Add target architecture MinGW.

With this change GIT can be compiled and linked using MinGW. Builtins
that only read the repository such as the log family and grep already
work.

Simple stubs are provided for a number of functions that the Windows C
runtime does not offer. They will be completed in later patches.
However, a fix for the snprintf/vsnprintf replacement is applied here
to avoid buffer overflows.

Dmitry Kakurin pointed out that access(..., X_OK) would always fails on
Vista and suggested the -D__USE_MINGW_ACCESS workaround.

Signed-off-by: Johannes Sixt <johannes.sixt@telecom.at>

3 files changed, 207 insertions, 3 deletions

diff --git a/compat/mingw.c b/compat/mingw.c
new file mode 100644
index 0000000000..075448d245
--- /dev/null
+++ b/compat/mingw.c
@@ -0,0 +1,57 @@
+#include "../git-compat-util.h"
+
+unsigned int _CRT_fmode = _O_BINARY;
+
+unsigned int sleep (unsigned int seconds)
+{
+	Sleep(seconds*1000);
+	return 0;
+}
+
+int mkstemp(char *template)
+{
+	char *filename = mktemp(template);
+	if (filename == NULL)
+		return -1;
+	return open(filename, O_RDWR | O_CREAT, 0600);
+}
+
+int gettimeofday(struct timeval *tv, void *tz)
+{
+	return -1;
+}
+
+int poll(struct pollfd *ufds, unsigned int nfds, int timeout)
+{
+	return -1;
+}
+
+struct tm *gmtime_r(const time_t *timep, struct tm *result)
+{
+	/* gmtime() in MSVCRT.DLL is thread-safe, but not reentrant */
+	memcpy(result, gmtime(timep), sizeof(struct tm));
+	return result;
+}
+
+struct tm *localtime_r(const time_t *timep, struct tm *result)
+{
+	/* localtime() in MSVCRT.DLL is thread-safe, but not reentrant */
+	memcpy(result, localtime(timep), sizeof(struct tm));
+	return result;
+}
+
+struct passwd *getpwuid(int uid)
+{
+	static struct passwd p;
+	return &p;
+}
+
+int setitimer(int type, struct itimerval *in, struct itimerval *out)
+{
+	return -1;
+}
+
+int sigaction(int sig, struct sigaction *in, struct sigaction *out)
+{
+	return -1;
+}
diff --git a/compat/mingw.h b/compat/mingw.h
new file mode 100644
index 0000000000..e5c0c6ba21
--- /dev/null
+++ b/compat/mingw.h
@@ -0,0 +1,134 @@
+#include <winsock2.h>
+
+/*
+ * things that are not available in header files
+ */
+
+typedef int pid_t;
+#define hstrerror strerror
+
+#define S_IFLNK    0120000 /* Symbolic link */
+#define S_ISLNK(x) (((x) & S_IFMT) == S_IFLNK)
+#define S_ISSOCK(x) 0
+#define S_IRGRP 0
+#define S_IWGRP 0
+#define S_IXGRP 0
+#define S_ISGID 0
+#define S_IROTH 0
+#define S_IXOTH 0
+
+#define WIFEXITED(x) ((unsigned)(x) < 259)	/* STILL_ACTIVE */
+#define WEXITSTATUS(x) ((x) & 0xff)
+#define WIFSIGNALED(x) ((unsigned)(x) > 259)
+
+#define SIGKILL 0
+#define SIGCHLD 0
+#define SIGPIPE 0
+#define SIGHUP 0
+#define SIGQUIT 0
+#define SIGALRM 100
+
+#define F_GETFD 1
+#define F_SETFD 2
+#define FD_CLOEXEC 0x1
+
+struct passwd {
+	char *pw_name;
+	char *pw_gecos;
+	char *pw_dir;
+};
+
+struct pollfd {
+	int fd;           /* file descriptor */
+	short events;     /* requested events */
+	short revents;    /* returned events */
+};
+#define POLLIN 1
+#define POLLHUP 2
+
+typedef void (__cdecl *sig_handler_t)(int);
+struct sigaction {
+	sig_handler_t sa_handler;
+	unsigned sa_flags;
+};
+#define sigemptyset(x) (void)0
+#define SA_RESTART 0
+
