win32: use our own dirent.h

The mingw-runtime implemenation of opendir, readdir and closedir
sets errno to 0 on success, something that POSIX explicitly
forbids. 3ba7a06 ("A loose object is not corrupt if it cannot be
read due to EMFILE") introduce a dependency on this behaviour,
leading to a broken "git clone" on Windows.

compat/mingw.c contains an implementation of readdir, and
compat/msvc.c contains implementations of opendir and closedir.

Move these to compat/win32/dirent.[ch], and change to our own DIR
structure at the same time.

This provides a generic Win32-implementation of opendir, readdir
and closedir which works on both MinGW and MSVC and does not reset
errno, and as a result git clone is working again on Windows.

Signed-off-by: Erik Faye-Lund <kusmabite@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

2 files changed, 132 insertions, 0 deletions

diff --git a/compat/win32/dirent.c b/compat/win32/dirent.c
new file mode 100644
index 000000000..7a0debe51
--- /dev/null
+++ b/compat/win32/dirent.c
@@ -0,0 +1,108 @@
+#include "../git-compat-util.h"
+#include "dirent.h"
+
+struct DIR {
+	struct dirent dd_dir; /* includes d_type */
+	HANDLE dd_handle;     /* FindFirstFile handle */
+	int dd_stat;          /* 0-based index */
+	char dd_name[1];      /* extend struct */
+};
+
+DIR *opendir(const char *name)
+{
+	DWORD attrs = GetFileAttributesA(name);
+	int len;
+	DIR *p;
+
+	/* check for valid path */
+	if (attrs == INVALID_FILE_ATTRIBUTES) {
+		errno = ENOENT;
+		return NULL;
+	}
+
+	/* check if it's a directory */
+	if (!(attrs & FILE_ATTRIBUTE_DIRECTORY)) {
+		errno = ENOTDIR;
+		return NULL;
+	}
+
+	/* check that the pattern won't be too long for FindFirstFileA */
+	len = strlen(name);
+	if (is_dir_sep(name[len - 1]))
+		len--;
+	if (len + 2 >= MAX_PATH) {
+		errno = ENAMETOOLONG;
+		return NULL;
+	}
+
+	p = malloc(sizeof(DIR) + len + 2);
+	if (!p)
+		return NULL;
+
+	memset(p, 0, sizeof(DIR) + len + 2);
+	strcpy(p->dd_name, name);
+	p->dd_name[len] = '/';
+	p->dd_name[len+1] = '*';
+
+	p->dd_handle = INVALID_HANDLE_VALUE;
+	return p;
+}
+
+struct dirent *readdir(DIR *dir)
+{
+	WIN32_FIND_DATAA buf;
+	HANDLE handle;
+
+	if (!dir || !dir->dd_handle) {
+		errno = EBADF; /* No set_errno for mingw */
+		return NULL;
+	}
+
+	if (dir->dd_handle == INVALID_HANDLE_VALUE && dir->dd_stat == 0) {
+		DWORD lasterr;
+		handle = FindFirstFileA(dir->dd_name, &buf);
+		lasterr = GetLastError();
+		dir->dd_handle = handle;
+		if (handle == INVALID_HANDLE_VALUE && (lasterr != ERROR_NO_MORE_FILES)) {
+			errno = err_win_to_posix(lasterr);
+			return NULL;
+		}
+	} else if (dir->dd_handle == INVALID_HANDLE_VALUE) {
+		return NULL;
+	} else if (!FindNextFileA(dir->dd_handle, &buf)) {
+		DWORD lasterr = GetLastError();
+		FindClose(dir->dd_handle);
+		dir->dd_handle = INVALID_HANDLE_VALUE;
+		/* POSIX says you shouldn't set errno when readdir can't
+		   find any more files; so, if another error we leave it set. */
+		if (lasterr != ERROR_NO_MORE_FILES)
+			errno = err_win_to_posix(lasterr);
+		return NULL;
+	}
+
+	/* We get here if `buf' contains valid data.  */
+	strcpy(dir->dd_dir.d_name, buf.cFileName);
+	++dir->dd_stat;
+
+	/* Set file type, based on WIN32_FIND_DATA */
+	dir->dd_dir.d_type = 0;
+	if (buf.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY)
+		dir->dd_dir.d_type |= DT_DIR;
+	else
+		dir->dd_dir.d_type |= DT_REG;
+
+	return &dir->dd_dir;
+}
+
+int closedir(DIR *dir)
+{
+	if (!dir) {
+		errno = EBADF;
+		return -1;
+	}
+
+	if (dir->dd_handle != INVALID_HANDLE_VALUE)
+		FindClose(dir->dd_handle);
+	free(dir);
+	return 0;
+}
diff --git a/compat/win32/dirent.h b/compat/win32/dirent.h
new file mode 100644
index 000000000..927a25ca7
--- /dev/null
+++ b/compat/win32/dirent.h
@@ -0,0 +1,24 @@
+#ifndef DIRENT_H
+#define DIRENT_H
+
+typedef struct DIR DIR;
+
+#define DT_UNKNOWN 0
+#define DT_DIR     1
+#define DT_REG     2
+#define DT_LNK     3
+
+struct dirent {
+	long d_ino;                      /* Always zero. */
+	char d_name[FILENAME_MAX];       /* File name. */
+	union {
+		unsigned short d_reclen; /* Always zero. */
+		unsigned char  d_type;   /* Reimplementation adds this */
+	};
+};
+
+DIR *opendir(const char *dirname);
+struct dirent *readdir(DIR *dir);
+int closedir(DIR *dir);
+
+#endif /* DIRENT_H */