On Sat, 31 May 2014, Benjamin Baier wrote:
> This one splits up the malloc parameter, taking full potential from calloc,
> hurting readability a bit. which one is preferred? more
> readable/maintainable or using the calloc overflow protection?
In this case I think readability wins. I do not believe that there is a lot to
gain from overflow protection given the numbers used in these calculations
are very small (and many are already bounds checked in some form or other).
> Index: bootstrap.c
> ===================================================================
> RCS file: /cvs/src/usr.sbin/installboot/bootstrap.c,v
> retrieving revision 1.3
> diff -u -p -r1.3 bootstrap.c
> --- bootstrap.c 28 Dec 2013 12:01:33 -0000 1.3
> +++ bootstrap.c 31 May 2014 10:26:27 -0000
> @@ -68,10 +68,9 @@ bootstrap(int devfd, char *dev, char *bo
> fprintf(stderr, "bootstrap is %zu bytes "
> "(%zu sectors @ %u bytes = %zu bytes)\n",
> (ssize_t)sb.st_size, bootsec, dl.d_secsize, bootsize);
> - boot = malloc(bootsize);
> + boot = calloc(bootsec, dl.d_secsize);
> if (boot == NULL)
> - err(1, "malloc");
> - memset(boot, 0, bootsize);
> + err(1, "calloc");
> if (read(fd, boot, bootsize) != (ssize_t)sb.st_size)
> err(1, "read");
> close(fd);
> Index: i386_softraid.c
> ===================================================================
> RCS file: /cvs/src/usr.sbin/installboot/i386_softraid.c,v
> retrieving revision 1.1
> diff -u -p -r1.1 i386_softraid.c
> --- i386_softraid.c 19 Jan 2014 02:58:50 -0000 1.1
> +++ i386_softraid.c 31 May 2014 10:26:27 -0000
> @@ -129,11 +129,10 @@ sr_install_bootldr(int devfd, char *dev)
> inodeblk = nblocks - 1;
> bootsize = nblocks * SR_FS_BLOCKSIZE;
>
> - p = malloc(bootsize);
> + p = calloc(nblocks, SR_FS_BLOCKSIZE);
> if (p == NULL)
> err(1, NULL);
>
> - memset(p, 0, bootsize);
> fd = open(stage2, O_RDONLY, 0);
> if (fd == -1)
> err(1, NULL);
> Index: sparc64_installboot.c
> ===================================================================
> RCS file: /cvs/src/usr.sbin/installboot/sparc64_installboot.c,v
> retrieving revision 1.1
> diff -u -p -r1.1 sparc64_installboot.c
> --- sparc64_installboot.c 19 Jan 2014 02:58:50 -0000 1.1
> +++ sparc64_installboot.c 31 May 2014 10:26:27 -0000
> @@ -68,10 +68,9 @@ md_loadboot(void)
> if (blksize > SBSIZE - DEV_BSIZE)
> errx(1, "boot blocks too big (%zu > %d)",
> blksize, SBSIZE - DEV_BSIZE);
> - blkstore = malloc(blksize);
> + blkstore = calloc(blocks, DEV_BSIZE);
> if (blkstore == NULL)
> - err(1, "malloc");
> - memset(blkstore, 0, blksize);
> + err(1, "calloc");
> if (read(fd, blkstore, sb.st_size) != (ssize_t)sb.st_size)
> err(1, "read");
> close(fd);
--
"Action without study is fatal. Study without action is futile."
-- Mary Ritter Beard
