James G. Sack (jim) wrote:
> Christoph Maier wrote:
>..
>..my little program (attached).
I guess I got bitten again by improperly config'd thunderbird for
sending attachments. I can't now find the magic option to embed
attachments automatically, so I'll just paste it in
So, here's another try.
= = = = = = = = = = = =
/* mycmp.c
* mycmp orig copy
* compares orig to copy
* compares at most len(orig) bytes of both files
* quits at first difference
* reports whether 2nd has 'left-overs'
*
* compile via
* -----------
* make mycmp
* or
* gcc -Wall -o mycmp mycmp.c
* or on x86_64, to create a 32bit version
* gcc -m32 -Wall -o mycmp32 mycmp.c
*
* This code released to the public domain
* by James G. Sack (jim) 2006.11.21
****************************************************/
#include <stdio.h>
#include <stdlib.h> // for exit()
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h> // for O_RDONLY
#include <string.h> // for memcmp()
#include <unistd.h> // for read()
#define SIZ 64*1024
unsigned char
ibuf[SIZ],
dbuf[SIZ];
/* needed? */
#ifdef O_LARGEFILE
# define FLAGS (O_RDONLY | O_LARGEFILE)
#else
# define FLAGS O_RDONLY
#endif
int main(int ac, char* av[])
{
int ifil, dfil;
ssize_t isiz, dsiz;
long count;
if (ac < 3) {
printf("Usage: mycmp origfile copy\n");
exit(-1);
}
ifil = open(av[1], FLAGS);
if (ifil < 0) {
printf("ERR: Cannot open original '%s' for input\n", av[1]);
exit(99);
}
dfil = open(av[2], FLAGS);
if (dfil < 0) {
printf("ERR: Cannot open copy '%s' for input\n", av[2]);
exit(98);
}
count = 0;
do {
isiz = read(ifil, ibuf, SIZ);
dsiz = read(dfil, dbuf, SIZ);
if (isiz) {
//ASSERT: got data in ibuf, isiz > 0
if (dsiz < isiz) {
printf("FAIL: orig(%s) is longer than copy(%s); "
"copy has premature EOF at %ld bytes\n",
av[1], av[2], dsiz + count*SIZ);
exit(2);
}
//ASSERT: data in dbuf; dsiz >= isiz
// (could now hunt for 1st diff,
// or write a memcmp replacement)
if (memcmp(ibuf,dbuf,isiz)){
printf("FAIL: orig(%s) and copy(%s) mismatch "
"(at/after) %ld bytes\n",
av[1], av[2], count*SIZ);
exit(1);
}
++count;
}else{
//ASSERT: eof on original
; //nop -- but see dsiz test below
}
if (dsiz > isiz){
printf("FAIL/CURIOUS: orig(%s) shorter than copy(%s), "
"but matches up to orig EOF at %ld bytes\n",
av[1], av[2], isiz + (count-1)*SIZ);
exit(3);
}
}while (isiz > 0);
return 0;
}
/*===eof===*/
--
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