Add pxe command

Add pxe command, which is intended to mimic PXELINUX functionality.
'pxe get' uses tftp to retrieve a file based on UUID, MAC address or IP
address. 'pxe boot' interprets the contents of PXELINUX config like file
to boot using a specific initrd, kernel and kernel command line.

This patch also adds a README.pxe file - see it for more details on the
pxe command.

Signed-off-by: Jason Hobbs <jason.hobbs@calxeda.com>

1 files changed, 1355 insertions, 0 deletions

diff --git a/common/cmd_pxe.c b/common/cmd_pxe.c
new file mode 100644
index 0000000..3efd700
--- /dev/null
+++ b/common/cmd_pxe.c
@@ -0,0 +1,1355 @@
+/*
+ * Copyright 2010-2011 Calxeda, Inc.
+ *
+ * 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.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#include <common.h>
+#include <command.h>
+#include <malloc.h>
+#include <linux/string.h>
+#include <linux/ctype.h>
+#include <errno.h>
+#include <linux/list.h>
+
+#include "menu.h"
+
+#define MAX_TFTP_PATH_LEN 127
+
+
+/*
+ * Like getenv, but prints an error if envvar isn't defined in the
+ * environment.  It always returns what getenv does, so it can be used in
+ * place of getenv without changing error handling otherwise.
+ */
+static char *from_env(char *envvar)
+{
+	char *ret;
+
+	ret = getenv(envvar);
+
+	if (!ret)
+		printf("missing environment variable: %s\n", envvar);
+
+	return ret;
+}
+
+/*
+ * Convert an ethaddr from the environment to the format used by pxelinux
+ * filenames based on mac addresses. Convert's ':' to '-', and adds "01-" to
+ * the beginning of the ethernet address to indicate a hardware type of
+ * Ethernet. Also converts uppercase hex characters into lowercase, to match
+ * pxelinux's behavior.
+ *
+ * Returns 1 for success, -ENOENT if 'ethaddr' is undefined in the
+ * environment, or some other value < 0 on error.
+ */
+static int format_mac_pxe(char *outbuf, size_t outbuf_len)
+{
+	size_t ethaddr_len;
+	char *p, *ethaddr;
+
+	ethaddr = from_env("ethaddr");
+
+	if (!ethaddr)
+		return -ENOENT;
+
+	ethaddr_len = strlen(ethaddr);
+
+	/*
+	 * ethaddr_len + 4 gives room for "01-", ethaddr, and a NUL byte at
+	 * the end.
+	 */
+	if (outbuf_len < ethaddr_len + 4) {
+		printf("outbuf is too small (%d < %d)\n",
+				outbuf_len, ethaddr_len + 4);
+
+		return -EINVAL;
+	}
+
+	strcpy(outbuf, "01-");
+
+	for (p = outbuf + 3; *ethaddr; ethaddr++, p++) {
+		if (*ethaddr == ':')
+			*p = '-';
+		else
+			*p = tolower(*ethaddr);
+	}
+
+	*p = '\0';
+
+	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(char *bootfile_path, size_t bootfile_path_size)
+{
+	char *bootfile, *last_slash;
+	size_t path_len;
+
+	bootfile = from_env("bootfile");
+
+	if (!bootfile) {
+		bootfile_path[0] = '\0';
+		return 1;
+	}
+
+	last_slash = strrchr(bootfile, '/');
+
+	if (last_slash == NULL) {
+		bootfile_path[0] = '\0';
+		return 1;
+	}
+
+	path_len = (last_slash - bootfile) + 1;
+
+	if (bootfile_path_size < path_len) {
+		printf("bootfile_path too small. (%d < %d)\n",
+				bootfile_path_size, path_len);
+
+		return -1;
+	}
+
+	strncpy(bootfile_path, bootfile, path_len);
+
+	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(char *file_path, void *file_addr)
+{
+	size_t path_len;
+	char relfile[MAX_TFTP_PATH_LEN+1];
+	char addr_buf[10];
+	char *tftp_argv[] = {"tftp", NULL, NULL, NULL};
+	int err;
+
+	err = get_bootfile_path(relfile, sizeof(relfile));
+
+	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, "%p", file_addr);
+
+	tftp_argv[1] = addr_buf;
+	tftp_argv[2] = relfile;
+
+	if (do_tftpb(NULL, 0, 3, tftp_argv))
+		return -ENOENT;
+
+	return 1;
+}
+
+/*
+ * Retrieve the file at 'file_path' to the locate given by 'file_addr'. If
+ * 'bootfile' was specified in the environment, the path to bootfile will be
+ * prepended to 'file_path' and the resulting path will be used.
