Merge branch '2021-07-28-setexpr-fmt-support'

- Add a new feature (and CONFIG option) to allow setexpr to take format
  (%d, etc) arguments.

13 files changed, 949 insertions, 5 deletions

diff --git a/.azure-pipelines.yml b/.azure-pipelines.yml
index e3a994e..c088e1a 100644
--- a/.azure-pipelines.yml
+++ b/.azure-pipelines.yml
@@ -374,6 +374,8 @@ jobs:
           BUILDMAN: "mx6 -x boundary,engicam,freescale,technexion,toradex"
         imx:
           BUILDMAN: "mx -x mx6,freescale,technexion,toradex"
+        imx8:
+          BUILDMAN: "imx8"
         keystone2_keystone3:
           BUILDMAN: "k2 k3"
         samsung_socfpga:
@@ -433,7 +435,7 @@ jobs:
         uniphier:
           BUILDMAN: "uniphier"
         aarch64_catch_all:
-          BUILDMAN: "aarch64 -x bcm,k3,tegra,ls1,ls2,lx216,mvebu,uniphier,renesas,sunxi,samsung,socfpga,rk,versal,zynq"
+          BUILDMAN: "aarch64 -x bcm,imx8,k3,tegra,ls1,ls2,lx216,mvebu,uniphier,renesas,sunxi,samsung,socfpga,rk,versal,zynq"
         rockchip:
           BUILDMAN: "rk"
         renesas:
diff --git a/MAINTAINERS b/MAINTAINERS
index 8a18b3b..776ff70 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1050,6 +1050,12 @@ F:	arch/sandbox/
 F:	doc/arch/sandbox.rst
 F:	include/dt-bindings/*/sandbox*.h
 
+SETEXPR
+M:	Roland Gaudig <roland.gaudig@weidmueller.com>
+S:	Maintained
+F:	cmd/printf.c
+F:	doc/usage/setexpr.rst
+
 SH
 M:	Marek Vasut <marek.vasut+renesas@gmail.com>
 M:	Nobuhiro Iwamatsu <iwamatsu@nigauri.org>
diff --git a/cmd/Kconfig b/cmd/Kconfig
index e40d390..f1bcf9e 100644
--- a/cmd/Kconfig
+++ b/cmd/Kconfig
@@ -1414,6 +1414,14 @@ config CMD_SETEXPR
 	  Also supports loading the value at a memory location into a variable.
 	  If CONFIG_REGEX is enabled, setexpr also supports a gsub function.
 
+config CMD_SETEXPR_FMT
+	bool "setexpr_fmt"
+	default n
+	depends on CMD_SETEXPR
+	help
+	  Evaluate format string expression and store result in an environment
+	    variable.
+
 endmenu
 
 menu "Android support commands"
diff --git a/cmd/Makefile b/cmd/Makefile
index 9d10e07..ed36694 100644
--- a/cmd/Makefile
+++ b/cmd/Makefile
@@ -141,6 +141,7 @@ obj-$(CONFIG_CMD_SF) += sf.o
 obj-$(CONFIG_CMD_SCSI) += scsi.o disk.o
 obj-$(CONFIG_CMD_SHA1SUM) += sha1sum.o
 obj-$(CONFIG_CMD_SETEXPR) += setexpr.o
+obj-$(CONFIG_CMD_SETEXPR_FMT) += printf.o
 obj-$(CONFIG_CMD_SPI) += spi.o
 obj-$(CONFIG_CMD_STRINGS) += strings.o
 obj-$(CONFIG_CMD_SMC) += smccc.o
diff --git a/cmd/printf.c b/cmd/printf.c
new file mode 100644
index 0000000..e024676
--- /dev/null
+++ b/cmd/printf.c
@@ -0,0 +1,647 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2021 Weidmüller Interface GmbH & Co. KG
+ * Roland Gaudig <roland.gaudig@weidmueller.com>
+ *
+ * Copyright 1999 Dave Cinege
+ * Portions copyright (C) 1990-1996 Free Software Foundation, Inc.
+ *
+ * Licensed under GPLv2 or later, see file LICENSE in this source tree.
+ */
+/*
+ * This file provides a shell printf like format string expansion as required
+ * for the setexpr <name> fmt <format> <value> command.
+ * This source file was mostly taken from the BusyBox project (www.busybox.net)
+ * In contrast to the original sources the output is not written to stdout
+ * anymore but into a char array, which can be used as input for the env_set()
+ * function.
+ */
+/* Usage: printf format [argument...]
