environment: move has_symlinks into repo_config_values

Move the global 'has_symlinks' configuration into the
repository-specific 'repo_config_values' struct.

Introduce 'repo_has_symlinks()' getter for readability.
Callers access this configuration by passing in 'repo'
when possible, and explicitly fall back to
'the_repository' the rest of the time.

Introduce 'platform_has_symlinks()' macro to allow
platform specific-customization, primarily to help MinGW.
Platforms can override this in their respective headers.

Mentored-by: Christian Couder <christian.couder@gmail.com>
Mentored-by: Ayush Chandekar <ayu.chandekar@gmail.com>
Mentored-by: Olamide Caleb Bello <belkid98@gmail.com>
Signed-off-by: Tian Yuchen <cat@malon.dev>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

apply.c

@@ -4511,7 +4511,7 @@ static int try_create_file(struct apply_state *state, const char *path,
 		return !!mkdir(path, 0777);
 	}
 
-	if (has_symlinks && S_ISLNK(mode))
+	if (repo_has_symlinks(state->repo) && S_ISLNK(mode))
 		/* Although buf:size is counted string, it also is NUL
 		 * terminated.
 		 */

combine-diff.c

@@ -1078,7 +1078,7 @@ static void show_patch_diff(struct combine_diff_path *elem, int num_parent,
 			/* if symlinks don't work, assume symlink if all parents
 			 * are symlinks
 			 */
-			is_file = has_symlinks;
+			is_file = repo_has_symlinks(rev->repo);
 			for (i = 0; !is_file && i < num_parent; i++)
 				is_file = !S_ISLNK(elem->parent[i].mode);
 			if (!is_file)

compat/mingw.c

@@ -7,6 +7,7 @@
 #include "config.h"
 #include "dir.h"
 #include "environment.h"
+#include "repository.h"
 #include "gettext.h"
 #include "run-command.h"
 #include "strbuf.h"
@@ -1043,7 +1044,7 @@ int mingw_chdir(const char *dirname)
 	if (xutftowcs_path(wdirname, dirname) < 0)
 		return -1;
 
-	if (has_symlinks) {
+	if (repo_has_symlinks(the_repository)) {
 		HANDLE hnd = CreateFileW(wdirname, 0,
 				FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE, NULL,
 				OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS, NULL);
@@ -2903,7 +2904,7 @@ int symlink(const char *target, const char *link)
 	int len;
 
 	/* fail if symlinks are disabled or API is not supported (WinXP) */
-	if (!has_symlinks) {
+	if (!repo_has_symlinks(the_repository)) {
 		errno = ENOSYS;
 		return -1;
 	}
@@ -3173,15 +3174,23 @@ static void setup_windows_environment(void)
 		if (!tmp && (tmp = getenv("USERPROFILE")))
 			setenv("HOME", tmp, 1);
 	}
+}
 
+int mingw_platform_has_symlinks(void)
+{
+	static int has_symlinks = -1;
 	/*
 	 * Change 'core.symlinks' default to false, unless native symlinks are
 	 * enabled in MSys2 (via 'MSYS=winsymlinks:nativestrict'). Thus we can
 	 * run the test suite (which doesn't obey config files) with or without
 	 * symlink support.
 	 */
-	if (!(tmp = getenv("MSYS")) || !strstr(tmp, "winsymlinks:nativestrict"))
-		has_symlinks = 0;
+	if (has_symlinks < 0) {
+		const char *tmp = getenv("MSYS");
+		has_symlinks = (tmp && strstr(tmp, "winsymlinks:nativestrict")) ? 1 : 0;
+	}
+
+	return has_symlinks;
 }
 
 static void get_current_user_sid(PSID *sid, HANDLE *linked_token)

compat/mingw.h

@@ -208,6 +208,9 @@ void open_in_gdb(void);
  */
 int err_win_to_posix(DWORD winerr);
 
+int mingw_platform_has_symlinks(void);
+#define platform_has_symlinks() mingw_platform_has_symlinks()
+
 #ifndef NO_UNIX_SOCKETS
 int mingw_have_unix_sockets(void);
 #undef have_unix_sockets

entry.c

@@ -321,7 +321,8 @@ static int write_entry(struct cache_entry *ce, char *path, struct conv_attrs *ca
 		 * We can't make a real symlink; write out a regular file entry
 		 * with the symlink destination as its contents.
 		 */
-		if (!has_symlinks || to_tempfile)
+		if (!repo_has_symlinks(state->istate && state->istate->repo ?
+				       state->istate->repo : the_repository) || to_tempfile)
 			goto write_file_entry;
 
 		ret = symlink(new_blob, path);

environment.c

@@ -43,7 +43,6 @@ static int zlib_compression_seen;
 
 int trust_ctime = 1;
 int check_stat = 1;
-int has_symlinks = 1;
 int minimum_abbrev = 4, default_abbrev = -1;
 int ignore_case;
 int assume_unchanged;
@@ -148,6 +147,13 @@ int repo_trust_executable_bit(struct repository *repo)
 		: 1;
 }
 
