Improve performance of mking(1) by keeping a list of "chunks" in memory,

that keeps track of a particular region of the image. In particular the
image_data() function needs to return to the caller whether a region
contains data or is all zeroes. This required reading the region from
the temporary file and comparing the bytes. When image_data() is used
multiple times for the same region, this will get painful fast.

With a chunk describing a region of the image, we now also have a way
to refer to the image provided on the command line. This means we don't
need to copy the image into a temporary file. We just keep track of the
file descriptor and offset within the source file on a per-chunk basis.

For streams (pipes, sockets, fifos, etc) we now use the temporary file
as a swap file. We read from the input file and create a chunk of type
"zeroes" for each sequence of zeroes that's a multiple of the sector
size. Otherwise, we allocte from the swap file, mmap(2) it, read into
the mmap(2)'d memory and create a chunk representing data.

For regular files, we use SEEK_HOLE and SEEK_DATA to handle sparse files
eficiently and create a chunk of type zeroes for holes and a chunk of
type data for data regions. For data regions, we still compare the bytes
we read to handle differences between a file system's block size and our
sector size.

After reading all files, image_write() is used by schemes to scribble in
the reserved sectors. Since this never amounts to much, keep this data
in memory in chunks of exactly 1 sector.

The output image is created by looking using the chunk list to find the
data and write it out to the output file. For chunks of type "zeroes"
we prefer to seek, but fall back to writing zeroes to handle pipes.
For chunks of type "file" and "memoty" we simply write.

The net effect of this is that for reasonably large images the execution
time drops from 1-2 minutes to 10-20 seconds. A typical speedup is about
5 to 8 times, depending on partition sizes, output format whether in
input files are sparse or not.

Bump version to 20141001.

2 files changed, 586 insertions, 94 deletions

diff --git a/usr.bin/mkimg/Makefile b/usr.bin/mkimg/Makefile
index 7745566..563ca58 100644
--- a/usr.bin/mkimg/Makefile
+++ b/usr.bin/mkimg/Makefile
@@ -6,7 +6,7 @@ PROG=	mkimg
 SRCS=	format.c image.c mkimg.c scheme.c
 MAN=	mkimg.1
 
-MKIMG_VERSION=20140927
+MKIMG_VERSION=20141001
 CFLAGS+=-DMKIMG_VERSION=${MKIMG_VERSION}
 CFLAGS+=-DSPARSE_WRITE
 
diff --git a/usr.bin/mkimg/image.c b/usr.bin/mkimg/image.c
index f448d98..3e7c7d2 100644
--- a/usr.bin/mkimg/image.c
+++ b/usr.bin/mkimg/image.c
@@ -27,71 +27,462 @@
 #include <sys/cdefs.h>
 __FBSDID("$FreeBSD$");
 
+#include <sys/mman.h>
+#include <sys/queue.h>
+#include <sys/stat.h>
 #include <sys/types.h>
 #include <assert.h>
 #include <errno.h>
 #include <limits.h>
 #include <paths.h>
+#include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 #include <unistd.h>
 
 #include "image.h"
 #include "mkimg.h"
 
-#define	BUFFER_SIZE	(1024*1024)
+struct chunk {
+	STAILQ_ENTRY(chunk) ch_list;
+	size_t	ch_size;		/* Size of chunk in bytes. */
+	lba_t	ch_block;		/* Block address in image. */
+	union {
+		struct {
+			off_t	ofs;	/* Offset in backing file. */
+			int	fd;	/* FD of backing file. */
+		} file;
+		struct {
+			void	*ptr;	/* Pointer to data in memory */
+		} mem;
+	} ch_u;
+	u_int	ch_type;
+#define	CH_TYPE_ZEROES		0	/* Chunk is a gap (no data). */
+#define	CH_TYPE_FILE		1	/* File-backed chunk. */
+#define	CH_TYPE_MEMORY		2	/* Memory-backed chunk */
+};
+
+static STAILQ_HEAD(chunk_head, chunk) image_chunks;
+static u_int image_nchunks;
+
+static char image_swap_file[PATH_MAX];
+static int image_swap_fd = -1;
+static u_int image_swap_pgsz;
+static off_t image_swap_size;
 
-static char image_tmpfile[PATH_MAX];
-static int image_fd = -1;
 static lba_t image_size;
 
