[git commit] cksum: code shrink

[Denys Vlasenko]

commit: https://git.busybox.net/busybox/commit/?id=da49e7057a6efada17ba43d046770c95d0bd71a6
branch: https://git.busybox.net/busybox/commit/?id=refs/heads/master

function                                             old     new   delta
cksum_main                                           281     262     -19

Signed-off-by: Denys Vlasenko <vda.linux at googlemail.com>
---
 coreutils/cksum.c | 47 ++++++++++++++++++++++++-----------------------
 1 file changed, 24 insertions(+), 23 deletions(-)

diff --git a/coreutils/cksum.c b/coreutils/cksum.c
index 059a33310..e46e249f2 100644
--- a/coreutils/cksum.c
+++ b/coreutils/cksum.c
@@ -31,9 +31,6 @@ int cksum_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int cksum_main(int argc UNUSED_PARAM, char **argv)
 {
 	uint32_t *crc32_table = crc32_filltable(NULL, 1);
-	uint32_t crc;
-	off_t length, filesize;
-	int bytes_read;
 	int exit_code = EXIT_SUCCESS;
 
 #if ENABLE_DESKTOP
@@ -45,38 +42,42 @@ int cksum_main(int argc UNUSED_PARAM, char **argv)
 
 	setup_common_bufsiz();
 	do {
+		uint32_t crc;
+		off_t filesize;
 		int fd = open_or_warn_stdin(*argv ? *argv : bb_msg_standard_input);
 
 		if (fd < 0) {
 			exit_code = EXIT_FAILURE;
 			continue;
 		}
-		crc = 0;
-		length = 0;
 
+		crc = 0;
+		filesize = 0;
 #define read_buf bb_common_bufsiz1
-		while ((bytes_read = safe_read(fd, read_buf, COMMON_BUFSIZE)) > 0) {
-			length += bytes_read;
+		for (;;) {
+			uoff_t t;
+			int bytes_read = safe_read(fd, read_buf, COMMON_BUFSIZE);
+			if (bytes_read > 0) {
+				filesize += bytes_read;
+			} else {
+				/* Checksum filesize bytes, LSB first, and exit */
+				close(fd);
+				fd = -1; /* break flag */
+				t = filesize;
+				bytes_read = 0;
+				while (t != 0) {
+					read_buf[bytes_read++] = (uint8_t)t;
+					t >>= 8;
+				}
+			}
 			crc = crc32_block_endian1(crc, read_buf, bytes_read, crc32_table);
+			if (fd < 0)
+				break;
 		}
-		close(fd);
-
-		filesize = length;
 
-		while (length) {
-			crc = (crc << 8) ^ crc32_table[(uint8_t)(crc >> 24) ^ (uint8_t)length];
-			/* must ensure that shift is unsigned! */
-			if (sizeof(length) <= sizeof(unsigned))
-				length = (unsigned)length >> 8;
-			else if (sizeof(length) <= sizeof(unsigned long))
-				length = (unsigned long)length >> 8;
-			else
-				length = (unsigned long long)length >> 8;
-		}
 		crc = ~crc;
-
-		printf((*argv ? "%"PRIu32" %"OFF_FMT"i %s\n" : "%"PRIu32" %"OFF_FMT"i\n"),
-				crc, filesize, *argv);
+		printf((*argv ? "%u %"OFF_FMT"u %s\n" : "%u %"OFF_FMT"u\n"),
+				(unsigned)crc, filesize, *argv);
 	} while (*argv && *++argv);
 
 	fflush_stdout_and_exit(exit_code);