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From 06e677d2db434aa3d11b14a7a8bf6c48c8caf4ac Mon Sep 17 00:00:00 2001
From: Jonathan Nieder <jrnieder@gmail.com>
Date: Wed, 12 Oct 2011 03:38:42 -0500
Subject: [PATCH 12/12] Makefile: add a knob to turn off hardlinks within same
directory
The git builtins in $(gitexecdir) are implemented as hard links to a
single git binary by default, so even the overhead of symlink
resolution is not needed to run them. However, the trick can be
harmful, in two cases:
- on Windows, some tools to estimate directory size hugely
overestimate the size of git (each hardlink counts as taking up the
same amount of space as git.exe)
- various filesystems have limits on the number of hardlinks that
can be made to a particular file --- Linux's LINK_MAX is 127,
_POSIX_LINK_MAX is 8, and btrfs has a limit of 4096 /
($len_filename + 8) or so links to a given inode in a single
directory.
Normally that second case is not a problem (when ln fails, "make
install" falls back to "ln -s"), but if git is tar'ed up on one
filesystem and then extracted on a more limited one, it can result in
"Too many links" errors.
Nowadays people are encouraged to (and typically do) run builtins
using the "git" command name directly rather than those dashed forms
in scripts, making the use of hardlinks for the dashed forms a
somewhat pointless optimization. Introduce a new knob to allow people
to turn it off with a simple "make install NO_HARDLINKS=YesPlease".
Typically someone using this setting would want to set
NO_CROSS_DIRECTORY_HARDLINKS, too, but that is not enforced, so you
can make $(bindir)/git and $(gitexecdir)/git into hardlinks to the
same inode and still make sure your tarball avoids the btrfs limits if
you want.
Requested-by: Bastian Blank <waldi@debian.org>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
---
Makefile | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/Makefile b/Makefile
index 51b8e48..1e518f5 100644
--- a/Makefile
+++ b/Makefile
@@ -251,6 +251,10 @@ all::
# Define NO_CROSS_DIRECTORY_HARDLINKS if you plan to distribute the installed
# programs as a tar, where bin/ and libexec/ might be on different file systems.
#
+# Define NO_HARDLINKS if you plan to distribute the installed programs as a tar
+# that might be extracted on a filesystem like btrfs that does not cope well
+# with many links to one inode in one directory.
+#
# Define USE_NED_ALLOCATOR if you want to replace the platforms default
# memory allocators with the nedmalloc allocator written by Niall Douglas.
#
@@ -2552,12 +2556,14 @@ endif
} && \
for p in $(filter $(install_bindir_programs),$(BUILT_INS)); do \
$(RM) "$$bindir/$$p" && \
+ test -z "$(NO_HARDLINKS)" && \
ln "$$bindir/git$X" "$$bindir/$$p" 2>/dev/null || \
ln -s "git$X" "$$bindir/$$p" 2>/dev/null || \
cp "$$bindir/git$X" "$$bindir/$$p" || exit; \
done && \
for p in $(BUILT_INS); do \
$(RM) "$$execdir/$$p" && \
+ test -z "$(NO_HARDLINKS)" && \
ln "$$execdir/git$X" "$$execdir/$$p" 2>/dev/null || \
ln -s "git$X" "$$execdir/$$p" 2>/dev/null || \
cp "$$execdir/git$X" "$$execdir/$$p" || exit; \
@@ -2565,6 +2571,7 @@ endif
remote_curl_aliases="$(REMOTE_CURL_ALIASES)" && \
for p in $$remote_curl_aliases; do \
$(RM) "$$execdir/$$p" && \
+ test -z "$(NO_HARDLINKS)" && \
ln "$$execdir/git-remote-http$X" "$$execdir/$$p" 2>/dev/null || \
ln -s "git-remote-http$X" "$$execdir/$$p" 2>/dev/null || \
cp "$$execdir/git-remote-http$X" "$$execdir/$$p" || exit; \
--
1.7.10
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