-static void
-cleanup(void)
+static int
+is_empty_sector(void *buf)
 {
+	uint64_t *p = buf;
+	size_t n, max;
+
+	assert(((uintptr_t)p & 3) == 0);
 
-	if (image_fd != -1)
-		close(image_fd);
-	unlink(image_tmpfile);
+	max = secsz / sizeof(uint64_t);
+	for (n = 0; n < max; n++) {
+		if (p[n] != 0UL)
+			return (0);
+	}
+	return (1);
 }
 
-int
-image_copyin(lba_t blk, int fd, uint64_t *sizep)
+/*
+ * Swap file handlng.
+ */
+
+static off_t
+image_swap_alloc(size_t size)
+{
+	off_t ofs;
+	size_t unit;
+
+	unit = (secsz > image_swap_pgsz) ? secsz : image_swap_pgsz;
+	assert((unit & (unit - 1)) == 0);
+
+	size = (size + unit - 1) & ~(unit - 1);
+
+	ofs = image_swap_size;
+	image_swap_size += size;
+	if (ftruncate(image_swap_fd, image_swap_size) == -1) {
+		image_swap_size = ofs;
+		ofs = -1LL;
+	}
+	return (ofs);
+}
+
+/*
+ * Image chunk handling.
+ */
+
+static struct chunk *
+image_chunk_find(lba_t blk)
+{
+	static struct chunk *last = NULL;
+	struct chunk *ch;
+
+	ch = (last != NULL && last->ch_block <= blk)
+	    ? last : STAILQ_FIRST(&image_chunks);
+	while (ch != NULL) {
+		if (ch->ch_block <= blk &&
+		    (lba_t)(ch->ch_block + (ch->ch_size / secsz)) > blk) {
+			last = ch;
+			break;
+		}
+		ch = STAILQ_NEXT(ch, ch_list);
+	}
+	return (ch);
+}
+
+static size_t
+image_chunk_grow(struct chunk *ch, size_t sz)
+{
+	size_t dsz, newsz;
+
+	newsz = ch->ch_size + sz;
+	if (newsz > ch->ch_size) {
+		ch->ch_size = newsz;
+		return (0);
+	}
+	/* We would overflow -- create new chunk for remainder. */
+	dsz = SIZE_MAX - ch->ch_size;
+	assert(dsz < sz);
+	ch->ch_size = SIZE_MAX;
+	return (sz - dsz);
+}
+
+static struct chunk *
+image_chunk_memory(struct chunk *ch, lba_t blk)
+{
+	struct chunk *new;
+	void *ptr;
+
+	ptr = calloc(1, secsz);
+	if (ptr == NULL)
+		return (NULL);
+
+	if (ch->ch_block < blk) {
+		new = malloc(sizeof(*new));
+		if (new == NULL) {
+			free(ptr);
+			return (NULL);
+		}
+		memcpy(new, ch, sizeof(*new));
+		ch->ch_size = (blk - ch->ch_block) * secsz;
+		new->ch_block = blk;
+		new->ch_size -= ch->ch_size;
+		STAILQ_INSERT_AFTER(&image_chunks, ch, new, ch_list);
+		image_nchunks++;
+		ch = new;
+	}
+
+	if (ch->ch_size > secsz) {
+		new = malloc(sizeof(*new));
+		if (new == NULL) {
+			free(ptr);
+			return (NULL);
+		}
+		memcpy(new, ch, sizeof(*new));
+		ch->ch_size = secsz;
+		new->ch_block++;
+		new->ch_size -= secsz;
+		STAILQ_INSERT_AFTER(&image_chunks, ch, new, ch_list);
+		image_nchunks++;
+	}
+
+	ch->ch_type = CH_TYPE_MEMORY;
+	ch->ch_u.mem.ptr = ptr;
+	return (ch);
+}
+
+static int
+image_chunk_skipto(lba_t to)
+{
+	struct chunk *ch;
+	lba_t from;
+	size_t sz;
+
+	ch = STAILQ_LAST(&image_chunks, chunk, ch_list);
+	from = (ch != NULL) ? ch->ch_block + (ch->ch_size / secsz) : 0LL;
+
+	assert(from <= to);
+
+	/* Nothing to do? */
+	if (from == to)
+		return (0);
+	/* Avoid bugs due to overflows. */
+	if ((uintmax_t)(to - from) > (uintmax_t)(SIZE_MAX / secsz))
+		return (EFBIG);
+	sz = (to - from) * secsz;
