Use libsodium instead of OpenSSL for binary cache signing

Sodium's Ed25519 signatures are much shorter than OpenSSL's RSA
signatures. Public keys are also much shorter, so they're now
specified directly in the nix.conf option ‘binary-cache-public-keys’.

The new command ‘nix-store --generate-binary-cache-key’ generates and
prints a public and secret key.

2 files changed, 20 insertions, 7 deletions

diff --git a/src/libutil/util.cc b/src/libutil/util.cc
index 0d903f2f0d43..4f3010880286 100644
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@@ -925,18 +925,24 @@ std::vector<const char *> stringsToCharPtrs(const Strings & ss)
 }
 
 
-string runProgram(Path program, bool searchPath, const Strings & args)
+string runProgram(Path program, bool searchPath, const Strings & args,
+    const string & input)
 {
     checkInterrupt();
 
     /* Create a pipe. */
-    Pipe pipe;
-    pipe.create();
+    Pipe stdout, stdin;
+    stdout.create();
+    if (!input.empty()) stdin.create();
 
     /* Fork. */
     Pid pid = startProcess([&]() {
-        if (dup2(pipe.writeSide, STDOUT_FILENO) == -1)
+        if (dup2(stdout.writeSide, STDOUT_FILENO) == -1)
             throw SysError("dupping stdout");
+        if (!input.empty()) {
+            if (dup2(stdin.readSide, STDIN_FILENO) == -1)
+                throw SysError("dupping stdin");
+        }
 
         Strings args_(args);
         args_.push_front(program);
@@ -950,9 +956,16 @@ string runProgram(Path program, bool searchPath, const Strings & args)
         throw SysError(format("executing ‘%1%’") % program);
     });
 
-    pipe.writeSide.close();
+    stdout.writeSide.close();
+
+    /* FIXME: This can deadlock if the input is too long. */
+    if (!input.empty()) {
+        stdin.readSide.close();
+        writeFull(stdin.writeSide, input);
+        stdin.writeSide.close();
+    }
 
-    string result = drainFD(pipe.readSide);
+    string result = drainFD(stdout.readSide);
 
     /* Wait for the child to finish. */
     int status = pid.wait(true);
diff --git a/src/libutil/util.hh b/src/libutil/util.hh
index 186ee71f45d0..1a2dda527121 100644
--- a/src/libutil/util.hh
+++ b/src/libutil/util.hh
@@ -285,7 +285,7 @@ pid_t startProcess(std::function<void()> fun, const ProcessOptions & options = P
 /* Run a program and return its stdout in a string (i.e., like the
    shell backtick operator). */
 string runProgram(Path program, bool searchPath = false,
-    const Strings & args = Strings());
+    const Strings & args = Strings(), const string & input = "");
 
 MakeError(ExecError, Error)