pxe: Move pxe_utils files

Move the header file into the main include/ directory so we can use it
from the bootmethod code. Move the C file into boot/ since it relates to
booting.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Artem Lapkin <email2tema@gmail.com>
Tested-by: Artem Lapkin <email2tema@gmail.com>
Reviewed-by: Ramon Fried <rfried.dev@gmail.com>

2 files changed, 1463 insertions, 0 deletions

diff --git a/boot/Makefile b/boot/Makefile
index a19e85cf6c8..2938c3f1458 100644
--- a/boot/Makefile
+++ b/boot/Makefile
@@ -14,6 +14,9 @@ obj-$(CONFIG_CMD_BOOTM) += bootm.o bootm_os.o
 obj-$(CONFIG_CMD_BOOTZ) += bootm.o bootm_os.o
 obj-$(CONFIG_CMD_BOOTI) += bootm.o bootm_os.o
 
+obj-$(CONFIG_CMD_PXE) += pxe_utils.o
+obj-$(CONFIG_CMD_SYSBOOT) += pxe_utils.o
+
 endif
 
 obj-y += image.o image-board.o
diff --git a/boot/pxe_utils.c b/boot/pxe_utils.c
new file mode 100644
index 00000000000..972f9b06b0d
--- /dev/null
+++ b/boot/pxe_utils.c
@@ -0,0 +1,1460 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright 2010-2011 Calxeda, Inc.
+ * Copyright (c) 2014, NVIDIA CORPORATION.  All rights reserved.
+ */
+
+#include <common.h>
+#include <command.h>
+#include <env.h>
+#include <image.h>
+#include <log.h>
+#include <malloc.h>
+#include <mapmem.h>
+#include <lcd.h>
+#include <net.h>
+#include <fdt_support.h>
+#include <linux/libfdt.h>
+#include <linux/string.h>
+#include <linux/ctype.h>
+#include <errno.h>
+#include <linux/list.h>
+
+#include <splash.h>
+#include <asm/io.h>
+
+#include "menu.h"
+#include "cli.h"
+
+#include "pxe_utils.h"
+
+#define MAX_TFTP_PATH_LEN 512
+
+int format_mac_pxe(char *outbuf, size_t outbuf_len)
+{
+	uchar ethaddr[6];
+
+	if (outbuf_len < 21) {
+		printf("outbuf is too small (%zd < 21)\n", outbuf_len);
+
+		return -EINVAL;
+	}
+
+	if (!eth_env_get_enetaddr_by_index("eth", eth_get_dev_index(), ethaddr))
+		return -ENOENT;
+
+	sprintf(outbuf, "01-%02x-%02x-%02x-%02x-%02x-%02x",
+		ethaddr[0], ethaddr[1], ethaddr[2],
+		ethaddr[3], ethaddr[4], ethaddr[5]);
+
+	return 1;
+}
+
+/*
+ * Returns the directory the file specified in the bootfile env variable is
+ * in. If bootfile isn't defined in the environment, return NULL, which should
+ * be interpreted as "don't prepend anything to paths".
+ */
+static int get_bootfile_path(const char *file_path, char *bootfile_path,
+			     size_t bootfile_path_size, bool allow_abs_path)
+{
+	char *bootfile, *last_slash;
+	size_t path_len = 0;
+
+	/* Only syslinux allows absolute paths */
+	if (file_path[0] == '/' && allow_abs_path)
+		goto ret;
+
+	bootfile = from_env("bootfile");
+
+	if (!bootfile)
+		goto ret;
+
+	last_slash = strrchr(bootfile, '/');
+
+	if (!last_slash)
+		goto ret;
+
+	path_len = (last_slash - bootfile) + 1;
+
+	if (bootfile_path_size < path_len) {
+		printf("bootfile_path too small. (%zd < %zd)\n",
+		       bootfile_path_size, path_len);
+
+		return -1;
+	}
+
+	strncpy(bootfile_path, bootfile, path_len);
+
+ ret:
+	bootfile_path[path_len] = '\0';
+
+	return 1;
+}
+
+/*
+ * As in pxelinux, paths to files referenced from files we retrieve are
+ * relative to the location of bootfile. get_relfile takes such a path and
+ * joins it with the bootfile path to get the full path to the target file. If
+ * the bootfile path is NULL, we use file_path as is.
+ *
+ * Returns 1 for success, or < 0 on error.
+ */
+static int get_relfile(struct pxe_context *ctx, const char *file_path,
+		       unsigned long file_addr)
+{
+	size_t path_len;
+	char relfile[MAX_TFTP_PATH_LEN + 1];
+	char addr_buf[18];
+	int err;
+
+	err = get_bootfile_path(file_path, relfile, sizeof(relfile),
+				ctx->allow_abs_path);
+
+	if (err < 0)
+		return err;
+
+	path_len = strlen(file_path);
+	path_len += strlen(relfile);
+
+	if (path_len > MAX_TFTP_PATH_LEN) {
+		printf("Base path too long (%s%s)\n", relfile, file_path);
+
+		return -ENAMETOOLONG;
+	}
+
+	strcat(relfile, file_path);
+
+	printf("Retrieving file: %s\n", relfile);
+
+	sprintf(addr_buf, "%lx", file_addr);
+
+	return ctx->getfile(ctx, relfile, addr_buf);
+}
+
+int get_pxe_file(struct pxe_context *ctx, const char *file_path,
+		 unsigned long file_addr)
+{
+	unsigned long config_file_size;
+	char *tftp_filesize;
+	int err;
+	char *buf;
+
+	err = get_relfile(ctx, file_path, file_addr);
+
+	if (err < 0)
+		return err;
+
+	/*
+	 * the file comes without a NUL byte at the end, so find out its size
+	 * and add the NUL byte.
