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-rw-r--r--efi/adv.c297
1 files changed, 297 insertions, 0 deletions
diff --git a/efi/adv.c b/efi/adv.c
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+/* ----------------------------------------------------------------------- *
+ *
+ * Copyright 2007-2008 H. Peter Anvin - All Rights Reserved
+ * Copyright 2012 Intel Corporation; author: H. Peter Anvin
+ * Chandramouli Narayanan
+ *
+ * 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, Inc., 53 Temple Place Ste 330,
+ * Boston MA 02111-1307, USA; either version 2 of the License, or
+ * (at your option) any later version; incorporated herein by reference.
+ *
+ * ----------------------------------------------------------------------- */
+
+/*
+ * adv.c
+ *
+ * Core ADV I/O
+ * Code consolidated from libinstaller/adv*.c and core/adv.inc with the
+ * addition of EFI support
+ *
+ * Return 0 on success, -1 on error, and set errno.
+ *
+ */
+#define _GNU_SOURCE
+
+#include <syslinux/config.h>
+#include <string.h>
+#include "adv.h"
+
+unsigned char syslinux_adv[2 * ADV_SIZE];
+
+static void cleanup_adv(unsigned char *advbuf)
+{
+ int i;
+ uint32_t csum;
+
+ /* Make sure both copies agree, and update the checksum */
+ *(uint32_t *)advbuf = ADV_MAGIC1;
+
+ csum = ADV_MAGIC2;
+ for (i = 8; i < ADV_SIZE - 4; i += 4)
+ csum -= *(uint32_t *)(advbuf + i);
+
+ *(uint32_t *)(advbuf + 4) = csum;
+ *(uint32_t *)(advbuf + ADV_SIZE - 4) = ADV_MAGIC3;
+
+ memcpy(advbuf + ADV_SIZE, advbuf, ADV_SIZE);
+}
+
+void syslinux_reset_adv(unsigned char *advbuf)
+{
+ /* Create an all-zero ADV */
+ memset(advbuf + 2 * 4, 0, ADV_LEN);
+ cleanup_adv(advbuf);
+}
+
+static int adv_consistent(const unsigned char *p)
+{
+ int i;
+ uint32_t csum;
+
+ if (*(uint32_t *)p != ADV_MAGIC1 ||
+ *(uint32_t *)(p + ADV_SIZE - 4) != ADV_MAGIC3)
+ return 0;
+
+ csum = 0;
+ for (i = 4; i < ADV_SIZE - 4; i += 4)
+ csum += *(uint32_t *)(p + i);
+
+ return csum == ADV_MAGIC2;
+}
+
+/*
+ * Verify that an in-memory ADV is consistent, making the copies consistent.
+ * If neither copy is OK, return -1 and call syslinux_reset_adv().
+ */
+int syslinux_validate_adv(unsigned char *advbuf)
+{
+ if (adv_consistent(advbuf + 0 * ADV_SIZE)) {
+ memcpy(advbuf + ADV_SIZE, advbuf, ADV_SIZE);
+ return 0;
+ } else if (adv_consistent(advbuf + 1 * ADV_SIZE)) {
+ memcpy(advbuf, advbuf + ADV_SIZE, ADV_SIZE);
+ return 0;
+ } else {
+ syslinux_reset_adv(advbuf);
+ return -1;
+ }
+}
+
+/*
+ * Read the ADV from an existing instance, or initialize if invalid.
+ * Returns -1 on fatal errors, 0 if ADV is okay, 1 if the ADV is
+ * invalid, and 2 if the file does not exist.
+ */
+
+/* make_filespec
+ * Take the ASCII pathname and filename and concatenate them
+ * into an allocated memory space as unicode file specification string.
+ * The path and cfg ASCII strings are assumed to be null-terminated.
+ * For EFI, the separation character in the path name is '\'
+ * and therefore it is assumed that the file spec uses '\' as separation char
+ *
+ * The function returns
+ * 0 if successful and fspec is a valid allocated CHAR16 pointer
+ * Caller is responsible to free up the allocated filespec string
+ * -1 otherwise
+ *
+ */
+static int make_filespec(CHAR16 **fspec, const char *path, const char *cfg)
+{
+ CHAR16 *p;
+ int size, append;
+
+ /* allocate size for a CHAR16 string */
+ size = sizeof(CHAR16) * (strlena((CHAR8 *)path)+strlena((CHAR8 *)cfg)+2); /* including null */
+ *fspec = malloc(size);
+ if (!*fspec) return -1;
+
+ append = path[strlena((CHAR8 *)path) - 1] != '\\';
+ for (p = *fspec; *path; path++, p++)
+ *p = (CHAR16)*path;
+ /* append the separation character to the path if need be */
+ if (append) *p++ = (CHAR16)'\\';
+ for (; *cfg; cfg++, p++)
+ *p = (CHAR16)*cfg;
+ *p = (CHAR16)CHAR_NULL;
+
+ return 0;
+}
+
+
+/* TODO:
+ * set_attributes() and clear_attributes() are supported for VFAT only
+ */
+int read_adv(const char *path, const char *cfg)
+{
+ CHAR16 *file;
+ EFI_FILE_HANDLE fd;
+ EFI_FILE_INFO st;
+ int err = 0;
+ int rv;
+
+ rv = make_filespec(&file, path, cfg);
+ if (rv < 0 || !file) {
+ efi_perror(L"read_adv");
+ return -1;
+ }
+
+ /* TBD: Not sure if EFI accepts the attribute read only
+ * even if an existing file is opened for read access
+ */
+ fd = efi_open(file, EFI_FILE_MODE_READ);
+ if (!fd) {
+ if (efi_errno != EFI_NOT_FOUND) {
+ err = -1;
+ } else {
+ syslinux_reset_adv(syslinux_adv);
+ err = 2; /* Nonexistence is not a fatal error */
+ }
+ } else if (!efi_fstat(fd, &st)) {
+ err = -1;
+ } else if (st.FileSize < 2 * ADV_SIZE) {
+ /* Too small to be useful */
+ syslinux_reset_adv(syslinux_adv);
+ err = 0; /* Nothing to read... */
+ } else if (efi_xpread(fd, syslinux_adv, 2 * ADV_SIZE,
+ st.FileSize - 2 * ADV_SIZE) != 2 * ADV_SIZE) {
+ err = -1;
+ } else {
+ /* We got it... maybe? */
+ err = syslinux_validate_adv(syslinux_adv) ? 1 : 0;
+ }
+
+ if (err < 0)
+ efi_perror(file);
+ if (fd)
+ efi_close(fd);
+ free(file);
+
+ return err;
+}
+
+/* For EFI platform, initialize ADV by opening ldlinux.sys
+ * as configured and return the primary (adv0) and alternate (adv1)
+ * data into caller's buffer. File remains open for subsequent
+ * operations. This routine is to be called from comboot vector.
