[POWERPC] zImage: Add more flexible gunzip convenience functions

At present, arch/powerpc/boot/main.c includes a gunzip() function
which is a convenient wrapper around zlib.  However, it doesn't
conveniently allow decompressing part of an image to one location,
then the remainder to a different address.

This patch adds a new set of more flexible convenience wrappers around
zlib, moving them to their own file, gunzip_util.c, in the process.
These wrappers allow decompressing sections of the compressed image to
different locations.  In addition, they transparently handle
uncompressed data, avoiding special case code to handle uncompressed
vmlinux images.

The patch also converts main.c to use the new wrappers, using the new
flexibility to avoid decompressing the vmlinux's ELF header twice as
we did previously.  That in turn means we avoid extending our
allocations for the vmlinux to allow space for the extra copy of the
ELF header.

Signed-off-by: David Gibson <dwg@au1.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 140 insertions, 0 deletions

diff --git a/arch/powerpc/boot/gunzip_util.c b/arch/powerpc/boot/gunzip_util.c
new file mode 100644
index 000000000000..3d9ff8f081c6
--- /dev/null
+++ b/arch/powerpc/boot/gunzip_util.c
@@ -0,0 +1,140 @@
+/*
+ * Copyright 2007 David Gibson, IBM Corporation.
+ * Based on earlier work, Copyright (C) Paul Mackerras 1997.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <stddef.h>
+#include "string.h"
+#include "stdio.h"
+#include "ops.h"
+#include "gunzip_util.h"
+
+struct gunzip_state state;
+
+#define HEAD_CRC        2
+#define EXTRA_FIELD     4
+#define ORIG_NAME       8
+#define COMMENT         0x10
+#define RESERVED        0xe0
+
+void gunzip_start(struct gunzip_state *state, void *src, int srclen)
+{
+        char *hdr = src;
+        int hdrlen = 0;
+
+        memset(state, 0, sizeof(*state));
+
+        /* Check for gzip magic number */
+        if ((hdr[0] == 0x1f) && (hdr[1] == 0x8b)) {
+                /* gzip data, initialize zlib parameters */
+                int r, flags;
+
+                state->s.workspace = state->scratch;
+                if (zlib_inflate_workspacesize() > sizeof(state->scratch)) {
+                        printf("insufficient scratch space for gunzip\n\r");
+                        exit();
+                }
+
+                /* skip header */
+                hdrlen = 10;
+                flags = hdr[3];
+                if (hdr[2] != Z_DEFLATED || (flags & RESERVED) != 0) {
+                        printf("bad gzipped data\n\r");
+                        exit();
+                }
+                if ((flags & EXTRA_FIELD) != 0)
+                        hdrlen = 12 + hdr[10] + (hdr[11] << 8);
+                if ((flags & ORIG_NAME) != 0)
+                        while (hdr[hdrlen++] != 0)
+                                ;
+                if ((flags & COMMENT) != 0)
+                        while (hdr[hdrlen++] != 0)
+                                ;
+                if ((flags & HEAD_CRC) != 0)
+                        hdrlen += 2;
+                if (hdrlen >= srclen) {
+                        printf("gunzip_start: ran out of data in header\n\r");
+                        exit();
+                }
+
+                r = zlib_inflateInit2(&state->s, -MAX_WBITS);
+                if (r != Z_OK) {
+                        printf("inflateInit2 returned %d\n\r", r);
+                        exit();
+                }
+        }
+
+        state->s.next_in = src + hdrlen;
+        state->s.avail_in = srclen - hdrlen;
+}
+
+int gunzip_partial(struct gunzip_state *state, void *dst, int dstlen)
+{
+        int len;
+
+        if (state->s.workspace) {
+                /* gunzipping */
+                int r;
+
+                state->s.next_out = dst;
+                state->s.avail_out = dstlen;
+                r = zlib_inflate(&state->s, Z_FULL_FLUSH);
+                if (r != Z_OK && r != Z_STREAM_END) {
+                        printf("inflate returned %d msg: %s\n\r", r, state->s.msg);
+                        exit();
+                }
+                len = state->s.next_out - (unsigned char *)dst;
+        } else {
+                /* uncompressed image */
+                len = min(state->s.avail_in, (unsigned)dstlen);
+                memcpy(dst, state->s.next_in, len);
+                state->s.next_in += len;
+                state->s.avail_in -= len;
+        }
+        return len;
+}
+
+void gunzip_exactly(struct gunzip_state *state, void *dst, int dstlen)
+{
+        int len;
+
+        len  = gunzip_partial(state, dst, dstlen);
+        if (len < dstlen) {
+                printf("gunzip_block: ran out of data\n\r");
+                exit();
+        }
+}
+
+void gunzip_discard(struct gunzip_state *state, int len)
+{
+        static char discard_buf[128];
+
+        while (len > sizeof(discard_buf)) {
+                gunzip_exactly(state, discard_buf, sizeof(discard_buf));
+                len -= sizeof(discard_buf);
+        }
+
+        if (len > 0)
+                gunzip_exactly(state, discard_buf, len);
+}
+
+int gunzip_finish(struct gunzip_state *state, void *dst, int dstlen)
+{
+        int len;
+
+        if (state->s.workspace) {
+                len = gunzip_partial(state, dst, dstlen);
+                zlib_inflateEnd(&state->s);
+        } else {
+                /* uncompressed image */
+                len = min(state->s.avail_in, (unsigned)dstlen);
+                memcpy(dst, state->s.next_in, len);
+        }
+
+        return len;
+}