+ *
+ * A front end to the printf function that lets it be used from the shell.
+ *
+ * Backslash escapes:
+ *
+ * \" = double quote
+ * \\ = backslash
+ * \a = alert (bell)
+ * \b = backspace
+ * \c = produce no further output
+ * \f = form feed
+ * \n = new line
+ * \r = carriage return
+ * \t = horizontal tab
+ * \v = vertical tab
+ * \0ooo = octal number (ooo is 0 to 3 digits)
+ * \xhhh = hexadecimal number (hhh is 1 to 3 digits)
+ *
+ * Additional directive:
+ *
+ * %b = print an argument string, interpreting backslash escapes
+ *
+ * The 'format' argument is re-used as many times as necessary
+ * to convert all of the given arguments.
+ *
+ * David MacKenzie <djm@gnu.ai.mit.edu>
+ */
+/* 19990508 Busy Boxed! Dave Cinege */
+
+//config:config PRINTF
+//config:	bool "printf (3.8 kb)"
+//config:	default y
+//config:	help
+//config:	printf is used to format and print specified strings.
+//config:	It's similar to 'echo' except it has more options.
+
+//applet:IF_PRINTF(APPLET_NOFORK(printf, printf, BB_DIR_USR_BIN, BB_SUID_DROP, printf))
+
+//kbuild:lib-$(CONFIG_PRINTF) += printf.o
+//kbuild:lib-$(CONFIG_ASH_PRINTF)  += printf.o
+//kbuild:lib-$(CONFIG_HUSH_PRINTF) += printf.o
+
+//usage:#define printf_trivial_usage
+//usage:       "FORMAT [ARG]..."
+//usage:#define printf_full_usage "\n\n"
+//usage:       "Format and print ARG(s) according to FORMAT (a-la C printf)"
+//usage:
+//usage:#define printf_example_usage
+//usage:       "$ printf \"Val=%d\\n\" 5\n"
+//usage:       "Val=5\n"
+
+/* A note on bad input: neither bash 3.2 nor coreutils 6.10 stop on it.
+ * They report it:
+ *  bash: printf: XXX: invalid number
+ *  printf: XXX: expected a numeric value
+ *  bash: printf: 123XXX: invalid number
+ *  printf: 123XXX: value not completely converted
+ * but then they use 0 (or partially converted numeric prefix) as a value
+ * and continue. They exit with 1 in this case.
+ * Both accept insane field width/precision (e.g. %9999999999.9999999999d).
+ * Both print error message and assume 0 if %*.*f width/precision is "bad"
+ *  (but negative numbers are not "bad").
+ * Both accept negative numbers for %u specifier.
+ *
+ * We try to be compatible.
+ */
+
+#include <common.h>
+#include <ctype.h>
+#include <errno.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#define WANT_HEX_ESCAPES 0
+#define PRINT_CONVERSION_ERROR 1
+#define PRINT_TRUNCATED_ERROR 2
+#define PRINT_SIZE_ERROR 4
+
+struct print_inf {
+	char *str;
+	size_t size;
+	size_t offset;
+	unsigned int error;
+};
+
+typedef void (*converter)(const char *arg, void *result);
+
+/**
+ * printf_str() - print formatted into char array with length checks
+ *
+ * This function povides a printf like function for printing into a char array
+ * with checking the boundaries.
+ * Unlike snprintf, all checks are performed inside this function and status
+ * reports are stored inside the print_inf struct. That way, this function can
+ * be used almost as drop-in replacement without needing much code changes.
+ * Unlike snprintf errors are not reported by return value, but inside the
+ * error member of struct print_inf. The output stored inside the struct
+ * print_inf str member shall only be used when the error member is 0.
+ *
+ * @inf: Info structure for print operation
+ * @char: format string with optional arguments
+ */
+static void printf_str(struct print_inf *inf, char *format, ...)
+{
+	va_list args;
+	int i;
+
+	if (!inf)
+		return;
+
+	/* Do not write anything if previous error is pending */
+	if (inf->error)
+		return;
+
+	/* Check if end of receiving buffer is already reached */
+	if (inf->offset >= inf->size) {
+		inf->error |= PRINT_SIZE_ERROR;
+		return;
+	}
+
+	size_t remaining = inf->size - inf->offset;
+
+	va_start(args, format);
+	i = vsnprintf(inf->str + inf->offset, remaining, format, args);
+	va_end(args);
+
+	if (i >= remaining)
+		inf->error |= PRINT_TRUNCATED_ERROR;
+	else if (i < 0)
+		inf->error |= PRINT_CONVERSION_ERROR;
+	else
+		inf->offset += i;
+}
+
+/**
+ * putchar_str() - Print single character into char array with length checks
+ *
+ * This function provices a putchar like function, which stores the output
+ * into a char array with checking boundaries.
