From be66a6c43dcba42c56f66a8706721a76098f8e25 Mon Sep 17 00:00:00 2001 From: Johannes Schindelin Date: Sat, 25 Apr 2009 11:57:14 +0200 Subject: [PATCH] Add an option not to use link(src, dest) && unlink(src) when that is unreliable It seems that accessing NTFS partitions with ufsd (at least on my EeePC) has an unnerving bug: if you link() a file and unlink() it right away, the target of the link() will have the correct size, but consist of NULs. It seems as if the calls are simply not serialized correctly, as single-stepping through the function move_temp_to_file() works flawlessly. As ufsd is "Commertial software" (sic!), I cannot fix it, and have to work around it in Git. At the same time, it seems that this fixes msysGit issues 222 and 229 to assume that Windows cannot handle link() && unlink(). Signed-off-by: Johannes Schindelin Acked-by: Johannes Sixt Signed-off-by: Junio C Hamano --- Documentation/config.txt | 5 +++++ Makefile | 8 ++++++++ cache.h | 2 ++ config.c | 5 +++++ environment.c | 4 ++++ sha1_file.c | 5 ++++- 6 files changed, 28 insertions(+), 1 deletion(-) diff --git a/Documentation/config.txt b/Documentation/config.txt index 31885690f0..d31adb6719 100644 --- a/Documentation/config.txt +++ b/Documentation/config.txt @@ -429,6 +429,11 @@ relatively high IO latencies. With this set to 'true', git will do the index comparison to the filesystem data in parallel, allowing overlapping IO's. +core.unreliableHardlinks:: + Some filesystem drivers cannot properly handle hardlinking a file + and deleting the source right away. In such a case, you need to + set this config variable to 'true'. + alias.*:: Command aliases for the linkgit:git[1] command wrapper - e.g. after defining "alias.last = cat-file commit HEAD", the invocation diff --git a/Makefile b/Makefile index 6f602c7bbf..5c8e83a997 100644 --- a/Makefile +++ b/Makefile @@ -171,6 +171,10 @@ all:: # Define UNRELIABLE_FSTAT if your system's fstat does not return the same # information on a not yet closed file that lstat would return for the same # file after it was closed. +# +# Define UNRELIABLE_HARDLINKS if your operating systems has problems when +# hardlinking a file to another name and unlinking the original file right +# away (some NTFS drivers seem to zero the contents in that scenario). GIT-VERSION-FILE: .FORCE-GIT-VERSION-FILE @$(SHELL_PATH) ./GIT-VERSION-GEN @@ -835,6 +839,7 @@ ifneq (,$(findstring MINGW,$(uname_S))) NO_NSEC = YesPlease USE_WIN32_MMAP = YesPlease UNRELIABLE_FSTAT = UnfortunatelyYes + UNRELIABLE_HARDLINKS = UnfortunatelySometimes COMPAT_CFLAGS += -D__USE_MINGW_ACCESS -DNOGDI -Icompat -Icompat/regex -Icompat/fnmatch COMPAT_CFLAGS += -DSNPRINTF_SIZE_CORR=1 COMPAT_CFLAGS += -DSTRIP_EXTENSION=\".exe\" @@ -1018,6 +1023,9 @@ else COMPAT_OBJS += compat/win32mmap.o endif endif +ifdef UNRELIABLE_HARDLINKS + COMPAT_CFLAGS += -DUNRELIABLE_HARDLINKS=1 +endif ifdef NO_PREAD COMPAT_CFLAGS += -DNO_PREAD COMPAT_OBJS += compat/pread.o diff --git a/cache.h b/cache.h index ab1294d6fb..ff9e145be0 100644 --- a/cache.h +++ b/cache.h @@ -554,6 +554,8 @@ extern enum branch_track git_branch_track; extern enum rebase_setup_type autorebase; extern enum push_default_type push_default; +extern int unreliable_hardlinks; + #define GIT_REPO_VERSION 0 extern int repository_format_version; extern int check_repository_format(void); diff --git a/config.c b/config.c index 8c1ae598a9..1750cfb85e 100644 --- a/config.c +++ b/config.c @@ -495,6 +495,11 @@ static int git_default_core_config(const char *var, const char *value) return 0; } + if (!strcmp(var, "core.unreliablehardlinks")) { + unreliable_hardlinks = git_config_bool(var, value); + return 0; + } + /* Add other config variables here and to Documentation/config.txt. */ return 0; } diff --git a/environment.c b/environment.c index 4696885b22..10578d24d7 100644 --- a/environment.c +++ b/environment.c @@ -43,6 +43,10 @@ unsigned whitespace_rule_cfg = WS_DEFAULT_RULE; enum branch_track git_branch_track = BRANCH_TRACK_REMOTE; enum rebase_setup_type autorebase = AUTOREBASE_NEVER; enum push_default_type push_default = PUSH_DEFAULT_UNSPECIFIED; +#ifndef UNRELIABLE_HARDLINKS +#define UNRELIABLE_HARDLINKS 0 +#endif +int unreliable_hardlinks = UNRELIABLE_HARDLINKS; /* Parallel index stat data preload? */ int core_preload_index = 0; diff --git a/sha1_file.c b/sha1_file.c index 8fe135dc61..11969fc161 100644 --- a/sha1_file.c +++ b/sha1_file.c @@ -2225,7 +2225,9 @@ int move_temp_to_file(const char *tmpfile, const char *filename) { int ret = 0; - if (link(tmpfile, filename)) + if (unreliable_hardlinks) + goto try_rename; + else if (link(tmpfile, filename)) ret = errno; /* @@ -2240,6 +2242,7 @@ int move_temp_to_file(const char *tmpfile, const char *filename) * left to unlink. */ if (ret && ret != EEXIST) { + try_rename: if (!rename(tmpfile, filename)) goto out; ret = errno; -- 2.11.4.GIT