RFC: memmap() now returns NULL on failure.

[Krzysztof Halasa]

Originally, most callers expected -1 while some thought they'd get NULL
on failure. NULL seems cleaner to me.

Of course is we want to allow memmapping of "/dev/ram" or something
alike then we can't apply this patch, we need to fix the NULL-expecters
instead. Alternatively we could pass &mem as an argument (that's what
individual fs memmap implementations do).

Signed-off-by: Krzysztof Hałasa <khc at pm.waw.pl>

diff --git a/arch/arm/lib/bootu.c b/arch/arm/lib/bootu.c
index 0d155cb..478525e 100644
--- a/arch/arm/lib/bootu.c
+++ b/arch/arm/lib/bootu.c
@@ -17,7 +17,7 @@ static int do_bootu(int argc, char *argv[])
 
 	fd = open(argv[1], O_RDONLY);
 	if (fd > 0)
-		kernel = (void *)memmap(fd, PROT_READ);
+		kernel = memmap(fd, PROT_READ);
 
 	if (!kernel)
 		kernel = (void *)simple_strtoul(argv[1], NULL, 0);
diff --git a/commands/bmp.c b/commands/bmp.c
index 4130474..97e5877 100644
--- a/commands/bmp.c
+++ b/commands/bmp.c
@@ -74,7 +74,7 @@ static int do_bmp(int argc, char *argv[])
 	}
 
 	fb = memmap(fd, PROT_READ | PROT_WRITE);
-	if (fb == (void *)-1) {
+	if (fb == NULL) {
 		perror("memmap");
 		goto failed_memmap;
 	}
diff --git a/commands/go.c b/commands/go.c
index e9e9d40..11b0cff 100644
--- a/commands/go.c
+++ b/commands/go.c
@@ -49,7 +49,7 @@ static int do_go(int argc, char *argv[])
 		}
 
 		addr = memmap(fd, PROT_READ);
-		if (addr == (void *)-1) {
+		if (addr == NULL) {
 			perror("memmap");
 			goto out;
 		}
diff --git a/common/digest.c b/common/digest.c
index a327395..7cc5dc3 100644
--- a/common/digest.c
+++ b/common/digest.c
@@ -97,7 +97,7 @@ int digest_file_window(struct digest *d, char *filename,
 	}
 
 	buf = memmap(fd, PROT_READ);
-	if (buf == (void *)-1) {
+	if (buf == NULL) {
 		buf = xmalloc(4096);
 		flags = 1;
 	}
diff --git a/fs/fs.c b/fs/fs.c
index 04dace4..4ebd2bc 100644
--- a/fs/fs.c
+++ b/fs/fs.c
@@ -781,7 +781,7 @@ void *memmap(int fd, int flags)
 	struct device_d *dev;
 	struct fs_driver_d *fsdrv;
 	FILE *f = &files[fd];
-	void *ret = (void *)-1;
+	void *ret = NULL;
 
 	if (check_fd(fd))
 		return ret;