1 files changed, 414 insertions, 167 deletions

diff --git a/compat/mingw.c b/compat/mingw.c
index 858ca14a57..34b3880b29 100644
--- a/compat/mingw.c
+++ b/compat/mingw.c
@@ -5,6 +5,8 @@
 #include "../strbuf.h"
 #include "../run-command.h"
 #include "../cache.h"
+#include "win32/lazyload.h"
+#include "../config.h"
 
 #define HCAST(type, handle) ((type)(intptr_t)handle)
 
@@ -202,6 +204,60 @@ static int ask_yes_no_if_possible(const char *format, ...)
 	}
 }
 
+/* Windows only */
+enum hide_dotfiles_type {
+	HIDE_DOTFILES_FALSE = 0,
+	HIDE_DOTFILES_TRUE,
+	HIDE_DOTFILES_DOTGITONLY
+};
+
+static enum hide_dotfiles_type hide_dotfiles = HIDE_DOTFILES_DOTGITONLY;
+static char *unset_environment_variables;
+
+int mingw_core_config(const char *var, const char *value, void *cb)
+{
+	if (!strcmp(var, "core.hidedotfiles")) {
+		if (value && !strcasecmp(value, "dotgitonly"))
+			hide_dotfiles = HIDE_DOTFILES_DOTGITONLY;
+		else
+			hide_dotfiles = git_config_bool(var, value);
+		return 0;
+	}
+
+	if (!strcmp(var, "core.unsetenvvars")) {
+		free(unset_environment_variables);
+		unset_environment_variables = xstrdup(value);
+		return 0;
+	}
+
+	return 0;
+}
+
+/* Normalizes NT paths as returned by some low-level APIs. */
+static wchar_t *normalize_ntpath(wchar_t *wbuf)
+{
+	int i;
+	/* fix absolute path prefixes */
+	if (wbuf[0] == '\\') {
+		/* strip NT namespace prefixes */
+		if (!wcsncmp(wbuf, L"\\??\\", 4) ||
+		    !wcsncmp(wbuf, L"\\\\?\\", 4))
+			wbuf += 4;
+		else if (!wcsnicmp(wbuf, L"\\DosDevices\\", 12))
+			wbuf += 12;
+		/* replace remaining '...UNC\' with '\\' */
+		if (!wcsnicmp(wbuf, L"UNC\\", 4)) {
+			wbuf += 2;
+			*wbuf = '\\';
+		}
+	}
+	/* convert backslashes to slashes */
+	for (i = 0; wbuf[i]; i++)
+		if (wbuf[i] == '\\')
+			wbuf[i] = '/';
+	return wbuf;
+}
+
 int mingw_unlink(const char *pathname)
 {
 	int ret, tries = 0;
@@ -341,6 +397,19 @@ 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 +429,12 @@ 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 +442,21 @@ 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 +473,7 @@ 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;
@@ -562,9 +648,11 @@ static inline long long filetime_to_hnsec(const FILETIME *ft)
 	return winTime - 116444736000000000LL;
 }
 
-static inline time_t filetime_to_time_t(const FILETIME *ft)
+static inline void filetime_to_timespec(const FILETIME *ft, struct timespec *ts)
 {
-	return (time_t)(filetime_to_hnsec(ft) / 10000000);
+	long long hnsec = filetime_to_hnsec(ft);
+	ts->tv_sec = (time_t)(hnsec / 10000000);
+	ts->tv_nsec = (hnsec % 10000000) * 100;
 }
 