+	if (ch != NULL && ch->ch_type == CH_TYPE_ZEROES) {
+		sz = image_chunk_grow(ch, sz);
+		if (sz == 0)
+			return (0);
+		from = ch->ch_block + (ch->ch_size / secsz);
+	}
+	ch = malloc(sizeof(*ch));
+	if (ch == NULL)
+		return (ENOMEM);
+	memset(ch, 0, sizeof(*ch));
+	ch->ch_block = from;
+	ch->ch_size = sz;
+	ch->ch_type = CH_TYPE_ZEROES;
+	STAILQ_INSERT_TAIL(&image_chunks, ch, ch_list);
+	image_nchunks++;
+	return (0);
+}
+
+static int
+image_chunk_append(lba_t blk, size_t sz, off_t ofs, int fd)
+{
+	struct chunk *ch;
+
+	ch = STAILQ_LAST(&image_chunks, chunk, ch_list);
+	if (ch != NULL && ch->ch_type == CH_TYPE_FILE) {
+		if (fd == ch->ch_u.file.fd &&
+		    blk == (lba_t)(ch->ch_block + (ch->ch_size / secsz)) &&
+		    ofs == (off_t)(ch->ch_u.file.ofs + ch->ch_size)) {
+			sz = image_chunk_grow(ch, sz);
+			if (sz == 0)
+				return (0);
+			blk = ch->ch_block + (ch->ch_size / secsz);
+			ofs = ch->ch_u.file.ofs + ch->ch_size;
+		}
+	}
+	ch = malloc(sizeof(*ch));
+	if (ch == NULL)
+		return (ENOMEM);
+	memset(ch, 0, sizeof(*ch));
+	ch->ch_block = blk;
+	ch->ch_size = sz;
+	ch->ch_type = CH_TYPE_FILE;
+	ch->ch_u.file.ofs = ofs;
+	ch->ch_u.file.fd = fd;
+	STAILQ_INSERT_TAIL(&image_chunks, ch, ch_list);
+	image_nchunks++;
+	return (0);
+}
+
+static int
+image_chunk_copyin(lba_t blk, void *buf, size_t sz, off_t ofs, int fd)
+{
+	uint8_t *p = buf;
+	int error;
+
+	error = 0;
+	sz = (sz + secsz - 1) & ~(secsz - 1);
+	while (!error && sz > 0) {
+		if (is_empty_sector(p))
+			error = image_chunk_skipto(blk + 1);
+		else
+			error = image_chunk_append(blk, secsz, ofs, fd);
+		blk++;
+		p += secsz;
+		sz -= secsz;
+		ofs += secsz;
+	}
+	return (error);
+}
+
+/*
+ * File mapping support.
+ */
+
+static void *
+image_file_map(int fd, off_t ofs, size_t sz)
+{
+	void *ptr;
+	size_t unit;
+	int flags, prot;
+
+	unit = (secsz > image_swap_pgsz) ? secsz : image_swap_pgsz;
+	assert((unit & (unit - 1)) == 0);
+
+	flags = MAP_NOCORE | MAP_NOSYNC | MAP_SHARED;
+	/* Allow writing to our swap file only. */
+	prot = PROT_READ | ((fd == image_swap_fd) ? PROT_WRITE : 0);
+	sz = (sz + unit - 1) & ~(unit - 1);
+	ptr = mmap(NULL, sz, prot, flags, fd, ofs);
+	return ((ptr == MAP_FAILED) ? NULL : ptr);
+}
+
+static int
+image_file_unmap(void *buffer, size_t sz)
+{
+	size_t unit;
+
+	unit = (secsz > image_swap_pgsz) ? secsz : image_swap_pgsz;
+	sz = (sz + unit - 1) & ~(unit - 1);
+	munmap(buffer, sz);
+	return (0);
+}
+
+/*
+ * Input/source file handling.
+ */
+
+static int
+image_copyin_stream(lba_t blk, int fd, uint64_t *sizep)
 {
 	char *buffer;
 	uint64_t bytesize;
-	ssize_t bcnt, rdsz;
-	int error, partial;
+	off_t swofs;
+	size_t iosz;
+	ssize_t rdsz;
+	int error;
 
-	assert(BUFFER_SIZE % secsz == 0);
+	/*
+	 * This makes sure we're doing I/O in multiples of the page
+	 * size as well as of the sector size. 2MB is the minimum
+	 * by virtue of secsz at least 512 bytes and the page size
+	 * at least 4K bytes.
+	 */
+	iosz = secsz * image_swap_pgsz;
 
