tar,smemcap: commonalyze checksumming code for tar header

function                                             old     new   delta
chksum_and_xwrite_tar_header                           -      99     +99
writeheader                                          280     199     -81
chksum_and_xwrite                                    102       -    -102
------------------------------------------------------------------------------
(add/remove: 2/1 grow/shrink: 0/1 up/down: 99/-183)           Total: -84 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 2 insertions, 29 deletions

diff --git a/archival/tar.c b/archival/tar.c
index 94fb61a29..9de37592e 100644
--- a/archival/tar.c
+++ b/archival/tar.c
@@ -254,32 +254,6 @@ static void putOctal(char *cp, int len, off_t value)
 }
 #define PUT_OCTAL(a, b) putOctal((a), sizeof(a), (b))
 
-static void chksum_and_xwrite(int fd, struct tar_header_t* hp)
-{
-        /* POSIX says that checksum is done on unsigned bytes
-         * (Sun and HP-UX gets it wrong... more details in
-         * GNU tar source) */
-        const unsigned char *cp;
-        int chksum, size;
-
-        strcpy(hp->magic, "ustar  ");
-
-        /* Calculate and store the checksum (i.e., the sum of all of the bytes of
-         * the header).  The checksum field must be filled with blanks for the
-         * calculation.  The checksum field is formatted differently from the
-         * other fields: it has 6 digits, a null, then a space -- rather than
-         * digits, followed by a null like the other fields... */
-        memset(hp->chksum, ' ', sizeof(hp->chksum));
-        cp = (const unsigned char *) hp;
-        chksum = 0;
-        size = sizeof(*hp);
-        do { chksum += *cp++; } while (--size);
-        putOctal(hp->chksum, sizeof(hp->chksum)-1, chksum);
-
-        /* Now write the header out to disk */
-        xwrite(fd, hp, sizeof(*hp));
-}
-
 # if ENABLE_FEATURE_TAR_GNU_EXTENSIONS
 static void writeLongname(int fd, int type, const char *name, int dir)
 {
@@ -310,7 +284,7 @@ static void writeLongname(int fd, int type, const char *name, int dir)
         /* + dir: account for possible '/' */
 
         PUT_OCTAL(header.size, size);
-        chksum_and_xwrite(fd, &header);
+        chksum_and_xwrite_tar_header(fd, &header);
 
         /* Write filename[/] and pad the block. */
         /* dir=0: writes 'name<NUL>', pads */
@@ -441,8 +415,7 @@ static int writeTarHeader(struct TarBallInfo *tbInfo,
                                 header_name, S_ISDIR(statbuf->st_mode));
 # endif
 
-        /* Now write the header out to disk */
-        chksum_and_xwrite(tbInfo->tarFd, &header);
+        chksum_and_xwrite_tar_header(tbInfo->tarFd, &header);
 
         /* Now do the verbose thing (or not) */
         if (tbInfo->verboseFlag) {