From 62446cb66567e967e1af2b6a0c152fdeb98508c8 Mon Sep 17 00:00:00 2001
From: Steven Knight <knight@baldmt.com>
Date: Fri, 23 Aug 2002 02:14:44 +0000
Subject: Implement spawn() using os.system() on Posix OSes.  (Anthony Roach)

---
 src/CHANGES.txt            |  4 +++
 src/engine/SCons/Action.py | 62 +++++++++++++++++++++++++++++++++-------------
 test/DVIPDF.py             |  3 ++-
 test/DVIPDFFLAGS.py        |  3 ++-
 test/F77PATH.py            |  6 ++---
 5 files changed, 55 insertions(+), 23 deletions(-)

diff --git a/src/CHANGES.txt b/src/CHANGES.txt
index fb8196e..80a0db6 100644
--- a/src/CHANGES.txt
+++ b/src/CHANGES.txt
@@ -32,6 +32,10 @@ RELEASE 0.09 -
  - Fix differently ordered targets causing unnecessary rebuilds
    on case insensitive systems.
 
+ - Use os.system() to execute external commands whenever the "env"
+   utility is available, which is much faster than fork()/exec(),
+   and fixes the -j option on several platforms.
+
 
 
 RELEASE 0.08 - Mon, 15 Jul 2002 12:08:51 -0500
diff --git a/src/engine/SCons/Action.py b/src/engine/SCons/Action.py
index e2fe07f..7aecf00 100644
--- a/src/engine/SCons/Action.py
+++ b/src/engine/SCons/Action.py
@@ -58,23 +58,51 @@ def quote(x):
 
 if os.name == 'posix':
 
-    def defaultSpawn(cmd, args, env):
-        pid = os.fork()
-        if not pid:
-            # Child process.
-            exitval = 127
-            args = ['sh', '-c', string.join(map(quote, args))]
-            try:
-                os.execvpe('sh', args, env)
-            except OSError, e:
-                exitval = exitvalmap[e[0]]
-                sys.stderr.write("scons: %s: %s\n" % (cmd, e[1]))
-            os._exit(exitval)
-        else:
-            # Parent process.
-            pid, stat = os.waitpid(pid, 0)
-            ret = stat >> 8
-            return ret
+    def escape(arg):
+        "escape shell special characters"
+        slash = '\\'
+        special = '"\'`&;><| \t#()*?$~!'
+
+        arg = string.replace(arg, slash, slash+slash)
+        for c in special:
+            arg = string.replace(arg, c, slash+c)
+
+        return arg
+
+    # If the env command exists, then we can use os.system()
+    # to spawn commands, otherwise we fall back on os.fork()/os.exec().
+    # os.system() is prefered because it seems to work better with
+    # threads (i.e. -j) and is more efficient than forking Python.
+    if SCons.Util.WhereIs('env'):
+        def defaultSpawn(cmd, args, env):
+            if env:
+                s = 'env -i '
+                for key in env.keys():
+                    s = s + '%s=%s '%(key, escape(env[key]))
+                s = s + 'sh -c '
+                s = s + escape(string.join(map(quote, args)))
+            else:
+                s = string.join(map(quote, args))
+
+            return os.system(s) >> 8
+    else:
+        def defaultSpawn(cmd, args, env):
+            pid = os.fork()
+            if not pid:
+                # Child process.
+                exitval = 127
+                args = ['sh', '-c', string.join(map(quote, args))]
+                try:
+                    os.execvpe('sh', args, env)
+                except OSError, e:
+                    exitval = exitvalmap[e[0]]
+                    sys.stderr.write("scons: %s: %s\n" % (cmd, e[1]))
+                os._exit(exitval)
+            else:
+                # Parent process.
+                pid, stat = os.waitpid(pid, 0)
+                ret = stat >> 8
+                return ret
 
 elif os.name == 'nt':
 
diff --git a/test/DVIPDF.py b/test/DVIPDF.py
index d22cfd8..25856dc 100644
--- a/test/DVIPDF.py
+++ b/test/DVIPDF.py
@@ -100,8 +100,9 @@ test.fail_test(test.read('test2.pdf') != "This is a .tex test.\n")
 
 
 dvipdf = test.where_is('dvipdf')
+tex = test.where_is('tex')
 
-if dvipdf:
+if dvipdf and tex:
 
     test.write("wrapper.py", """import os
 import string
diff --git a/test/DVIPDFFLAGS.py b/test/DVIPDFFLAGS.py
index e6f9146..9962253 100644
--- a/test/DVIPDFFLAGS.py
+++ b/test/DVIPDFFLAGS.py
@@ -106,8 +106,9 @@ test.fail_test(test.read('test2.pdf') != " -x\nThis is a .tex test.\n")
 
 
 dvipdf = test.where_is('dvipdf')
+tex = test.where_is('tex')
 
-if dvipdf:
+if dvipdf and tex:
 
     test.write("wrapper.py", """import os
 import string
diff --git a/test/F77PATH.py b/test/F77PATH.py
index ad38bf1..3dcc280 100644
--- a/test/F77PATH.py
+++ b/test/F77PATH.py
@@ -42,10 +42,8 @@ args = prog + ' ' + subdir_prog + ' ' + variant_prog
 test = TestSCons.TestSCons()
 
 if not test.where_is('g77'):
-    print "g77 is not installed on this system."
-    print "Cannot test F77PATH."
-    test.no_result(1)
-
+    test.pass_test()
+    
 test.subdir('include', 'subdir', ['subdir', 'include'], 'inc2')
 
 test.write('SConstruct', """
-- 
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