win32: save a few bytes in device file support

3 files changed, 40 insertions, 43 deletions

diff --git a/coreutils/dd.c b/coreutils/dd.c
index 10066575e..d29357dae 100644
--- a/coreutils/dd.c
+++ b/coreutils/dd.c
@@ -433,12 +433,7 @@ int dd_main(int argc UNUSED_PARAM, char **argv)
                 xmove_fd(xopen(infile, O_RDONLY), ifd);
 #else
                 xmove_fd(mingw_xopen(infile, O_RDONLY), ifd);
-                if (!strcmp(infile, "/dev/zero")) {
-                        mingw_read_zero(ifd);
-                }
-                else if (!strcmp(infile, "/dev/urandom")) {
-                        mingw_read_random(ifd);
-                }
+                update_dev_fd(get_dev_type(infile), ifd);
 #endif
         } else {
                 infile = bb_msg_standard_input;
diff --git a/include/mingw.h b/include/mingw.h
index a54a6ac85..bc0772574 100644
--- a/include/mingw.h
+++ b/include/mingw.h
@@ -367,10 +367,12 @@ int fsync(int fd);
 int kill(pid_t pid, int sig);
 int link(const char *oldpath, const char *newpath);
 NOIMPL(mknod,const char *name UNUSED_PARAM, mode_t mode UNUSED_PARAM, dev_t device UNUSED_PARAM);
+/* order of devices must match that in get_dev_type */
+enum {DEV_NULL, DEV_ZERO, DEV_URANDOM, NOT_DEVICE};
+int get_dev_type(const char *filename);
+void update_dev_fd(int dev, int fd);
 int mingw_open (const char *filename, int oflags, ...);
 int mingw_xopen(const char *filename, int oflags);
-void mingw_read_zero(int fd);
-void mingw_read_random(int fd);
 ssize_t mingw_read(int fd, void *buf, size_t count);
 int mingw_close(int fd);
 int pipe(int filedes[2]);
diff --git a/win32/mingw.c b/win32/mingw.c
index d73a4d96e..8141e45a5 100644
--- a/win32/mingw.c
+++ b/win32/mingw.c
@@ -141,14 +141,33 @@ int err_win_to_posix(DWORD winerr)
 static int zero_fd = -1;
 static int rand_fd = -1;
 
-void mingw_read_zero(int fd)
+/*
+ * Determine if 'filename' corresponds to one of the supported
+ * device files.  Constants for these are defined as an enum
+ * in mingw.h.
+ */
+int get_dev_type(const char *filename)
 {
-        zero_fd = fd;
+        int i;
+        const char *devname[NOT_DEVICE] = { "null", "zero", "urandom" };
+
+        if (filename && !strncmp(filename, "/dev/", 5)) {
+                for (i=0; i<NOT_DEVICE; ++i ) {
+                        if (!strcmp(filename+5, devname[i])) {
+                                return i;
+                        }
+                }
+        }
+
+        return NOT_DEVICE;
 }
 
-void mingw_read_random(int fd)
+void update_dev_fd(int dev, int fd)
 {
-        rand_fd = fd;
+        if (dev == DEV_ZERO)
+                zero_fd = fd;
+        else if (dev == DEV_URANDOM)
+                rand_fd = fd;
 }
 
 #undef open
@@ -157,47 +176,28 @@ int mingw_open (const char *filename, int oflags, ...)
         va_list args;
         unsigned mode;
         int fd;
-        int special = 0;
-        int devnull = 0;
-        int devzero = 0;
-        int devrand = 0;
+        int special = (oflags & O_SPECIAL);
+        int dev = get_dev_type(filename);
+
+        /* /dev/null is always allowed, others only if O_SPECIAL is set */
+        if (dev != NOT_DEVICE && (dev == DEV_NULL || special)) {
+                filename = "nul";
+                oflags = O_RDWR;
+        }
 
         va_start(args, oflags);
         mode = va_arg(args, int);
         va_end(args);
 
-        if (oflags & O_SPECIAL) {
-                oflags &= ~O_SPECIAL;
-                special = 1;
+        fd = open(filename, oflags&~O_SPECIAL, mode);
+        if (fd >= 0) {
+                update_dev_fd(dev, fd);
         }
-        if (filename && !strncmp(filename, "/dev/", 5)) {
-                if (!strcmp(filename+5, "null")) {
-                        devnull = 1;
-                }
-                else if (special) {
-                        if (!strcmp(filename+5, "zero"))
-                                devzero = 1;
-                        else if (!strcmp(filename+5, "urandom"))
-                                devrand = 1;
-                }
-
-                if (devnull || devzero || devrand ) {
-                        filename = "nul";
-                        oflags = O_RDWR;
-                }
-        }
-        fd = open(filename, oflags, mode);
-        if (fd < 0 && (oflags & O_ACCMODE) != O_RDONLY && errno == EACCES) {
+        else if ((oflags & O_ACCMODE) != O_RDONLY && errno == EACCES) {
                 DWORD attrs = GetFileAttributes(filename);
                 if (attrs != INVALID_FILE_ATTRIBUTES && (attrs & FILE_ATTRIBUTE_DIRECTORY))
                         errno = EISDIR;
         }
-        if (fd >= 0 ) {
-                if (devzero)
-                        zero_fd = fd;
-                else if (devrand)
-                        rand_fd = fd;
-        }
         return fd;
 }