+ *
+ * @inf: Info structure for print operation
+ * @char: Single character to be printed
+ */
+static void putchar_str(struct print_inf *inf, char c)
+{
+	printf_str(inf, "%c", c);
+}
+
+static char process_escape_sequence(const char **ptr)
+{
+	const char *q;
+	unsigned int num_digits;
+	unsigned int n;
+	unsigned int base;
+
+	num_digits = 0;
+	n = 0;
+	base = 8;
+	q = *ptr;
+
+	if (WANT_HEX_ESCAPES && *q == 'x') {
+		++q;
+		base = 16;
+		++num_digits;
+	}
+
+	/* bash requires leading 0 in octal escapes:
+	 * \02 works, \2 does not (prints \ and 2).
+	 * We treat \2 as a valid octal escape sequence.
+	 */
+	do {
+		unsigned int r;
+		unsigned int d = (unsigned char)(*q) - '0';
+#if WANT_HEX_ESCAPES
+		if (d >= 10) {
+			d = (unsigned char)tolower(*q) - 'a';
+			//d += 10;
+			/* The above would map 'A'-'F' and 'a'-'f' to 10-15,
+			 * however, some chars like '@' would map to 9 < base.
+			 * Do not allow that, map invalid chars to N > base:
+			 */
+			if ((int)d >= 0)
+				d += 10;
+		}
+#endif
+		if (d >= base) {
+			if (WANT_HEX_ESCAPES && base == 16) {
+				--num_digits;
+				if (num_digits == 0) {
+					/* \x<bad_char>: return '\',
+					 * leave ptr pointing to x
+					 */
+					return '\\';
+				}
+			}
+			break;
+		}
+
+		r = n * base + d;
+		if (r > 255)
+			break;
+
+		n = r;
+		++q;
+	} while (++num_digits < 3);
+
+	if (num_digits == 0) {
+		/* Not octal or hex escape sequence.
+		 * Is it one-letter one?
+		 */
+		/* bash builtin "echo -e '\ec'" interprets \e as ESC,
+		 * but coreutils "/bin/echo -e '\ec'" does not.
+		 * Manpages tend to support coreutils way.
+		 * Update: coreutils added support for \e on 28 Oct 2009.
+		 */
+		static const char charmap[] = {
+			'a',  'b', 'e', 'f',  'n',  'r',  't',  'v',  '\\', '\0',
+			'\a', '\b', 27, '\f', '\n', '\r', '\t', '\v', '\\', '\\',
+		};
+
+		const char *p = charmap;
+
+		do {
+			if (*p == *q) {
+				q++;
+				break;
+			}
+		} while (*++p != '\0');
+		/* p points to found escape char or NUL,
+		 * advance it and find what it translates to.
+		 * Note that \NUL and unrecognized sequence \z return '\'
+		 * and leave ptr pointing to NUL or z.
+		 */
+		n = p[sizeof(charmap) / 2];
+	}
+
+	*ptr = q;
+
+	return (char)n;
+}
+
+static char *skip_whitespace(const char *s)
+{
+	/* In POSIX/C locale (the only locale we care about: do we REALLY want
+	 * to allow Unicode whitespace in, say, .conf files? nuts!)
+	 * isspace is only these chars: "\t\n\v\f\r" and space.
+	 * "\t\n\v\f\r" happen to have ASCII codes 9,10,11,12,13.
+	 * Use that.
+	 */
+	while (*s == ' ' || (unsigned char)(*s - 9) <= (13 - 9))
+		s++;
+
+	return (char *)s;
+}
+
+/* Like strcpy but can copy overlapping strings. */
+static void overlapping_strcpy(char *dst, const char *src)
+{
+	/* Cheap optimization for dst == src case -
+	 * better to have it here than in many callers.