+	 */
+	tftp_filesize = from_env("filesize");
+
+	if (!tftp_filesize)
+		return -ENOENT;
+
+	if (strict_strtoul(tftp_filesize, 16, &config_file_size) < 0)
+		return -EINVAL;
+
+	buf = map_sysmem(file_addr + config_file_size, 1);
+	*buf = '\0';
+	unmap_sysmem(buf);
+
+	return 1;
+}
+
+#define PXELINUX_DIR "pxelinux.cfg/"
+
+int get_pxelinux_path(struct pxe_context *ctx, const char *file,
+		      unsigned long pxefile_addr_r)
+{
+	size_t base_len = strlen(PXELINUX_DIR);
+	char path[MAX_TFTP_PATH_LEN + 1];
+
+	if (base_len + strlen(file) > MAX_TFTP_PATH_LEN) {
+		printf("path (%s%s) too long, skipping\n",
+		       PXELINUX_DIR, file);
+		return -ENAMETOOLONG;
+	}
+
+	sprintf(path, PXELINUX_DIR "%s", file);
+
+	return get_pxe_file(ctx, path, pxefile_addr_r);
+}
+
+/*
+ * Wrapper to make it easier to store the file at file_path in the location
+ * specified by envaddr_name. file_path will be joined to the bootfile path,
+ * if any is specified.
+ *
+ * Returns 1 on success or < 0 on error.
+ */
+static int get_relfile_envaddr(struct pxe_context *ctx, const char *file_path,
+			       const char *envaddr_name)
+{
+	unsigned long file_addr;
+	char *envaddr;
+
+	envaddr = from_env(envaddr_name);
+
+	if (!envaddr)
+		return -ENOENT;
+
+	if (strict_strtoul(envaddr, 16, &file_addr) < 0)
+		return -EINVAL;
+
+	return get_relfile(ctx, file_path, file_addr);
+}
+
+/*
+ * Allocates memory for and initializes a pxe_label. This uses malloc, so the
+ * result must be free()'d to reclaim the memory.
+ *
+ * Returns NULL if malloc fails.
+ */
+static struct pxe_label *label_create(void)
+{
+	struct pxe_label *label;
+
+	label = malloc(sizeof(struct pxe_label));
+
+	if (!label)
+		return NULL;
+
+	memset(label, 0, sizeof(struct pxe_label));
+
+	return label;
+}
+
+/*
+ * Free the memory used by a pxe_label, including that used by its name,
+ * kernel, append and initrd members, if they're non NULL.
+ *
+ * So - be sure to only use dynamically allocated memory for the members of
+ * the pxe_label struct, unless you want to clean it up first. These are
+ * currently only created by the pxe file parsing code.
+ */
+static void label_destroy(struct pxe_label *label)
+{
+	if (label->name)
+		free(label->name);
+
+	if (label->kernel)
+		free(label->kernel);
+
+	if (label->config)
+		free(label->config);
+
+	if (label->append)
+		free(label->append);
+
+	if (label->initrd)
+		free(label->initrd);
+
+	if (label->fdt)
+		free(label->fdt);
+
+	if (label->fdtdir)
+		free(label->fdtdir);
+
+	if (label->fdtoverlays)
+		free(label->fdtoverlays);
+
+	free(label);
+}
+
+/*
+ * Print a label and its string members if they're defined.
+ *
+ * This is passed as a callback to the menu code for displaying each
+ * menu entry.
+ */
+static void label_print(void *data)
+{
+	struct pxe_label *label = data;
+	const char *c = label->menu ? label->menu : label->name;
+
+	printf("%s:\t%s\n", label->num, c);
+}
+
+/*
+ * Boot a label that specified 'localboot'. This requires that the 'localcmd'
+ * environment variable is defined. Its contents will be executed as U-Boot
+ * command.  If the label specified an 'append' line, its contents will be
+ * used to overwrite the contents of the 'bootargs' environment variable prior
+ * to running 'localcmd'.
+ *
+ * Returns 1 on success or < 0 on error.
+ */
+static int label_localboot(struct pxe_label *label)
+{
+	char *localcmd;
+
+	localcmd = from_env("localcmd");
+
+	if (!localcmd)
+		return -ENOENT;
+
+	if (label->append) {
+		char bootargs[CONFIG_SYS_CBSIZE];
+
+		cli_simple_process_macros(label->append, bootargs,
+					  sizeof(bootargs));
+		env_set("bootargs", bootargs);
+	}
+
+	debug("running: %s\n", localcmd);
+
+	return run_command_list(localcmd, strlen(localcmd), 0);
+}
+
+/*
+ * Loads fdt overlays specified in 'fdtoverlays'.