+ *
+ * Returns 1 on success, or < 0 for error.
+ */
+static int get_pxe_file(char *file_path, void *file_addr)
+{
+	unsigned long config_file_size;
+	char *tftp_filesize;
+	int err;
+
+	err = get_relfile(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;
+
+	*(char *)(file_addr + config_file_size) = '\0';
+
+	return 1;
+}
+
+#define PXELINUX_DIR "pxelinux.cfg/"
+
+/*
+ * Retrieves a file in the 'pxelinux.cfg' folder. Since this uses get_pxe_file
+ * to do the hard work, the location of the 'pxelinux.cfg' folder is generated
+ * from the bootfile path, as described above.
+ *
+ * Returns 1 on success or < 0 on error.
+ */
+static int get_pxelinux_path(char *file, void *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(path, pxefile_addr_r);
+}
+
+/*
+ * Looks for a pxe file with a name based on the pxeuuid environment variable.
+ *
+ * Returns 1 on success or < 0 on error.
+ */
+static int pxe_uuid_path(void *pxefile_addr_r)
+{
+	char *uuid_str;
+
+	uuid_str = from_env("pxeuuid");
+
+	if (!uuid_str)
+		return -ENOENT;
+
+	return get_pxelinux_path(uuid_str, pxefile_addr_r);
+}
+
+/*
+ * Looks for a pxe file with a name based on the 'ethaddr' environment
+ * variable.
+ *
+ * Returns 1 on success or < 0 on error.
+ */
+static int pxe_mac_path(void *pxefile_addr_r)
+{
+	char mac_str[21];
+	int err;
+
+	err = format_mac_pxe(mac_str, sizeof(mac_str));
+
+	if (err < 0)
+		return err;
+
+	return get_pxelinux_path(mac_str, pxefile_addr_r);
+}
+
+/*
+ * Looks for pxe files with names based on our IP address. See pxelinux
+ * documentation for details on what these file names look like.  We match
+ * that exactly.
+ *
+ * Returns 1 on success or < 0 on error.
+ */
+static int pxe_ipaddr_paths(void *pxefile_addr_r)
+{
+	char ip_addr[9];
+	int mask_pos, err;
+
+	sprintf(ip_addr, "%08X", ntohl(NetOurIP));
+
+	for (mask_pos = 7; mask_pos >= 0;  mask_pos--) {
+		err = get_pxelinux_path(ip_addr, pxefile_addr_r);
+
+		if (err > 0)
+			return err;
+
+		ip_addr[mask_pos] = '\0';
+	}
+
+	return -ENOENT;
+}
+
+/*
+ * Entry point for the 'pxe get' command.
+ * This Follows pxelinux's rules to download a config file from a tftp server.
+ * The file is stored at the location given by the pxefile_addr_r environment
+ * variable, which must be set.
+ *
+ * UUID comes from pxeuuid env variable, if defined
+ * MAC addr comes from ethaddr env variable, if defined
+ * IP
+ *
+ * see http://syslinux.zytor.com/wiki/index.php/PXELINUX
+ *
+ * Returns 0 on success or 1 on error.
+ */
+static int
+do_pxe_get(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
+{
+	char *pxefile_addr_str;
+	void *pxefile_addr_r;
+	int err;
+
+	if (argc != 1)
+		return cmd_usage(cmdtp);
+
+
+	pxefile_addr_str = from_env("pxefile_addr_r");
+
+	if (!pxefile_addr_str)
+		return 1;
+
+	err = strict_strtoul(pxefile_addr_str, 16,
+				(unsigned long *)&pxefile_addr_r);
+	if (err < 0)
+		return 1;
+
+	/*
+	 * Keep trying paths until we successfully get a file we're looking
+	 * for.
