dd: support conv=fsync

dd: support "dd --" if CONFIG_DESKTOP=y

function                                             old     new   delta
static.conv_words                                      -      28     +28
dd_main                                             1369    1373      +4
static.keywords                                      848     827     -21
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 1/1 up/down: 32/-21)             Total: 11 bytes

1 files changed, 86 insertions, 60 deletions

diff --git a/coreutils/dd.c b/coreutils/dd.c
index f3330e624..e172b0c29 100644
--- a/coreutils/dd.c
+++ b/coreutils/dd.c
@@ -79,23 +79,31 @@ static bool write_and_stats(const void *buf, size_t len, size_t obs,
 #endif
 
 int dd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
-int dd_main(int argc, char **argv)
+int dd_main(int argc ATTRIBUTE_UNUSED, char **argv)
 {
 	enum {
-		FLAG_SYNC    = 1 << 0,
-		FLAG_NOERROR = 1 << 1,
-		FLAG_NOTRUNC = 1 << 2,
-		FLAG_TWOBUFS = 1 << 3,
-		FLAG_COUNT   = 1 << 4,
+		/* Must be in the same order as OP_conv_XXX! */
+		/* (see "flags |= (1 << what)" below) */
+		FLAG_NOTRUNC = 1 << 0,
+		FLAG_SYNC    = 1 << 1,
+		FLAG_NOERROR = 1 << 2,
+		FLAG_FSYNC   = 1 << 3,
+		/* end of conv flags */
+		FLAG_TWOBUFS = 1 << 4,
+		FLAG_COUNT   = 1 << 5,
 	};
 	static const char keywords[] ALIGN1 =
 		"bs=\0""count=\0""seek=\0""skip=\0""if=\0""of=\0"
 #if ENABLE_FEATURE_DD_IBS_OBS
-		"ibs=\0""obs=\0""conv=\0""notrunc\0""sync\0""noerror\0"
+		"ibs=\0""obs=\0""conv=\0"
 #endif
 		;
+#if ENABLE_FEATURE_DD_IBS_OBS
+	static const char conv_words[] ALIGN1 =
+		"notrunc\0""sync\0""noerror\0""fsync\0";
+#endif
 	enum {
-		OP_bs = 1,
+		OP_bs = 0,
 		OP_count,
 		OP_seek,
 		OP_skip,
@@ -105,9 +113,23 @@ int dd_main(int argc, char **argv)
 		OP_ibs,
 		OP_obs,
 		OP_conv,
-		OP_conv_notrunc,
+		/* Must be in the same order as FLAG_XXX! */
+		OP_conv_notrunc = 0,
 		OP_conv_sync,
 		OP_conv_noerror,
+		OP_conv_fsync,
+	/* Unimplemented conv=XXX: */
+	//nocreat       do not create the output file
+	//excl          fail if the output file already exists
+	//fdatasync     physically write output file data before finishing
+	//swab          swap every pair of input bytes
+	//lcase         change upper case to lower case
+	//ucase         change lower case to upper case
+	//block         pad newline-terminated records with spaces to cbs-size
+	//unblock       replace trailing spaces in cbs-size records with newline
+	//ascii         from EBCDIC to ASCII
+	//ebcdic        from ASCII to EBCDIC
+	//ibm           from ASCII to alternate EBCDIC
 #endif
 	};
 	int exitcode = EXIT_FAILURE;
@@ -138,85 +160,85 @@ int dd_main(int argc, char **argv)
 	signal_SA_RESTART_empty_mask(SIGUSR1, dd_output_status);
 #endif
 
-	for (n = 1; n < argc; n++) {
-		smalluint key_len;
-		smalluint what;
-		char *key;
+	for (n = 1; argv[n]; n++) {
+		int what;
+		char *val;
 		char *arg = argv[n];
 
