[flashrom] [PATCH] RFC: enable flashrom to write images of arbitrary size

[Peter Mamonov]

Flashrom restricts an image size to be equal to a ROM capacity. This is
inconvenient in case of large and slow ROM chips, when only part of the ROM
should be updated. This patch removes this restriction in a quick-and-dirty
manner.

Signed-off-by: Peter Mamonov 
---
 flashrom.c | 26 +++++++++++++++-----------
 1 file changed, 15 insertions(+), 11 deletions(-)

diff --git a/flashrom.c b/flashrom.c
index d51a44c..f805e00 100644
--- a/flashrom.c
+++ b/flashrom.c
@@ -1255,30 +1255,30 @@ int read_buf_from_file(unsigned char *buf, unsigned long size,

if ((image = fopen(filename, "rb")) == NULL) {
    	msg_gerr("Error: opening file "%s" failed: %s\n", filename, strerror(errno));
-		return 1;
+		return -1;
    }
    if (fstat(fileno(image), &image_stat) != 0) {
    	msg_gerr("Error: getting metadata of file "%s" failed: %s\n", filename, strerror(errno));
    	fclose(image);
-		return 1;
+		return -1;
    }
-	if (image_stat.st_size != size) {
+	if (image_stat.st_size > size) {
    	msg_gerr("Error: Image size (%jd B) doesn't match the flash chip's size (%lu B)!\n",
    		 (intmax_t)image_stat.st_size, size);
-		fclose(image);
-		return 1;
+		return -1;
    }
+	size = image_stat.st_size;
    numbytes = fread(buf, 1, size, image);
    if (fclose(image)) {
    	msg_gerr("Error: closing file "%s" failed: %s\n", filename, strerror(errno));
-		return 1;
+		return -1;
    }
    if (numbytes != size) {
    	msg_gerr("Error: Failed to read complete file. Got %ld bytes, "
    		 "wanted %ld!\n", numbytes, size);
-		return 1;
+		return -1;
    }
-	return 0;
+	return size;
 #endif
 }

@@ -1481,7 +1481,10 @@ static int walk_eraseregions(struct flashctx *flash, int erasefunction,
    	 * members so the loop below won't be executed for them.
    	 */
    	len = eraser.eraseblocks[i].size;
-		for (j = 0; j < eraser.eraseblocks[i].count; j++) {
+		for (j = 0;
+		     j < eraser.eraseblocks[i].count &&
+		     start + len <= flash->chip->total_size * 1024;
+		     j++) {
    		/* Print this for every block except the first one. */
    		if (i || j)
    			msg_cdbg(", ");
@@ -1988,11 +1991,12 @@ int doit(struct flashctx *flash, int force, const char *filename, int read_it,
    }

if (write_it || verify_it) {
-		if (read_buf_from_file(newcontents, size, filename)) {
+		size = read_buf_from_file(newcontents, size, filename);
+		if (size < 0) {
    		ret = 1;
    		goto out;
    	}
-
+		flash->chip->total_size = size / 1024; /* FIXME */
 #if CONFIG_INTERNAL == 1
    	if (programmer == PROGRAMMER_INTERNAL && cb_check_image(newcontents, size) < 0) {
    		if (force_boardmismatch) {