+	 */
+	if (pxe_uuid_path(pxefile_addr_r) > 0
+		|| pxe_mac_path(pxefile_addr_r) > 0
+		|| pxe_ipaddr_paths(pxefile_addr_r) > 0
+		|| get_pxelinux_path("default", pxefile_addr_r) > 0) {
+
+		printf("Config file found\n");
+
+		return 0;
+	}
+
+	printf("Config file not found\n");
+
+	return 1;
+}
+
+/*
+ * 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(char *file_path, char *envaddr_name)
+{
+	void *file_addr;
+	char *envaddr;
+
+	envaddr = from_env(envaddr_name);
+
+	if (!envaddr)
+		return -ENOENT;
+
+	if (strict_strtoul(envaddr, 16, (unsigned long *)&file_addr) < 0)
+		return -EINVAL;
+
+	return get_relfile(file_path, file_addr);
+}
+
+/*
+ * A note on the pxe file parser.
+ *
+ * We're parsing files that use syslinux grammar, which has a few quirks.
+ * String literals must be recognized based on context - there is no
+ * quoting or escaping support. There's also nothing to explicitly indicate
+ * when a label section completes. We deal with that by ending a label
+ * section whenever we see a line that doesn't include.
+ *
+ * As with the syslinux family, this same file format could be reused in the
+ * future for non pxe purposes. The only action it takes during parsing that
+ * would throw this off is handling of include files. It assumes we're using
+ * pxe, and does a tftp download of a file listed as an include file in the
+ * middle of the parsing operation. That could be handled by refactoring it to
+ * take a 'include file getter' function.
+ */
+
+/*
+ * Describes a single label given in a pxe file.
+ *
+ * Create these with the 'label_create' function given below.
+ *
+ * name - the name of the menu as given on the 'menu label' line.
+ * kernel - the path to the kernel file to use for this label.
+ * append - kernel command line to use when booting this label
+ * initrd - path to the initrd to use for this label.
+ * attempted - 0 if we haven't tried to boot this label, 1 if we have.
+ * localboot - 1 if this label specified 'localboot', 0 otherwise.
+ * list - lets these form a list, which a pxe_menu struct will hold.
+ */
+struct pxe_label {
+	char *name;
+	char *kernel;
+	char *append;
+	char *initrd;
+	int attempted;
+	int localboot;
+	struct list_head list;
+};
+
+/*
+ * Describes a pxe menu as given via pxe files.
+ *
+ * title - the name of the menu as given by a 'menu title' line.
+ * default_label - the name of the default label, if any.
+ * timeout - time in tenths of a second to wait for a user key-press before
+ *           booting the default label.
+ * prompt - if 0, don't prompt for a choice unless the timeout period is
+ *          interrupted.  If 1, always prompt for a choice regardless of
+ *          timeout.
+ * labels - a list of labels defined for the menu.
+ */
+struct pxe_menu {
+	char *title;
+	char *default_label;
+	int timeout;
+	int prompt;
+	struct list_head labels;
+};
+
+/*
+ * 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->append)
+		free(label->append);
+
+	if (label->initrd)
+		free(label->initrd);
+
+	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;
+
+	printf("Label: %s\n", label->name);
+
+	if (label->kernel)
+		printf("\tkernel: %s\n", label->kernel);
+
+	if (label->append)
+		printf("\tappend: %s\n", label->append);
+
+	if (label->initrd)
+		printf("\tinitrd: %s\n", label->initrd);
+}
+
+/*
+ * 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, *dupcmd;
+	int ret;
+
+	localcmd = from_env("localcmd");
+
+	if (!localcmd)
+		return -ENOENT;
+
+	/*
+	 * dup the command to avoid any issues with the version of it existing
+	 * in the environment changing during the execution of the command.
+	 */
+	dupcmd = strdup(localcmd);
+
+	if (!dupcmd)
+		return -ENOMEM;
+
+	if (label->append)
+		setenv("bootargs", label->append);
+
+	printf("running: %s\n", dupcmd);
+
+	ret = run_command2(dupcmd, 0);
+
+	free(dupcmd);
+
+	return ret;
+}
+
+/*
+ * 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 void label_boot(struct pxe_label *label)
+{
+	char *bootm_argv[] = { "bootm", NULL, NULL, NULL, NULL };
+	int bootm_argc = 3;
+
+	label_print(label);
+
+	label->attempted = 1;
+
+	if (label->localboot) {
+		label_localboot(label);
+		return;
+	}
+
+	if (label->kernel == NULL) {
+		printf("No kernel given, skipping %s\n",
+				label->name);
+		return;
+	}
+
+	if (label->initrd) {
+		if (get_relfile_envaddr(label->initrd, "ramdisk_addr_r") < 0) {
+			printf("Skipping %s for failure retrieving initrd\n",
+					label->name);
+			return;
+		}
+
+		bootm_argv[2] = getenv("ramdisk_addr_r");
+	} else {
+		bootm_argv[2] = "-";
+	}
+
+	if (get_relfile_envaddr(label->kernel, "kernel_addr_r") < 0) {
+		printf("Skipping %s for failure retrieving kernel\n",
+				label->name);
+		return;
+	}
+
+	if (label->append)
+		setenv("bootargs", label->append);
+
+	bootm_argv[1] = getenv("kernel_addr_r");
+
+	/*
+	 * fdt usage is optional.  If there is an fdt_addr specified, we will
+	 * pass it along to bootm, and adjust argc appropriately.
