From 8a61b67d502ed4fbd5f480ca9458884b55ce7a95 Mon Sep 17 00:00:00 2001
From: Ron Yorston <rmy@pobox.com>
Date: Wed, 27 May 2015 15:14:20 +0100
Subject: mingw: add routine to pipe a file descriptor to/from a command

---
 include/mingw.h |   1 +
 win32/popen.c   | 146 +++++++++++++++++++++++++++++++++++++++++++++++++-------
 2 files changed, 129 insertions(+), 18 deletions(-)

diff --git a/include/mingw.h b/include/mingw.h
index d6ed909b5..bf8cd0c4c 100644
--- a/include/mingw.h
+++ b/include/mingw.h
@@ -142,6 +142,7 @@ int mingw_rename(const char*, const char*);
 #define rename mingw_rename
 
 FILE *mingw_popen(const char *cmd, const char *mode);
+int mingw_popen_fd(const char *cmd, const char *mode, int fd0, pid_t *pid);
 int mingw_pclose(FILE *fd);
 #undef popen
 #undef pclose
diff --git a/win32/popen.c b/win32/popen.c
index a7b2c7ec9..93d51bb55 100644
--- a/win32/popen.c
+++ b/win32/popen.c
@@ -26,24 +26,10 @@ static int mingw_pipe(HANDLE *readwrite)
 	return 0;
 }
 
-FILE *mingw_popen(const char *cmd, const char *mode)
+static pipe_data *find_pipe(void)
 {
 	int i;
 	pipe_data *p = NULL;
-	FILE *fptr = NULL;
-	STARTUPINFO siStartInfo;
-	int success;
-	int fd;
-	int len, count;
-	int ip, ic;
-	char *cmd_buff = NULL;
-	const char *s;
-	char *t;
-
-	if ( cmd == NULL || *cmd == '\0' || mode == NULL ||
-			(*mode != 'r' && *mode != 'w') ) {
-		return NULL;
-	}
 
 	/* find an unused pipe structure */
 	for ( i=0; i<num_pipes; ++i ) {
@@ -67,6 +53,35 @@ FILE *mingw_popen(const char *cmd, const char *mode)
 		num_pipes += 10;
 	}
 
+	p->pipe[0] = INVALID_HANDLE_VALUE;
+	p->pipe[1] = INVALID_HANDLE_VALUE;
+
+	return p;
+}
+
+FILE *mingw_popen(const char *cmd, const char *mode)
+{
+	pipe_data *p;
+	FILE *fptr = NULL;
+	STARTUPINFO siStartInfo;
+	int success;
+	int fd;
+	int len, count;
+	int ip, ic;
+	char *cmd_buff = NULL;
+	const char *s;
+	char *t;
+
+	if ( cmd == NULL || *cmd == '\0' || mode == NULL ||
+			(*mode != 'r' && *mode != 'w') ) {
+		return NULL;
+	}
+
+	/* find an unused pipe structure */
+	if ( (p=find_pipe()) == NULL ) {
+		return NULL;
+	}
+
 	/* count double quotes */
 	count = 0;
 	for ( s=cmd; *s; ++s ) {
@@ -91,9 +106,6 @@ FILE *mingw_popen(const char *cmd, const char *mode)
 	*t++ = '"';
 	*t = '\0';
 
-	p->pipe[0] = INVALID_HANDLE_VALUE;
-	p->pipe[1] = INVALID_HANDLE_VALUE;
-
 	/* Create the pipe */
 	if ( mingw_pipe(p->pipe) == -1 ) {
 		goto finito;
@@ -168,6 +180,104 @@ finito:
 	return fptr;
 }
 
+/*
+ * Open a pipe to a command where the file descriptor fd0 is used
+ * as input to the command (read mode) or as the destination of the
+ * output from the command (write mode).  The pid of the command is
+ * returned in the variable pid, which can be NULL.
+ */
+int mingw_popen_fd(const char *cmd, const char *mode, int fd0, pid_t *pid)
+{
+	pipe_data *p;
+	STARTUPINFO siStartInfo;
+	int success;
+	int fd = -1;
+	int ip, ic;
+
+	if ( cmd == NULL || *cmd == '\0' || mode == NULL ||
+			(*mode != 'r' && *mode != 'w') ) {
+		return -1;
+	}
+
+	/* find an unused pipe structure */
+	if ( (p=find_pipe()) == NULL ) {
+		return -1;
+	}
+
+	/* Create the pipe */
+	if ( mingw_pipe(p->pipe) == -1 ) {
+		goto finito;
+	}
+
+	/* index of parent end of pipe */
+	ip = !(*mode == 'r');
+	/* index of child end of pipe */
+	ic = (*mode == 'r');
+
+	/* Make the parent end of the pipe non-inheritable */
+	SetHandleInformation(p->pipe[ip], HANDLE_FLAG_INHERIT, 0);
+
+	/* Now create the child process */
+	ZeroMemory(&siStartInfo, sizeof(STARTUPINFO));
+	siStartInfo.cb = sizeof(STARTUPINFO);
+	if ( *mode == 'r' ) {
+		siStartInfo.hStdInput = (HANDLE)_get_osfhandle(fd0);
+		siStartInfo.hStdOutput = p->pipe[ic];
+	}
+	else {
+		siStartInfo.hStdInput = p->pipe[ic];
+		siStartInfo.hStdOutput = (HANDLE)_get_osfhandle(fd0);
+	}
+	siStartInfo.hStdError = GetStdHandle(STD_ERROR_HANDLE);
+	siStartInfo.wShowWindow = SW_HIDE;
+	siStartInfo.dwFlags = STARTF_USESTDHANDLES|STARTF_USESHOWWINDOW;
+
+	success = CreateProcess(NULL,
+				(LPTSTR)cmd,       /* command line */
+				NULL,              /* process security attributes */
+				NULL,              /* primary thread security attributes */
+				TRUE,              /* handles are inherited */
+				0,                 /* creation flags */
+				NULL,              /* use parent's environment */
+				NULL,              /* use parent's current directory */
+				&siStartInfo,      /* STARTUPINFO pointer */
+				&p->piProcInfo);   /* receives PROCESS_INFORMATION */
+
+	if ( !success ) {
+		goto finito;
+	}
+
+	/* close child end of pipe */
+	CloseHandle(p->pipe[ic]);
+	p->pipe[ic] = INVALID_HANDLE_VALUE;
+
+	if ( *mode == 'r' ) {
+		fd = _open_osfhandle((long)p->pipe[ip], _O_RDONLY|_O_BINARY);
+	}
+	else {
+		fd = _open_osfhandle((long)p->pipe[ip], _O_WRONLY|_O_BINARY);
+	}
+
+finito:
+	if ( fd == -1 ) {
+		if ( p->pipe[0] != INVALID_HANDLE_VALUE ) {
+			CloseHandle(p->pipe[0]);
+		}
+		if ( p->pipe[1] != INVALID_HANDLE_VALUE ) {
+			CloseHandle(p->pipe[1]);
+		}
+	}
+	else {
+		p->mode = *mode;
+		p->fd = fd;
+		if ( pid ) {
+			*pid = (pid_t)p->piProcInfo.dwProcessId;
+		}
+	}
+
+	return fd;
+}
+
 int mingw_pclose(FILE *fp)
 {
 	int i, ip, fd;
-- 
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