dd.c

Android 一些工具

		(void)memset(out.dbp, 0, out.dbsz - out.dbcnt);
		out.dbcnt = out.dbsz;
	}
	/* If there are pending sparse blocks, make sure
	 * to write out the final block un-sparse
	 */
	if ((out.dbcnt == 0) && pending) {
		memset(out.db, 0, out.dbsz);
		out.dbcnt = out.dbsz;
		out.dbp = out.db + out.dbcnt;
		pending -= out.dbsz;
	}
	if (out.dbcnt)
		dd_out(1);

	/*
	 * Reporting nfs write error may be defered until next
	 * write(2) or close(2) system call.  So, we need to do an
	 * extra check.  If an output is stdout, the file structure
	 * may be shared among with other processes and close(2) just
	 * decreases the reference count.
	 */
	if (out.fd == STDOUT_FILENO && fsync(out.fd) == -1 && errno != EINVAL) {
		fprintf(stderr, "fsync stdout: %s\n", strerror(errno));
		exit(1);
		/* NOTREACHED */
	}
	if (close(out.fd) == -1) {
		fprintf(stderr, "close: %s\n", strerror(errno));
		exit(1);
		/* NOTREACHED */
	}
}

void
dd_out(int force)
{
	static int warned;
	int64_t cnt, n, nw;
	u_char *outp;

	/*
	 * Write one or more blocks out.  The common case is writing a full
	 * output block in a single write; increment the full block stats.
	 * Otherwise, we're into partial block writes.  If a partial write,
	 * and it's a character device, just warn.  If a tape device, quit.
	 *
	 * The partial writes represent two cases.  1: Where the input block
	 * was less than expected so the output block was less than expected.
	 * 2: Where the input block was the right size but we were forced to
	 * write the block in multiple chunks.  The original versions of dd(1)
	 * never wrote a block in more than a single write, so the latter case
	 * never happened.
	 *
	 * One special case is if we're forced to do the write -- in that case
	 * we play games with the buffer size, and it's usually a partial write.
	 */
	outp = out.db;
	for (n = force ? out.dbcnt : out.dbsz;; n = out.dbsz) {
		for (cnt = n;; cnt -= nw) {

			if (!force && ddflags & C_SPARSE) {
				int sparse, i;
				sparse = 1;	/* Is buffer sparse? */
				for (i = 0; i < cnt; i++)
					if (outp[i] != 0) {
						sparse = 0;
						break;
					}
				if (sparse) {
					pending += cnt;
					outp += cnt;
					nw = 0;
					break;
				}
			}
			if (pending != 0) {
				if (lseek(out.fd, pending, SEEK_CUR) ==
				    -1) {
					fprintf(stderr,
						"%s: seek error creating "
						"sparse file: %s\n",
						out.name, strerror(errno));
					exit(1);
				}
			}
			nw = bwrite(out.fd, outp, cnt);
			if (nw <= 0) {
				if (nw == 0) {
					fprintf(stderr, "%s: end of device\n",
						out.name);
					exit(1);
					/* NOTREACHED */
				}
				if (errno != EINTR) {
					fprintf(stderr, "%s: write error: %s\n",
						out.name, strerror(errno));
					/* NOTREACHED */
					exit(1);
				}
				nw = 0;
			}
			if (pending) {
				st.bytes += pending;
				st.sparse += pending/out.dbsz;
				st.out_full += pending/out.dbsz;
				pending = 0;
			}
			outp += nw;
			st.bytes += nw;
			if (nw == n) {
				if (n != out.dbsz)
					++st.out_part;
				else
					++st.out_full;
				break;
			}
			++st.out_part;
			if (nw == cnt)
				break;
			if (out.flags & ISCHR && !warned) {
				warned = 1;
				fprintf(stderr, "%s: short write on character "
					"device\n", out.name);
			}
			if (out.flags & ISTAPE) {
				fprintf(stderr,
					"%s: short write on tape device",
					out.name);
				exit(1);
				/* NOTREACHED */
			}
		}
		if ((out.dbcnt -= n) < out.dbsz)
			break;
	}

	/* Reassemble the output block. */
	if (out.dbcnt)
		(void)memmove(out.db, out.dbp - out.dbcnt, out.dbcnt);
	out.dbp = out.db + out.dbcnt;

	if (progress)
		(void)write(STDERR_FILENO, ".", 1);
}

/*
 * A protected against SIGINFO write
 */
ssize_t
bwrite(int fd, const void *buf, size_t len)
{
	sigset_t oset;
	ssize_t rv;
	int oerrno;

