Merge branch 'js/mingw-o-append'

Further fix for O_APPEND emulation on Windows

* js/mingw-o-append:
mingw: fix mingw_open_append to work with named pipes
t0051: test GIT_TRACE to a windows named pipe

diff --git a/Makefile b/Makefile
index b567ccca45883c15bc9b8dbd60abe6a88186620f..13e1c5247824d8db94126cb91d35df57440c9384 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -740,6 +740,7 @@ TEST_BUILTINS_OBJS += test-submodule-config.o
 TEST_BUILTINS_OBJS += test-subprocess.o
 TEST_BUILTINS_OBJS += test-urlmatch-normalization.o
 TEST_BUILTINS_OBJS += test-wildmatch.o
+TEST_BUILTINS_OBJS += test-windows-named-pipe.o
 TEST_BUILTINS_OBJS += test-write-cache.o
 
 TEST_PROGRAMS_NEED_X += test-dump-fsmonitor

diff --git a/compat/mingw.c b/compat/mingw.c
index 858ca14a57351062d2bba147c72ed460fb0aa533..18caf21969a5917e8e6c6d754beffbba2741e6c2 100644 (file)
--- a/compat/mingw.c
+++ b/compat/mingw.c
@@ -341,6 +341,19 @@ int mingw_mkdir(const char *path, int mode)
        return ret;
 }
 
+/*
+ * Calling CreateFile() using FILE_APPEND_DATA and without FILE_WRITE_DATA
+ * is documented in [1] as opening a writable file handle in append mode.
+ * (It is believed that) this is atomic since it is maintained by the
+ * kernel unlike the O_APPEND flag which is racily maintained by the CRT.
+ *
+ * [1] https://docs.microsoft.com/en-us/windows/desktop/fileio/file-access-rights-constants
+ *
+ * This trick does not appear to work for named pipes.  Instead it creates
+ * a named pipe client handle that cannot be written to.  Callers should
+ * just use the regular _wopen() for them.  (And since client handle gets
+ * bound to a unique server handle, it isn't really an issue.)
+ */
 static int mingw_open_append(wchar_t const *wfilename, int oflags, ...)
 {
        HANDLE handle;
@@ -360,10 +373,12 @@ static int mingw_open_append(wchar_t const *wfilename, int oflags, ...)
                        NULL, create, FILE_ATTRIBUTE_NORMAL, NULL);
        if (handle == INVALID_HANDLE_VALUE)
                return errno = err_win_to_posix(GetLastError()), -1;
+
        /*
         * No O_APPEND here, because the CRT uses it only to reset the
-        * file pointer to EOF on write(); but that is not necessary
-        * for a file created with FILE_APPEND_DATA.
+        * file pointer to EOF before each write(); but that is not
+        * necessary (and may lead to races) for a file created with
+        * FILE_APPEND_DATA.
         */
        fd = _open_osfhandle((intptr_t)handle, O_BINARY);
        if (fd < 0)
@@ -371,6 +386,21 @@ static int mingw_open_append(wchar_t const *wfilename, int oflags, ...)
        return fd;
 }
 
+/*
+ * Does the pathname map to the local named pipe filesystem?
+ * That is, does it have a "//./pipe/" prefix?
+ */
+static int is_local_named_pipe_path(const char *filename)
+{
+       return (is_dir_sep(filename[0]) &&
+               is_dir_sep(filename[1]) &&
+               filename[2] == '.'  &&
+               is_dir_sep(filename[3]) &&
+               !strncasecmp(filename+4, "pipe", 4) &&
+               is_dir_sep(filename[8]) &&
+               filename[9]);
+}
+
 int mingw_open (const char *filename, int oflags, ...)
 {
        typedef int (*open_fn_t)(wchar_t const *wfilename, int oflags, ...);
@@ -387,7 +417,7 @@ int mingw_open (const char *filename, int oflags, ...)
        if (filename && !strcmp(filename, "/dev/null"))
                filename = "nul";
 
-       if (oflags & O_APPEND)
+       if ((oflags & O_APPEND) && !is_local_named_pipe_path(filename))
                open_fn = mingw_open_append;
        else
                open_fn = _wopen;

diff --git a/t/helper/test-tool.c b/t/helper/test-tool.c
index bef50c4dcc7c595c22074b3f5ceb62cf260a6393..b87a8c1f229ce51eaa29d37614370c058389ca4b 100644 (file)
--- a/t/helper/test-tool.c
+++ b/t/helper/test-tool.c
@@ -45,6 +45,9 @@ static struct test_cmd cmds[] = {
        { "subprocess", cmd__subprocess },
        { "urlmatch-normalization", cmd__urlmatch_normalization },
        { "wildmatch", cmd__wildmatch },
+#ifdef GIT_WINDOWS_NATIVE
+       { "windows-named-pipe", cmd__windows_named_pipe },
+#endif
        { "write-cache", cmd__write_cache },
 };
 