+ */
+#ifdef CONFIG_OF_LIBFDT_OVERLAY
+static void label_boot_fdtoverlay(struct pxe_context *ctx,
+				  struct pxe_label *label)
+{
+	char *fdtoverlay = label->fdtoverlays;
+	struct fdt_header *working_fdt;
+	char *fdtoverlay_addr_env;
+	ulong fdtoverlay_addr;
+	ulong fdt_addr;
+	int err;
+
+	/* Get the main fdt and map it */
+	fdt_addr = hextoul(env_get("fdt_addr_r"), NULL);
+	working_fdt = map_sysmem(fdt_addr, 0);
+	err = fdt_check_header(working_fdt);
+	if (err)
+		return;
+
+	/* Get the specific overlay loading address */
+	fdtoverlay_addr_env = env_get("fdtoverlay_addr_r");
+	if (!fdtoverlay_addr_env) {
+		printf("Invalid fdtoverlay_addr_r for loading overlays\n");
+		return;
+	}
+
+	fdtoverlay_addr = hextoul(fdtoverlay_addr_env, NULL);
+
+	/* Cycle over the overlay files and apply them in order */
+	do {
+		struct fdt_header *blob;
+		char *overlayfile;
+		char *end;
+		int len;
+
+		/* Drop leading spaces */
+		while (*fdtoverlay == ' ')
+			++fdtoverlay;
+
+		/* Copy a single filename if multiple provided */
+		end = strstr(fdtoverlay, " ");
+		if (end) {
+			len = (int)(end - fdtoverlay);
+			overlayfile = malloc(len + 1);
+			strncpy(overlayfile, fdtoverlay, len);
+			overlayfile[len] = '\0';
+		} else
+			overlayfile = fdtoverlay;
+
+		if (!strlen(overlayfile))
+			goto skip_overlay;
+
+		/* Load overlay file */
+		err = get_relfile_envaddr(ctx, overlayfile,
+					  "fdtoverlay_addr_r");
+		if (err < 0) {
+			printf("Failed loading overlay %s\n", overlayfile);
+			goto skip_overlay;
+		}
+
+		/* Resize main fdt */
+		fdt_shrink_to_minimum(working_fdt, 8192);
+
+		blob = map_sysmem(fdtoverlay_addr, 0);
+		err = fdt_check_header(blob);
+		if (err) {
+			printf("Invalid overlay %s, skipping\n",
+			       overlayfile);
+			goto skip_overlay;
+		}
+
+		err = fdt_overlay_apply_verbose(working_fdt, blob);
+		if (err) {
+			printf("Failed to apply overlay %s, skipping\n",
+			       overlayfile);
+			goto skip_overlay;
+		}
+
+skip_overlay:
+		if (end)
+			free(overlayfile);
+	} while ((fdtoverlay = strstr(fdtoverlay, " ")));
+}
+#endif
+
+/*
+ * Boot according to the contents of a pxe_label.
+ *
+ * If we can't boot for any reason, we return.  A successful boot never
+ * returns.
+ *
+ * The kernel will be stored in the location given by the 'kernel_addr_r'
+ * environment variable.
+ *
+ * If the label specifies an initrd file, it will be stored in the location
+ * given by the 'ramdisk_addr_r' environment variable.
+ *
+ * If the label specifies an 'append' line, its contents will overwrite that
+ * of the 'bootargs' environment variable.
+ */
+static int label_boot(struct pxe_context *ctx, struct pxe_label *label)
+{
+	char *bootm_argv[] = { "bootm", NULL, NULL, NULL, NULL };
+	char *zboot_argv[] = { "zboot", NULL, "0", NULL, NULL };
+	char *kernel_addr = NULL;
+	char *initrd_addr_str = NULL;
+	char initrd_filesize[10];
+	char initrd_str[28];
+	char mac_str[29] = "";
+	char ip_str[68] = "";
+	char *fit_addr = NULL;
+	int bootm_argc = 2;
+	int zboot_argc = 3;
+	int len = 0;
+	ulong kernel_addr_r;
+	void *buf;
+
+	label_print(label);
+
+	label->attempted = 1;
+
+	if (label->localboot) {
+		if (label->localboot_val >= 0)
+			label_localboot(label);
+		return 0;
+	}
+
+	if (!label->kernel) {
+		printf("No kernel given, skipping %s\n",
+		       label->name);
+		return 1;
+	}
+
+	if (label->initrd) {
+		if (get_relfile_envaddr(ctx, label->initrd, "ramdisk_addr_r") < 0) {
+			printf("Skipping %s for failure retrieving initrd\n",
+			       label->name);
+			return 1;
+		}
+
+		initrd_addr_str = env_get("ramdisk_addr_r");
+		strncpy(initrd_filesize, env_get("filesize"), 9);
+
+		strncpy(initrd_str, initrd_addr_str, 18);
+		strcat(initrd_str, ":");
+		strncat(initrd_str, initrd_filesize, 9);
+	}
+
+	if (get_relfile_envaddr(ctx, label->kernel, "kernel_addr_r") < 0) {
+		printf("Skipping %s for failure retrieving kernel\n",
+		       label->name);
+		return 1;
+	}
+
+	if (label->ipappend & 0x1) {
+		sprintf(ip_str, " ip=%s:%s:%s:%s",
+			env_get("ipaddr"), env_get("serverip"),
+			env_get("gatewayip"), env_get("netmask"));
+	}
+
+	if (IS_ENABLED(CONFIG_CMD_NET))	{
+		if (label->ipappend & 0x2) {
+			int err;
+
+			strcpy(mac_str, " BOOTIF=");
+			err = format_mac_pxe(mac_str + 8, sizeof(mac_str) - 8);
+			if (err < 0)
+				mac_str[0] = '\0';
+		}
+	}
+
+	if ((label->ipappend & 0x3) || label->append) {
+		char bootargs[CONFIG_SYS_CBSIZE] = "";
+		char finalbootargs[CONFIG_SYS_CBSIZE];
+
+		if (strlen(label->append ?: "") +
+		    strlen(ip_str) + strlen(mac_str) + 1 > sizeof(bootargs)) {
+			printf("bootarg overflow %zd+%zd+%zd+1 > %zd\n",
+			       strlen(label->append ?: ""),
+			       strlen(ip_str), strlen(mac_str),
+			       sizeof(bootargs));
+			return 1;
+		}
+
+		if (label->append)
+			strncpy(bootargs, label->append, sizeof(bootargs));
+
+		strcat(bootargs, ip_str);
+		strcat(bootargs, mac_str);
+
+		cli_simple_process_macros(bootargs, finalbootargs,
+					  sizeof(finalbootargs));
+		env_set("bootargs", finalbootargs);
+		printf("append: %s\n", finalbootargs);
+	}
+
+	kernel_addr = env_get("kernel_addr_r");
+
+	/* for FIT, append the configuration identifier */
+	if (label->config) {
+		int len = strlen(kernel_addr) + strlen(label->config) + 1;
+
+		fit_addr = malloc(len);
+		if (!fit_addr) {
+			printf("malloc fail (FIT address)\n");
+			return 1;
+		}
+		snprintf(fit_addr, len, "%s%s", kernel_addr, label->config);
+		kernel_addr = fit_addr;
+	}
+
+	/*
+	 * fdt usage is optional:
+	 * It handles the following scenarios.
