From 6bd5bd386a4612661d3b224bf27cad7e9b4032bb Mon Sep 17 00:00:00 2001
From: Patrick McDermott <patrick.mcdermott@libiquity.com>
Date: Wed, 05 Jul 2023 17:51:43 -0400
Subject: mknod: Find path relative to pkg data dir

All tests now pass.
---
diff --git a/configure.ac b/configure.ac
index 76c6a07..c7dbab8 100644
--- a/configure.ac
+++ b/configure.ac
@@ -47,8 +47,8 @@ AC_CHECK_FUNCS(
 		fread free fscanf fseek fstat fwrite getgrgid getpwuid \
 		localtime lstat malloc memcmp memcpy memset mkdir mkfifo open \
 		printf puts readlink scandir sleep snprintf sprintf stat \
-		strchr strcmp strcpy strerror strftime strlen strncpy strtol \
-		unlink vfprintf
+		strchr strcmp strcpy strerror strftime strlen strncmp strncpy \
+		strtol unlink vfprintf
 	],
 	[],
 	[funcs_missing=true])
diff --git a/helpers/mknod.c b/helpers/mknod.c
index 9e40080..9504b09 100644
--- a/helpers/mknod.c
+++ b/helpers/mknod.c
@@ -142,6 +142,7 @@ main(int argc, char *argv[])
 	char           type;
 	long int       major;
 	long int       minor;
+	size_t         work_area_len;
 	size_t         specials_file_name_len;
 	char          *specials_file_name;
 	char          *specials_lock_name;
@@ -229,6 +230,27 @@ main(int argc, char *argv[])
 		return EXIT_FAILURE;
 	}
 
+	/* Find path of file relative to binary package data directory within
+	 * build work area. */
+	work_area_len = strlen(work_area);
+	if (work_area[work_area_len - 1] == '/') {
+		--work_area_len;
+	}
+	if (strncmp(name, work_area, work_area_len) != 0 ||
+			name[work_area_len] != '/') {
+		_err(_("Node \"%s\" not within work area \"%s\""),
+				name, work_area);
+		return EXIT_FAILURE;
+	}
+	do {
+		++work_area_len;
+		if (name[work_area_len] == '\0') {
+			_err(_("Node \"%s\" not within a binary package data "
+						"directory"), name);
+			return EXIT_FAILURE;
+		}
+	} while (name[work_area_len] != '/');
+
 	specials_file_name_len = strlen(work_area) + strlen("/specials") + 1;
 	specials_file_name = malloc(specials_file_name_len * 2 + 1);
 	if (specials_file_name == NULL) {
@@ -297,7 +319,7 @@ main(int argc, char *argv[])
 	}
 
 	if (fprintf(specials_file, "%c     %8ld  %8ld  %s\n",
-				type, major, minor, name) < 0) {
+				type, major, minor, name + work_area_len) < 0) {
 		_errno(_("Failed to write specials file"));
 		fclose(specials_file);
 		unlink(specials_lock_name);
--
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