Re: sizeof(struct ...)

["René Scharfe" <rene.scharfe@lsrfire.ath.cx>]

Oh no, whitespace damage!  The major downside of getting a new
machine is that Thunderbird needs to be beaten into submission
again. :-(  Here's the patch a second time, hopefully intact.

René


 archive-zip.c |   24 ++++++++++++++++++------
 1 files changed, 18 insertions(+), 6 deletions(-)

diff --git a/archive-zip.c b/archive-zip.c
index ae5572a..4caaec4 100644
--- a/archive-zip.c
+++ b/archive-zip.c
@@ -35,6 +35,7 @@ struct zip_local_header {
 	unsigned char size[4];
 	unsigned char filename_length[2];
 	unsigned char extra_length[2];
+	unsigned char _end[0];
 };
 
 struct zip_dir_header {
@@ -55,6 +56,7 @@ struct zip_dir_header {
 	unsigned char attr1[2];
 	unsigned char attr2[4];
 	unsigned char offset[4];
+	unsigned char _end[0];
 };
 
 struct zip_dir_trailer {
@@ -66,8 +68,18 @@ struct zip_dir_trailer {
 	unsigned char size[4];
 	unsigned char offset[4];
 	unsigned char comment_length[2];
+	unsigned char _end[0];
 };
 
+/*
+ * On ARM, padding is added at the end of the struct, so a simple
+ * sizeof(struct ...) reports two bytes more than the payload size
+ * we're interested in.
+ */
+#define ZIP_LOCAL_HEADER_SIZE	offsetof(struct zip_local_header, _end)
+#define ZIP_DIR_HEADER_SIZE	offsetof(struct zip_dir_header, _end)
+#define ZIP_DIR_TRAILER_SIZE	offsetof(struct zip_dir_trailer, _end)
+
 static void copy_le16(unsigned char *dest, unsigned int n)
 {
 	dest[0] = 0xff & n;
@@ -211,7 +223,7 @@ static int write_zip_entry(const unsigne
 	}
 
 	/* make sure we have enough free space in the dictionary */
-	direntsize = sizeof(struct zip_dir_header) + pathlen;
+	direntsize = ZIP_DIR_HEADER_SIZE + pathlen;
 	while (zip_dir_size < zip_dir_offset + direntsize) {
 		zip_dir_size += ZIP_DIRECTORY_MIN_SIZE;
 		zip_dir = xrealloc(zip_dir, zip_dir_size);
@@ -234,8 +246,8 @@ static int write_zip_entry(const unsigne
 	copy_le16(dirent.attr1, 0);
 	copy_le32(dirent.attr2, attr2);
 	copy_le32(dirent.offset, zip_offset);
-	memcpy(zip_dir + zip_dir_offset, &dirent, sizeof(struct zip_dir_header));
-	zip_dir_offset += sizeof(struct zip_dir_header);
+	memcpy(zip_dir + zip_dir_offset, &dirent, ZIP_DIR_HEADER_SIZE);
+	zip_dir_offset += ZIP_DIR_HEADER_SIZE;
 	memcpy(zip_dir + zip_dir_offset, path, pathlen);
 	zip_dir_offset += pathlen;
 	zip_dir_entries++;
@@ -251,8 +263,8 @@ static int write_zip_entry(const unsigne
 	copy_le32(header.size, uncompressed_size);
 	copy_le16(header.filename_length, pathlen);
 	copy_le16(header.extra_length, 0);
-	write_or_die(1, &header, sizeof(struct zip_local_header));
-	zip_offset += sizeof(struct zip_local_header);
+	write_or_die(1, &header, ZIP_LOCAL_HEADER_SIZE);
+	zip_offset += ZIP_LOCAL_HEADER_SIZE;
 	write_or_die(1, path, pathlen);
 	zip_offset += pathlen;
 	if (compressed_size > 0) {
@@ -282,7 +294,7 @@ static void write_zip_trailer(const unsi
 	copy_le16(trailer.comment_length, sha1 ? 40 : 0);
 
 	write_or_die(1, zip_dir, zip_dir_offset);
-	write_or_die(1, &trailer, sizeof(struct zip_dir_trailer));
+	write_or_die(1, &trailer, ZIP_DIR_TRAILER_SIZE);
 	if (sha1)
 		write_or_die(1, sha1_to_hex(sha1), 40);