From fd326f72be58758cc22fb0e75b95b7430013193e Mon Sep 17 00:00:00 2001
From: Thadeu Lima de Souza Cascardo <cascardo@cascardo.eti.br>
Date: Thu, 27 Mar 2014 18:38:02 -0300
Subject: [PATCH] Change the dump function to also be able to load a component.

It might be desirable to load a kernel and initrd and save it to a
bootimg. They need to be padded with zeroes to align to a page size.

Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@cascardo.eti.br>
---
 bootimg.c | 66 +++++++++++++++++++++++++++++++++++++++++--------------
 1 file changed, 50 insertions(+), 16 deletions(-)

diff --git a/bootimg.c b/bootimg.c
index 9ce6fb8..b015c10 100644
--- a/bootimg.c
+++ b/bootimg.c
@@ -23,51 +23,85 @@
 #include <fcntl.h>
 #include <unistd.h>
 #include <errno.h>
+#include <sys/stat.h>
 
-static int dump(int fd, size_t len, int pgsz, char *fname)
+static int dump_or_load(int fd, size_t *len, int pgsz, char *fname, int dump)
 {
-	int out;
+	int cfd;
 	char *page;
 	int i, npages;
 	int r;
+	int ifd, ofd;
+	int rem;
 	page = malloc(pgsz);
 	if (!page)
 		return -ENOMEM;
-	out = open(fname, O_WRONLY | O_CREAT | O_EXCL, 0644);
-	if (out < 0)
-		return -errno;
-	npages = (len + pgsz - 1) / pgsz;
+	if (dump)
+		cfd = open(fname, O_WRONLY | O_CREAT | O_EXCL, 0644);
+	else
+		cfd = open(fname, O_RDONLY);
+	if (cfd < 0)
+		goto out;
+	if (dump) {
+		ifd = fd;
+		ofd = cfd;
+	} else {
+		struct stat s;
+		r = fstat(cfd, &s);
+		if (r < 0) {
+			goto out;
+		}
+		*len = s.st_size;
+		ifd = cfd;
+		ofd = fd;
+	}
+	npages = (*len + pgsz - 1) / pgsz;
 	for (i = 1; i <= npages; i++) {
 		if (i == npages) {
-			len = len & (pgsz - 1);
-			if (len > 0) {
-				r = read(fd, page, len);
-				if (r != len)
+			rem = *len & (pgsz - 1);
+			if (rem > 0) {
+				r = read(ifd, page, rem);
+				if (r != rem)
 					goto out;
-				r = write(out, page, len);
-				if (r != len)
+				r = write(ofd, page, rem);
+				if (r != rem)
 					goto out;
+				/* Write padding */
+				if (!dump) {
+					memset(page, 0, pgsz - rem);
+					write(ofd, page, pgsz - rem);
+				}
 			}
 		} else {
-			r = read(fd, page, pgsz);
+			r = read(ifd, page, pgsz);
 			if (r != pgsz)
 				goto out;
-			r = write(out, page, pgsz);
+			r = write(ofd, page, pgsz);
 			if (r != pgsz)
 				goto out;
 		}
 	}
 	free(page);
-	close(out);
+	close(cfd);
 	return 0;
 out:
 	free(page);
-	close(out);
+	close(cfd);
 	if (r < 0)
 		return -errno;
 	return -EINVAL;
 }
 
+static int dump(int fd, size_t len, int pgsz, char *fname)
+{
+	return dump_or_load(fd, &len, pgsz, fname, 1);
+}
+
+static int load(int fd, size_t *len, int pgsz, char *fname)
+{
+	return dump_or_load(fd, len, pgsz, fname, 0);
+}
+
 int main(int argc, char **argv)
 {
 	int fd;
-- 
2.20.1