+	 *
+	 * Scenario 1: If fdt_addr_r specified and "fdt" or "fdtdir" label is
+	 * defined in pxe file, retrieve fdt blob from server. Pass fdt_addr_r to
+	 * bootm, and adjust argc appropriately.
+	 *
+	 * If retrieve fails and no exact fdt blob is specified in pxe file with
+	 * "fdt" label, try Scenario 2.
+	 *
+	 * Scenario 2: If there is an fdt_addr specified, pass it along to
+	 * bootm, and adjust argc appropriately.
+	 *
+	 * Scenario 3: fdt blob is not available.
+	 */
+	bootm_argv[3] = env_get("fdt_addr_r");
+
+	/* if fdt label is defined then get fdt from server */
+	if (bootm_argv[3]) {
+		char *fdtfile = NULL;
+		char *fdtfilefree = NULL;
+
+		if (label->fdt) {
+			fdtfile = label->fdt;
+		} else if (label->fdtdir) {
+			char *f1, *f2, *f3, *f4, *slash;
+
+			f1 = env_get("fdtfile");
+			if (f1) {
+				f2 = "";
+				f3 = "";
+				f4 = "";
+			} else {
+				/*
+				 * For complex cases where this code doesn't
+				 * generate the correct filename, the board
+				 * code should set $fdtfile during early boot,
+				 * or the boot scripts should set $fdtfile
+				 * before invoking "pxe" or "sysboot".
+				 */
+				f1 = env_get("soc");
+				f2 = "-";
+				f3 = env_get("board");
+				f4 = ".dtb";
+				if (!f1) {
+					f1 = "";
+					f2 = "";
+				}
+				if (!f3) {
+					f2 = "";
+					f3 = "";
+				}
+			}
+
+			len = strlen(label->fdtdir);
+			if (!len)
+				slash = "./";
+			else if (label->fdtdir[len - 1] != '/')
+				slash = "/";
+			else
+				slash = "";
+
+			len = strlen(label->fdtdir) + strlen(slash) +
+				strlen(f1) + strlen(f2) + strlen(f3) +
+				strlen(f4) + 1;
+			fdtfilefree = malloc(len);
+			if (!fdtfilefree) {
+				printf("malloc fail (FDT filename)\n");
+				goto cleanup;
+			}
+
+			snprintf(fdtfilefree, len, "%s%s%s%s%s%s",
+				 label->fdtdir, slash, f1, f2, f3, f4);
+			fdtfile = fdtfilefree;
+		}
+
+		if (fdtfile) {
+			int err = get_relfile_envaddr(ctx, fdtfile,
+						      "fdt_addr_r");
+
+			free(fdtfilefree);
+			if (err < 0) {
+				bootm_argv[3] = NULL;
+
+				if (label->fdt) {
+					printf("Skipping %s for failure retrieving FDT\n",
+					       label->name);
+					goto cleanup;
+				}
+			}
+
+#ifdef CONFIG_OF_LIBFDT_OVERLAY
+			if (label->fdtoverlays)
+				label_boot_fdtoverlay(ctx, label);
+#endif
+		} else {
+			bootm_argv[3] = NULL;
+		}
+	}
+
+	bootm_argv[1] = kernel_addr;
+	zboot_argv[1] = kernel_addr;
+
+	if (initrd_addr_str) {
+		bootm_argv[2] = initrd_str;
+		bootm_argc = 3;
+
+		zboot_argv[3] = initrd_addr_str;
+		zboot_argv[4] = initrd_filesize;
+		zboot_argc = 5;
+	}
+
+	if (!bootm_argv[3])
+		bootm_argv[3] = env_get("fdt_addr");
+
+	if (bootm_argv[3]) {
+		if (!bootm_argv[2])
+			bootm_argv[2] = "-";
+		bootm_argc = 4;
+	}
+
+	kernel_addr_r = genimg_get_kernel_addr(kernel_addr);
+	buf = map_sysmem(kernel_addr_r, 0);
+	/* Try bootm for legacy and FIT format image */
+	if (genimg_get_format(buf) != IMAGE_FORMAT_INVALID)
+		do_bootm(ctx->cmdtp, 0, bootm_argc, bootm_argv);
+	/* Try booting an AArch64 Linux kernel image */
+	else if (IS_ENABLED(CONFIG_CMD_BOOTI))
+		do_booti(ctx->cmdtp, 0, bootm_argc, bootm_argv);
+	/* Try booting a Image */
+	else if (IS_ENABLED(CONFIG_CMD_BOOTZ))
+		do_bootz(ctx->cmdtp, 0, bootm_argc, bootm_argv);
+	/* Try booting an x86_64 Linux kernel image */
+	else if (IS_ENABLED(CONFIG_CMD_ZBOOT))
+		do_zboot_parent(ctx->cmdtp, 0, zboot_argc, zboot_argv, NULL);
+
+	unmap_sysmem(buf);
+
+cleanup:
+	if (fit_addr)
+		free(fit_addr);
+	return 1;
+}
+
+/*
+ * Tokens for the pxe file parser.
