From 4daf57b4fdc80422d6448c0a7914699fdedb95b8 Mon Sep 17 00:00:00 2001
From: Ron Yorston <rmy@pobox.com>
Date: Wed, 13 Oct 2021 16:22:21 +0100
Subject: realpath: improved support for Windows paths

Upstream commit 94eb1c4dc (libbb: better coreutils compatibility
for realpath) made some changes to xmalloc_realpath_coreutils().
This now needs to be updated to handle Windows paths.

- Expose the macro is_unc_path() and part of the recent change to
  bb_get_last_path_component_nostrip() as a separate funtion,
  get_last_slash();

- Convert a couple of errors relating to network filesystems to
  ENOENT;

- Adjust xmalloc_realpath_coreutils() to handle Windows directory
  separators, relative paths and UNC paths.
---
 include/mingw.h                 |  3 +++
 libbb/get_last_path_component.c | 23 ++++++++++++++++-------
 libbb/xreadlink.c               | 34 ++++++++++++++++++++++++++++++++++
 win32/mingw.c                   |  5 ++---
 4 files changed, 55 insertions(+), 10 deletions(-)

diff --git a/include/mingw.h b/include/mingw.h
index 6ace91470..06fb3b289 100644
--- a/include/mingw.h
+++ b/include/mingw.h
@@ -518,6 +518,8 @@ int utimes(const char *file_name, const struct timeval times[2]);
  * MinGW specific
  */
 #define is_dir_sep(c) ((c) == '/' || (c) == '\\')
+#define is_unc_path(x) (strlen(x) > 4 && is_dir_sep(x[0]) && \
+							is_dir_sep(x[1]) && !is_dir_sep(x[2]))
 
 pid_t FAST_FUNC mingw_spawn(char **argv);
 pid_t FAST_FUNC mingw_spawn_detach(char **argv);
@@ -580,3 +582,4 @@ int skip_ansi_emulation(int reset);
 int unix_path(const char *path);
 int has_path(const char *file);
 int is_relative_path(const char *path);
+char *get_last_slash(const char *path);
diff --git a/libbb/get_last_path_component.c b/libbb/get_last_path_component.c
index 06033e139..254aabafd 100644
--- a/libbb/get_last_path_component.c
+++ b/libbb/get_last_path_component.c
@@ -23,6 +23,21 @@ const char* FAST_FUNC bb_basename(const char *name)
 	return name;
 }
 
+#if ENABLE_PLATFORM_MINGW32
+char *get_last_slash(const char *path)
+{
+	const char *start = path + root_len(path);
+	char *slash = strrchr(start, '/');
+	char *bslash = strrchr(start, '\\');
+
+	if (slash && bslash)
+		slash = MAX(slash, bslash);
+	else if (!slash)
+		slash = bslash;
+	return slash;
+}
+#endif
+
 /*
  * "/"        -> "/"
  * "abc"      -> "abc"
@@ -33,13 +48,7 @@ char* FAST_FUNC bb_get_last_path_component_nostrip(const char *path)
 {
 #if ENABLE_PLATFORM_MINGW32
 	const char *start = path + root_len(path);
-	char *slash = strrchr(start, '/');
-	char *bslash = strrchr(start, '\\');
-
-	if (slash && bslash)
-		slash = MAX(slash, bslash);
-	else if (!slash)
-		slash = bslash;
+	char *slash = get_last_slash(path);
 
 	if (!slash && has_dos_drive_prefix(path) && path[2] != '\0')
 		return (char *)path + 2;
diff --git a/libbb/xreadlink.c b/libbb/xreadlink.c
index 024ee9047..e6cf90310 100644
--- a/libbb/xreadlink.c
+++ b/libbb/xreadlink.c
@@ -156,7 +156,11 @@ char* FAST_FUNC xmalloc_realpath_coreutils(char *path)
 			 * $ realpath symlink
 			 * /usr/bin/qwe
 			 */
+#if ENABLE_PLATFORM_MINGW32
+			if (is_relative_path(target)) {
+#else
 			if (target[0] != '/') {
+#endif
 				/*
 				 * $ ln -s target_does_not_exist symlink
 				 * $ readlink -f symlink
@@ -175,6 +179,35 @@ char* FAST_FUNC xmalloc_realpath_coreutils(char *path)
 			return buf;
 		}
 
+#if ENABLE_PLATFORM_MINGW32
+		/* ignore leading and trailing slashes */
+		/* but keep leading slashes of UNC path */
+		if (!is_unc_path(path)) {
+			while (is_dir_sep(path[0]) && is_dir_sep(path[1]))
+				++path;
+		}
+		i = strlen(path) - 1;
+		while (i > 0 && is_dir_sep(path[i]))
+			i--;
+		c = path[i + 1];
+		path[i + 1] = '\0';
+
+		last_slash = get_last_slash(path);
+		if (last_slash == path + root_len(path))
+			buf = xstrdup(path);
+		else if (last_slash) {
+			char c2 = *last_slash;
+			*last_slash = '\0';
+			buf = xmalloc_realpath(path);
+			*last_slash++ = c2;
+			if (buf) {
+				unsigned len = strlen(buf);
+				buf = xrealloc(buf, len + strlen(last_slash) + 2);
+				buf[len++] = c2;
+				strcpy(buf + len, last_slash);
+			}
+		}
+#else
 		/* ignore leading and trailing slashes */
 		while (path[0] == '/' && path[1] == '/')
 			++path;
@@ -198,6 +231,7 @@ char* FAST_FUNC xmalloc_realpath_coreutils(char *path)
 				strcpy(buf + len, last_slash);
 			}
 		}
+#endif
 		path[i + 1] = c;
 	}
 
diff --git a/win32/mingw.c b/win32/mingw.c
index fa68ea608..d4855a7e7 100644
--- a/win32/mingw.c
+++ b/win32/mingw.c
@@ -64,6 +64,8 @@ int err_win_to_posix(void)
 	case ERROR_BAD_FORMAT: error = ENOEXEC; break;
 	case ERROR_BAD_LENGTH: error = EINVAL; break;
 	case ERROR_BAD_PATHNAME: error = ENOENT; break;
+	case ERROR_BAD_NET_NAME: error = ENOENT; break;
+	case ERROR_BAD_NETPATH: error = ENOENT; break;
 	case ERROR_BAD_PIPE: error = EPIPE; break;
 	case ERROR_BAD_UNIT: error = ENODEV; break;
 	case ERROR_BAD_USERNAME: error = EINVAL; break;
@@ -1877,9 +1879,6 @@ void hide_console(void)
 }
 #endif
 
-#define is_unc_path(x) (strlen(x) > 4 && is_dir_sep(x[0]) && \
-							is_dir_sep(x[1]) && !is_dir_sep(x[2]))
-
 /* Return the length of the root of a UNC path, i.e. the '//host/share'
  * component, or 0 if the path doesn't look like that. */
 int unc_root_len(const char *dir)
-- 
cgit v1.2.3-55-g6feb