From 04be39734f6a5fe2e724a0c7b813ea1dd6ed3a29 Mon Sep 17 00:00:00 2001 From: Eelco Dolstra Date: Sun, 8 Jan 2006 17:16:03 +0000 Subject: [PATCH] * Resolve all symlink components in the location of the temporary build directory (TMPDIR, i.e., /tmp). Fixes NIX-26. --- src/libutil/util.cc | 23 +++++++++++++++++++++-- src/libutil/util.hh | 6 ++++-- 2 files changed, 25 insertions(+), 4 deletions(-) diff --git a/src/libutil/util.cc b/src/libutil/util.cc index 5a728617d..188453d16 100644 --- a/src/libutil/util.cc +++ b/src/libutil/util.cc @@ -53,7 +53,7 @@ Path absPath(Path path, Path dir) } -Path canonPath(const Path & path) +Path canonPath(const Path & path, bool resolveSymlinks) { string s; @@ -61,6 +61,11 @@ Path canonPath(const Path & path) throw Error(format("not an absolute path: `%1%'") % path); string::const_iterator i = path.begin(), end = path.end(); + string temp; + + /* Count the number of times we follow a symlink and stop at some + arbitrary (but high) limit to prevent infinite loops. */ + unsigned int followCount = 0, maxFollow = 1024; while (1) { @@ -84,6 +89,20 @@ Path canonPath(const Path & path) else { s += '/'; while (i != end && *i != '/') s += *i++; + + /* If s points to a symlink, resolve it and restart (since + the symlink target might contain new symlinks). */ + if (resolveSymlinks && isLink(s)) { + followCount++; + if (followCount >= maxFollow) + throw Error(format("infinite symlink recursion in path `%1%'") % path); + temp = absPath(readLink(s), dirOf(s)) + + string(i, end); + i = temp.begin(); /* restart */ + end = temp.end(); + s = ""; + /* !!! potential for infinite loop */ + } } } @@ -264,7 +283,7 @@ void makePathReadOnly(const Path & path) static Path tempName() { static int counter = 0; - Path tmpRoot = canonPath(getEnv("TMPDIR", "/tmp")); + Path tmpRoot = canonPath(getEnv("TMPDIR", "/tmp"), true); return (format("%1%/nix-%2%-%3%") % tmpRoot % getpid() % counter++).str(); } diff --git a/src/libutil/util.hh b/src/libutil/util.hh index 9601e65b3..aac2acd17 100644 --- a/src/libutil/util.hh +++ b/src/libutil/util.hh @@ -64,8 +64,10 @@ string getEnv(const string & key, const string & def = ""); Path absPath(Path path, Path dir = ""); /* Canonicalise a path by removing all `.' or `..' components and - double or trailing slashes. */ -Path canonPath(const Path & path); + double or trailing slashes. Optionally resolves all symlink + components such that each component of the resulting path is *not* + a symbolic link. */ +Path canonPath(const Path & path, bool resolveSymlinks = false); /* Return the directory part of the given canonical path, i.e., everything before the final `/'. If the path is the root or an