+ */
+void efi_adv_init(void)
+{
+ union syslinux_derivative_info sdi;
+
+ get_derivative_info(&sdi);
+
+ if (sdi.c.filesystem == SYSLINUX_FS_SYSLINUX)
+ read_adv("", SYSLINUX_FILE);
+ else {
+ __syslinux_adv_ptr = &syslinux_adv[8]; /* skip head, csum */
+ __syslinux_adv_size = ADV_LEN;
+
+ syslinux_validate_adv(syslinux_adv);
+ }
+}
+
+/* For EFI platform, write 2 * ADV_SIZE data to the file opened
+ * at ADV initialization. (i.e ldlinux.sys).
+ *
+ * TODO:
+ * 1. Validate assumption: write back to file from __syslinux_adv_ptr
+ * 2. What if there errors?
+ * 3. Do we need to set the attributes of the sys file?
+ *
+ */
+int efi_adv_write(void)
+{
+ char *name;
+ unsigned char advtmp[2 * ADV_SIZE];
+ unsigned char *advbuf = syslinux_adv;
+ int rv;
+ int err = 0;
+ EFI_FILE_HANDLE fd; /* handle to ldlinux.sys */
+ CHAR16 *file;
+ EFI_FILE_INFO st, xst;
+ union syslinux_derivative_info sdi;
+
+ get_derivative_info(&sdi);
+ if (sdi.c.filesystem != SYSLINUX_FS_SYSLINUX)
+ return -1;
+
+ name = SYSLINUX_FILE;
+ rv = make_filespec(&file, "", name);
+ if (rv < 0 || !file) {
+ efi_errno = EFI_OUT_OF_RESOURCES;
+ efi_perror(L"efi_adv_write:");
+ return -1;
+ }
+
+ fd = efi_open(file, EFI_FILE_MODE_READ);
+ if (fd == (EFI_FILE_HANDLE)NULL) {
+ err = -1;
+ efi_printerr(L"efi_adv_write: Unable to open file %s\n", file);
+ } else if (efi_fstat(fd, &st)) {
+ err = -1;
+ efi_printerr(L"efi_adv_write: Unable to get info for file %s\n", file);
+ } else if (st.FileSize < 2 * ADV_SIZE) {
+ /* Too small to be useful */
+ err = -2;
+ efi_printerr(L"efi_adv_write: File size too small to be useful for file %s\n", file);
+ } else if (efi_xpread(fd, advtmp, 2 * ADV_SIZE,
+ st.FileSize - 2 * ADV_SIZE) != 2 * ADV_SIZE) {
+ err = -1;
+ efi_printerr(L"efi_adv_write: Error reading ADV data from file %s\n", file);
+ } else {
+ cleanup_adv(advbuf);
+ err = syslinux_validate_adv(advbuf) ? -2 : 0;
+
+ if (!err) {
+ /* Got a good one, write our own ADV here */
+ efi_clear_attributes(fd);
+
+ /* Need to re-open read-write */
+ efi_close(fd);
+ /* There is no SYNC attribute with EFI open */
+ fd = efi_open(file, EFI_FILE_MODE_READ | EFI_FILE_MODE_WRITE);
+ if (fd == (EFI_FILE_HANDLE)NULL) {
+ err = -1;
+ } else if (efi_fstat(fd, &xst) || xst.FileSize != st.FileSize) {
+ efi_perror(L"efi_adv_write: file status error/mismatch");
+ err = -2;
+ }
+ /* Write our own version ... */
+ if (efi_xpwrite(fd, advbuf, 2 * ADV_SIZE,
+ st.FileSize - 2 * ADV_SIZE) != 2 * ADV_SIZE) {
+ err = -1;
+ efi_printerr(L"efi_adv_write: Error write ADV data to file %s\n", file);
+ }
+ if (!err) {
+ efi_sync(fd);
+ efi_set_attributes(fd);
+ }
+ }
+ }
+
+ if (err == -2)
+ efi_printerr(L"%s: cannot write auxilliary data (need --update)?\n",
+ file);
+ else if (err == -1)
+ efi_perror(L"efi_adv_write:");
+
+ if (fd)
+ efi_close(fd);
+ if (file)
+ free(file);
+
+ return err;
+}
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