diff --git a/t/helper/test-tool.h b/t/helper/test-tool.h
index 321982e4bc0366281af400f67ebd2ca3e68fffe7..e074957279f16cce0cf2c6ea1fc5401fb1aac42b 100644 (file)
--- a/t/helper/test-tool.h
+++ b/t/helper/test-tool.h
@@ -41,6 +41,9 @@ int cmd__submodule_config(int argc, const char **argv);
 int cmd__subprocess(int argc, const char **argv);
 int cmd__urlmatch_normalization(int argc, const char **argv);
 int cmd__wildmatch(int argc, const char **argv);
+#ifdef GIT_WINDOWS_NATIVE
+int cmd__windows_named_pipe(int argc, const char **argv);
+#endif
 int cmd__write_cache(int argc, const char **argv);
 
 #endif

diff --git a/t/helper/test-windows-named-pipe.c b/t/helper/test-windows-named-pipe.c
new file mode 100644 (file)
index 0000000..b4b752b
--- /dev/null
+++ b/t/helper/test-windows-named-pipe.c
@@ -0,0 +1,72 @@
+#include "test-tool.h"
+#include "git-compat-util.h"
+#include "strbuf.h"
+
+#ifdef GIT_WINDOWS_NATIVE
+static const char *usage_string = "<pipe-filename>";
+
+#define TEST_BUFSIZE (4096)
+
+int cmd__windows_named_pipe(int argc, const char **argv)
+{
+       const char *filename;
+       struct strbuf pathname = STRBUF_INIT;
+       int err;
+       HANDLE h;
+       BOOL connected;
+       char buf[TEST_BUFSIZE + 1];
+
+       if (argc < 2)
+               goto print_usage;
+       filename = argv[1];
+       if (strchr(filename, '/') || strchr(filename, '\\'))
+               goto print_usage;
+       strbuf_addf(&pathname, "//./pipe/%s", filename);
+
+       /*
+        * Create a single instance of the server side of the named pipe.
+        * This will allow exactly one client instance to connect to it.
+        */
+       h = CreateNamedPipeA(
+               pathname.buf,
+               PIPE_ACCESS_INBOUND | FILE_FLAG_FIRST_PIPE_INSTANCE,
+               PIPE_TYPE_MESSAGE | PIPE_READMODE_MESSAGE | PIPE_WAIT,
+               PIPE_UNLIMITED_INSTANCES,
+               TEST_BUFSIZE, TEST_BUFSIZE, 0, NULL);
+       if (h == INVALID_HANDLE_VALUE) {
+               err = err_win_to_posix(GetLastError());
+               fprintf(stderr, "CreateNamedPipe failed: %s\n",
+                       strerror(err));
+               return err;
+       }
+
+       connected = ConnectNamedPipe(h, NULL)
+               ? TRUE
+               : (GetLastError() == ERROR_PIPE_CONNECTED);
+       if (!connected) {
+               err = err_win_to_posix(GetLastError());
+               fprintf(stderr, "ConnectNamedPipe failed: %s\n",
+                       strerror(err));
+               CloseHandle(h);
+               return err;
+       }
+
+       while (1) {
+               DWORD nbr;
+               BOOL success = ReadFile(h, buf, TEST_BUFSIZE, &nbr, NULL);
+               if (!success || nbr == 0)
+                       break;
+               buf[nbr] = 0;
+
+               write(1, buf, nbr);
+       }
+
+       DisconnectNamedPipe(h);
+       CloseHandle(h);
+       return 0;
+
+print_usage:
+       fprintf(stderr, "usage: %s %s\n", argv[0], usage_string);
+       return 1;
+}
+#endif

diff --git a/t/t0051-windows-named-pipe.sh b/t/t0051-windows-named-pipe.sh
new file mode 100755 (executable)
index 0000000..10ac92d
--- /dev/null
+++ b/t/t0051-windows-named-pipe.sh
@@ -0,0 +1,17 @@
+#!/bin/sh
+
+test_description='Windows named pipes'
+
+. ./test-lib.sh
+
+test_expect_success MINGW 'o_append write to named pipe' '
+       GIT_TRACE="$(pwd)/expect" git status >/dev/null 2>&1 &&
+       { test-tool windows-named-pipe t0051 >actual 2>&1 & } &&
+       pid=$! &&
+       sleep 1 &&
+       GIT_TRACE=//./pipe/t0051 git status >/dev/null 2>warning &&
+       wait $pid &&
+       test_cmp expect actual
+'
+
+test_done