-	buffer = malloc(BUFFER_SIZE);
-	if (buffer == NULL)
-		return (ENOMEM);
 	bytesize = 0;
-	partial = 0;
-	while (1) {
-		rdsz = read(fd, buffer, BUFFER_SIZE);
-		if (rdsz <= 0) {
-			error = (rdsz < 0) ? errno : 0;
-			break;
-		}
-		if (partial)
-			abort();
-		bytesize += rdsz;
-		bcnt = (rdsz + secsz - 1) / secsz;
-		error = image_write(blk, buffer, bcnt);
+	do {
+		swofs = image_swap_alloc(iosz);
+		if (swofs == -1LL)
+			return (errno);
+		buffer = image_file_map(image_swap_fd, swofs, iosz);
+		if (buffer == NULL)
+			return (errno);
+		rdsz = read(fd, buffer, iosz);
+		if (rdsz > 0)
+			error = image_chunk_copyin(blk, buffer, rdsz, swofs,
+			    image_swap_fd);
+		else if (rdsz < 0)
+			error = errno;
+		else
+			error = 0;
+		image_file_unmap(buffer, iosz);
+		/* XXX should we relinguish unused swap space? */
 		if (error)
+			return (error);
+
+		bytesize += rdsz;
+		blk += (rdsz + secsz - 1) / secsz;
+	} while (rdsz > 0);
+
+	if (sizep != NULL)
+		*sizep = bytesize;
+	return (0);
+}
+
+static int
+image_copyin_mapped(lba_t blk, int fd, uint64_t *sizep)
+{
+	off_t cur, data, end, hole, pos;
+	void *buf;
+	uint64_t bytesize;
+	size_t iosz, sz;
+	int error;
+
+	/*
+	 * We'd like to know the size of the file and we must
+	 * be able to seek in order to mmap(2). If this isn't
+	 * possible, then treat the file as a stream/pipe.
+	 */
+	end = lseek(fd, 0L, SEEK_END);
+	if (end == -1L)
+		return (image_copyin_stream(blk, fd, sizep));
+
+	/*
+	 * We need the file opened for the duration and our
+	 * caller is going to close the file. Make a dup(2)
+	 * so that control the faith of the descriptor.
+	 */
+	fd = dup(fd);
+	if (fd == -1)
+		return (errno);
+
+	iosz = secsz * image_swap_pgsz;
+
+	bytesize = 0;
+	cur = pos = 0;
+	error = 0;
+	while (!error && cur < end) {
+		hole = lseek(fd, cur, SEEK_HOLE);
+		data = lseek(fd, cur, SEEK_DATA);
+
+		/*
+		 * Treat the entire file as data if sparse files
+		 * are not supported by the underlying file system.
+		 */
+		if (hole == -1 && data == -1) {
+			data = cur;
+			hole = end;
+		}
+
+		if (cur == hole && data > hole) {
+			hole = pos;
+			pos = data & ~((uint64_t)secsz - 1);
+
+			blk += (pos - hole) / secsz;
+			error = image_chunk_skipto(blk);
+
+			bytesize += pos - hole;
+			cur = data;
+		} else if (cur == data && hole > data) {
+			data = pos;
+			pos = (hole + secsz - 1) & ~((uint64_t)secsz - 1);
+
+			while (data < pos) {
+				sz = (pos - data > (off_t)iosz)
+				    ? iosz : (size_t)(pos - data);
+
+				buf = image_file_map(fd, data, sz);
+				if (buf != NULL) {
+					error = image_chunk_copyin(blk, buf,
+					    sz, data, fd);
+					image_file_unmap(buf, sz);
+				} else
+					error = errno;
+
+				blk += sz / secsz;
+				bytesize += sz;
+				data += sz;
+			}
+			cur = hole;
+		} else {
+			/*
+			 * I don't know what this means or whether it
+			 * can happen at all...
+			 */
+			error = EDOOFUS;
 			break;
-		blk += bcnt;
-		partial = ((ssize_t)(bcnt * secsz) != rdsz) ? 1 : 0;
+		}
 	}
-	free(buffer);
-	if (sizep != NULL)
+	if (error)
+		close(fd);
+	if (!error && sizep != NULL)
 		*sizep = bytesize;
 	return (error);
 }
 
 int
+image_copyin(lba_t blk, int fd, uint64_t *sizep)
+{
+	struct stat sb;
+	int error;
+
+	error = image_chunk_skipto(blk);
+	if (!error) {
+		if (fstat(fd, &sb) == -1 || !S_ISREG(sb.st_mode))
+			error = image_copyin_stream(blk, fd, sizep);
+		else
+			error = image_copyin_mapped(blk, fd, sizep);
+	}
+	return (error);
+}
+
+/*
+ * Output/sink file handling.
+ */
+
+int
 image_copyout(int fd)
 {
 	int error;
@@ -115,71 +506,124 @@ image_copyout_done(int fd)
 	return (error);
 }
 