 /**
@@ -623,9 +711,9 @@ static int do_lstat(int follow, const char *file_name, struct stat *buf)
 		buf->st_size = fdata.nFileSizeLow |
 			(((off_t)fdata.nFileSizeHigh)<<32);
 		buf->st_dev = buf->st_rdev = 0; /* not used by Git */
-		buf->st_atime = filetime_to_time_t(&(fdata.ftLastAccessTime));
-		buf->st_mtime = filetime_to_time_t(&(fdata.ftLastWriteTime));
-		buf->st_ctime = filetime_to_time_t(&(fdata.ftCreationTime));
+		filetime_to_timespec(&(fdata.ftLastAccessTime), &(buf->st_atim));
+		filetime_to_timespec(&(fdata.ftLastWriteTime), &(buf->st_mtim));
+		filetime_to_timespec(&(fdata.ftCreationTime), &(buf->st_ctim));
 		if (fdata.dwFileAttributes & FILE_ATTRIBUTE_REPARSE_POINT) {
 			WIN32_FIND_DATAW findbuf;
 			HANDLE handle = FindFirstFileW(wfilename, &findbuf);
@@ -706,6 +794,29 @@ static int do_stat_internal(int follow, const char *file_name, struct stat *buf)
 	return do_lstat(follow, alt_name, buf);
 }
 
+static int get_file_info_by_handle(HANDLE hnd, struct stat *buf)
+{
+	BY_HANDLE_FILE_INFORMATION fdata;
+
+	if (!GetFileInformationByHandle(hnd, &fdata)) {
+		errno = err_win_to_posix(GetLastError());
+		return -1;
+	}
+
+	buf->st_ino = 0;
+	buf->st_gid = 0;
+	buf->st_uid = 0;
+	buf->st_nlink = 1;
+	buf->st_mode = file_attr_to_st_mode(fdata.dwFileAttributes);
+	buf->st_size = fdata.nFileSizeLow |
+		(((off_t)fdata.nFileSizeHigh)<<32);
+	buf->st_dev = buf->st_rdev = 0; /* not used by Git */
+	filetime_to_timespec(&(fdata.ftLastAccessTime), &(buf->st_atim));
+	filetime_to_timespec(&(fdata.ftLastWriteTime), &(buf->st_mtim));
+	filetime_to_timespec(&(fdata.ftCreationTime), &(buf->st_ctim));
+	return 0;
+}
+
 int mingw_lstat(const char *file_name, struct stat *buf)
 {
 	return do_stat_internal(0, file_name, buf);
@@ -718,32 +829,31 @@ int mingw_stat(const char *file_name, struct stat *buf)
 int mingw_fstat(int fd, struct stat *buf)
 {
 	HANDLE fh = (HANDLE)_get_osfhandle(fd);
-	BY_HANDLE_FILE_INFORMATION fdata;
+	DWORD avail, type = GetFileType(fh) & ~FILE_TYPE_REMOTE;
 
-	if (fh == INVALID_HANDLE_VALUE) {
-		errno = EBADF;
-		return -1;
-	}
-	/* direct non-file handles to MS's fstat() */
-	if (GetFileType(fh) != FILE_TYPE_DISK)
-		return _fstati64(fd, buf);
+	switch (type) {
+	case FILE_TYPE_DISK:
+		return get_file_info_by_handle(fh, buf);
 
-	if (GetFileInformationByHandle(fh, &fdata)) {
-		buf->st_ino = 0;
-		buf->st_gid = 0;
-		buf->st_uid = 0;
+	case FILE_TYPE_CHAR:
+	case FILE_TYPE_PIPE:
+		/* initialize stat fields */
+		memset(buf, 0, sizeof(*buf));
 		buf->st_nlink = 1;
-		buf->st_mode = file_attr_to_st_mode(fdata.dwFileAttributes);
-		buf->st_size = fdata.nFileSizeLow |
-			(((off_t)fdata.nFileSizeHigh)<<32);
-		buf->st_dev = buf->st_rdev = 0; /* not used by Git */
-		buf->st_atime = filetime_to_time_t(&(fdata.ftLastAccessTime));
-		buf->st_mtime = filetime_to_time_t(&(fdata.ftLastWriteTime));
-		buf->st_ctime = filetime_to_time_t(&(fdata.ftCreationTime));
+
+		if (type == FILE_TYPE_CHAR) {
+			buf->st_mode = _S_IFCHR;
+		} else {
+			buf->st_mode = _S_IFIFO;
+			if (PeekNamedPipe(fh, NULL, 0, NULL, &avail, NULL))
+				buf->st_size = avail;
+		}
 		return 0;
+
+	default:
+		errno = EBADF;
+		return -1;
 	}
-	errno = EBADF;
-	return -1;
 }
 
