On 19.03.13 22:03, Junio C Hamano wrote:
> Torsten Bögershausen <tboegi@xxxxxx> writes:
>
>> Use a compile switch IGNORECYGWINFSTRICKS to disable the usage
>> of cygwin_lstat_fn() only in path.c
>
> The analysis of the problem and the basic idea to disable the
> fast-but-lying fstricks in the code that matters may be good, but
> the implementation is questionable.
>
> What if we later need to move functions around, etc., so that some
> other calls in path.c still do want to use the fstricks bit while
> the existing ones in the file want the real lstat() information?
>
> Actually, that already is the case. The call to lstat() in
> validate_headref() only cares about the S_ISXXX() type and can
> afford to use the fast-and-lying one, no?
>
> How about doing something like this in the generic codepath, and
> implement your own cygwin_true_mode_bits() function at the cygwin
> compatibility layer, and add
>
> #define true_mode_bits cygwin_true_mode_bits
>
> in the compat/cygwin.h file? The change has the documentation value
> to clarify what each lstat() is used for, too.
>
> Ideally, the "#ifndef true_mode_bits" part may want to become a
> generic helper function if there are lstat() calls in other files
> that cygwin wants to use the real lstat() not the fast-but-lying
> one, but one step at a time.
>
> Hrm?
>
> path.c | 18 ++++++++++++++++--
> 1 file changed, 16 insertions(+), 2 deletions(-)
>
> diff --git a/path.c b/path.c
> index d3d3f8b..d0b31e5 100644
> --- a/path.c
> +++ b/path.c
> @@ -14,6 +14,21 @@
> #include "strbuf.h"
> #include "string-list.h"
>
> +#ifndef true_mode_bits
> +/*
> + * The replacement lstat(2) we use on Cygwin is incomplete and
> + * lies about permission bits; most of the time we do not care,
> + * but the callsites of this wrpper do care.
> + */
> +static int true_mode_bits(const char *path, int *mode)
> +{
> + struct stat st;
> + if (lstat(path, &st) < 0)
> + return -1;
> + return st.st_mode;
> +}
> +#endif
> +
> static char bad_path[] = "/bad-path/";
>
> static char *get_pathname(void)
> @@ -400,9 +415,8 @@ int set_shared_perm(const char *path, int mode)
> return 0;
> }
> if (!mode) {
> - if (lstat(path, &st) < 0)
> + if (true_mode_bits(path, &mode) < 0)
> return -1;
> - mode = st.st_mode;
> orig_mode = mode;
> } else
> orig_mode = 0;
>
Thanks for review, I Changed the function name into get_st_mode_bits(),
but that is only a suggestion.
-- >8 --
Subject: [PATCH] Make core.sharedRepository work under cygwin 1.7
When core.sharedRepository is used, set_shared_perm() in path.c
needs lstat() to return the correct POSIX permissions.
The default for cygwin is core.ignoreCygwinFSTricks = false, which
means that the fast implementation in do_stat() is used instead of lstat().
lstat() under cygwin uses the Windows security model to implement
POSIX-like permissions.
The user, group or everyone bits can be set individually.
do_stat() simplifes the file permission bits, and may return a wrong value:
The read-only attribute of a file is used to calculate
the permissions, resulting in either rw-r--r-- or r--r--r--
One effect of the simplified do_stat() is that t1301 failes.
Add a function cygwin_get_st_mode_bits() which returns the POSIX permissions.
When not compiling for cygwin, true_mode_bits() in path.c is used.
Side note:
t1301 passes under cygwin 1.5.
The "user write" bit is synchronized with the "read only" attribute of a file:
$ chmod 444 x
$ attrib x
A R C:\temp\pt\x
cygwin 1.7 would show
A C:\temp\pt\x
Signed-off-by: Torsten Bögershausen <tboegi@xxxxxx>
---
compat/cygwin.c | 13 +++++++++++++
compat/cygwin.h | 5 +++++
git-compat-util.h | 1 +
path.c | 20 +++++++++++++++++---
4 files changed, 36 insertions(+), 3 deletions(-)
diff --git a/compat/cygwin.c b/compat/cygwin.c
index 5428858..871b41d 100644
--- a/compat/cygwin.c
+++ b/compat/cygwin.c
@@ -1,3 +1,4 @@
+#define CYGWIN_C
#define WIN32_LEAN_AND_MEAN
#ifdef CYGWIN_V15_WIN32API
#include "../git-compat-util.h"
@@ -10,6 +11,18 @@
#endif
#include "../cache.h" /* to read configuration */
+/*
+ * Return POSIX permission bits, regardless of core.ignorecygwinfstricks
+ */
+int cygwin_get_st_mode_bits(const char *path, int *mode)
+{
+ struct stat st;
+ if (lstat(path, &st) < 0)
+ return -1;
+ *mode = st.st_mode;
+ return 0;
+}
+
static inline void filetime_to_timespec(const FILETIME *ft, struct timespec *ts)
{
long long winTime = ((long long)ft->dwHighDateTime << 32) +
diff --git a/compat/cygwin.h b/compat/cygwin.h
index a3229f5..c04965a 100644
--- a/compat/cygwin.h
+++ b/compat/cygwin.h
@@ -4,6 +4,11 @@
typedef int (*stat_fn_t)(const char*, struct stat*);
extern stat_fn_t cygwin_stat_fn;
extern stat_fn_t cygwin_lstat_fn;
+int cygwin_get_st_mode_bits(const char *path, int *mode);
+#define get_st_mode_bits(p,m) cygwin_get_st_mode_bits((p),(m))
+#ifndef CYGWIN_C
+/* cygwin.c needs the original lstat() */
#define stat(path, buf) (*cygwin_stat_fn)(path, buf)
#define lstat(path, buf) (*cygwin_lstat_fn)(path, buf)
+#endif
diff --git a/git-compat-util.h b/git-compat-util.h
index b7eaaa9..04a67ad 100644
--- a/git-compat-util.h
+++ b/git-compat-util.h
@@ -160,6 +160,7 @@
typedef long intptr_t;
typedef unsigned long uintptr_t;
#endif
+int get_st_mode_bits(const char *path, int *mode);
#if defined(__CYGWIN__)
#undef _XOPEN_SOURCE
#include <grp.h>
diff --git a/path.c b/path.c
index d3d3f8b..2fdccc2 100644
--- a/path.c
+++ b/path.c
@@ -14,6 +14,22 @@
#include "strbuf.h"
#include "string-list.h"
+#ifndef get_st_mode_bits
+/*
+ * The replacement lstat(2) we use on Cygwin is incomplete and
+ * may return wrong permission bits. Most of the time we do not care,
+ * but the callsites of this wrapper do care.
+ */
+int get_st_mode_bits(const char *path, int *mode)
+{
+ struct stat st;
+ if (lstat(path, &st) < 0)
+ return -1;
+ *mode = st.st_mode;
+ return 0;
+}
+#endif
+
static char bad_path[] = "/bad-path/";
static char *get_pathname(void)
@@ -391,7 +407,6 @@ const char *enter_repo(const char *path, int strict)
int set_shared_perm(const char *path, int mode)
{
- struct stat st;
int tweak, shared, orig_mode;
if (!shared_repository) {
@@ -400,9 +415,8 @@ int set_shared_perm(const char *path, int mode)
return 0;
}
if (!mode) {
- if (lstat(path, &st) < 0)
+ if (get_st_mode_bits(path, &mode) < 0)
return -1;
- mode = st.st_mode;
orig_mode = mode;
} else
orig_mode = 0;
--
1.8.2.341.g543621f
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