+	 */
+	bootm_argv[3] = getenv("fdt_addr");
+
+	if (bootm_argv[3])
+		bootm_argc = 4;
+
+	do_bootm(NULL, 0, bootm_argc, bootm_argv);
+}
+
+/*
+ * 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_APPEND,
+	T_INITRD,
+	T_LOCALBOOT,
+	T_DEFAULT,
+	T_PROMPT,
+	T_INCLUDE,
+	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},
+	{"localboot", T_LOCALBOOT},
+	{"append", T_APPEND},
+	{"initrd", T_INITRD},
+	{"include", T_INCLUDE},
+	{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 = 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;
+	unsigned long temp;
+
+	get_token(c, &t, L_SLITERAL);
+
+	if (t.type != T_STRING) {
+		printf("Expected string: %.*s\n", (int)(*c - s), s);
+		return -EINVAL;
+	}
+
+	if (strict_strtoul(t.val, 10, &temp) < 0) {
+		printf("Expected unsigned integer: %s\n", t.val);
+		return -EINVAL;
+	}
+
+	*dst = (int)temp;
+
+	free(t.val);
+
+	return 1;
+}
+
+static int parse_pxefile_top(char *p, 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(char **c, char *base,
+				struct pxe_menu *cfg, int nest_level)
+{
+	char *include_path;
+	char *s = *c;
+	int err;
+
+	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(include_path, base);
+
+	if (err < 0) {
+		printf("Couldn't retrieve %s\n", include_path);
+		return err;
+	}
+
+	return parse_pxefile_top(base, cfg, nest_level);
+}
+
+/*
+ * Parse lines that begin with 'menu'.
+ *
+ * b and nest are provided to handle the 'menu include' case.
+ *
+ * b should be the address where the file currently being parsed is stored.
+ *
+ * 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(char **c, struct pxe_menu *cfg, char *b, int nest_level)
+{
+	struct token t;
+	char *s = *c;
+	int err;
+
+	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(c, b + strlen(b) + 1, cfg,
+						nest_level + 1);
+		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)
+			free(cfg->default_label);
+
+		cfg->default_label = strdup(label->name);
+
+		if (!cfg->default_label)
+			return -ENOMEM;
+
+		break;
+	default:
+		printf("Ignoring malformed menu command: %.*s\n",
+				(int)(*c - s), s);
+	}
+
+	eol_or_eof(c);
+
+	return 0;
+}
+
+/*
+ * 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;
+	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:
+			err = parse_sliteral(c, &label->kernel);
+			break;
+
+		case T_APPEND:
+			err = parse_sliteral(c, &label->append);
+			break;
+
+		case T_INITRD:
+			err = parse_sliteral(c, &label->initrd);
+			break;
+
+		case T_LOCALBOOT:
+			err = parse_integer(c, &label->localboot);
+			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(char *p, 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:
+			err = parse_menu(&p, cfg, b, 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:
+			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_PROMPT:
+			err = parse_integer(&p, &cfg->prompt);
+			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;
+	}
+}
+
+/*
+ * Free the memory used by a pxe_menu and its labels.
+ */
+static 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);
+}
+
+/*
+ * Entry point for parsing a pxe file. This is only used for the top level
+ * file.
+ *
+ * Returns NULL if there is an error, otherwise, returns a pointer to a
+ * pxe_menu struct populated with the results of parsing the pxe file (and any
+ * files it includes). The resulting pxe_menu struct can be free()'d by using
+ * the destroy_pxe_menu() function.