 static inline void time_t_to_filetime(time_t t, FILETIME *ft)
@@ -887,8 +997,29 @@ struct tm *localtime_r(const time_t *timep, struct tm *result)
 
 char *mingw_getcwd(char *pointer, int len)
 {
-	wchar_t wpointer[MAX_PATH];
-	if (!_wgetcwd(wpointer, ARRAY_SIZE(wpointer)))
+	wchar_t cwd[MAX_PATH], wpointer[MAX_PATH];
+	DWORD ret = GetCurrentDirectoryW(ARRAY_SIZE(cwd), cwd);
+
+	if (!ret || ret >= ARRAY_SIZE(cwd)) {
+		errno = ret ? ENAMETOOLONG : err_win_to_posix(GetLastError());
+		return NULL;
+	}
+	ret = GetLongPathNameW(cwd, wpointer, ARRAY_SIZE(wpointer));
+	if (!ret && GetLastError() == ERROR_ACCESS_DENIED) {
+		HANDLE hnd = CreateFileW(cwd, 0,
+			FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE, NULL,
+			OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS, NULL);
+		if (hnd == INVALID_HANDLE_VALUE)
+			return NULL;
+		ret = GetFinalPathNameByHandleW(hnd, wpointer, ARRAY_SIZE(wpointer), 0);
+		CloseHandle(hnd);
+		if (!ret || ret >= ARRAY_SIZE(wpointer))
+			return NULL;
+		if (xwcstoutf(pointer, normalize_ntpath(wpointer), len) < 0)
+			return NULL;
+		return pointer;
+	}
+	if (!ret || ret >= ARRAY_SIZE(wpointer))
 		return NULL;
 	if (xwcstoutf(pointer, wpointer, len) < 0)
 		return NULL;
@@ -897,8 +1028,8 @@ char *mingw_getcwd(char *pointer, int len)
 }
 
 /*
- * See http://msdn2.microsoft.com/en-us/library/17w5ykft(vs.71).aspx
- * (Parsing C++ Command-Line Arguments)
+ * See "Parsing C++ Command-Line Arguments" at Microsoft's Docs:
+ * https://docs.microsoft.com/en-us/cpp/cpp/parsing-cpp-command-line-arguments
  */
 static const char *quote_arg(const char *arg)
 {
@@ -1040,44 +1171,142 @@ static char *path_lookup(const char *cmd, int exe_only)
 	return prog;
 }
 
-static int do_putenv(char **env, const char *name, int size, int free_old);
+static const wchar_t *wcschrnul(const wchar_t *s, wchar_t c)
+{
+	while (*s && *s != c)
+		s++;
+	return s;
+}
+
+/* Compare only keys */
+static int wenvcmp(const void *a, const void *b)
+{
+	wchar_t *p = *(wchar_t **)a, *q = *(wchar_t **)b;
+	size_t p_len, q_len;
+
+	/* Find the keys */
+	p_len = wcschrnul(p, L'=') - p;
+	q_len = wcschrnul(q, L'=') - q;
 
-/* used number of elements of environ array, including terminating NULL */
-static int environ_size = 0;
-/* allocated size of environ array, in bytes */
-static int environ_alloc = 0;
+	/* If the length differs, include the shorter key's NUL */
+	if (p_len < q_len)
+		p_len++;
+	else if (p_len > q_len)
+		p_len = q_len + 1;
+
+	return _wcsnicmp(p, q, p_len);
+}
+
+/* We need a stable sort to convert the environment between UTF-16 <-> UTF-8 */
+#ifndef INTERNAL_QSORT
+#include "qsort.c"
+#endif
 