+int repo_has_symlinks(struct repository *repo)
+{
+	return repo->initialized
+		? repo_config_values(repo)->has_symlinks
+		: platform_has_symlinks();
+}
+
 int have_git_dir(void)
 {
 	return startup_info->have_repository
@@ -336,7 +342,8 @@ int git_default_core_config(const char *var, const char *value,
 	}
 
 	if (!strcmp(var, "core.symlinks")) {
-		has_symlinks = git_config_bool(var, value);
+		struct repo_config_values *cfg = repo_config_values(the_repository);
+		cfg->has_symlinks = git_config_bool(var, value);
 		return 0;
 	}
 
@@ -727,5 +734,6 @@ void repo_config_values_init(struct repo_config_values *cfg)
 	cfg->attributes_file = NULL;
 	cfg->apply_sparse_checkout = 0;
 	cfg->trust_executable_bit = 1;
+	cfg->has_symlinks = platform_has_symlinks();
 	cfg->branch_track = BRANCH_TRACK_REMOTE;
 }

environment.h

@@ -92,6 +92,7 @@ struct repo_config_values {
 	char *attributes_file;
 	int apply_sparse_checkout;
 	int trust_executable_bit;
+	int has_symlinks;
 
 	/* section "branch" config values */
 	enum branch_track branch_track;
@@ -126,6 +127,8 @@ int git_default_core_config(const char *var, const char *value,
 
 int repo_trust_executable_bit(struct repository *repo);
 
+int repo_has_symlinks(struct repository *repo);
+
 void repo_config_values_init(struct repo_config_values *cfg);
 
 /*
@@ -163,7 +166,6 @@ extern char *git_work_tree_cfg;
 /* Environment bits from configuration mechanism */
 extern int trust_ctime;
 extern int check_stat;
-extern int has_symlinks;
 extern int minimum_abbrev, default_abbrev;
 extern int ignore_case;
 extern int assume_unchanged;

git-compat-util.h

@@ -245,6 +245,10 @@ static inline int git_is_dir_sep(int c)
 #define is_dir_sep git_is_dir_sep
 #endif
 
+#ifndef platform_has_symlinks
+#define platform_has_symlinks() 1
+#endif
+
 #ifndef offset_1st_component
 static inline int git_offset_1st_component(const char *path)
 {

read-cache.c

@@ -207,7 +207,7 @@ static unsigned int st_mode_from_ce(const struct cache_entry *ce)
 {
 	switch (ce->ce_mode & S_IFMT) {
 	case S_IFLNK:
-		return has_symlinks ? S_IFLNK : (S_IFREG | 0644);
+		return repo_has_symlinks(the_repository) ? S_IFLNK : (S_IFREG | 0644);
 	case S_IFREG:
 		return (ce->ce_mode & (repo_trust_executable_bit(the_repository) ? 0755 : 0644)) | S_IFREG;
 	case S_IFGITLINK:
@@ -325,7 +325,7 @@ static int ce_match_stat_basic(const struct cache_entry *ce, struct stat *st)
 		break;
 	case S_IFLNK:
 		if (!S_ISLNK(st->st_mode) &&
-		    (has_symlinks || !S_ISREG(st->st_mode)))
+		    (repo_has_symlinks(the_repository) || !S_ISREG(st->st_mode)))
 			changed |= TYPE_CHANGED;
 		break;
 	case S_IFGITLINK:
@@ -740,7 +740,8 @@ int add_to_index(struct index_state *istate, const char *path, struct stat *st,
 		ce->ce_flags |= CE_INTENT_TO_ADD;
 
 
-	if (repo_trust_executable_bit(istate->repo) && has_symlinks) {
+	if (repo_trust_executable_bit(istate->repo) &&
+	    repo_has_symlinks(istate->repo)) {
 		ce->ce_mode = create_ce_mode(st_mode);
 	} else {
 		/* If there is an existing entry, pick the mode bits and type

read-cache.h

@@ -17,8 +17,7 @@ static inline unsigned int ce_mode_from_stat(struct repository *repo,
 					     const struct cache_entry *ce,
 					     unsigned int mode)
 {
-	extern int has_symlinks;
-	if (S_ISREG(mode) && !has_symlinks &&
+	if (S_ISREG(mode) && !repo_has_symlinks(repo) &&
 	    ce && S_ISLNK(ce->ce_mode))
 		return ce->ce_mode;
 	if (S_ISREG(mode) && !repo_trust_executable_bit(repo)) {