From f8cd904e05b95c5a3ca7cf570c0503a25a2095ca Mon Sep 17 00:00:00 2001 From: Eelco Dolstra Date: Sat, 27 Mar 2004 17:58:04 +0000 Subject: * Disallow the Nix store or any of its parents from being symlinks. This is because the contents of these symlinks are not incorporated into the hashes of derivations, and could therefore cause a mismatch between the build system and the target system. E.g., if `/nix/store' is a symlink to `/data/nix/store', then a builder could expand this path and store the result. If on the target system `/nix/store' is not a symlink, or is a symlink that points somewhere else, we have a dangling pointer. The trigger for this change is that gcc 3.3.3 does exactly that (it applies realpath() to some files, such as libraries, which causes our impurity checker to bail out.) An annoying side-effect of this change is that it makes it harder to move the Nix store to a different file system. On Linux, bind mounts can be used instead of symlink for this purpose (e.g., `mount -o bind /data/nix/store /nix/store'). --- src/libmain/shared.cc | 35 +++++++++++++++++++++++++++++------ 1 file changed, 29 insertions(+), 6 deletions(-) (limited to 'src/libmain') diff --git a/src/libmain/shared.cc b/src/libmain/shared.cc index a93d6cb50186..42f17cf4edea 100644 --- a/src/libmain/shared.cc +++ b/src/libmain/shared.cc @@ -1,7 +1,10 @@ - #include #include +#include +#include +#include + extern "C" { #include } @@ -27,6 +30,22 @@ void setLogType(string lt) } +void checkStoreNotSymlink(Path path) +{ + struct stat st; + while (path.size()) { + if (lstat(path.c_str(), &st)) + throw SysError(format("getting status of `%1%'") % path); + if (S_ISLNK(st.st_mode)) + throw Error(format( + "the path `%1%' is a symlink; " + "this is not allowed for the Nix store and its parent directories") + % path); + path = dirOf(path); + } +} + + /* Initialize and reorder arguments, then call the actual argument processor. */ static void initAndRun(int argc, char * * argv) @@ -39,11 +58,15 @@ static void initAndRun(int argc, char * * argv) } /* Setup Nix paths. */ - nixStore = NIX_STORE_DIR; - nixDataDir = NIX_DATA_DIR; - nixLogDir = NIX_LOG_DIR; - nixStateDir = (string) NIX_STATE_DIR; - nixDBPath = (string) NIX_STATE_DIR + "/db"; + nixStore = canonPath(NIX_STORE_DIR); + nixDataDir = canonPath(NIX_DATA_DIR); + nixLogDir = canonPath(NIX_LOG_DIR); + nixStateDir = canonPath(NIX_STATE_DIR); + nixDBPath = canonPath(NIX_STATE_DIR) + "/db"; + + /* Check that the store directory and its parent are not + symlinks. */ + checkStoreNotSymlink(nixStore); /* Catch SIGINT. */ struct sigaction act, oact; -- cgit 1.4.1