+ */
+enum token_type {
+	T_EOL,
+	T_STRING,
+	T_EOF,
+	T_MENU,
+	T_TITLE,
+	T_TIMEOUT,
+	T_LABEL,
+	T_KERNEL,
+	T_LINUX,
+	T_APPEND,
+	T_INITRD,
+	T_LOCALBOOT,
+	T_DEFAULT,
+	T_PROMPT,
+	T_INCLUDE,
+	T_FDT,
+	T_FDTDIR,
+	T_FDTOVERLAYS,
+	T_ONTIMEOUT,
+	T_IPAPPEND,
+	T_BACKGROUND,
+	T_INVALID
+};
+
+/*
+ * A token - given by a value and a type.
+ */
+struct token {
+	char *val;
+	enum token_type type;
+};
+
+/*
+ * Keywords recognized.
+ */
+static const struct token keywords[] = {
+	{"menu", T_MENU},
+	{"title", T_TITLE},
+	{"timeout", T_TIMEOUT},
+	{"default", T_DEFAULT},
+	{"prompt", T_PROMPT},
+	{"label", T_LABEL},
+	{"kernel", T_KERNEL},
+	{"linux", T_LINUX},
+	{"localboot", T_LOCALBOOT},
+	{"append", T_APPEND},
+	{"initrd", T_INITRD},
+	{"include", T_INCLUDE},
+	{"devicetree", T_FDT},
+	{"fdt", T_FDT},
+	{"devicetreedir", T_FDTDIR},
+	{"fdtdir", T_FDTDIR},
+	{"fdtoverlays", T_FDTOVERLAYS},
+	{"ontimeout", T_ONTIMEOUT,},
+	{"ipappend", T_IPAPPEND,},
+	{"background", T_BACKGROUND,},
+	{NULL, T_INVALID}
+};
+
+/*
+ * Since pxe(linux) files don't have a token to identify the start of a
+ * literal, we have to keep track of when we're in a state where a literal is
+ * expected vs when we're in a state a keyword is expected.
+ */
+enum lex_state {
+	L_NORMAL = 0,
+	L_KEYWORD,
+	L_SLITERAL
+};
+
+/*
+ * get_string retrieves a string from *p and stores it as a token in
+ * *t.
+ *
+ * get_string used for scanning both string literals and keywords.
+ *
+ * Characters from *p are copied into t-val until a character equal to
+ * delim is found, or a NUL byte is reached. If delim has the special value of
+ * ' ', any whitespace character will be used as a delimiter.
+ *
+ * If lower is unequal to 0, uppercase characters will be converted to
+ * lowercase in the result. This is useful to make keywords case
+ * insensitive.
+ *
+ * The location of *p is updated to point to the first character after the end
+ * of the token - the ending delimiter.
+ *
+ * On success, the new value of t->val is returned. Memory for t->val is
+ * allocated using malloc and must be free()'d to reclaim it.  If insufficient
+ * memory is available, NULL is returned.
+ */
+static char *get_string(char **p, struct token *t, char delim, int lower)
+{
+	char *b, *e;
+	size_t len, i;
+
+	/*
+	 * b and e both start at the beginning of the input stream.
+	 *
+	 * e is incremented until we find the ending delimiter, or a NUL byte
+	 * is reached. Then, we take e - b to find the length of the token.
+	 */
+	b = *p;
+	e = *p;
+
+	while (*e) {
+		if ((delim == ' ' && isspace(*e)) || delim == *e)
+			break;
+		e++;
+	}
+
+	len = e - b;
+
+	/*
+	 * Allocate memory to hold the string, and copy it in, converting
+	 * characters to lowercase if lower is != 0.
+	 */
+	t->val = malloc(len + 1);
+	if (!t->val)
+		return NULL;
+
+	for (i = 0; i < len; i++, b++) {
+		if (lower)
+			t->val[i] = tolower(*b);
+		else
+			t->val[i] = *b;
+	}
+
+	t->val[len] = '\0';
+
+	/*
+	 * Update *p so the caller knows where to continue scanning.
+	 */
+	*p = e;
+
+	t->type = T_STRING;
+
+	return t->val;
+}
+
+/*
+ * Populate a keyword token with a type and value.
+ */
+static void get_keyword(struct token *t)
+{
+	int i;
+
+	for (i = 0; keywords[i].val; i++) {
+		if (!strcmp(t->val, keywords[i].val)) {
+			t->type = keywords[i].type;
+			break;
+		}
+	}
+}
+
+/*
+ * Get the next token.  We have to keep track of which state we're in to know
+ * if we're looking to get a string literal or a keyword.
+ *
+ * *p is updated to point at the first character after the current token.
+ */
+static void get_token(char **p, struct token *t, enum lex_state state)
+{
+	char *c = *p;
+
+	t->type = T_INVALID;
+
+	/* eat non EOL whitespace */
+	while (isblank(*c))
+		c++;
+
+	/*
+	 * eat comments. note that string literals can't begin with #, but
+	 * can contain a # after their first character.
