141/376: Filter Nix-specific ANSI escape sequences from stderr

[Ludovic Court�s]

civodul pushed a commit to tag 1.8
in repository guix.

commit 954188af2747e796eb4428c493db9aa06ed1af38
Author: Eelco Dolstra <eelco.dols...@logicblox.com>
Date:   Wed Aug 20 14:17:07 2014 +0200

    Filter Nix-specific ANSI escape sequences from stderr
    
    The Nixpkgs stdenv prints some custom escape sequences to denote
    nesting and stuff like that. Most terminals (e.g. xterm, konsole)
    ignore them, but some do not (e.g. xfce4-terminal). So for the benefit
    of the latter, filter them out.
---
 src/libstore/build.cc |   38 +++++++++++++++++++++++++++++++++++++-
 1 files changed, 37 insertions(+), 1 deletions(-)

diff --git a/src/libstore/build.cc b/src/libstore/build.cc
index aa539a1..ef0a304 100644
--- a/src/libstore/build.cc
+++ b/src/libstore/build.cc
@@ -2441,6 +2441,42 @@ void DerivationGoal::deleteTmpDir(bool force)
 }
 
 
+/* Filter out the special ANSI escape codes generated by Nixpkgs'
+   stdenv (used to denote nesting etc.). */
+static string filterNixEscapes(const string & s)
+{
+    string t, r;
+    enum { stTop, stEscape, stCSI } state = stTop;
+    for (auto c : s) {
+        if (state == stTop) {
+            if (c == '\e') {
+                state = stEscape;
+                r = c;
+            } else
+                t += c;
+        } else if (state == stEscape) {
+            r += c;
+            if (c == '[')
+                state = stCSI;
+            else {
+                t += r;
+                state = stTop;
+            }
+        } else {
+            r += c;
+            if (c >= 0x40 && c != 0x7e) {
+                if (c != 'p' && c != 'q' && c != 's' && c != 'a' && c != 'b')
+                    t += r;
+                state = stTop;
+                r.clear();
+            }
+        }
+    }
+    t += r;
+    return t;
+}
+
+
 void DerivationGoal::handleChildOutput(int fd, const string & data)
 {
     if ((hook && fd == hook->builderOut.readSide) ||
@@ -2455,7 +2491,7 @@ void DerivationGoal::handleChildOutput(int fd, const 
string & data)
             return;
         }
         if (verbosity >= settings.buildVerbosity)
-            writeToStderr(data);
+            writeToStderr(filterNixEscapes(data));
         if (bzLogFile) {
             int err;
             BZ2_bzWrite(&err, bzLogFile, (unsigned char *) data.data(), 
data.size());