git/compat
Johannes Schindelin fe21c6b285 mingw: reencode environment variables on the fly (UTF-16 <-> UTF-8)
On Windows, the authoritative environment is encoded in UTF-16. In Git
for Windows, we convert that to UTF-8 (because UTF-16 is *such* a
foreign idea to Git that its source code is unprepared for it).

Previously, out of performance concerns, we converted the entire
environment to UTF-8 in one fell swoop at the beginning, and upon
putenv() and run_command() converted it back.

Having a private copy of the environment comes with its own perils: when
a library used by Git's source code tries to modify the environment, it
does not really work (in Git for Windows' case, libcurl, see
https://github.com/git-for-windows/git/compare/bcad1e6d58^...bcad1e6d58^2
for a glimpse of the issues).

Hence, it makes our environment handling substantially more robust if we
switch to on-the-fly-conversion in `getenv()`/`putenv()` calls. Based
on an initial version in the MSVC context by Jeff Hostetler, this patch
makes it so.

Surprisingly, this has a *positive* effect on speed: at the time when
the current code was written, we tested the performance, and there were
*so many* `getenv()` calls that it seemed better to convert everything
in one go. In the meantime, though, Git has obviously been cleaned up a
bit with regards to `getenv()` calls so that the Git processes spawned
by the test suite use an average of only 40 `getenv()`/`putenv()` calls
over the process lifetime.

Speaking of the entire test suite: the total time spent in the
re-encoding in the current code takes about 32.4 seconds (out of 113
minutes runtime), whereas the code introduced in this patch takes only
about 8.2 seconds in total. Not much, but it proves that we need not be
concerned about the performance impact introduced by this patch.

Helped-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-10-31 11:43:14 +09:00
..
nedmalloc
poll Replace Free Software Foundation address in license notices 2017-11-09 13:21:21 +09:00
regex Replace Free Software Foundation address in license notices 2017-11-09 13:21:21 +09:00
vcbuild vcbuild/README: update to accommodate for missing common-cmds.h 2018-07-16 14:30:34 -07:00
win32 Win32: simplify loading of DLL functions 2017-09-26 11:02:49 +09:00
apple-common-crypto.h
basename.c
bswap.h bswap: add 64 bit endianness helper get_be64 2017-09-24 10:39:37 +09:00
cygwin.c cygwin: allow pushing to UNC paths 2017-07-05 14:01:03 -07:00
cygwin.h cygwin: allow pushing to UNC paths 2017-07-05 14:01:03 -07:00
fopen.c git_fopen: fix a sparse 'not declared' warning 2017-05-26 12:33:55 +09:00
gmtime.c
hstrerror.c
inet_ntop.c
inet_pton.c
memmem.c
mingw.c mingw: reencode environment variables on the fly (UTF-16 <-> UTF-8) 2018-10-31 11:43:14 +09:00
mingw.h mingw: reencode environment variables on the fly (UTF-16 <-> UTF-8) 2018-10-31 11:43:14 +09:00
mkdir.c
mkdtemp.c
mmap.c
msvc.c
msvc.h
obstack.c Replace Free Software Foundation address in license notices 2017-11-09 13:21:21 +09:00
obstack.h Replace Free Software Foundation address in license notices 2017-11-09 13:21:21 +09:00
pread.c
precompose_utf8.c config: don't include config.h by default 2017-06-15 12:56:22 -07:00
precompose_utf8.h compat/precompose_utf8.h: use more common include guard style 2018-08-15 11:52:09 -07:00
qsort.c
qsort_s.c
setenv.c
sha1-chunked.c
sha1-chunked.h
snprintf.c
stat.c
strcasestr.c
strdup.c
strlcpy.c
strtoimax.c
strtoumax.c
terminal.c
terminal.h
unsetenv.c
win32.h
win32mmap.c
winansi.c