From 231f7fd15f9696e97c48b91e2b847648cab87e09 Mon Sep 17 00:00:00 2001
From: Alexandre Oliva <oliva@dcc.unicamp.br>
Date: Mon, 22 Feb 1999 20:47:30 +0000
Subject: [PATCH] * ltmain.in: create on-demand executable as
 $progdir/$$-$program, and rename it to $progdir/$program only when it's
 finished, to avoid race conditions.  We can still get the program linked
 multiple times, if multiple instances are started simultaneously and the
 program does not exist, but they are very unlikely to interfere with each
 other.  There's still a possibility that one process removes the $program
 another has just created, and doesn't replace it before the other tries to
 run it, in a system whose `mv' is not atomic, so it will $rm then $mv, but so
 what? :-) Locking files have been avoided to prevent dead-locks in case they
 are left over after a reboot or crash.

---
 ChangeLog | 12 ++++++++++++
 ltmain.in | 26 ++++++++++++++++++--------
 2 files changed, 30 insertions(+), 8 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index a8cfd687e..b130c58c9 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,17 @@
 1999-02-22  Alexandre Oliva  <oliva@dcc.unicamp.br>
 
+	* ltmain.in: create on-demand executable as $progdir/$$-$program,
+	and rename it to $progdir/$program only when it's finished, to
+	avoid race conditions.  We can still get the program linked
+	multiple times, if multiple instances are started simultaneously
+	and the program does not exist, but they are very unlikely to
+	interfere with each other.  There's still a possibility that one
+	process removes the $program another has just created, and doesn't 
+	replace it before the other tries to run it, in a system whose
+	`mv' is not atomic, so it will $rm then $mv, but so what? :-)
+	Locking files have been avoided to prevent dead-locks in case they 
+	are left over after a reboot or crash.
+
 	* TODO: removed ILD, soon to be merged, and added convenience
 	libraries docs
 
diff --git a/ltmain.in b/ltmain.in
index d934fc521..fe1dedd82 100644
--- a/ltmain.in
+++ b/ltmain.in
@@ -2544,7 +2544,7 @@ static const void *lt_preloaded_setup() {
       fi
 
       if test "$shlibpath_overrides_runpath" != yes; then
-	compile_for_build_command=`echo "X$compile_command" | $Xsed -e "s%@BUILD_LIBDIRS_FLAGS@%$build_libdirs_flags%" -e "s%@BUILD_RPATH@%$build_rpath%" -e "s%@HARDCODE_BUILD_LIBDIRS@%$build_libdirs%" -e 's%@THISDIR@%\$thisdir%g' -e 's%@OUTPUT@%\$progdir/\$program%g'`
+	compile_for_build_command=`echo "X$compile_command" | $Xsed -e "s%@BUILD_LIBDIRS_FLAGS@%$build_libdirs_flags%" -e "s%@BUILD_RPATH@%$build_rpath%" -e "s%@HARDCODE_BUILD_LIBDIRS@%$build_libdirs%" -e 's%@THISDIR@%\$thisdir%g' -e 's%@OUTPUT@%\$progdir/\$file%g'`
       fi
 
       # Replace the output file specification.
@@ -2661,16 +2661,26 @@ else
   progdir=\"\$thisdir/$objdir/$objdir\"
 
   if test ! -f \"\$progdir/\$program\" || \\
-     { newestfile=\`ls -1dt \"\$progdir/\$program\" \"\$progdir/../\$program\" 2>/dev/null | sed 1q\`; \\
-       test \"X\$newestfile\" != \"X\$progdir/\$program\"; }; then
-    if test ! -d \"\$progdir\"; then
-      $mkdir \"\$progdir\"
+     { file=\`ls -1dt \"\$progdir/\$program\" \"\$progdir/../\$program\" 2>/dev/null | sed 1q\`; \\
+       test \"X\$file\" != \"X\$progdir/\$program\"; }; then
+
+    file=\"\$\$-\$program\"
+
+    $rm \"\$progdir/\$file\""
+
+	  echo >> $output "\
+
+    # link executable that uses uninstalled libraries
+    if (cd \"\$thisdir\" && $compile_for_build_command); then :
     else
-      $rm \"\$progdir/\$program\"
+      $rm \"\$progdir/\$file\"
+      exit 1
     fi
 
-    # link executable that uses uninstalled libraries
-    (cd \$thisdir && $compile_for_build_command) || exit 1
+    $mv \"\$progdir/\$file\" \"\$progdir/\$program\" 2>/dev/null ||
+    { $rm \"\$progdir/\$program\";
+      $mv \"\$progdir/\$file\" \"\$progdir/\$program\"; }
+    $rm \"\$progdir/\$file\"
   fi"
 	fi
 
-- 
2.47.3