1 files changed, 59 insertions, 1 deletions

diff --git a/src/lib/common.c b/src/lib/common.c
index 111366782..eee19c731 100644
--- a/src/lib/common.c
+++ b/src/lib/common.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2014-2022 Firejail Authors
+ * Copyright (C) 2014-2023 Firejail Authors
  *
  * This file is part of firejail project
  *
@@ -404,6 +404,64 @@ char *replace_cntrl_chars(const char *str, char c) {
         return rv;
 }
 
+// Replaces each control character in str with an escape sequence, such as by
+// replacing '\n' (0x0a) with "\\n" (0x5c6e).
+char *escape_cntrl_chars(const char *str) {
+        if (str == NULL)
+                return NULL;
+
+        unsigned int cntrl_chars = 0;
+        const char *c = str;
+        while (*c) {
+                switch (*c++) {
+                case '\b':
+                case '\a':
+                case '\e':
+                case '\f':
+                case '\n':
+                case '\r':
+                case '\t':
+                case '\v':
+                case '\"':
+                case '\'':
+                case '\?':
+                case '\\':
+                        ++cntrl_chars;
+                default:
+                        break;
+                }
+        }
+        char *ptr, *rv = malloc(strlen(str) + cntrl_chars + 1);
+        if (!rv)
+                errExit("malloc");
+        ptr = rv;
+        c = str;
+        while (*c) {
+                if (iscntrl(*c)) {
+                        *ptr++ = '\\';
+                        switch (*c) {
+                        case '\b': *ptr++ = 'b'; break;
+                        case '\a': *ptr++ = 'a'; break;
+                        case '\e': *ptr++ = 'e'; break;
+                        case '\f': *ptr++ = 'f'; break;
+                        case '\n': *ptr++ = 'n'; break;
+                        case '\r': *ptr++ = 'r'; break;
+                        case '\t': *ptr++ = 't'; break;
+                        case '\v': *ptr++ = 'v'; break;
+                        case '\"': *ptr++ = '\"'; break;
+                        case '\'': *ptr++ = '\''; break;
+                        case '\?': *ptr++ = '?'; break;
+                        case '\\': *ptr++ = '\\'; break;
+                        }
+                } else {
+                        *ptr++ = *c;
+                }
+                c++;
+        }
+        *ptr = '\0';
+        return rv;
+}
+
 int has_cntrl_chars(const char *str) {
         assert(str);