+ */
+static struct pxe_menu *parse_pxefile(char *menucfg)
+{
+	struct pxe_menu *cfg;
+
+	cfg = malloc(sizeof(struct pxe_menu));
+
+	if (!cfg)
+		return NULL;
+
+	memset(cfg, 0, sizeof(struct pxe_menu));
+
+	INIT_LIST_HEAD(&cfg->labels);
+
+	if (parse_pxefile_top(menucfg, cfg, 1) < 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;
+
+	/*
+	 * Create a menu and add items for all the labels.
+	 */
+	m = menu_create(cfg->title, cfg->timeout, cfg->prompt, label_print);
+
+	if (!m)
+		return NULL;
+
+	list_for_each(pos, &cfg->labels) {
+		label = list_entry(pos, struct pxe_label, list);
+
+		if (menu_item_add(m, label->name, label) != 1) {
+			menu_destroy(m);
+			return NULL;
+		}
+	}
+
+	/*
+	 * After we've created items for each label in the menu, set the
+	 * menu's default label if one was specified.
+	 */
+	if (cfg->default_label) {
+		err = menu_default_set(m, cfg->default_label);
+		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_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(label);
+	}
+}
+
+/*
+ * Boot the system as prescribed by a pxe_menu.
+ *
+ * Use the menu system to either get the user's choice or the default, based
+ * on config or user input.  If there is no default or user's choice,
+ * attempted to boot labels in the order they were given in pxe files.
+ * If the default or user's choice fails to boot, attempt to boot other
+ * labels in the order they were given in pxe files.
+ *
+ * If this function returns, there weren't any labels that successfully
+ * booted, or the user interrupted the menu selection via ctrl+c.
+ */
+static void handle_pxe_menu(struct pxe_menu *cfg)
+{
+	void *choice;
+	struct menu *m;
+	int err;
+
+	m = pxe_menu_to_menu(cfg);
+	if (!m)
+		return;
+
+	err = menu_get_choice(m, &choice);
+
+	menu_destroy(m);
+
+	if (err < 1)
+		return;
+
+	label_boot(choice);
+
+	boot_unattempted_labels(cfg);
+}
+
+/*
+ * Boots a system using a pxe file
+ *
+ * Returns 0 on success, 1 on error.
+ */
+static int
+do_pxe_boot(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
+{
+	unsigned long pxefile_addr_r;
+	struct pxe_menu *cfg;
+	char *pxefile_addr_str;
+
+	if (argc == 1) {
+		pxefile_addr_str = from_env("pxefile_addr_r");
+		if (!pxefile_addr_str)
+			return 1;
+
+	} else if (argc == 2) {
+		pxefile_addr_str = argv[1];
+	} else {
+		return cmd_usage(cmdtp);
+	}
+
+	if (strict_strtoul(pxefile_addr_str, 16, &pxefile_addr_r) < 0) {
+		printf("Invalid pxefile address: %s\n", pxefile_addr_str);
+		return 1;
+	}
+
+	cfg = parse_pxefile((char *)(pxefile_addr_r));
+
+	if (cfg == NULL) {
+		printf("Error parsing config file\n");
+		return 1;
+	}
+
+	handle_pxe_menu(cfg);
+
+	destroy_pxe_menu(cfg);
+
+	return 0;
+}
+
+static cmd_tbl_t cmd_pxe_sub[] = {
+	U_BOOT_CMD_MKENT(get, 1, 1, do_pxe_get, "", ""),
+	U_BOOT_CMD_MKENT(boot, 2, 1, do_pxe_boot, "", "")
+};
+
+int do_pxe(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
+{
+	cmd_tbl_t *cp;
+
+	if (argc < 2)
+		return cmd_usage(cmdtp);
+
+	/* drop initial "pxe" arg */
+	argc--;
+	argv++;
+
+	cp = find_cmd_tbl(argv[0], cmd_pxe_sub, ARRAY_SIZE(cmd_pxe_sub));
+
+	if (cp)
+		return cp->cmd(cmdtp, flag, argc, argv);
+
+	return cmd_usage(cmdtp);
+}
+
+U_BOOT_CMD(
+	pxe, 3, 1, do_pxe,
+	"commands to get and boot from pxe files",
+	"get - try to retrieve a pxe file using tftp\npxe "
+	"boot [pxefile_addr_r] - boot from the pxe file at pxefile_addr_r\n"
+);