removing requirement to seek inside of bsdiff

moving writing of header out of bsdiff and into calling function

diff --git a/bsdiff.c b/bsdiff.c
index 960f1e9..c61a36c 100644 (file)
--- a/bsdiff.c
+++ b/bsdiff.c
@@ -38,6 +38,14 @@ __FBSDID("$FreeBSD: src/usr.bin/bsdiff/bsdiff/bsdiff.c,v 1.1 2005/08/06 01:59:05
 #include <string.h>
 #include <unistd.h>
 
+struct bsdiff_header
+{
+       uint8_t signature[8];
+       uint64_t ctrl_block_length;
+       uint64_t diff_block_length;
+       uint64_t new_file_length;
+};
+
 #if defined(__linux__)
 #include <err.h>
 #else
@@ -230,7 +238,7 @@ static void offtout(off_t x,uint8_t *buf)
        if(x<0) buf[7]|=0x80;
 }
 
-int bsdiff(uint8_t* old, off_t oldsize, uint8_t* new, off_t newsize, FILE* pf)
+int bsdiff(uint8_t* old, off_t oldsize, uint8_t* new, off_t newsize, FILE* pf, struct bsdiff_header* header)
 {
        off_t *I,*V;
        off_t scan,pos,len;
@@ -242,7 +250,6 @@ int bsdiff(uint8_t* old, off_t oldsize, uint8_t* new, off_t newsize, FILE* pf)
        off_t dblen,eblen;
        uint8_t *db,*eb;
        uint8_t buf[8];
-       uint8_t header[32];
        BZFILE * pfbz2;
        int bz2err;
 
@@ -268,12 +275,10 @@ int bsdiff(uint8_t* old, off_t oldsize, uint8_t* new, off_t newsize, FILE* pf)
                32      ??      Bzip2ed ctrl block
                ??      ??      Bzip2ed diff block
                ??      ??      Bzip2ed extra block */
-       memcpy(header,"BSDIFF40",8);
-       offtout(0, header + 8);
-       offtout(0, header + 16);
-       offtout(newsize, header + 24);
-       if (fwrite(header, 32, 1, pf) != 1)
-               err(1, "fwrite(%s)", "patch");
+       memcpy(header->signature,"BSDIFF40",sizeof(header->signature));
+       header->ctrl_block_length = 0;
+       header->diff_block_length = 0;
+       header->new_file_length = newsize;
 
        /* Compute the differences, writing ctrl as we go */
        if ((pfbz2 = BZ2_bzWriteOpen(&bz2err, pf, 9, 0, 0)) == NULL)
@@ -366,8 +371,8 @@ int bsdiff(uint8_t* old, off_t oldsize, uint8_t* new, off_t newsize, FILE* pf)
 
        /* Compute size of compressed ctrl data */
        if ((len = ftello(pf)) == -1)
-               err(1, "ftello");
-       offtout(len-32, header + 8);
+               err(1, "ftello64");
+       header->ctrl_block_length = len-32;
 
        /* Write compressed diff data */
        if ((pfbz2 = BZ2_bzWriteOpen(&bz2err, pf, 9, 0, 0)) == NULL)
@@ -381,8 +386,8 @@ int bsdiff(uint8_t* old, off_t oldsize, uint8_t* new, off_t newsize, FILE* pf)
 
        /* Compute size of compressed diff data */
        if ((newsize = ftello(pf)) == -1)
-               err(1, "ftello");
-       offtout(newsize - len, header + 16);
+               err(1, "ftello64");
+       header->diff_block_length = newsize - len;
 
        /* Write compressed extra data */
        if ((pfbz2 = BZ2_bzWriteOpen(&bz2err, pf, 9, 0, 0)) == NULL)
@@ -394,12 +399,6 @@ int bsdiff(uint8_t* old, off_t oldsize, uint8_t* new, off_t newsize, FILE* pf)
        if (bz2err != BZ_OK)
                errx(1, "BZ2_bzWriteClose, bz2err = %d", bz2err);
 
-       /* Seek to the beginning, write the header, and close the file */
-       if (fseeko(pf, 0, SEEK_SET))
-               err(1, "fseeko");
-       if (fwrite(header, 32, 1, pf) != 1)
-               err(1, "fwrite(%s)", "patch");
-
        /* Free the memory we used */
        free(db);
        free(eb);
@@ -413,6 +412,7 @@ int main(int argc,char *argv[])
        int fd;
        uint8_t *old,*new;
        off_t oldsize,newsize;
+       struct bsdiff_header header;
        FILE * pf;
 
        if(argc!=4) errx(1,"usage: %s oldfile newfile patchfile\n",argv[0]);
@@ -440,9 +440,17 @@ int main(int argc,char *argv[])
        if ((pf = fopen(argv[3], "w")) == NULL)
                err(1, "%s", argv[3]);
 
-       if (bsdiff(old, oldsize, new, newsize, pf))
+       /* Save space for header */
+       if (fwrite(&header, sizeof(header), 1, pf) != 1)
+               err(1, "Failed to write header");
+
+       if (bsdiff(old, oldsize, new, newsize, pf, &header))
                err(1, "bsdiff");
 
+       if (fseek(pf, 0, SEEK_SET) ||
+               fwrite(&header, sizeof(header), 1, pf) != 1)
+               err(1, "Failed to write header");
+
        if (fclose(pf))
                err(1, "fclose");