 /*
- * Create environment block suitable for CreateProcess. Merges current
- * process environment and the supplied environment changes.
+ * Build an environment block combining the inherited environment
+ * merged with the given list of settings.
+ *
+ * Values of the form "KEY=VALUE" in deltaenv override inherited values.
+ * Values of the form "KEY" in deltaenv delete inherited values.
+ *
+ * Multiple entries in deltaenv for the same key are explicitly allowed.
+ *
+ * We return a contiguous block of UNICODE strings with a final trailing
+ * zero word.
  */
 static wchar_t *make_environment_block(char **deltaenv)
 {
-	wchar_t *wenvblk = NULL;
-	char **tmpenv;
-	int i = 0, size = environ_size, wenvsz = 0, wenvpos = 0;
+	wchar_t *wenv = GetEnvironmentStringsW(), *wdeltaenv, *result, *p;
+	size_t wlen, s, delta_size, size;
+
+	wchar_t **array = NULL;
+	size_t alloc = 0, nr = 0, i;
+
+	size = 1; /* for extra NUL at the end */
+
+	/* If there is no deltaenv to apply, simply return a copy. */
+	if (!deltaenv || !*deltaenv) {
+		for (p = wenv; p && *p; ) {
+			size_t s = wcslen(p) + 1;
+			size += s;
+			p += s;
+		}
+
+		ALLOC_ARRAY(result, size);
+		memcpy(result, wenv, size * sizeof(*wenv));
+		FreeEnvironmentStringsW(wenv);
+		return result;
+	}
+
+	/*
+	 * If there is a deltaenv, let's accumulate all keys into `array`,
+	 * sort them using the stable git_qsort() and then copy, skipping
+	 * duplicate keys
+	 */
+	for (p = wenv; p && *p; ) {
+		ALLOC_GROW(array, nr + 1, alloc);
+		s = wcslen(p) + 1;
+		array[nr++] = p;
+		p += s;
+		size += s;
+	}
+
+	/* (over-)assess size needed for wchar version of deltaenv */
+	for (delta_size = 0, i = 0; deltaenv[i]; i++)
+		delta_size += strlen(deltaenv[i]) * 2 + 1;
+	ALLOC_ARRAY(wdeltaenv, delta_size);
+
+	/* convert the deltaenv, appending to array */
+	for (i = 0, p = wdeltaenv; deltaenv[i]; i++) {
+		ALLOC_GROW(array, nr + 1, alloc);
+		wlen = xutftowcs(p, deltaenv[i], wdeltaenv + delta_size - p);
+		array[nr++] = p;
+		p += wlen + 1;
+	}
+
+	git_qsort(array, nr, sizeof(*array), wenvcmp);
+	ALLOC_ARRAY(result, size + delta_size);
+
+	for (p = result, i = 0; i < nr; i++) {
+		/* Skip any duplicate keys; last one wins */
+		while (i + 1 < nr && !wenvcmp(array + i, array + i + 1))
+		       i++;
+
+		/* Skip "to delete" entry */
+		if (!wcschr(array[i], L'='))
+			continue;
+
+		size = wcslen(array[i]) + 1;
+		memcpy(p, array[i], size * sizeof(*p));
+		p += size;
+	}
+	*p = L'\0';
 
-	while (deltaenv && deltaenv[i])
-		i++;
+	free(array);
+	free(wdeltaenv);
+	FreeEnvironmentStringsW(wenv);
+	return result;
+}
 
-	/* copy the environment, leaving space for changes */
-	ALLOC_ARRAY(tmpenv, size + i);
-	memcpy(tmpenv, environ, size * sizeof(char*));
+static void do_unset_environment_variables(void)
+{
+	static int done;
+	char *p = unset_environment_variables;
+
+	if (done || !p)
+		return;
+	done = 1;
 
-	/* merge supplied environment changes into the temporary environment */
-	for (i = 0; deltaenv && deltaenv[i]; i++)
-		size = do_putenv(tmpenv, deltaenv[i], size, 0);
+	for (;;) {
+		char *comma = strchr(p, ',');
 