	(void)sigprocmask(SIG_BLOCK, &infoset, &oset);
	rv = write(fd, buf, len);
	oerrno = errno;
	(void)sigprocmask(SIG_SETMASK, &oset, NULL);
	errno = oerrno;
	return (rv);
}

/*
 * Position input/output data streams before starting the copy.  Device type
 * dependent.  Seekable devices use lseek, and the rest position by reading.
 * Seeking past the end of file can cause null blocks to be written to the
 * output.
 */
void
pos_in(void)
{
	int bcnt, cnt, nr, warned;

	/* If not a pipe or tape device, try to seek on it. */
	if (!(in.flags & (ISPIPE|ISTAPE))) {
		if (lseek(in.fd,
		    (off_t)in.offset * (off_t)in.dbsz, SEEK_CUR) == -1) {
			fprintf(stderr, "%s: seek error: %s",
				in.name, strerror(errno));
			exit(1);
			/* NOTREACHED */
		}
		return;
		/* NOTREACHED */
	}

	/*
	 * Read the data.  If a pipe, read until satisfy the number of bytes
	 * being skipped.  No differentiation for reading complete and partial
	 * blocks for other devices.
	 */
	for (bcnt = in.dbsz, cnt = in.offset, warned = 0; cnt;) {
		if ((nr = read(in.fd, in.db, bcnt)) > 0) {
			if (in.flags & ISPIPE) {
				if (!(bcnt -= nr)) {
					bcnt = in.dbsz;
					--cnt;
				}
			} else
				--cnt;
			continue;
		}

		if (nr == 0) {
			if (files_cnt > 1) {
				--files_cnt;
				continue;
			}
			fprintf(stderr, "skip reached end of input\n");
			exit(1);
			/* NOTREACHED */
		}

		/*
		 * Input error -- either EOF with no more files, or I/O error.
		 * If noerror not set die.  POSIX requires that the warning
		 * message be followed by an I/O display.
		 */
		if (ddflags & C_NOERROR) {
			if (!warned) {

				fprintf(stderr, "%s: error occurred\n",
					in.name);
				warned = 1;
				summary();
			}
			continue;
		}
		fprintf(stderr, "%s: read error: %s", in.name, strerror(errno));
		exit(1);
		/* NOTREACHED */
	}
}

void
pos_out(void)
{
//	struct mtop t_op;
	int cnt, n;

	/*
	 * If not a tape, try seeking on the file.  Seeking on a pipe is
	 * going to fail, but don't protect the user -- they shouldn't
	 * have specified the seek operand.
	 */
	if (!(out.flags & ISTAPE)) {
		if (lseek(out.fd,
		    (off_t)out.offset * (off_t)out.dbsz, SEEK_SET) == -1) {
			fprintf(stderr, "%s: seek error: %s\n",
				out.name, strerror(errno));
			exit(1);
			/* NOTREACHED */
		}
		return;
	}

	/* If no read access, try using mtio. */
	if (out.flags & NOREAD) {
/*		t_op.mt_op = MTFSR;
		t_op.mt_count = out.offset;

		if (ioctl(out.fd, MTIOCTOP, &t_op) < 0)*/
			fprintf(stderr, "%s: cannot read", out.name);
			exit(1);
			/* NOTREACHED */
		return;
	}

	/* Read it. */
	for (cnt = 0; cnt < out.offset; ++cnt) {
		if ((n = read(out.fd, out.db, out.dbsz)) > 0)
			continue;

		if (n < 0) {
			fprintf(stderr, "%s: cannot position by reading: %s\n",
				out.name, strerror(errno));
			exit(1);
			/* NOTREACHED */
		}

		/*
		 * If reach EOF, fill with NUL characters; first, back up over
		 * the EOF mark.  Note, cnt has not yet been incremented, so
		 * the EOF read does not count as a seek'd block.
		 */
/*		t_op.mt_op = MTBSR;
		t_op.mt_count = 1;
		if (ioctl(out.fd, MTIOCTOP, &t_op) == -1) */ {
			fprintf(stderr, "%s: cannot position\n", out.name);
			exit(1);
			/* NOTREACHED */
		}

		while (cnt++ < out.offset)
			if ((n = bwrite(out.fd, out.db, out.dbsz)) != out.dbsz) {
				fprintf(stderr, "%s: cannot position "
					"by writing: %s\n",
					out.name, strerror(errno));
				exit(1);
				/* NOTREACHED */
			}
		break;
	}
}

