path = npath;
+    debug_return_bool(true);
+}