-	/* create environment block from temporary environment */
-	for (i = 0; tmpenv[i]; i++) {
-		size = 2 * strlen(tmpenv[i]) + 2; /* +2 for final \0 */
-		ALLOC_GROW(wenvblk, (wenvpos + size) * sizeof(wchar_t), wenvsz);
-		wenvpos += xutftowcs(&wenvblk[wenvpos], tmpenv[i], size) + 1;
+		if (comma)
+			*comma = '\0';
+		unsetenv(p);
+		if (!comma)
+			break;
+		p = comma + 1;
 	}
-	/* add final \0 terminator */
-	wenvblk[wenvpos] = 0;
-	free(tmpenv);
-	return wenvblk;
 }
 
 struct pinfo_t {
@@ -1098,9 +1327,12 @@ static pid_t mingw_spawnve_fd(const char *cmd, const char **argv, char **deltaen
 	wchar_t wcmd[MAX_PATH], wdir[MAX_PATH], *wargs, *wenvblk = NULL;
 	unsigned flags = CREATE_UNICODE_ENVIRONMENT;
 	BOOL ret;
+	HANDLE cons;
+
+	do_unset_environment_variables();
 
 	/* Determine whether or not we are associated to a console */
-	HANDLE cons = CreateFile("CONOUT$", GENERIC_WRITE,
+	cons = CreateFile("CONOUT$", GENERIC_WRITE,
 			FILE_SHARE_WRITE, NULL, OPEN_EXISTING,
 			FILE_ATTRIBUTE_NORMAL, NULL);
 	if (cons == INVALID_HANDLE_VALUE) {
@@ -1319,87 +1551,83 @@ int mingw_kill(pid_t pid, int sig)
 }
 
 /*
- * Compare environment entries by key (i.e. stopping at '=' or '\0').
+ * UTF-8 versions of getenv(), putenv() and unsetenv().
+ * Internally, they use the CRT's stock UNICODE routines
+ * to avoid data loss.
  */
-static int compareenv(const void *v1, const void *v2)
+char *mingw_getenv(const char *name)
 {
-	const char *e1 = *(const char**)v1;
-	const char *e2 = *(const char**)v2;
+#define GETENV_MAX_RETAIN 30
+	static char *values[GETENV_MAX_RETAIN];
+	static int value_counter;
+	int len_key, len_value;
+	wchar_t *w_key;
+	char *value;
+	wchar_t w_value[32768];
 
-	for (;;) {
-		int c1 = *e1++;
-		int c2 = *e2++;
-		c1 = (c1 == '=') ? 0 : tolower(c1);
-		c2 = (c2 == '=') ? 0 : tolower(c2);
-		if (c1 > c2)
-			return 1;
-		if (c1 < c2)
-			return -1;
-		if (c1 == 0)
-			return 0;
-	}
-}
+	if (!name || !*name)
+		return NULL;
 
-static int bsearchenv(char **env, const char *name, size_t size)
-{
-	unsigned low = 0, high = size;
-	while (low < high) {
-		unsigned mid = low + ((high - low) >> 1);
-		int cmp = compareenv(&env[mid], &name);
-		if (cmp < 0)
-			low = mid + 1;
-		else if (cmp > 0)
-			high = mid;
-		else
-			return mid;
+	len_key = strlen(name) + 1;
+	/* We cannot use xcalloc() here because that uses getenv() itself */
+	w_key = calloc(len_key, sizeof(wchar_t));
+	if (!w_key)
+		die("Out of memory, (tried to allocate %u wchar_t's)", len_key);
+	xutftowcs(w_key, name, len_key);
+	len_value = GetEnvironmentVariableW(w_key, w_value, ARRAY_SIZE(w_value));
+	if (!len_value && GetLastError() == ERROR_ENVVAR_NOT_FOUND) {
+		free(w_key);
+		return NULL;
 	}
-	return ~low; /* not found, return 1's complement of insert position */
+	free(w_key);
+
+	len_value = len_value * 3 + 1;
+	/* We cannot use xcalloc() here because that uses getenv() itself */
+	value = calloc(len_value, sizeof(char));
+	if (!value)
+		die("Out of memory, (tried to allocate %u bytes)", len_value);
+	xwcstoutf(value, w_value, len_value);
+
+	/*
+	 * We return `value` which is an allocated value and the caller is NOT
+	 * expecting to have to free it, so we keep a round-robin array,
+	 * invalidating the buffer after GETENV_MAX_RETAIN getenv() calls.
+	 */
+	free(values[value_counter]);
+	values[value_counter++] = value;
+	if (value_counter >= ARRAY_SIZE(values))
+		value_counter = 0;
+
+	return value;
 }
 