+	 */
+	if (*c == '#') {
+		while (*c && *c != '\n')
+			c++;
+	}
+
+	if (*c == '\n') {
+		t->type = T_EOL;
+		c++;
+	} else if (*c == '\0') {
+		t->type = T_EOF;
+		c++;
+	} else if (state == L_SLITERAL) {
+		get_string(&c, t, '\n', 0);
+	} else if (state == L_KEYWORD) {
+		/*
+		 * when we expect a keyword, we first get the next string
+		 * token delimited by whitespace, and then check if it
+		 * matches a keyword in our keyword list. if it does, it's
+		 * converted to a keyword token of the appropriate type, and
+		 * if not, it remains a string token.
+		 */
+		get_string(&c, t, ' ', 1);
+		get_keyword(t);
+	}
+
+	*p = c;
+}
+
+/*
+ * Increment *c until we get to the end of the current line, or EOF.
+ */
+static void eol_or_eof(char **c)
+{
+	while (**c && **c != '\n')
+		(*c)++;
+}
+
+/*
+ * All of these parse_* functions share some common behavior.
+ *
+ * They finish with *c pointing after the token they parse, and return 1 on
+ * success, or < 0 on error.
+ */
+
+/*
+ * Parse a string literal and store a pointer it at *dst. String literals
+ * terminate at the end of the line.
+ */
+static int parse_sliteral(char **c, char **dst)
+{
+	struct token t;
+	char *s = *c;
+
+	get_token(c, &t, L_SLITERAL);
+
+	if (t.type != T_STRING) {
+		printf("Expected string literal: %.*s\n", (int)(*c - s), s);
+		return -EINVAL;
+	}
+
+	*dst = t.val;
+
+	return 1;
+}
+
+/*
+ * Parse a base 10 (unsigned) integer and store it at *dst.
+ */
+static int parse_integer(char **c, int *dst)
+{
+	struct token t;
+	char *s = *c;
+
+	get_token(c, &t, L_SLITERAL);
+
+	if (t.type != T_STRING) {
+		printf("Expected string: %.*s\n", (int)(*c - s), s);
+		return -EINVAL;
+	}
+
+	*dst = simple_strtol(t.val, NULL, 10);
+
+	free(t.val);
+
+	return 1;
+}
+
+static int parse_pxefile_top(struct pxe_context *ctx, char *p, ulong base,
+			     struct pxe_menu *cfg, int nest_level);
+
+/*
+ * Parse an include statement, and retrieve and parse the file it mentions.
+ *
+ * base should point to a location where it's safe to store the file, and
+ * nest_level should indicate how many nested includes have occurred. For this
+ * include, nest_level has already been incremented and doesn't need to be
+ * incremented here.
+ */
+static int handle_include(struct pxe_context *ctx, char **c, unsigned long base,
+			  struct pxe_menu *cfg, int nest_level)
+{
+	char *include_path;
+	char *s = *c;
+	int err;
+	char *buf;
+	int ret;
+
+	err = parse_sliteral(c, &include_path);
+
+	if (err < 0) {
+		printf("Expected include path: %.*s\n", (int)(*c - s), s);
+		return err;
+	}
+
+	err = get_pxe_file(ctx, include_path, base);
+
+	if (err < 0) {
+		printf("Couldn't retrieve %s\n", include_path);
+		return err;
+	}
+
+	buf = map_sysmem(base, 0);
+	ret = parse_pxefile_top(ctx, buf, base, cfg, nest_level);
+	unmap_sysmem(buf);
+
+	return ret;
+}
+
+/*
+ * Parse lines that begin with 'menu'.
+ *
+ * base and nest are provided to handle the 'menu include' case.
+ *
+ * base should point to a location where it's safe to store the included file.
+ *
+ * nest_level should be 1 when parsing the top level pxe file, 2 when parsing
+ * a file it includes, 3 when parsing a file included by that file, and so on.
+ */
+static int parse_menu(struct pxe_context *ctx, char **c, struct pxe_menu *cfg,
+		      unsigned long base, int nest_level)
+{
+	struct token t;
+	char *s = *c;
+	int err = 0;
+
+	get_token(c, &t, L_KEYWORD);
+
+	switch (t.type) {
+	case T_TITLE:
+		err = parse_sliteral(c, &cfg->title);
+
+		break;
+
+	case T_INCLUDE:
+		err = handle_include(ctx, c, base, cfg, nest_level + 1);
+		break;
+
+	case T_BACKGROUND:
+		err = parse_sliteral(c, &cfg->bmp);
+		break;
+
+	default:
+		printf("Ignoring malformed menu command: %.*s\n",
+		       (int)(*c - s), s);
+	}
+
+	if (err < 0)
+		return err;
+
+	eol_or_eof(c);
+
+	return 1;
+}
+
+/*
+ * Handles parsing a 'menu line' when we're parsing a label.
+ */
+static int parse_label_menu(char **c, struct pxe_menu *cfg,
+			    struct pxe_label *label)
+{
+	struct token t;
+	char *s;
+
+	s = *c;
+
+	get_token(c, &t, L_KEYWORD);
+
+	switch (t.type) {
+	case T_DEFAULT:
+		if (!cfg->default_label)
+			cfg->default_label = strdup(label->name);
+
+		if (!cfg->default_label)
+			return -ENOMEM;
+
+		break;
+	case T_LABEL:
+		parse_sliteral(c, &label->menu);
+		break;
+	default:
+		printf("Ignoring malformed menu command: %.*s\n",
+		       (int)(*c - s), s);
+	}
+
+	eol_or_eof(c);
+
+	return 0;
+}
+
+/*
+ * Handles parsing a 'kernel' label.
