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[cpio] Split out bzImage initrd CPIO header construction

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iPXE will construct CPIO headers for images that have a non-empty
command line, thereby allowing raw images (without CPIO headers) to be
injected into a dynamically constructed initrd.  This feature is
currently implemented within the BIOS-only bzImage format support.

Split out the CPIO header construction logic to allow for reuse in
other contexts such as in a UEFI build.

Signed-off-by: Michael Brown <mcb30@ipxe.org>
This commit is contained in:
Michael Brown
2021-05-17 14:57:48 +01:00
parent fc8bd4ba1a
commit bfca3db41e
5 changed files with 110 additions and 56 deletions
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52
src/arch/x86/image/bzimage.c
View File

@@ -326,32 +326,6 @@ static void bzimage_set_cmdline ( struct image *image,
DBGC ( image, "bzImage %p command line \"%s\"\n", image, cmdline );
}
/**
* Parse standalone image command line for cpio parameters
*
* @v image bzImage file
* @v cpio CPIO header
* @v cmdline Command line
*/
static void bzimage_parse_cpio_cmdline ( struct image *image,
struct cpio_header *cpio,
const char *cmdline ) {
char *arg;
char *end;
unsigned int mode;
/* Look for "mode=" */
if ( ( arg = strstr ( cmdline, "mode=" ) ) ) {
arg += 5;
mode = strtoul ( arg, &end, 8 /* Octal for file mode */ );
if ( *end && ( *end != ' ' ) ) {
DBGC ( image, "bzImage %p strange \"mode=\""
"terminator '%c'\n", image, *end );
}
cpio_set_field ( cpio->c_mode, ( 0100000 | mode ) );
}
}
/**
* Align initrd length
*
@@ -374,11 +348,9 @@ static inline size_t bzimage_align ( size_t len ) {
static size_t bzimage_load_initrd ( struct image *image,
struct image *initrd,
userptr_t address ) {
char *filename = initrd->cmdline;
char *cmdline;
const char *filename = cpio_name ( initrd );
struct cpio_header cpio;
size_t offset;
size_t name_len;
size_t pad_len;
/* Do not include kernel image itself as an initrd */
@@ -386,25 +358,7 @@ static size_t bzimage_load_initrd ( struct image *image,
return 0;
/* Create cpio header for non-prebuilt images */
if ( filename && filename[0] ) {
cmdline = strchr ( filename, ' ' );
name_len = ( ( cmdline ? ( ( size_t ) ( cmdline - filename ) )
: strlen ( filename ) ) + 1 /* NUL */ );
memset ( &cpio, '0', sizeof ( cpio ) );
memcpy ( cpio.c_magic, CPIO_MAGIC, sizeof ( cpio.c_magic ) );
cpio_set_field ( cpio.c_mode, 0100644 );
cpio_set_field ( cpio.c_nlink, 1 );
cpio_set_field ( cpio.c_filesize, initrd->len );
cpio_set_field ( cpio.c_namesize, name_len );
if ( cmdline ) {
bzimage_parse_cpio_cmdline ( image, &cpio,
( cmdline + 1 /* ' ' */ ));
}
offset = ( ( sizeof ( cpio ) + name_len + 0x03 ) & ~0x03 );
} else {
offset = 0;
name_len = 0;
}
offset = cpio_header ( initrd, &cpio );
/* Copy in initrd image body (and cpio header if applicable) */
if ( address ) {
@@ -413,7 +367,7 @@ static size_t bzimage_load_initrd ( struct image *image,
memset_user ( address, 0, 0, offset );
copy_to_user ( address, 0, &cpio, sizeof ( cpio ) );
copy_to_user ( address, sizeof ( cpio ), filename,
( name_len - 1 /* NUL (or space) */ ) );
cpio_name_len ( initrd ) );
}
DBGC ( image, "bzImage %p initrd %p [%#08lx,%#08lx,%#08lx)"
"%s%s\n", image, initrd, user_to_phys ( address, 0 ),

1
src/arch/x86/image/initrd.c
View File

@@ -29,6 +29,7 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
#include <ipxe/uaccess.h>
#include <ipxe/init.h>
#include <ipxe/memblock.h>
#include <ipxe/cpio.h>
/** @file
*