From 05c45f301de6f4b5528969b97b9cc1891b1a985c Mon Sep 17 00:00:00 2001 From: Eelco Dolstra Date: Tue, 29 Aug 2017 11:51:16 +0200 Subject: [PATCH] readLink(): Handle symlinks in /proc Symlinks like /proc/self/exe report a stat() size of 0, so use a buffer of at least PATH_MAX instead. --- src/libutil/util.cc | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/libutil/util.cc b/src/libutil/util.cc index 2f410f7e3..605e89ce2 100644 --- a/src/libutil/util.cc +++ b/src/libutil/util.cc @@ -219,13 +219,14 @@ Path readLink(const Path & path) struct stat st = lstat(path); if (!S_ISLNK(st.st_mode)) throw Error(format("'%1%' is not a symlink") % path); - char buf[st.st_size]; - ssize_t rlsize = readlink(path.c_str(), buf, st.st_size); + auto bufSize = std::max(st.st_size, (off_t) PATH_MAX + 1); + char buf[bufSize]; + ssize_t rlsize = readlink(path.c_str(), buf, bufSize); if (rlsize == -1) throw SysError(format("reading symbolic link '%1%'") % path); - else if (rlsize > st.st_size) + else if (rlsize > bufSize) throw Error(format("symbolic link '%1%' size overflow %2% > %3%") - % path % rlsize % st.st_size); + % path % rlsize % bufSize); return string(buf, rlsize); }