-int
-image_copyout_region(int fd, lba_t blk, lba_t size)
+static int
+image_copyout_memory(int fd, size_t size, void *ptr)
 {
-	char *buffer;
-	off_t ofs;
+
+	if (write(fd, ptr, size) == -1)
+		return (errno);
+	return (0);
+}
+
+static int
+image_copyout_zeroes(int fd, size_t size)
+{
+	static uint8_t *zeroes = NULL;
 	size_t sz;
-	ssize_t rdsz, wrsz;
 	int error;
 
-	ofs = lseek(fd, 0L, SEEK_CUR);
+	if (lseek(fd, (off_t)size, SEEK_CUR) != -1)
+		return (0);
+
+	/*
+	 * If we can't seek, we must write.
+	 */
+
+	if (zeroes == NULL) {
+		zeroes = calloc(1, secsz);
+		if (zeroes == NULL)
+			return (ENOMEM);
+	}
+
+	while (size > 0) {
+		sz = (size > secsz) ? secsz : size;
+		error = image_copyout_memory(fd, sz, zeroes);
+		if (error)
+			return (error);
+		size -= sz;
+	}
+	return (0);
+}
+
+static int
+image_copyout_file(int fd, size_t size, int ifd, off_t iofs)
+{
+	void *buf;
+	size_t iosz, sz;
+	int error;
+
+	iosz = secsz * image_swap_pgsz;
+
+	while (size > 0) {
+		sz = (size > iosz) ? iosz : size;
+		buf = image_file_map(ifd, iofs, sz);
+		if (buf == NULL)
+			return (errno);
+		error = image_copyout_memory(fd, sz, buf);
+		image_file_unmap(buf, sz);
+		if (error)
+			return (error);
+		size -= sz;
+		iofs += sz;
+	}
+	return (0);
+}
+
+int
+image_copyout_region(int fd, lba_t blk, lba_t size)
+{
+	struct chunk *ch;
+	size_t ofs, sz;
+	int error;
 
-	blk *= secsz;
-	if (lseek(image_fd, blk, SEEK_SET) != blk)
-		return (errno);
-	buffer = malloc(BUFFER_SIZE);
-	if (buffer == NULL)
-		return (errno);
-	error = 0;
 	size *= secsz;
+
 	while (size > 0) {
-		sz = (BUFFER_SIZE < size) ? BUFFER_SIZE : size;
-		rdsz = read(image_fd, buffer, sz);
-		if (rdsz <= 0) {
-			error = (rdsz < 0) ? errno : 0;
+		ch = image_chunk_find(blk);
+		if (ch == NULL)
+			return (EINVAL);
+		ofs = (blk - ch->ch_block) * secsz;
+		sz = ch->ch_size - ofs;
+		sz = ((lba_t)sz < size) ? sz : (size_t)size;
+		switch (ch->ch_type) {
+		case CH_TYPE_ZEROES:
+			error = image_copyout_zeroes(fd, sz);
 			break;
-		}
-		wrsz = (ofs == -1) ?
-		    write(fd, buffer, rdsz) :
-		    sparse_write(fd, buffer, rdsz);
-		if (wrsz < 0) {
-			error = errno;
+		case CH_TYPE_FILE:
+			error = image_copyout_file(fd, sz, ch->ch_u.file.fd,
+			    ch->ch_u.file.ofs + ofs);
+			break;
+		case CH_TYPE_MEMORY:
+			error = image_copyout_memory(fd, sz, ch->ch_u.mem.ptr);
 			break;
+		default:
+			return (EDOOFUS);
 		}
-		assert(wrsz == rdsz);
-		size -= rdsz;
+		size -= sz;
+		blk += sz / secsz;
 	}
-	free(buffer);
-	return (error);
+	return (0);
 }
 
 int
 image_data(lba_t blk, lba_t size)
 {
-	char *buffer, *p;
-
-	blk *= secsz;
-	if (lseek(image_fd, blk, SEEK_SET) != blk)
-		return (1);
-
-	size *= secsz;
-	buffer = malloc(size);
-	if (buffer == NULL)
-		return (1);
+	struct chunk *ch;
+	lba_t lim;
 
-	if (read(image_fd, buffer, size) != (ssize_t)size) {
-		free(buffer);
-		return (1);
+	while (1) {
+		ch = image_chunk_find(blk);
+		if (ch == NULL)
+			return (0);
+		if (ch->ch_type != CH_TYPE_ZEROES)
+			return (1);
+		lim = ch->ch_block + (ch->ch_size / secsz);
+		if (lim >= blk + size)
+			return (0);
+		size -= lim - blk;
+		blk = lim;
 	}
-
-	p = buffer;
-	while (size > 0 && *p == '\0')
-		size--, p++;
-
-	free(buffer);
-	return ((size == 0) ? 0 : 1);
+	/*NOTREACHED*/
 }
 
 lba_t
@@ -192,39 +636,87 @@ image_get_size(void)
 int
 image_set_size(lba_t blk)
 {
+	int error;
 
-	image_size = blk;
-	if (ftruncate(image_fd, blk * secsz) == -1)
-		return (errno);
-	return (0);
+	error = image_chunk_skipto(blk);
+	if (!error)
+		image_size = blk;
+	return (error);
 }
 
 int
 image_write(lba_t blk, void *buf, ssize_t len)
 {
+	struct chunk *ch;
 
-	blk *= secsz;
-	if (lseek(image_fd, blk, SEEK_SET) != blk)
-		return (errno);
-	len *= secsz;
-	if (sparse_write(image_fd, buf, len) != len)
-		return (errno);
+	while (len > 0) {
+		if (!is_empty_sector(buf)) {
+			ch = image_chunk_find(blk);
+			if (ch == NULL)
+				return (ENXIO);
+			/* We may not be able to write to files. */
+			if (ch->ch_type == CH_TYPE_FILE)
+				return (EINVAL);
+			if (ch->ch_type == CH_TYPE_ZEROES) {
+				ch = image_chunk_memory(ch, blk);
+				if (ch == NULL)
+					return (ENOMEM);
+			}
+			assert(ch->ch_type == CH_TYPE_MEMORY);
+			memcpy(ch->ch_u.mem.ptr, buf, secsz);
+		}
+		blk++;
+		buf = (char *)buf + secsz;
+		len--;
+	}
 	return (0);
 }
 
+static void
+image_cleanup(void)
+{
+	struct chunk *ch;
+
+	while ((ch = STAILQ_FIRST(&image_chunks)) != NULL) {
+		switch (ch->ch_type) {
+		case CH_TYPE_FILE:
+			/* We may be closing the same file multiple times. */
+			if (ch->ch_u.file.fd != -1)
+				close(ch->ch_u.file.fd);
+			break;
+		case CH_TYPE_MEMORY:
+			free(ch->ch_u.mem.ptr);
+			break;
+		default:
+			break;
+		}
+		STAILQ_REMOVE_HEAD(&image_chunks, ch_list);
+		free(ch);
+	}
+	if (image_swap_fd != -1)
+		close(image_swap_fd);
+	unlink(image_swap_file);
+}
+
 int
 image_init(void)
 {
 	const char *tmpdir;
 
-	if (atexit(cleanup) == -1)
+	STAILQ_INIT(&image_chunks);
+	image_nchunks = 0;
+
+	image_swap_size = 0;
+	image_swap_pgsz = getpagesize();
+
+	if (atexit(image_cleanup) == -1)
 		return (errno);
 	if ((tmpdir = getenv("TMPDIR")) == NULL || *tmpdir == '\0')
 		tmpdir = _PATH_TMP;
-	snprintf(image_tmpfile, sizeof(image_tmpfile), "%s/mkimg-XXXXXX",
+	snprintf(image_swap_file, sizeof(image_swap_file), "%s/mkimg-XXXXXX",
 	    tmpdir);
-	image_fd = mkstemp(image_tmpfile);
-	if (image_fd == -1)
+	image_swap_fd = mkstemp(image_swap_file);
+	if (image_swap_fd == -1)
 		return (errno);
 	return (0);
 }