1 files changed, 36 insertions, 31 deletions

diff --git a/src/libutil/util.cc b/src/libutil/util.cc
index 012f1d071..4266a5474 100644
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@@ -23,6 +23,7 @@
 #include <sys/types.h>
 #include <sys/socket.h>
 #include <sys/wait.h>
+#include <sys/time.h>
 #include <sys/un.h>
 #include <unistd.h>
 
@@ -97,10 +98,10 @@ void replaceEnv(std::map<std::string, std::string> newEnv)
 }
 
 
-Path absPath(Path path, Path dir)
+Path absPath(Path path, std::optional<Path> dir, bool resolveSymlinks)
 {
     if (path[0] != '/') {
-        if (dir == "") {
+        if (!dir) {
 #ifdef __GNU__
             /* GNU (aka. GNU/Hurd) doesn't have any limitation on path
                lengths and doesn't define `PATH_MAX'.  */
@@ -116,9 +117,9 @@ Path absPath(Path path, Path dir)
             free(buf);
 #endif
         }
-        path = dir + "/" + path;
+        path = *dir + "/" + path;
     }
-    return canonPath(path);
+    return canonPath(path, resolveSymlinks);
 }
 
 
@@ -360,7 +361,6 @@ void writeFile(const Path & path, Source & source, mode_t mode)
     }
 }
 
-
 string readLine(int fd)
 {
     string s;
@@ -478,6 +478,17 @@ Path createTempDir(const Path & tmpRoot, const Path & prefix,
 }
 
 
+std::pair<AutoCloseFD, Path> createTempFile(const Path & prefix)
+{
+    Path tmpl(getEnv("TMPDIR").value_or("/tmp") + "/" + prefix + ".XXXXXX");
+    // Strictly speaking, this is UB, but who cares...
+    AutoCloseFD fd(mkstemp((char *) tmpl.c_str()));
+    if (!fd)
+        throw SysError("creating temporary file '%s'", tmpl);
+    return {std::move(fd), tmpl};
+}
+
+
 std::string getUserName()
 {
     auto pw = getpwuid(geteuid());
@@ -558,20 +569,31 @@ Paths createDirs(const Path & path)
 }
 
 
-void createSymlink(const Path & target, const Path & link)
+void createSymlink(const Path & target, const Path & link,
+    std::optional<time_t> mtime)
 {
     if (symlink(target.c_str(), link.c_str()))
         throw SysError(format("creating symlink from '%1%' to '%2%'") % link % target);
+    if (mtime) {
+        struct timeval times[2];
+        times[0].tv_sec = *mtime;
+        times[0].tv_usec = 0;
+        times[1].tv_sec = *mtime;
+        times[1].tv_usec = 0;
+        if (lutimes(link.c_str(), times))
+            throw SysError("setting time of symlink '%s'", link);
+    }
 }
 
 
-void replaceSymlink(const Path & target, const Path & link)
+void replaceSymlink(const Path & target, const Path & link,
+    std::optional<time_t> mtime)
 {
     for (unsigned int n = 0; true; n++) {
         Path tmp = canonPath(fmt("%s/.%d_%s", dirOf(link), n, baseNameOf(link)));
 
         try {
-            createSymlink(target, tmp);
+            createSymlink(target, tmp, mtime);
         } catch (SysError & e) {
             if (e.errNo == EEXIST) continue;
             throw;
@@ -983,12 +1005,14 @@ std::vector<char *> stringsToCharPtrs(const Strings & ss)
     return res;
 }
 
-
+// Output = "standard out" output stream
 string runProgram(Path program, bool searchPath, const Strings & args,
     const std::optional<std::string> & input)
 {
     RunOptions opts(program, args);
     opts.searchPath = searchPath;
+    // This allows you to refer to a program with a pathname relative to the
+    // PATH variable.
     opts.input = input;
 
     auto res = runProgram(opts);
@@ -999,6 +1023,7 @@ string runProgram(Path program, bool searchPath, const Strings & args,
     return res.second;
 }
 
+// Output = error code + "standard out" output stream
 std::pair<int, std::string> runProgram(const RunOptions & options_)
 {
     RunOptions options(options_);
@@ -1071,6 +1096,8 @@ void runProgram2(const RunOptions & options)
 
         if (options.searchPath)
             execvp(options.program.c_str(), stringsToCharPtrs(args_).data());
+            // This allows you to refer to a program with a pathname relative
+            // to the PATH variable.
         else
             execv(options.program.c_str(), stringsToCharPtrs(args_).data());
 
@@ -1205,28 +1232,6 @@ template StringSet tokenizeString(std::string_view s, const string & separators)
 template vector<string> tokenizeString(std::string_view s, const string & separators);
 
 
-string concatStringsSep(const string & sep, const Strings & ss)
-{
-    string s;
-    for (auto & i : ss) {
-        if (s.size() != 0) s += sep;
-        s += i;
-    }
-    return s;
-}
-
-
-string concatStringsSep(const string & sep, const StringSet & ss)
-{
-    string s;
-    for (auto & i : ss) {
-        if (s.size() != 0) s += sep;
-        s += i;
-    }
-    return s;
-}
-
-
 string chomp(const string & s)
 {
     size_t i = s.find_last_not_of(" \n\r\t");