win32: dd: support if=/dev/zero on Windows

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>

1 files changed, 16 insertions, 4 deletions

diff --git a/coreutils/dd.c b/coreutils/dd.c
index 7c1a0c0df..eb9f8885f 100644
--- a/coreutils/dd.c
+++ b/coreutils/dd.c
@@ -168,6 +168,7 @@ int dd_main(int argc UNUSED_PARAM, char **argv)
 #endif
         };
         int exitcode = EXIT_FAILURE;
+        int devzero = 0;
         size_t ibs = 512, obs = 512;
         ssize_t n, w;
         char *ibuf, *obuf;
@@ -285,7 +286,12 @@ int dd_main(int argc UNUSED_PARAM, char **argv)
 #endif
 
         if (infile != NULL)
-                xmove_fd(xopen(infile, O_RDONLY), ifd);
+                if (ENABLE_PLATFORM_MINGW32 && !strcmp(infile, "/dev/zero")) {
+                        flags |= FLAG_NOERROR;
+                        devzero = 1;
+                }
+                else
+                        xmove_fd(xopen(infile, O_RDONLY), ifd);
         else {
                 infile = bb_msg_standard_input;
         }
@@ -312,7 +318,7 @@ int dd_main(int argc UNUSED_PARAM, char **argv)
         } else {
                 outfile = bb_msg_standard_output;
         }
-        if (skip) {
+        if (skip && !devzero) {
                 if (lseek(ifd, skip * ibs, SEEK_CUR) < 0) {
                         while (skip-- > 0) {
                                 n = safe_read(ifd, ibuf, ibs);
@@ -329,7 +335,12 @@ int dd_main(int argc UNUSED_PARAM, char **argv)
         }
 
         while (!(flags & FLAG_COUNT) || (G.in_full + G.in_part != count)) {
-                n = safe_read(ifd, ibuf, ibs);
+                if (devzero) {
+                        memset(ibuf, 0, ibs);
+                        n = ibs;
+                }
+                else
+                        n = safe_read(ifd, ibuf, ibs);
                 if (n == 0)
                         break;
                 if (n < 0) {
@@ -383,7 +394,8 @@ int dd_main(int argc UNUSED_PARAM, char **argv)
                 if (w < 0) goto out_status;
                 if (w > 0) G.out_part++;
         }
-        if (close(ifd) < 0) {
+
+        if (!devzero && close(ifd) < 0) {
  die_infile:
                 bb_simple_perror_msg_and_die(infile);
         }