new helper: dump_align()

dump_skip to given alignment...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

arch/powerpc/platforms/cell/spufs/coredump.c

@@ -156,7 +156,7 @@ static int spufs_arch_write_note(struct spu_context *ctx, int i,
 	if (!dump_emit(cprm, fullname, en.n_namesz))
 		goto Eio;
 
-	if (!dump_skip(cprm, roundup(cprm->written, 4) - cprm->written))
+	if (!dump_align(cprm, 4))
 		goto Eio;
 
 	do {

fs/binfmt_elf.c

@@ -1225,12 +1225,6 @@ static int notesize(struct memelfnote *en)
 	return sz;
 }
 
-static int alignfile(struct coredump_params *cprm)
-{
-	static const char buf[4] = { 0, };
-	return dump_emit(cprm, buf, roundup(cprm->written, 4) - cprm->written);
-}
-
 static int writenote(struct memelfnote *men, struct coredump_params *cprm)
 {
 	struct elf_note en;
@@ -1239,8 +1233,8 @@ static int writenote(struct memelfnote *men, struct coredump_params *cprm)
 	en.n_type = men->type;
 
 	return dump_emit(cprm, &en, sizeof(en)) &&
-	    dump_emit(cprm, men->name, en.n_namesz) && alignfile(cprm) &&
-	    dump_emit(cprm, men->data, men->datasz) && alignfile(cprm);
+	    dump_emit(cprm, men->name, en.n_namesz) && dump_align(cprm, 4) &&
+	    dump_emit(cprm, men->data, men->datasz) && dump_align(cprm, 4);
 }
 
 static void fill_elf_header(struct elfhdr *elf, int segs,

fs/binfmt_elf_fdpic.c

@@ -1267,12 +1267,6 @@ static int notesize(struct memelfnote *en)
 
 /* #define DEBUG */
 
-static int alignfile(struct coredump_params *cprm)
-{
-	static const char buf[4] = { 0, };
-	return dump_emit(cprm, buf, roundup(cprm->written, 4) - cprm->written);
-}
-
 static int writenote(struct memelfnote *men, struct coredump_params *cprm)
 {
 	struct elf_note en;
@@ -1281,8 +1275,8 @@ static int writenote(struct memelfnote *men, struct coredump_params *cprm)
 	en.n_type = men->type;
 
 	return dump_emit(cprm, &en, sizeof(en)) &&
-		dump_emit(cprm, men->name, en.n_namesz) && alignfile(cprm) &&
-		dump_emit(cprm, men->data, men->datasz) && alignfile(cprm);
+		dump_emit(cprm, men->name, en.n_namesz) && dump_align(cprm, 4) &&
+		dump_emit(cprm, men->data, men->datasz) && dump_align(cprm, 4);
 }
 
 static inline void fill_elf_fdpic_header(struct elfhdr *elf, int segs)

fs/coredump.c

@@ -728,3 +728,12 @@ int dump_skip(struct coredump_params *cprm, size_t nr)
 	}
 }
 EXPORT_SYMBOL(dump_skip);
+
+int dump_align(struct coredump_params *cprm, int align)
+{
+	unsigned mod = cprm->written & (align - 1);
+	if (align & (align - 1))
+		return -EINVAL;
+	return mod ? dump_skip(cprm, align - mod) : 0;
+}
+EXPORT_SYMBOL(dump_align);

include/linux/coredump.h

@@ -13,6 +13,7 @@
 struct coredump_params;
 extern int dump_skip(struct coredump_params *cprm, size_t nr);
 extern int dump_emit(struct coredump_params *cprm, const void *addr, int nr);
+extern int dump_align(struct coredump_params *cprm, int align);
 #ifdef CONFIG_COREDUMP
 extern void do_coredump(siginfo_t *siginfo);
 #else