From 62947fadbb189ea47ef9780d530dd0e9f037efdb Mon Sep 17 00:00:00 2001 From: Bert Belder Date: Fri, 26 Oct 2018 11:13:45 +0200 Subject: [PATCH 1/3] Win32: symlink: move phantom symlink creation to a separate function Signed-off-by: Bert Belder --- compat/mingw.c | 91 +++++++++++++++++++++++++++----------------------- 1 file changed, 49 insertions(+), 42 deletions(-) diff --git a/compat/mingw.c b/compat/mingw.c index e7a8f40f34..6f9a82eb74 100644 --- a/compat/mingw.c +++ b/compat/mingw.c @@ -399,6 +399,54 @@ static void process_phantom_symlinks(void) LeaveCriticalSection(&phantom_symlinks_cs); } +static int create_phantom_symlink(wchar_t *wtarget, wchar_t *wlink) +{ + int len; + + /* create file symlink */ + if (!CreateSymbolicLinkW(wlink, wtarget, symlink_file_flags)) { + errno = err_win_to_posix(GetLastError()); + return -1; + } + + /* convert to directory symlink if target exists */ + switch (process_phantom_symlink(wtarget, wlink)) { + case PHANTOM_SYMLINK_RETRY: { + /* if target doesn't exist, add to phantom symlinks list */ + wchar_t wfullpath[MAX_LONG_PATH]; + struct phantom_symlink_info *psi; + + /* convert to absolute path to be independent of cwd */ + len = GetFullPathNameW(wlink, MAX_LONG_PATH, wfullpath, NULL); + if (!len || len >= MAX_LONG_PATH) { + errno = err_win_to_posix(GetLastError()); + return -1; + } + + /* over-allocate and fill phantom_symlink_info structure */ + psi = xmalloc(sizeof(struct phantom_symlink_info) + + sizeof(wchar_t) * (len + wcslen(wtarget) + 2)); + psi->wlink = (wchar_t *)(psi + 1); + wcscpy(psi->wlink, wfullpath); + psi->wtarget = psi->wlink + len + 1; + wcscpy(psi->wtarget, wtarget); + + EnterCriticalSection(&phantom_symlinks_cs); + psi->next = phantom_symlinks; + phantom_symlinks = psi; + LeaveCriticalSection(&phantom_symlinks_cs); + break; + } + case PHANTOM_SYMLINK_DIRECTORY: + /* if we created a dir symlink, process other phantom symlinks */ + process_phantom_symlinks(); + break; + default: + break; + } + return 0; +} + /* Normalizes NT paths as returned by some low-level APIs. */ static wchar_t *normalize_ntpath(wchar_t *wbuf) { @@ -2498,48 +2546,7 @@ int symlink(const char *target, const char *link) if (wtarget[len] == '/') wtarget[len] = '\\'; - /* create file symlink */ - if (!CreateSymbolicLinkW(wlink, wtarget, symlink_file_flags)) { - errno = err_win_to_posix(GetLastError()); - return -1; - } - - /* convert to directory symlink if target exists */ - switch (process_phantom_symlink(wtarget, wlink)) { - case PHANTOM_SYMLINK_RETRY: { - /* if target doesn't exist, add to phantom symlinks list */ - wchar_t wfullpath[MAX_LONG_PATH]; - struct phantom_symlink_info *psi; - - /* convert to absolute path to be independent of cwd */ - len = GetFullPathNameW(wlink, MAX_LONG_PATH, wfullpath, NULL); - if (!len || len >= MAX_LONG_PATH) { - errno = err_win_to_posix(GetLastError()); - return -1; - } - - /* over-allocate and fill phantom_symlink_info structure */ - psi = xmalloc(sizeof(struct phantom_symlink_info) - + sizeof(wchar_t) * (len + wcslen(wtarget) + 2)); - psi->wlink = (wchar_t *)(psi + 1); - wcscpy(psi->wlink, wfullpath); - psi->wtarget = psi->wlink + len + 1; - wcscpy(psi->wtarget, wtarget); - - EnterCriticalSection(&phantom_symlinks_cs); - psi->next = phantom_symlinks; - phantom_symlinks = psi; - LeaveCriticalSection(&phantom_symlinks_cs); - break; - } - case PHANTOM_SYMLINK_DIRECTORY: - /* if we created a dir symlink, process other phantom symlinks */ - process_phantom_symlinks(); - break; - default: - break; - } - return 0; + return create_phantom_symlink(wtarget, wlink); } #ifndef _WINNT_H From 669fe2a24babcd85dc4d96d90a860fb14d16d228 Mon Sep 17 00:00:00 2001 From: Bert Belder Date: Fri, 26 Oct 2018 11:51:51 +0200 Subject: [PATCH 2/3] Win32: symlink: specify symlink type in .gitattributes On Windows, symbolic links have a type: a "file symlink" must point at a file, and a "directory symlink" must point at a directory. If the type of symlink does not match its target, it doesn't work. Git does not record the type of symlink in the index or in a tree. On checkout it'll guess the type, which only works if the target exists at the time the symlink is created. This may often not be the case, for example when the link points at a directory inside a submodule. By specifying `symlink=file` or `symlink=dir` the user can specify what type of symlink Git should create, so Git doesn't have to rely on unreliable heuristics. Signed-off-by: Bert Belder Signed-off-by: Johannes Schindelin --- Documentation/gitattributes.txt | 30 ++++++++++++++++++ compat/mingw.c | 54 ++++++++++++++++++++++++++++++++- 2 files changed, 83 insertions(+), 1 deletion(-) diff --git a/Documentation/gitattributes.txt b/Documentation/gitattributes.txt index b8392fc330..ad0b4ea6c4 100644 --- a/Documentation/gitattributes.txt +++ b/Documentation/gitattributes.txt @@ -378,6 +378,36 @@ sign `$` upon checkout. Any byte sequence that begins with with `$Id$` upon check-in. +`symlink` +^^^^^^^^^ + +On Windows, symbolic links have a type: a "file symlink" must point at +a file, and a "directory symlink" must point at a directory. If the +type of symlink does not match its target, it doesn't work. + +Git does not record the type of symlink in the index or in a tree. On +checkout it'll guess the type, which only works if the target exists +at the time the symlink is created. This may often not be the case, +for example when the link points at a directory inside a submodule. + +The `symlink` attribute allows you to explicitly set the type of symlink +to `file` or `dir`, so Git doesn't have to guess. If you have a set of +symlinks that point at other files, you can do: + +------------------------ +*.gif symlink=file +------------------------ + +To tell Git that a symlink points at a directory, use: + +------------------------ +tools_folder symlink=dir +------------------------ + +The `symlink` attribute is ignored on platforms other than Windows, +since they don't distinguish between different types of symlinks. + + `filter` ^^^^^^^^ diff --git a/compat/mingw.c b/compat/mingw.c index 6f9a82eb74..7b1607c2e0 100644 --- a/compat/mingw.c +++ b/compat/mingw.c @@ -8,6 +8,7 @@ #include "../cache.h" #include "win32/lazyload.h" #include "../config.h" +#include "../attr.h" #define HCAST(type, handle) ((type)(intptr_t)handle) @@ -2526,6 +2527,33 @@ int link(const char *oldpath, const char *newpath) return 0; } +enum symlink_type { + SYMLINK_TYPE_UNSPECIFIED = 0, + SYMLINK_TYPE_FILE, + SYMLINK_TYPE_DIRECTORY, +}; + +static enum symlink_type check_symlink_attr(const char *link) +{ + static struct attr_check *check; + const char *value; + + if (!check) + check = attr_check_initl("symlink", NULL); + + git_check_attr(&the_index, link, check); + + value = check->items[0].value; + if (value == NULL) + ; + else if (!strcmp(value, "file")) + return SYMLINK_TYPE_FILE; + else if (!strcmp(value, "dir")) + return SYMLINK_TYPE_DIRECTORY; + + return SYMLINK_TYPE_UNSPECIFIED; +} + int symlink(const char *target, const char *link) { wchar_t wtarget[MAX_LONG_PATH], wlink[MAX_LONG_PATH]; @@ -2546,7 +2574,31 @@ int symlink(const char *target, const char *link) if (wtarget[len] == '/') wtarget[len] = '\\'; - return create_phantom_symlink(wtarget, wlink); + switch (check_symlink_attr(link)) { + case SYMLINK_TYPE_UNSPECIFIED: + /* Create a phantom symlink: it is initially created as a file + * symlink, but may change to a directory symlink later if/when + * the target exists. */ + return create_phantom_symlink(wtarget, wlink); + case SYMLINK_TYPE_FILE: + if (!CreateSymbolicLinkW(wlink, wtarget, symlink_file_flags)) + break; + return 0; + case SYMLINK_TYPE_DIRECTORY: + if (!CreateSymbolicLinkW(wlink, wtarget, + symlink_directory_flags)) + break; + /* There may be dangling phantom symlinks that point at this + * one, which should now morph into directory symlinks. */ + process_phantom_symlinks(); + return 0; + default: + BUG("unhandled symlink type"); + } + + /* CreateSymbolicLinkW failed. */ + errno = err_win_to_posix(GetLastError()); + return -1; } #ifndef _WINNT_H From d261879c56696c3dcd1990467e5464440cef6cc2 Mon Sep 17 00:00:00 2001 From: Bert Belder Date: Fri, 26 Oct 2018 23:42:09 +0200 Subject: [PATCH 3/3] Win32: symlink: add test for `symlink` attribute Signed-off-by: Bert Belder --- t/t2040-checkout-symlink-attr.sh | 51 ++++++++++++++++++++++++++++++++ 1 file changed, 51 insertions(+) create mode 100755 t/t2040-checkout-symlink-attr.sh diff --git a/t/t2040-checkout-symlink-attr.sh b/t/t2040-checkout-symlink-attr.sh new file mode 100755 index 0000000000..6b8a15116e --- /dev/null +++ b/t/t2040-checkout-symlink-attr.sh @@ -0,0 +1,51 @@ +#!/bin/sh + +test_description='checkout symlinks with `symlink` attribute on Windows + +Ensures that Git for Windows creates symlinks of the right type, +as specified by the `symlink` attribute in `.gitattributes`.' + +# Tell MSYS to create native symlinks. Without this flag test-lib's +# prerequisite detection for SYMLINKS doesn't detect the right thing. +MSYS=winsymlinks:nativestrict && export MSYS + +. ./test-lib.sh + +if ! test_have_prereq MINGW,SYMLINKS +then + skip_all='skipping $0: MinGW-only test, which requires symlink support.' + test_done +fi + +# Adds a symlink to the index without clobbering the work tree. +cache_symlink () { + sha=$(printf '%s' "$1" | git hash-object --stdin -w) && + git update-index --add --cacheinfo 120000,$sha,"$2" +} + +# MSYS2 is very forgiving, it will resolve symlinks even if the +# symlink type isn't correct. To make this test meaningful, try +# them with a native, non-MSYS executable. +cat_native () { + filename=$(cygpath -w "$1") && + cmd.exe /c "type \"$filename\"" +} + +test_expect_success 'checkout symlinks with attr' ' + cache_symlink file1 file-link && + cache_symlink dir dir-link && + + printf "file-link symlink=file\ndir-link symlink=dir\n" >.gitattributes && + git add .gitattributes && + + git checkout . && + + mkdir dir && + echo "contents1" >file1 && + echo "contents2" >dir/file2 && + + test "$(cat_native file-link)" = "contents1" && + test "$(cat_native dir-link/file2)" = "contents2" +' + +test_done