win32: let virtual /dev/fd/<num> files be opened

Add support for virtual /dev/fd files to represent file descriptors.

2 files changed, 22 insertions, 0 deletions

diff --git a/include/platform.h b/include/platform.h
index b2d918643..37e48dcc5 100644
--- a/include/platform.h
+++ b/include/platform.h
@@ -447,6 +447,8 @@ typedef unsigned smalluint;
 #define HAVE_SYS_STATFS_H 1
 #define HAVE_PRINTF_PERCENTM 1
 #define HAVE_WAIT3 1
+#define HAVE_DEV_FD 1
+#define DEV_FD_PREFIX "/dev/fd/"
 
 #if defined(__UCLIBC__)
 # if UCLIBC_VERSION < KERNEL_VERSION(0, 9, 32)
diff --git a/win32/mingw.c b/win32/mingw.c
index 11ae09043..3183cd78e 100644
--- a/win32/mingw.c
+++ b/win32/mingw.c
@@ -185,6 +185,19 @@ void update_special_fd(int dev, int fd)
                 rand_fd = fd;
 }
 
+#define PREFIX_LEN (sizeof(DEV_FD_PREFIX)-1)
+static int get_dev_fd(const char *filename)
+{
+        int fd;
+
+        if (filename && is_prefixed_with(filename, DEV_FD_PREFIX)) {
+                fd = bb_strtou(filename+PREFIX_LEN, NULL, 10);
+                if (errno == 0 && (HANDLE)_get_osfhandle(fd) != INVALID_HANDLE_VALUE)
+                        return fd;
+        }
+        return -1;
+}
+
 #undef open
 int mingw_open (const char *filename, int oflags, ...)
 {
@@ -199,6 +212,9 @@ int mingw_open (const char *filename, int oflags, ...)
                 filename = "nul";
                 oflags = O_RDWR;
         }
+        else if ((fd=get_dev_fd(filename)) >= 0) {
+                return fd;
+        }
 
         va_start(args, oflags);
         mode = va_arg(args, int);
@@ -240,8 +256,12 @@ ssize_t FAST_FUNC mingw_open_read_close(const char *fn, void *buf, size_t size)
 #undef fopen
 FILE *mingw_fopen (const char *filename, const char *otype)
 {
+        int fd;
+
         if (get_dev_type(filename) == DEV_NULL)
                 filename = "nul";
+        else if ((fd=get_dev_fd(filename)) >= 0)
+                return fdopen(fd, otype);
         return fopen(filename, otype);
 }