+ * expecting "filename" or "<fit_filename>#cfg"
+ */
+static int parse_label_kernel(char **c, struct pxe_label *label)
+{
+	char *s;
+	int err;
+
+	err = parse_sliteral(c, &label->kernel);
+	if (err < 0)
+		return err;
+
+	s = strstr(label->kernel, "#");
+	if (!s)
+		return 1;
+
+	label->config = malloc(strlen(s) + 1);
+	if (!label->config)
+		return -ENOMEM;
+
+	strcpy(label->config, s);
+	*s = 0;
+
+	return 1;
+}
+
+/*
+ * Parses a label and adds it to the list of labels for a menu.
+ *
+ * A label ends when we either get to the end of a file, or
+ * get some input we otherwise don't have a handler defined
+ * for.
+ *
+ */
+static int parse_label(char **c, struct pxe_menu *cfg)
+{
+	struct token t;
+	int len;
+	char *s = *c;
+	struct pxe_label *label;
+	int err;
+
+	label = label_create();
+	if (!label)
+		return -ENOMEM;
+
+	err = parse_sliteral(c, &label->name);
+	if (err < 0) {
+		printf("Expected label name: %.*s\n", (int)(*c - s), s);
+		label_destroy(label);
+		return -EINVAL;
+	}
+
+	list_add_tail(&label->list, &cfg->labels);
+
+	while (1) {
+		s = *c;
+		get_token(c, &t, L_KEYWORD);
+
+		err = 0;
+		switch (t.type) {
+		case T_MENU:
+			err = parse_label_menu(c, cfg, label);
+			break;
+
+		case T_KERNEL:
+		case T_LINUX:
+			err = parse_label_kernel(c, label);
+			break;
+
+		case T_APPEND:
+			err = parse_sliteral(c, &label->append);
+			if (label->initrd)
+				break;
+			s = strstr(label->append, "initrd=");
+			if (!s)
+				break;
+			s += 7;
+			len = (int)(strchr(s, ' ') - s);
+			label->initrd = malloc(len + 1);
+			strncpy(label->initrd, s, len);
+			label->initrd[len] = '\0';
+
+			break;
+
+		case T_INITRD:
+			if (!label->initrd)
+				err = parse_sliteral(c, &label->initrd);
+			break;
+
+		case T_FDT:
+			if (!label->fdt)
+				err = parse_sliteral(c, &label->fdt);
+			break;
+
+		case T_FDTDIR:
+			if (!label->fdtdir)
+				err = parse_sliteral(c, &label->fdtdir);
+			break;
+
+		case T_FDTOVERLAYS:
+			if (!label->fdtoverlays)
+				err = parse_sliteral(c, &label->fdtoverlays);
+			break;
+
+		case T_LOCALBOOT:
+			label->localboot = 1;
+			err = parse_integer(c, &label->localboot_val);
+			break;
+
+		case T_IPAPPEND:
+			err = parse_integer(c, &label->ipappend);
+			break;
+
+		case T_EOL:
+			break;
+
+		default:
+			/*
+			 * put the token back! we don't want it - it's the end
+			 * of a label and whatever token this is, it's
+			 * something for the menu level context to handle.
+			 */
+			*c = s;
+			return 1;
+		}
+
+		if (err < 0)
+			return err;
+	}
+}
+
+/*
+ * This 16 comes from the limit pxelinux imposes on nested includes.
+ *
+ * There is no reason at all we couldn't do more, but some limit helps prevent
+ * infinite (until crash occurs) recursion if a file tries to include itself.
+ */
+#define MAX_NEST_LEVEL 16
+
+/*
+ * Entry point for parsing a menu file. nest_level indicates how many times
+ * we've nested in includes.  It will be 1 for the top level menu file.
+ *
+ * Returns 1 on success, < 0 on error.