/*
 * def --
 * Copy input to output.  Input is buffered until reaches obs, and then
 * output until less than obs remains.  Only a single buffer is used.
 * Worst case buffer calculation is (ibs + obs - 1).
 */
void
def(void)
{
	uint64_t cnt;
	u_char *inp;
	const u_char *t;

	if ((t = ctab) != NULL)
		for (inp = in.dbp - (cnt = in.dbrcnt); cnt--; ++inp)
			*inp = t[*inp];

	/* Make the output buffer look right. */
	out.dbp = in.dbp;
	out.dbcnt = in.dbcnt;

	if (in.dbcnt >= out.dbsz) {
		/* If the output buffer is full, write it. */
		dd_out(0);

		/*
		 * Ddout copies the leftover output to the beginning of
		 * the buffer and resets the output buffer.  Reset the
		 * input buffer to match it.
	 	 */
		in.dbp = out.dbp;
		in.dbcnt = out.dbcnt;
	}
}

void
def_close(void)
{

	/* Just update the count, everything is already in the buffer. */
	if (in.dbcnt)
		out.dbcnt = in.dbcnt;
}

#ifdef	NO_CONV
/* Build a smaller version (i.e. for a miniroot) */
/* These can not be called, but just in case...  */
static const char no_block[] = "unblock and -DNO_CONV?\n";
void block(void)		{ fprintf(stderr, "%s", no_block + 2); exit(1); }
void block_close(void)		{ fprintf(stderr, "%s", no_block + 2); exit(1); }
void unblock(void)		{ fprintf(stderr, "%s", no_block); exit(1); }
void unblock_close(void)	{ fprintf(stderr, "%s", no_block); exit(1); }
#else	/* NO_CONV */

/*
 * Copy variable length newline terminated records with a max size cbsz
 * bytes to output.  Records less than cbs are padded with spaces.
 *
 * max in buffer:  MAX(ibs, cbsz)
 * max out buffer: obs + cbsz
 */
void
block(void)
{
	static int intrunc;
	int ch = 0;	/* pacify gcc */
	uint64_t cnt, maxlen;
	u_char *inp, *outp;
	const u_char *t;

	/*
	 * Record truncation can cross block boundaries.  If currently in a
	 * truncation state, keep tossing characters until reach a newline.
	 * Start at the beginning of the buffer, as the input buffer is always
	 * left empty.
	 */
	if (intrunc) {
		for (inp = in.db, cnt = in.dbrcnt;
		    cnt && *inp++ != '\n'; --cnt);
		if (!cnt) {
			in.dbcnt = 0;
			in.dbp = in.db;
			return;
		}
		intrunc = 0;
		/* Adjust the input buffer numbers. */
		in.dbcnt = cnt - 1;
		in.dbp = inp + cnt - 1;
	}

	/*
	 * Copy records (max cbsz size chunks) into the output buffer.  The
	 * translation is done as we copy into the output buffer.
	 */
	for (inp = in.dbp - in.dbcnt, outp = out.dbp; in.dbcnt;) {
		maxlen = MIN(cbsz, in.dbcnt);
		if ((t = ctab) != NULL)
			for (cnt = 0;
			    cnt < maxlen && (ch = *inp++) != '\n'; ++cnt)
				*outp++ = t[ch];
		else
			for (cnt = 0;
			    cnt < maxlen && (ch = *inp++) != '\n'; ++cnt)
				*outp++ = ch;
		/*
		 * Check for short record without a newline.  Reassemble the
		 * input block.
		 */
		if (ch != '\n' && in.dbcnt < cbsz) {
			(void)memmove(in.db, in.dbp - in.dbcnt, in.dbcnt);
			break;
		}

		/* Adjust the input buffer numbers. */
		in.dbcnt -= cnt;
		if (ch == '\n')
			--in.dbcnt;

		/* Pad short records with spaces. */
		if (cnt < cbsz)
			(void)memset(outp, ctab ? ctab[' '] : ' ', cbsz - cnt);
		else {
			/*
			 * If the next character wouldn't have ended the
			 * block, it's a truncation.
			 */
			if (!in.dbcnt || *inp != '\n')
				++st.trunc;

			/* Toss characters to a newline. */
			for (; in.dbcnt && *inp++ != '\n'; --in.dbcnt);
			if (!in.dbcnt)
				intrunc = 1;
			else
				--in.dbcnt;
		}

		/* Adjust output buffer numbers. */
		out.dbp += cbsz;
		if ((out.dbcnt += cbsz) >= out.dbsz)
			dd_out(0);
		outp = out.dbp;
	}
	in.dbp = in.db + in.dbcnt;
}