+struct itimerval {
+	struct timeval it_value, it_interval;
+};
+#define ITIMER_REAL 0
+
+#define st_blocks st_size/512	/* will be cleaned up later */
+#define lstat stat
+
+/*
+ * trivial stubs
+ */
+
+static inline int readlink(const char *path, char *buf, size_t bufsiz)
+{ errno = ENOSYS; return -1; }
+static inline int symlink(const char *oldpath, const char *newpath)
+{ errno = ENOSYS; return -1; }
+static inline int link(const char *oldpath, const char *newpath)
+{ errno = ENOSYS; return -1; }
+static inline int fchmod(int fildes, mode_t mode)
+{ errno = ENOSYS; return -1; }
+static inline int fork(void)
+{ errno = ENOSYS; return -1; }
+static inline unsigned int alarm(unsigned int seconds)
+{ return 0; }
+static inline int fsync(int fd)
+{ return 0; }
+static inline int getppid(void)
+{ return 1; }
+static inline void sync(void)
+{}
+static inline int getuid()
+{ return 1; }
+static inline struct passwd *getpwnam(const char *name)
+{ return NULL; }
+static inline int fcntl(int fd, int cmd, long arg)
+{
+	if (cmd == F_GETFD || cmd == F_SETFD)
+		return 0;
+	errno = EINVAL;
+	return -1;
+}
+
+/*
+ * simple adaptors
+ */
+
+static inline int mingw_mkdir(const char *path, int mode)
+{
+	return mkdir(path);
+}
+#define mkdir mingw_mkdir
+
+static inline int waitpid(pid_t pid, unsigned *status, unsigned options)
+{
+	if (options == 0)
+		return _cwait(status, pid, 0);
+	errno = EINVAL;
+	return -1;
+}
+
+
+static inline int pipe(int filedes[2])
+{ return _pipe(filedes, 8192, 0); }
+
+/*
+ * implementations of missing functions
+ */
+
+unsigned int sleep (unsigned int seconds);
+int mkstemp(char *template);
+int gettimeofday(struct timeval *tv, void *tz);
+int poll(struct pollfd *ufds, unsigned int nfds, int timeout);
+struct tm *gmtime_r(const time_t *timep, struct tm *result);
+struct tm *localtime_r(const time_t *timep, struct tm *result);
+int getpagesize(void);	/* defined in MinGW's libgcc.a */
+struct passwd *getpwuid(int uid);
+int setitimer(int type, struct itimerval *in, struct itimerval *out);
+int sigaction(int sig, struct sigaction *in, struct sigaction *out);
diff --git a/compat/snprintf.c b/compat/snprintf.c
index dbfc2d6b6e..580966e56a 100644
--- a/compat/snprintf.c
+++ b/compat/snprintf.c
@@ -1,12 +1,25 @@
 #include "../git-compat-util.h"
 
+/*
+ * The size parameter specifies the available space, i.e. includes
+ * the trailing NUL byte; but Windows's vsnprintf expects the
+ * number of characters to write without the trailing NUL.
+ */
+#ifndef SNPRINTF_SIZE_CORR
+#define SNPRINTF_SIZE_CORR 0
+#endif
+
 #undef vsnprintf
 int git_vsnprintf(char *str, size_t maxsize, const char *format, va_list ap)
 {
 	char *s;
-	int ret;
+	int ret = -1;
 
-	ret = vsnprintf(str, maxsize, format, ap);
+	if (maxsize > 0) {
+		ret = vsnprintf(str, maxsize-SNPRINTF_SIZE_CORR, format, ap);
+		/* Windows does not NUL-terminate if result fills buffer */
+		str[maxsize-1] = 0;
+	}
 	if (ret != -1)
 		return ret;
 
@@ -20,7 +33,7 @@ int git_vsnprintf(char *str, size_t maxsize, const char *format, va_list ap)
 		if (! str)
 			break;
 		s = str;
-		ret = vsnprintf(str, maxsize, format, ap);
+		ret = vsnprintf(str, maxsize-SNPRINTF_SIZE_CORR, format, ap);
 	}
 	free(s);
 	return ret;