+ */
+static int parse_pxefile_top(struct pxe_context *ctx, char *p, unsigned long base,
+			     struct pxe_menu *cfg, int nest_level)
+{
+	struct token t;
+	char *s, *b, *label_name;
+	int err;
+
+	b = p;
+
+	if (nest_level > MAX_NEST_LEVEL) {
+		printf("Maximum nesting (%d) exceeded\n", MAX_NEST_LEVEL);
+		return -EMLINK;
+	}
+
+	while (1) {
+		s = p;
+
+		get_token(&p, &t, L_KEYWORD);
+
+		err = 0;
+		switch (t.type) {
+		case T_MENU:
+			cfg->prompt = 1;
+			err = parse_menu(ctx, &p, cfg,
+					 base + ALIGN(strlen(b) + 1, 4),
+					 nest_level);
+			break;
+
+		case T_TIMEOUT:
+			err = parse_integer(&p, &cfg->timeout);
+			break;
+
+		case T_LABEL:
+			err = parse_label(&p, cfg);
+			break;
+
+		case T_DEFAULT:
+		case T_ONTIMEOUT:
+			err = parse_sliteral(&p, &label_name);
+
+			if (label_name) {
+				if (cfg->default_label)
+					free(cfg->default_label);
+
+				cfg->default_label = label_name;
+			}
+
+			break;
+
+		case T_INCLUDE:
+			err = handle_include(ctx, &p,
+					     base + ALIGN(strlen(b), 4), cfg,
+					     nest_level + 1);
+			break;
+
+		case T_PROMPT:
+			eol_or_eof(&p);
+			break;
+
+		case T_EOL:
+			break;
+
+		case T_EOF:
+			return 1;
+
+		default:
+			printf("Ignoring unknown command: %.*s\n",
+			       (int)(p - s), s);
+			eol_or_eof(&p);
+		}
+
+		if (err < 0)
+			return err;
+	}
+}
+
+/*
+ */
+void destroy_pxe_menu(struct pxe_menu *cfg)
+{
+	struct list_head *pos, *n;
+	struct pxe_label *label;
+
+	if (cfg->title)
+		free(cfg->title);
+
+	if (cfg->default_label)
+		free(cfg->default_label);
+
+	list_for_each_safe(pos, n, &cfg->labels) {
+		label = list_entry(pos, struct pxe_label, list);
+
+		label_destroy(label);
+	}
+
+	free(cfg);
+}
+
+struct pxe_menu *parse_pxefile(struct pxe_context *ctx, unsigned long menucfg)
+{
+	struct pxe_menu *cfg;
+	char *buf;
+	int r;
+
+	cfg = malloc(sizeof(struct pxe_menu));
+
+	if (!cfg)
+		return NULL;
+
+	memset(cfg, 0, sizeof(struct pxe_menu));
+
+	INIT_LIST_HEAD(&cfg->labels);
+
+	buf = map_sysmem(menucfg, 0);
+	r = parse_pxefile_top(ctx, buf, menucfg, cfg, 1);
+	unmap_sysmem(buf);
+
+	if (r < 0) {
+		destroy_pxe_menu(cfg);
+		return NULL;
+	}
+
+	return cfg;
+}
+
+/*
+ * Converts a pxe_menu struct into a menu struct for use with U-Boot's generic
+ * menu code.
+ */
+static struct menu *pxe_menu_to_menu(struct pxe_menu *cfg)
+{
+	struct pxe_label *label;
+	struct list_head *pos;
+	struct menu *m;
+	int err;
+	int i = 1;
+	char *default_num = NULL;
+
+	/*
+	 * Create a menu and add items for all the labels.
+	 */
+	m = menu_create(cfg->title, DIV_ROUND_UP(cfg->timeout, 10),
+			cfg->prompt, NULL, label_print, NULL, NULL);
+
+	if (!m)
+		return NULL;
+
+	list_for_each(pos, &cfg->labels) {
+		label = list_entry(pos, struct pxe_label, list);
+
+		sprintf(label->num, "%d", i++);
+		if (menu_item_add(m, label->num, label) != 1) {
+			menu_destroy(m);
+			return NULL;
+		}
+		if (cfg->default_label &&
+		    (strcmp(label->name, cfg->default_label) == 0))
+			default_num = label->num;
+	}
+
+	/*
+	 * After we've created items for each label in the menu, set the
+	 * menu's default label if one was specified.
+	 */
+	if (default_num) {
+		err = menu_default_set(m, default_num);
+		if (err != 1) {
+			if (err != -ENOENT) {
+				menu_destroy(m);
+				return NULL;
+			}
+
+			printf("Missing default: %s\n", cfg->default_label);
+		}
+	}
+
+	return m;
+}
+
+/*
+ * Try to boot any labels we have yet to attempt to boot.
+ */
+static void boot_unattempted_labels(struct pxe_context *ctx,
+				    struct pxe_menu *cfg)
+{
+	struct list_head *pos;
+	struct pxe_label *label;
+
+	list_for_each(pos, &cfg->labels) {
+		label = list_entry(pos, struct pxe_label, list);
+
+		if (!label->attempted)
+			label_boot(ctx, label);
+	}
+}
+
+void handle_pxe_menu(struct pxe_context *ctx, struct pxe_menu *cfg)
+{
+	void *choice;
+	struct menu *m;
+	int err;
+
+	if (IS_ENABLED(CONFIG_CMD_BMP)) {
+		/* display BMP if available */
+		if (cfg->bmp) {
+			if (get_relfile(ctx, cfg->bmp, image_load_addr)) {
+				if (CONFIG_IS_ENABLED(CMD_CLS))
+					run_command("cls", 0);
+				bmp_display(image_load_addr,
+					    BMP_ALIGN_CENTER, BMP_ALIGN_CENTER);
+			} else {
+				printf("Skipping background bmp %s for failure\n",
+				       cfg->bmp);
+			}
+		}
+	}
+
+	m = pxe_menu_to_menu(cfg);
+	if (!m)
+		return;
+
+	err = menu_get_choice(m, &choice);
+
+	menu_destroy(m);
+
+	/*
+	 * err == 1 means we got a choice back from menu_get_choice.
+	 *
+	 * err == -ENOENT if the menu was setup to select the default but no
+	 * default was set. in that case, we should continue trying to boot
+	 * labels that haven't been attempted yet.
+	 *
+	 * otherwise, the user interrupted or there was some other error and
+	 * we give up.
+	 */
+
+	if (err == 1) {
+		err = label_boot(ctx, choice);
+		if (!err)
+			return;
+	} else if (err != -ENOENT) {
+		return;
+	}
+
+	boot_unattempted_labels(ctx, cfg);
+}
+
+void pxe_setup_ctx(struct pxe_context *ctx, struct cmd_tbl *cmdtp,
+		   pxe_getfile_func getfile, void *userdata,
+		   bool allow_abs_path)
+{
+	ctx->cmdtp = cmdtp;
+	ctx->getfile = getfile;
+	ctx->userdata = userdata;
+	ctx->allow_abs_path = allow_abs_path;
+}