[PATCH] add support for loading lzma compressed kernels

[Florian Fainelli <florian@openwrt.org>]

Hi Eric,

This patch allows one to load a lzma compressed kernel using kexec -l.
As I wanted the lzma code to be very similar to the existing
zlib slurp_decompress I took lzread and associated routines
from the cpio lzma support. Tested on my x86 laptop using the
following commands:

lzma e bzImage bzImage.lzma
kexec -l bzImage.lzma

Having lzma support is particularly useful on some embedded
systems on which we have the kernel already lzma compressed
and available on a mtd partition.

Signed-off-by: Florian Fainelli <florian@openwrt.org>
-- 
diff -urN kexec-tools-2.0.1/configure.ac kexec-tools-2.0.1.lzma/configure.ac
--- kexec-tools-2.0.1/configure.ac	2009-08-13 01:28:04.000000000 +0200
+++ kexec-tools-2.0.1.lzma/configure.ac	2009-11-16 00:30:42.000000000 +0100
@@ -79,6 +79,9 @@
 AC_ARG_WITH([zlib], AC_HELP_STRING([--without-zlib],[disable zlib support]),
 	[ with_zlib="$withval"], [ with_zlib=yes ] )

+AC_ARG_WITH([lzma], AC_HELP_STRING([--without-lzma],[disable lzma support]),
+	[ with_lzma="$withval"], [ with_lzma=yes ] )
+
 AC_ARG_WITH([xen], AC_HELP_STRING([--without-xen],
 	[disable extended xen support]), [ with_xen="$withval"], [ with_xen=yes ] )

@@ -142,6 +145,12 @@
 		AC_MSG_NOTICE([zlib support disabled])))
 fi

+dnl See if I have a usable copy of lzma available
+if test "$with_lzma" = yes ; then
+	AC_CHECK_HEADER(lzma.h,
+		AC_CHECK_LIB(lzma, lzma_code_, ,
+		AC_MSG_NOTICE([lzma support disabled])))
+
 dnl find Xen control stack libraries
 if test "$with_xen" = yes ; then
 	AC_CHECK_HEADER(xenctrl.h,
diff -urN kexec-tools-2.0.1/include/kexec_lzma.h kexec-tools-2.0.1.lzma/include/kexec_lzma.h
--- kexec-tools-2.0.1/include/kexec_lzma.h	1970-01-01 01:00:00.000000000 +0100
+++ kexec-tools-2.0.1.lzma/include/kexec_lzma.h	2009-11-16 00:45:23.000000000 +0100
@@ -0,0 +1,24 @@
+#ifndef __KEXEC_LZMA_H
+#define __KEXEC_LZMA_H
+
+#include <sys/types.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <inttypes.h>
+#include <lzma.h>
+
+#define kBufferSize (1 << 15)
+
+typedef struct lzfile {
+	uint8_t buf[kBufferSize];
+	lzma_stream strm;
+	FILE *file;
+	int encoding;
+	int eof;
+} LZFILE;
+
+LZFILE *lzopen(const char *path, const char *mode);
+int lzclose(LZFILE *lzfile);
+ssize_t lzread(LZFILE *lzfile, void *buf, size_t len);
+
+#endif /* __KEXEC_LZMA_H */
Files kexec-tools-2.0.1/kexec/.kexec.c.swo and kexec-tools-2.0.1.lzma/kexec/.kexec.c.swo differ
diff -urN kexec-tools-2.0.1/kexec/Makefile kexec-tools-2.0.1.lzma/kexec/Makefile
--- kexec-tools-2.0.1/kexec/Makefile	2008-10-09 00:32:14.000000000 +0200
+++ kexec-tools-2.0.1.lzma/kexec/Makefile	2009-11-15 20:36:37.000000000 +0100
@@ -22,6 +22,7 @@
 KEXEC_SRCS += kexec/crashdump.c
 KEXEC_SRCS += kexec/crashdump-xen.c
 KEXEC_SRCS += kexec/phys_arch.c
+KEXEC_SRCS += kexec/lzma.c

 KEXEC_GENERATED_SRCS += $(PURGATORY_HEX_C)

