check return status of all write/fwrite functions as required by glibc 2.4

From: Luca Berra <bluca@vodka.it>

glibc 2.4 is pedantic on ignoring return values from fprintf, fwrite and
write, so now we check the rval and actually do something with it.
in the Grow.c case i only print a warning, since i don't think we can do
anything in case we fail invalidating those superblocks (is should never
happen, but then...)

Signed-off-by: Neil Brown <neilb@suse.de>

Assemble.c

@@ -451,7 +451,9 @@ int Assemble(struct supertype *st, char *mddev, int mdfd,
 
 			if (strcmp(update, "uuid")==0 &&
 			    ident->bitmap_fd)
-				bitmap_update_uuid(ident->bitmap_fd, info.uuid);
+				if (bitmap_update_uuid(ident->bitmap_fd, info.uuid) != 0)
+					fprintf(stderr, Name ": Could not update uuid on %s.\n",
+						devname);
 		} else
 #endif
 		{

Grow.c

@@ -801,7 +801,10 @@ int Grow_reshape(char *devname, int fd, int quiet, char *backup_file,
 		memset(&bsb, 0, sizeof(bsb));
 		for (i=odisks; i<d ; i++) {
 			lseek64(fdlist[i], (offsets[i]+last_block)<<9, 0);
-			write(fdlist[i], &bsb, sizeof(bsb));
+			if (write(fdlist[i], &bsb, sizeof(bsb)) < 0) {
+				fprintf(stderr, Name ": %s: failed to invalidate metadata for raid disk %d\n",
+					devname, i);
+			}
 		}
 
 		/* unsuspend. */

Monitor.c

@@ -521,7 +521,7 @@ static void alert(char *event, char *dev, char *disc, char *mailaddr, char *mail
 				int n;
 				fprintf(mp, "\nP.S. The /proc/mdstat file current contains the following:\n\n");
 				while ( (n=fread(buf, 1, sizeof(buf), mdstat)) > 0)
-					fwrite(buf, 1, n, mp);
+					n=fwrite(buf, 1, n, mp); /* yes, i don't care about the result */
 				fclose(mdstat);
 			}
 			fclose(mp);

bitmap.c

@@ -399,16 +399,22 @@ out:
 	return rv;
 }
 
-void bitmap_update_uuid(int fd, int *uuid)
+int bitmap_update_uuid(int fd, int *uuid)
 {
 	struct bitmap_super_s bm;
-	lseek(fd, 0, 0);
+	if (lseek(fd, 0, 0) != 0)
+		return 1;
 	if (read(fd, &bm, sizeof(bm)) != sizeof(bm))
-		return;
+		return 1;
 	if (bm.magic != __cpu_to_le32(BITMAP_MAGIC))
-		return;
+		return 1;
 	memcpy(bm.uuid, uuid, 16);
+	if (lseek(fd, 0, 0) != 0)
+		return 2;
+	if (write(fd, &bm, sizeof(bm)) != sizeof(bm)) {
+		lseek(fd, 0, 0);
+		return 2;
+	}
 	lseek(fd, 0, 0);
-	write(fd, &bm, sizeof(bm));
+	return 0;
-	lseek(fd, 0, 0);
 }

mdadm.h

@@ -381,7 +381,7 @@ extern int CreateBitmap(char *filename, int force, char uuid[16],
 			unsigned long long array_size,
 			int major);
 extern int ExamineBitmap(char *filename, int brief, struct supertype *st);
-extern void bitmap_update_uuid(int fd, int *uuid);
+extern int bitmap_update_uuid(int fd, int *uuid);
 
 extern int md_get_version(int fd);
 extern int get_linux_version(void);

super0.c

@@ -625,7 +625,8 @@ static int store_super0(struct supertype *st, int fd, void *sbv)
 	if (super->state & (1<<MD_SB_BITMAP_PRESENT)) {
 		struct bitmap_super_s * bm = (struct bitmap_super_s*)(super+1);
 		if (__le32_to_cpu(bm->magic) == BITMAP_MAGIC)
-			write(fd, bm, sizeof(*bm));
+			if (write(fd, bm, sizeof(*bm)) != sizeof(*bm))
+			    return 5;
 	}
 
 	fsync(fd);

super1.c

@@ -715,7 +715,8 @@ static int store_super1(struct supertype *st, int fd, void *sbv)
 			(((char*)sb)+1024);
 		if (__le32_to_cpu(bm->magic) == BITMAP_MAGIC) {
 			locate_bitmap1(st, fd, sbv);
-			write(fd, bm, sizeof(*bm));
+			if (write(fd, bm, sizeof(*bm)) != sizeof(*bm))
+			    return 5;
 		}
 	}
 	fsync(fd);