-//XXX:FIXME: we reject plain "dd --" This would cost ~20 bytes, so..
-//if (*arg == '-' && *++arg == '-' && !*++arg) continue;
-		key = strstr(arg, "=");
-		if (key == NULL)
+#if ENABLE_DESKTOP
+		/* "dd --". NB: coreutils 6.9 will complain if they see
+		 * more than one of them. We wouldn't. */
+		if (arg[0] == '-' && arg[1] == '-' && arg[2] == '\0')
+			continue;
+#endif
+		val = strchr(arg, '=');
+		if (val == NULL)
 			bb_show_usage();
-		key_len = key - arg + 1;
-		key = xstrndup(arg, key_len);
-		what = index_in_strings(keywords, key) + 1;
-		if (ENABLE_FEATURE_CLEAN_UP)
-			free(key);
-		if (what == 0)
+		*val = '\0';
+		what = index_in_strings(keywords, arg);
+		if (what < 0)
 			bb_show_usage();
-		arg += key_len;
+		/* *val = '='; - to preserve ps listing? */
+		val++;
 #if ENABLE_FEATURE_DD_IBS_OBS
 		if (what == OP_ibs) {
 			/* Must fit into positive ssize_t */
-			ibs = xatoul_range_sfx(arg, 1, ((size_t)-1L)/2, dd_suffixes);
-			continue;
+			ibs = xatoul_range_sfx(val, 1, ((size_t)-1L)/2, dd_suffixes);
+			/*continue;*/
 		}
 		if (what == OP_obs) {
-			obs = xatoul_range_sfx(arg, 1, ((size_t)-1L)/2, dd_suffixes);
-			continue;
+			obs = xatoul_range_sfx(val, 1, ((size_t)-1L)/2, dd_suffixes);
+			/*continue;*/
 		}
 		if (what == OP_conv) {
 			while (1) {
-				/* find ',', replace them with NUL so we can use arg for
+				/* find ',', replace them with NUL so we can use val for
 				 * index_in_strings() without copying.
-				 * We rely on arg being non-null, else strchr would fault.
+				 * We rely on val being non-null, else strchr would fault.
 				 */
-				key = strchr(arg, ',');
-				if (key)
-					*key = '\0';
-				what = index_in_strings(keywords, arg) + 1;
-				if (what < OP_conv_notrunc)
-					bb_error_msg_and_die(bb_msg_invalid_arg, arg, "conv");
-				if (what == OP_conv_notrunc)
-					flags |= FLAG_NOTRUNC;
-				if (what == OP_conv_sync)
-					flags |= FLAG_SYNC;
-				if (what == OP_conv_noerror)
-					flags |= FLAG_NOERROR;
-				if (!key) /* no ',' left, so this was the last specifier */
+				arg = strchr(val, ',');
+				if (arg)
+					*arg = '\0';
+				what = index_in_strings(conv_words, val);
+				if (what < 0)
+					bb_error_msg_and_die(bb_msg_invalid_arg, val, "conv");
+				flags |= (1 << what);
+				if (!arg) /* no ',' left, so this was the last specifier */
 					break;
-				arg = key + 1; /* skip this keyword and ',' */
+				/* *arg = ','; - to preserve ps listing? */
+				val = arg + 1; /* skip this keyword and ',' */
 			}
-			continue;
+			continue; /* we trashed 'what', can't fall through */
 		}
 #endif
 		if (what == OP_bs) {
-			ibs = obs = xatoul_range_sfx(arg, 1, ((size_t)-1L)/2, dd_suffixes);
-			continue;
+			ibs = obs = xatoul_range_sfx(val, 1, ((size_t)-1L)/2, dd_suffixes);
+			/*continue;*/
 		}
 		/* These can be large: */
 		if (what == OP_count) {
 			flags |= FLAG_COUNT;
-			count = XATOU_SFX(arg, dd_suffixes);
-			continue;
+			count = XATOU_SFX(val, dd_suffixes);
+			/*continue;*/
 		}
 		if (what == OP_seek) {
-			seek = XATOU_SFX(arg, dd_suffixes);
-			continue;
+			seek = XATOU_SFX(val, dd_suffixes);
+			/*continue;*/
 		}
 		if (what == OP_skip) {
-			skip = XATOU_SFX(arg, dd_suffixes);
-			continue;
+			skip = XATOU_SFX(val, dd_suffixes);
+			/*continue;*/
 		}
 		if (what == OP_if) {
-			infile = arg;
-			continue;
+			infile = val;
+			/*continue;*/
 		}
-		if (what == OP_of)
-			outfile = arg;
-	}
+		if (what == OP_of) {
+			outfile = val;
+			/*continue;*/
+		}
+	} /* end of "for (argv[n])" */
+
 //XXX:FIXME for huge ibs or obs, malloc'ing them isn't the brightest idea ever
 	ibuf = obuf = xmalloc(ibs);
 	if (ibs != obs) {
@@ -304,13 +326,17 @@ int dd_main(int argc, char **argv)
 			}
 		} else if (write_and_stats(ibuf, n, obs, outfile))
 			goto out_status;
+
+		if (flags & FLAG_FSYNC) {
+			if (fsync(ofd) < 0)
+				goto die_outfile;
+		}
 	}
 
 	if (ENABLE_FEATURE_DD_IBS_OBS && oc) {
 		w = full_write_or_warn(obuf, oc, outfile);
 		if (w < 0) goto out_status;
-		if (w > 0)
-			G.out_part++;
+		if (w > 0) G.out_part++;
 	}
 	if (close(ifd) < 0) {
  die_infile: