Implement reverse operation

1 files changed, 196 insertions, 102 deletions

diff --git a/mkubootenv.c b/mkubootenv.c
index 156e12d..4294b76 100644
--- a/mkubootenv.c
+++ b/mkubootenv.c
@@ -57,6 +57,7 @@
 #define TRAILER_SIZE		2
 
 #define err(fmt, args...)	fprintf(stderr, "%s: Error: " fmt, CMD_NAME, ##args)
+#define warn(fmt, args...)	fprintf(stderr, "%s: Warning: " fmt, CMD_NAME, ##args)
 #ifdef DEBUG
 # define dbg(fmt, args...)	fprintf(stdout, fmt, ##args)
 #else
@@ -65,165 +66,258 @@
 
 /* file "object" */
 struct file {
-	char *name;
+	const char *name;
 	int fd;
 	uint8_t *ptr;
-	struct stat sbuf;
+	size_t size;
 };
 
 static void usage_and_exit(int status) __attribute__((noreturn));
 
-static void usage_and_exit(int status)
+static inline void uboot_env_init_file(struct file *f)
 {
-	printf("usage: mkenv [-t <type>] [-s <size>] <source file> <target image file>\n"
-	       "  -s <size>  set size of the target image file to <size> bytes. If <size> is\n"
-	       "             bigger than the source file, the target image gets padded with null\n"
-	       "             bytes. If <size> is smaller than the source file, an error is emitted.\n"
-	       "  -r         reverse operation: get source file from target image file\n");
-	exit(status);
+	memset(f, 0, sizeof(struct file));
+	f->ptr = MAP_FAILED;
 }
 
-int main(int argc, char **argv)
+static int uboot_env_prepare_source(struct file *s)
 {
-	int i;
-	int status = EXIT_FAILURE;
-	struct file s, t;	/* source and target file */
-	ssize_t img_size = -1;
-	ssize_t min_img_size;
-	bool reverse = false;
-	uint8_t *p, *q;
-	uint32_t *crc;
-
-	if (argc < 2)
-		usage_and_exit(EXIT_FAILURE);
-
-	/* parse commandline options */
-	for (i = 1; (i + 1 < argc) && (argv[i][0] == '-'); i++) {
-		switch (argv[i][1]) {
-		case 's':
-			img_size = strtol(argv[++i], NULL, 10);
-			break;
-		case 'r':
-			reverse = true;
-			break;
-		case 'h':
-			status = EXIT_SUCCESS;
-			/* fall through */
-		default:
-			usage_and_exit(status);
-			break;
-		}
-	}
-
-	/* we expect two filenames */
-	if (i + 2 > argc)
-		usage_and_exit(EXIT_FAILURE);
-
-	s.name = argv[i];
-	t.name = argv[++i];
+	struct stat sbuf;
 
-	s.fd = open(s.name, O_RDONLY);
-	if (s.fd < 0) {
-		err("Can't open source file '%s': %s\n", s.name,
+	s->fd = open(s->name, O_RDONLY);
+	if (s->fd < 0) {
+		err("Can't open source file '%s': %s\n", s->name,
 				strerror(errno));
-		exit(EXIT_FAILURE);
+		return EXIT_FAILURE;
 	}
 
-	if (fstat(s.fd, &s.sbuf) < 0) {
-		err("Can't stat source file '%s': %s\n", s.name,
+	if (fstat(s->fd, &sbuf) < 0) {
+		err("Can't stat source file '%s': %s\n", s->name,
 				strerror(errno));
-		goto err_out_close_s;
+		close(s->fd);
+		return -1;
 	}
 
-	s.ptr = mmap(NULL, s.sbuf.st_size, PROT_READ, MAP_SHARED, s.fd, 0);
-	if (s.ptr == MAP_FAILED) {
-		err("Can't mmap source image file '%s': %s\n", s.name,
+	s->ptr = mmap(NULL, sbuf.st_size, PROT_READ, MAP_SHARED, s->fd, 0);
+	if (s->ptr == MAP_FAILED) {
+		err("Can't mmap source image file '%s': %s\n", s->name,
 				strerror(errno));
-		goto err_out_close_s;
+		close(s->fd);
+		return -1;
 	}
 
-	/* TODO: Check source file format:
-	 *	var=value\n
-	 */
+	s->size = sbuf.st_size;
 
-	/*
-	 * check whether the size hasn't been set or whether the source file +
-	 * CRC + trailer fits into the specified size.
-	 */
-	min_img_size = CRC32_SIZE + s.sbuf.st_size + TRAILER_SIZE;
-	if (img_size < 0)
-		img_size = min_img_size;
-	else if (img_size < min_img_size) {
-		err("Specified size (%zd) is too small for the source file to "
-				"fit into. Must be at least %zd bytes.\n",
-				img_size, min_img_size);
-		goto err_out_munmap_s;
-	}
+	return 0;
+}
 
-	t.fd = open(t.name, O_RDWR|O_CREAT|O_TRUNC, 0666);
-	if (t.fd < 0) {
-		err("Can't open target image file '%s': %s\n", t.name,
+static int uboot_env_prepare_target(struct file *t)
+{
+	t->fd = open(t->name, O_RDWR|O_CREAT|O_TRUNC, 0666);
+	if (t->fd < 0) {
+		err("Can't open target image file '%s': %s\n", t->name,
 				strerror(errno));
-		goto err_out_munmap_s;
+		return -1;
 	}
 
 	/*
 	 * seek to the end of the target file to write a byte, so we have the
 	 * whole target image size mapped for writing
 	 */
-	if (lseek(t.fd, img_size - 1, SEEK_SET) < 0) {
-		err("Can't seek in target image file '%s': %s\n", t.name,
+	if (lseek(t->fd, t->size - 1, SEEK_SET) < 0) {
+		err("Can't seek in target image file '%s': %s\n", t->name,
 				strerror(errno));
-		goto err_out_close_t;
+		close(t->fd);
+		return -1;
 	}
 
-	if (write(t.fd, "", 1) < 0) {
-		err("Can't write to target image file '%s': %s\n", t.name,
+	if (write(t->fd, "", 1) < 0) {
+		err("Can't write to target image file '%s': %s\n", t->name,
 				strerror(errno));
-		goto err_out_close_t;
+		close(t->fd);
+		return -1;
 	}
 
-	t.ptr = mmap(NULL, img_size, PROT_READ|PROT_WRITE, MAP_SHARED, t.fd, 0);
-	if (t.ptr == MAP_FAILED) {
-		err("Can't mmap target image file '%s': %s\n", t.name,
+	t->ptr = mmap(NULL, t->size, PROT_READ|PROT_WRITE, MAP_SHARED, t->fd, 0);
+	if (t->ptr == MAP_FAILED) {
+		err("Can't mmap target image file '%s': %s\n", t->name,
 				strerror(errno));
-		goto err_out_close_t;
+		close(t->fd);
+		return -1;
 	}
 
-	dbg("source file:       %s\n", s.name);
-	dbg("target image file: %s\n", t.name);
-	dbg("size:              %zd\n", img_size);
+	return 0;
+}
+
+static void uboot_env_cleanup_file(struct file *f)
+{
+	if (f->ptr != MAP_FAILED)
+		munmap(f->ptr, f->size);
+	if (f->fd > 0)
+		close(f->fd);
+}
+
+static void uboot_env_to_img(struct file *s, struct file *t)
+{
+	uint8_t *p, *q, *end;
+	uint32_t *crc;
+
+	dbg("source file (env):       %s\n", s->name);
+	dbg("target image file (bin): %s\n", t->name);
+	dbg("target size:             %zd\n", t->size);
 
 	/* CRC32 placeholder, will be filled later */
 	dbg("writing crc dummy...\n");
-	for (p = t.ptr; p < t.ptr + CRC32_SIZE; p++)
+	end = t->ptr + CRC32_SIZE;
+	for (p = t->ptr; p < end; p++)
 		*p = 0;
 
 	/* copy the source file, replacing \n by \0 */
 	dbg("writing data...\n");
-	for (q = s.ptr; q < s.ptr + s.sbuf.st_size; q++, p++)
+	end = s->ptr + s->size;
+	for (q = s->ptr; q < end; q++, p++)
 		*p = (*q == '\n') ? '\0' : *q;
 
 	/* trailer */
 	dbg("writing trailer...\n");
-	for (q = s.ptr + s.sbuf.st_size; q < s.ptr + img_size; q++)
+	end = s->ptr + t->size;
+	for (q = s->ptr + s->size; q < end; q++)
 		*p = 0;
 
 	/* now for the real CRC32 */
 	dbg("calculating crc...\n");
-	crc = (uint32_t *) t.ptr;
-	*crc = crc32(0, t.ptr + CRC32_SIZE, img_size - CRC32_SIZE);
+	crc = (uint32_t *) t->ptr;
+	*crc = crc32(0, t->ptr + CRC32_SIZE, t->size - CRC32_SIZE);
 	dbg("crc: %08x\n", *crc);
+}
+
+static void uboot_img_to_env(struct file *s, struct file *t)
+{
+	uint8_t *p, *q, *end;
+	uint32_t *crc;
+
+	dbg("source file (bin):       %s\n", s->name);
+	dbg("target image file (env): %s\n", t->name);
+	dbg("target size:             %zd\n", t->size);
+
+	/* TODO: check CRC */
+
+	p = t->ptr;
+	end = s->ptr + CRC32_SIZE + t->size;
+	for (q = s->ptr + CRC32_SIZE; q < end; p++, q++)
+		*p = (*q == '\0') ? '\n' : *q;
+}
+
+static void usage_and_exit(int status)
+{
+	printf("usage: mkenv [-t <type>] [-s <size>] <source file> <target file>\n"
+	       "  -s <size>  set size of the target image file to <size> bytes. If <size> is\n"
+	       "             bigger than the source file, the target image gets padded with null\n"
+	       "             bytes. If <size> is smaller than the source file, an error is emitted.\n"
+	       "  -r         reverse operation: get plaintext env file (target) from binary image\n"
+	       "             file (source)\n");
+	exit(status);
+}
+
+int main(int argc, char **argv)
+{
+	int i;
+	int status = EXIT_FAILURE;
+	ssize_t img_size = -1;
+	bool reverse = false;
+	struct file s, t;	/* source and target file */
+
+	if (argc < 2)
+		usage_and_exit(EXIT_FAILURE);
+
+	/* parse commandline options */
+	for (i = 1; (i + 1 < argc) && (argv[i][0] == '-'); i++) {
+		switch (argv[i][1]) {
+		case 's':
+			img_size = strtol(argv[++i], NULL, 10);
+			if (img_size <= 0) {
+				err("Invalid target image size: %zd. Must be greater than 0.\n", img_size);
+				exit(EXIT_FAILURE);
+			}
+			break;
+		case 'r':
+			reverse = true;
+			break;
+		case 'h':
+			status = EXIT_SUCCESS;
+			/* fall through */
+		default:
+			usage_and_exit(status);
+			break;
+		}
+	}
+
+	/* we expect two filenames */
+	if (i + 2 > argc)
+		usage_and_exit(EXIT_FAILURE);
+
+	if (reverse && img_size >= 0)
+		warn("Image size specified in reverse mode will be ignored\n");
+
+	uboot_env_init_file(&s);
+	uboot_env_init_file(&t);
+	s.name = argv[i];
+	t.name = argv[i+1];
+
+	if (uboot_env_prepare_source(&s))
+		exit(EXIT_FAILURE);
+
+	if (!reverse) {
+		ssize_t min_img_size = CRC32_SIZE + s.size + TRAILER_SIZE;
+
+		/* TODO: Check source file format:
+		 *	var=value\n
+		 */
+
+		/*
+		 * check whether the size hasn't been set or whether the source file +
+		 * CRC + trailer fits into the specified size.
+		 */
+		if (img_size < 0)
+			img_size = min_img_size;
+		else if (img_size < min_img_size) {
+			err("Specified size (%zd) is too small for the source file to "
+					"fit into. Must be at least %zd bytes.\n",
+					img_size, min_img_size);
+			goto cleanup_source;
+		}
+
+		t.size = img_size;
+		if (uboot_env_prepare_target(&t))
+			goto cleanup_source;
+
+		uboot_env_to_img(&s, &t);
+	} else {
+		uint8_t *p;
+		uint8_t *end;
+		bool found_data_end = false;
+
+		/* get the length of the data part */
+		end = s.ptr + CRC32_SIZE + s.size;
+		for (p = s.ptr + CRC32_SIZE; (p < end - 1) && (!found_data_end); p++) {
+			/* two null bytes mark the end of the data section */
+			if (*p == '\0' && *(p + 1) == '\0')
+				found_data_end = true;
+		}
+
+		/* calculate the plain text file size */
+		t.size = p - (s.ptr + CRC32_SIZE);
+		if (uboot_env_prepare_target(&t))
+			goto cleanup_source;
+
+		uboot_img_to_env(&s, &t);
+	}
 
 	status = EXIT_SUCCESS;
 
-	munmap(t.ptr, img_size);
-err_out_close_t:
-	close(t.fd);
-err_out_munmap_s:
-	munmap(s.ptr, s.sbuf.st_size);
-err_out_close_s:
-	close(s.fd);
+	uboot_env_cleanup_file(&t);
+cleanup_source:
+	uboot_env_cleanup_file(&s);
 
 	exit(status);
 }