diff -urN kexec-tools-2.0.1/kexec/kexec.c kexec-tools-2.0.1.lzma/kexec/kexec.c
--- kexec-tools-2.0.1/kexec/kexec.c	2009-03-18 09:38:55.000000000 +0100
+++ kexec-tools-2.0.1.lzma/kexec/kexec.c	2009-11-16 00:50:37.000000000 +0100
@@ -41,6 +41,9 @@
 #ifdef HAVE_LIBZ
 #include <zlib.h>
 #endif
+#ifdef HAVE_LIBLZMA
+#include <kexec_lzma.h>
+#endif
 #include <sha256.h>
 #include "kexec.h"
 #include "kexec-syscall.h"
@@ -609,6 +612,47 @@
 	*r_size =  size;
 	return buf;
 }
+#elif defined (HAVE_LIBLZMA)
+char *slurp_decompress_file(const char *filename, off_t *r_size)
+{
+	LZFILE *fp;
+	char *buf;
+	off_t size, allocated;
+	ssize_t result;
+
+	if (!filename) {
+		*r_size = 0;
+		return 0;
+	}
+	fp = lzopen(filename, "rb");
+	if (fp == 0) {
+		die("Cannot open `%s': %s\n", filename);
+	}
+	size = 0;
+	allocated = 65536;
+	buf = xmalloc(allocated);
+	do {
+		if (size == allocated) {
+			allocated <<= 1;
+			buf = xrealloc(buf, allocated);
+		}
+		result = lzread(fp, buf + size, allocated - size);
+		if (result < 0) {
+			if ((errno == EINTR) || (errno == EAGAIN))
+				continue;
+
+			die ("read on %s of %ld bytes failed\n",
+				filename, (allocated - size) + 0UL);
+		}
+		size += result;
+	} while(result > 0);
+	result = lzclose(fp);
+	if (result != LZMA_OK) {
+		die ("Close of %s failed\n", filename);
+	}
+	*r_size =  size;
+	return buf;
+}
 #else
 char *slurp_decompress_file(const char *filename, off_t *r_size)
 {
diff -urN kexec-tools-2.0.1/kexec/lzma.c kexec-tools-2.0.1.lzma/kexec/lzma.c
--- kexec-tools-2.0.1/kexec/lzma.c	1970-01-01 01:00:00.000000000 +0100
+++ kexec-tools-2.0.1.lzma/kexec/lzma.c	2009-11-16 00:44:56.000000000 +0100
@@ -0,0 +1,132 @@
+#include <sys/types.h>
+#include <inttypes.h>
+#include <string.h>
+#include <stdlib.h>
+#include <lzma.h>
+#include <kexec_lzma.h>
+
+#ifdef HAVE_LIBLZMA
+static LZFILE *lzopen_internal(const char *path, const char *mode, int fd)
+{
+	int level = 5;
+	int encoding = 0;
+	FILE *fp;
+	LZFILE *lzfile;
+	lzma_ret ret;
+	lzma_stream lzma_strm_tmp = LZMA_STREAM_INIT;
+
+	for (; *mode; mode++) {
+		if (*mode == 'w')
+			encoding = 1;
+		else if (*mode == 'r')
+			encoding = 0;
+		else if (*mode >= '1' && *mode <= '9')
+			level = *mode - '0';
+	}
+	if (fd != -1)
+		fp = fdopen(fd, encoding ? "w" : "r");
+	else
+		fp = fopen(path, encoding ? "w" : "r");
+	if (!fp)
+		return NULL;
+
+	lzfile = calloc(1, sizeof(*lzfile));
+
+	if (!lzfile) {
+		fclose(fp);
+		return NULL;
+	}
+
+	lzfile->file = fp;
+	lzfile->encoding = encoding;
+	lzfile->eof = 0;
+	lzfile->strm = lzma_strm_tmp;
+	if (encoding) {
+		lzma_options_lzma opt_lzma;
+		if (lzma_lzma_preset(&opt_lzma, level - 1))
+			return NULL;
+		ret = lzma_alone_encoder(&lzfile->strm, &opt_lzma);
+	} else {
+		ret = lzma_auto_decoder(&lzfile->strm,
+					UINT64_C(64) * 1024 * 1024, 0);
+	}
+	if (ret != LZMA_OK) {
+		fclose(fp);
+		free(lzfile);
+		return NULL;
+	}
+	return lzfile;
+}
+
+LZFILE *lzopen(const char *path, const char *mode)
+{
+	return lzopen_internal(path, mode, -1);
+}
+
+int lzclose(LZFILE *lzfile)
+{
+	lzma_ret ret;
+	int n;
+
+	if (!lzfile)
+		return -1;
+
+	if (lzfile->encoding) {
+		for (;;) {
+			lzfile->strm.avail_out = kBufferSize;
+			lzfile->strm.next_out = lzfile->buf;
+			ret = lzma_code(&lzfile->strm, LZMA_FINISH);
+			if (ret != LZMA_OK && ret != LZMA_STREAM_END)
+				return -1;
+			n = kBufferSize - lzfile->strm.avail_out;
+			if (n && fwrite(lzfile->buf, 1, n, lzfile->file) != n)
+				return -1;
+			if (ret == LZMA_STREAM_END)
+				break;
+		}
+	}
+	lzma_end(&lzfile->strm);
+
+	return fclose(lzfile->file);
+	free(lzfile);
+}
+
+ssize_t lzread(LZFILE *lzfile, void *buf, size_t len)
+{
+	lzma_ret ret;
+	int eof = 0;
+
+	if (!lzfile || lzfile->encoding)
+		return -1;
+
+	if (lzfile->eof)
+		return 0;
+
+	lzfile->strm.next_out = buf;
+	lzfile->strm.avail_out = len;
+
+	for (;;) {
+		if (!lzfile->strm.avail_in) {
+			lzfile->strm.next_in = lzfile->buf;
+			lzfile->strm.avail_in = fread(lzfile->buf, 1, kBufferSize, lzfile->file);
+			if (!lzfile->strm.avail_in)
+				eof = 1;
+		}
+
+		ret = lzma_code(&lzfile->strm, LZMA_RUN);
+		if (ret == LZMA_STREAM_END) {
+			lzfile->eof = 1;
+			return len - lzfile->strm.avail_out;
+		}
+
+		if (ret != LZMA_OK)
+			return -1;
+
+		if (!lzfile->strm.avail_out)
+			return len;
+
+		if (eof)
+			return -1;
+	}
+}
+#endif /* HAVE_LIBLZMA */

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