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authorEelco Dolstra <e.dolstra@tudelft.nl>2004-01-05T16·26+0000
committerEelco Dolstra <e.dolstra@tudelft.nl>2004-01-05T16·26+0000
commit4a373a3e9ac07a2d4c43d495c0a44883106ecfde (patch)
tree27f4e22f8d3573bfe1ebba1acfa2e46a735fecee /src/libutil/util.cc
parentf83c5e3e5f3e6b33c095d6559a4b3cd5922e88ce (diff)
* Implemented Eelco V.'s `nix-env -I' command to specify the default
  path of the Nix expression to be used with the import, upgrade, and
  query commands.  For instance,

  $ nix-env -I ~/nixpkgs/pkgs/system/i686-linux.nix

  $ nix-env --query --available   [aka -qa]
  sylpheed-0.9.7
  bison-1.875
  pango-1.2.5
  subversion-0.35.1
  ...

  $ nix-env -i sylpheed

  $ nix-env -u subversion

  There can be only one default at a time.

* If the path to a Nix expression is a symlink, follow the symlink
  prior to resolving relative path references in the expression.

Diffstat (limited to 'src/libutil/util.cc')
-rw-r--r--src/libutil/util.cc14
1 files changed, 14 insertions, 0 deletions
diff --git a/src/libutil/util.cc b/src/libutil/util.cc
index 60b86b162c9c..28e276a329b3 100644
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@@ -109,6 +109,20 @@ bool pathExists(const Path & path)
 }
 
 
+Path readLink(const Path & path)
+{
+    struct stat st;
+    if (lstat(path.c_str(), &st))
+        throw SysError(format("getting status of `%1%'") % path);
+    if (!S_ISLNK(st.st_mode))
+        throw Error(format("`%1%' is not a symlink") % path);
+    char buf[st.st_size];
+    if (readlink(path.c_str(), buf, st.st_size) != st.st_size)
+        throw SysError(format("reading symbolic link `%1%'") % path);
+    return string(buf, st.st_size);
+}
+
+
 Strings readDirectory(const Path & path)
 {
     Strings names;