From e666e1156fba936dce93ccfa2486f67369a97129 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <eelco.dolstra@logicblox.com>
Date: Fri, 28 Sep 2012 21:39:30 -0400
Subject: [PATCH] Handle octal escapes in /proc/self/mountinfo

---
 src/libstore/build.cc |  5 +++--
 src/libutil/util.cc   | 15 +++++++++++++++
 src/libutil/util.hh   |  6 ++++++
 3 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/src/libstore/build.cc b/src/libstore/build.cc
index ca66be3b4..fecee04d5 100644
--- a/src/libstore/build.cc
+++ b/src/libstore/build.cc
@@ -1914,8 +1914,9 @@ void DerivationGoal::initChild()
             Strings mounts = tokenizeString<Strings>(readFile("/proc/self/mountinfo", true), "\n");
             foreach (Strings::iterator, i, mounts) {
                 vector<string> fields = tokenizeString<vector<string> >(*i, " ");
-                if (mount(0, fields.at(4).c_str(), 0, MS_PRIVATE, 0) == -1)
-                    throw SysError(format("unable to make filesystem `%1%' private") % fields.at(4));
+                string fs = decodeOctalEscaped(fields.at(4));
+                if (mount(0, fs.c_str(), 0, MS_PRIVATE, 0) == -1)
+                    throw SysError(format("unable to make filesystem `%1%' private") % fs);
             }
 
             /* Bind-mount all the directories from the "host"
diff --git a/src/libutil/util.cc b/src/libutil/util.cc
index 7f95d3981..afb0dc0b2 100644
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@@ -1101,6 +1101,21 @@ bool endOfList(std::istream & str)
 }
 
 
+string decodeOctalEscaped(const string & s)
+{
+    string r;
+    for (string::const_iterator i = s.begin(); i != s.end(); ) {
+        if (*i != '\\') { r += *i++; continue; }
+        unsigned char c = 0;
+        ++i;
+        while (i != s.end() && *i >= '0' && *i < '8')
+            c = c * 8 + (*i++ - '0');
+        r += c;
+    }
+    return r;
+}
+
+
 void ignoreException()
 {
     try {
diff --git a/src/libutil/util.hh b/src/libutil/util.hh
index 408d99a96..d3861f730 100644
--- a/src/libutil/util.hh
+++ b/src/libutil/util.hh
@@ -332,6 +332,12 @@ string parseString(std::istream & str);
 bool endOfList(std::istream & str);
 
 
+/* Escape a string that contains octal-encoded escape codes such as
+   used in /etc/fstab and /proc/mounts (e.g. "foo\040bar" decodes to
+   "foo bar"). */
+string decodeOctalEscaped(const string & s);
+
+
 /* Exception handling in destructors: print an error message, then
    ignore the exception. */
 void ignoreException();