-/*
- * If name contains '=', then sets the variable, otherwise it unsets it
- * Size includes the terminating NULL. Env must have room for size + 1 entries
- * (in case of insert). Returns the new size. Optionally frees removed entries.
- */
-static int do_putenv(char **env, const char *name, int size, int free_old)
+int mingw_putenv(const char *namevalue)
 {
-	int i = bsearchenv(env, name, size - 1);
+	int size;
+	wchar_t *wide, *equal;
+	BOOL result;
 
-	/* optionally free removed / replaced entry */
-	if (i >= 0 && free_old)
-		free(env[i]);
+	if (!namevalue || !*namevalue)
+		return 0;
 
-	if (strchr(name, '=')) {
-		/* if new value ('key=value') is specified, insert or replace entry */
-		if (i < 0) {
-			i = ~i;
-			memmove(&env[i + 1], &env[i], (size - i) * sizeof(char*));
-			size++;
-		}
-		env[i] = (char*) name;
-	} else if (i >= 0) {
-		/* otherwise ('key') remove existing entry */
-		size--;
-		memmove(&env[i], &env[i + 1], (size - i) * sizeof(char*));
+	size = strlen(namevalue) * 2 + 1;
+	wide = calloc(size, sizeof(wchar_t));
+	if (!wide)
+		die("Out of memory, (tried to allocate %u wchar_t's)", size);
+	xutftowcs(wide, namevalue, size);
+	equal = wcschr(wide, L'=');
+	if (!equal)
+		result = SetEnvironmentVariableW(wide, NULL);
+	else {
+		*equal = L'\0';
+		result = SetEnvironmentVariableW(wide, equal + 1);
 	}
-	return size;
-}
+	free(wide);
 
-char *mingw_getenv(const char *name)
-{
-	char *value;
-	int pos = bsearchenv(environ, name, environ_size - 1);
-	if (pos < 0)
-		return NULL;
-	value = strchr(environ[pos], '=');
-	return value ? &value[1] : NULL;
-}
+	if (!result)
+		errno = err_win_to_posix(GetLastError());
 
-int mingw_putenv(const char *namevalue)
-{
-	ALLOC_GROW(environ, (environ_size + 1) * sizeof(char*), environ_alloc);
-	environ_size = do_putenv(environ, namevalue, environ_size, 1);
-	return 0;
+	return result ? 0 : -1;
 }
 
 /*
@@ -1547,7 +1775,8 @@ static void ensure_socket_initialization(void)
 			WSAGetLastError());
 
 	for (name = libraries; *name; name++) {
-		ipv6_dll = LoadLibrary(*name);
+		ipv6_dll = LoadLibraryExA(*name, NULL,
+					  LOAD_LIBRARY_SEARCH_SYSTEM32);
 		if (!ipv6_dll)
 			continue;
 
@@ -1768,18 +1997,63 @@ int mingw_getpagesize(void)
 	return si.dwAllocationGranularity;
 }
 
+/* See https://msdn.microsoft.com/en-us/library/windows/desktop/ms724435.aspx */
+enum EXTENDED_NAME_FORMAT {
+	NameDisplay = 3,
+	NameUserPrincipal = 8
+};
+
+static char *get_extended_user_info(enum EXTENDED_NAME_FORMAT type)
+{
+	DECLARE_PROC_ADDR(secur32.dll, BOOL, GetUserNameExW,
+		enum EXTENDED_NAME_FORMAT, LPCWSTR, PULONG);
+	static wchar_t wbuffer[1024];
+	DWORD len;
+
+	if (!INIT_PROC_ADDR(GetUserNameExW))
+		return NULL;
+
+	len = ARRAY_SIZE(wbuffer);
+	if (GetUserNameExW(type, wbuffer, &len)) {
+		char *converted = xmalloc((len *= 3));
+		if (xwcstoutf(converted, wbuffer, len) >= 0)
+			return converted;
+		free(converted);
+	}
+
+	return NULL;
+}
+
+char *mingw_query_user_email(void)
+{
+	return get_extended_user_info(NameUserPrincipal);
+}
+
 struct passwd *getpwuid(int uid)
 {
+	static unsigned initialized;
 	static char user_name[100];
-	static struct passwd p;
+	static struct passwd *p;
+	DWORD len;
+
+	if (initialized)
+		return p;
 
-	DWORD len = sizeof(user_name);
-	if (!GetUserName(user_name, &len))
+	len = sizeof(user_name);
+	if (!GetUserName(user_name, &len)) {
+		initialized = 1;
 		return NULL;
-	p.pw_name = user_name;
-	p.pw_gecos = "unknown";
-	p.pw_dir = NULL;
-	return &p;
+	}
+
+	p = xmalloc(sizeof(*p));
+	p->pw_name = user_name;
+	p->pw_gecos = get_extended_user_info(NameDisplay);
+	if (!p->pw_gecos)
+		p->pw_gecos = "unknown";
+	p->pw_dir = NULL;
+
+	initialized = 1;
+	return p;
 }
 
 static HANDLE timer_event;
@@ -1937,24 +2211,12 @@ int mingw_raise(int sig)
 
 int link(const char *oldpath, const char *newpath)
 {
-	typedef BOOL (WINAPI *T)(LPCWSTR, LPCWSTR, LPSECURITY_ATTRIBUTES);
-	static T create_hard_link = NULL;
 	wchar_t woldpath[MAX_PATH], wnewpath[MAX_PATH];
 	if (xutftowcs_path(woldpath, oldpath) < 0 ||
 		xutftowcs_path(wnewpath, newpath) < 0)
 		return -1;
 
-	if (!create_hard_link) {
-		create_hard_link = (T) GetProcAddress(
-			GetModuleHandle("kernel32.dll"), "CreateHardLinkW");
-		if (!create_hard_link)
-			create_hard_link = (T)-1;
-	}
-	if (create_hard_link == (T)-1) {
-		errno = ENOSYS;
-		return -1;
-	}
-	if (!create_hard_link(wnewpath, woldpath, NULL)) {
+	if (!CreateHardLinkW(wnewpath, woldpath, NULL)) {
 		errno = err_win_to_posix(GetLastError());
 		return -1;
 	}
@@ -2261,17 +2523,6 @@ void mingw_startup(void)
 	maxlen = wcslen(wargv[0]);
 	for (i = 1; i < argc; i++)
 		maxlen = max(maxlen, wcslen(wargv[i]));
-	for (i = 0; wenv[i]; i++)
-		maxlen = max(maxlen, wcslen(wenv[i]));
-
-	/*
-	 * nedmalloc can't free CRT memory, allocate resizable environment
-	 * list. Note that xmalloc / xmemdupz etc. call getenv, so we cannot
-	 * use it while initializing the environment itself.
-	 */
-	environ_size = i + 1;
-	environ_alloc = alloc_nr(environ_size * sizeof(char*));
-	environ = malloc_startup(environ_alloc);
 
 	/* allocate buffer (wchar_t encodes to max 3 UTF-8 bytes) */
 	maxlen = 3 * maxlen + 1;
@@ -2280,17 +2531,13 @@ void mingw_startup(void)
 	/* convert command line arguments and environment to UTF-8 */
 	for (i = 0; i < argc; i++)
 		__argv[i] = wcstoutfdup_startup(buffer, wargv[i], maxlen);
-	for (i = 0; wenv[i]; i++)
-		environ[i] = wcstoutfdup_startup(buffer, wenv[i], maxlen);
-	environ[i] = NULL;
 	free(buffer);
 
-	/* sort environment for O(log n) getenv / putenv */
-	qsort(environ, i, sizeof(char*), compareenv);
-
 	/* fix Windows specific environment settings */
 	setup_windows_environment();
 
+	unset_environment_variables = xstrdup("PERL5LIB");
+
 	/* initialize critical section for waitpid pinfo_t list */
 	InitializeCriticalSection(&pinfo_cs);