+	 */
+	if (dst != src) {
+		while ((*dst = *src) != '\0') {
+			dst++;
+			src++;
+		}
+	}
+}
+
+static int multiconvert(const char *arg, void *result, converter convert)
+{
+	if (*arg == '"' || *arg == '\'')
+		sprintf((char *)arg + strlen(arg), "%u", (unsigned char)arg[1]);
+	//errno = 0;
+	convert(arg, result);
+	/* Unlike their Posix counterparts, simple_strtoll and
+	 * simple_strtoull do not set errno
+	 *
+	 * if (errno) {
+	 *	printf("error invalid number '%s'", arg);
+	 *	return 1;
+	 * }
+	 */
+	return 0;
+}
+
+static void conv_strtoull(const char *arg, void *result)
+{
+	/* both coreutils 6.10 and bash 3.2:
+	 * $ printf '%x\n' -2
+	 * fffffffffffffffe
+	 * Mimic that:
+	 */
+	if (arg[0] == '-') {
+		*(unsigned long long *)result = simple_strtoll(arg, NULL, 16);
+		return;
+	}
+	/* Allow leading '+' - simple_strtoull() by itself does not allow it,
+	 * and probably shouldn't (other callers might require purely numeric
+	 * inputs to be allowed.
+	 */
+	if (arg[0] == '+')
+		arg++;
+	*(unsigned long long *)result = simple_strtoull(arg, NULL, 16);
+}
+
+static void conv_strtoll(const char *arg, void *result)
+{
+	if (arg[0] == '+')
+		arg++;
+	*(long long *)result = simple_strtoll(arg, NULL, 16);
+}
+
+/* Callers should check errno to detect errors */
+static unsigned long long my_xstrtoull(const char *arg)
+{
+	unsigned long long result;
+
+	if (multiconvert(arg, &result, conv_strtoull))
+		result = 0;
+	return result;
+}
+
+static long long my_xstrtoll(const char *arg)
+{
+	long long result;
+
+	if (multiconvert(arg, &result, conv_strtoll))
+		result = 0;
+	return result;
+}
+
+/* Handles %b; return 1 if output is to be short-circuited by \c */
+static int print_esc_string(struct print_inf *inf, const char *str)
+{
+	char c;
+
+	while ((c = *str) != '\0') {
+		str++;
+		if (c == '\\') {
+			/* %b also accepts 4-digit octals of the form \0### */
+			if (*str == '0') {
+				if ((unsigned char)(str[1] - '0') < 8) {
+					/* 2nd char is 0..7: skip leading '0' */
+					str++;
+				}
+			} else if (*str == 'c') {
+				return 1;
+			}
+			{
+				/* optimization: don't force arg to be on-stack,
+				 * use another variable for that.
+				 */
+				const char *z = str;
+
+				c = process_escape_sequence(&z);
+				str = z;
+			}
+		}
+		putchar_str(inf, c);
+	}
+
+	return 0;
+}
+
+static void print_direc(struct print_inf *inf, char *format, unsigned int fmt_length,
+			int field_width, int precision,
+			const char *argument)
+{
+	long long llv;
+	char saved;
+	char *have_prec, *have_width;
+
+	saved = format[fmt_length];
+	format[fmt_length] = '\0';
+
+	have_prec = strstr(format, ".*");
+	have_width = strchr(format, '*');
+	if (have_width - 1 == have_prec)
+		have_width = NULL;
+
+	/* multiconvert sets errno = 0, but %s needs it cleared */
+	errno = 0;
+
+	switch (format[fmt_length - 1]) {
+	case 'c':
+		printf_str(inf, format, *argument);
+		break;
+	case 'd':
+	case 'i':
+		llv = my_xstrtoll(skip_whitespace(argument));
+ print_long:
+		if (!have_width) {
+			if (!have_prec)
+				printf_str(inf, format, llv);
+			else
+				printf_str(inf, format, precision, llv);
+		} else {
+			if (!have_prec)
+				printf_str(inf, format, field_width, llv);
+			else
+				printf_str(inf, format, field_width, precision, llv);
+		}
+		break;
+	case 'o':
+	case 'u':
+	case 'x':
+	case 'X':
+		llv = my_xstrtoull(skip_whitespace(argument));
+		/* cheat: unsigned long and long have same width, so... */
+		goto print_long;
+	case 's':
+		/* Are char* and long long the same? */
+		if (sizeof(argument) == sizeof(llv)) {
+			llv = (long long)(ptrdiff_t)argument;
+			goto print_long;
+		} else {
+			/* Hope compiler will optimize it out by moving call
+			 * instruction after the ifs...
+			 */
+			if (!have_width) {
+				if (!have_prec)
+					printf_str(inf, format, argument,
+						   /*unused:*/ argument, argument);
+				else
+					printf_str(inf, format, precision,
+						   argument, /*unused:*/ argument);
+			} else {
+				if (!have_prec)
+					printf_str(inf, format, field_width,
+						   argument, /*unused:*/ argument);
+				else
+					printf_str(inf, format, field_width,
+						   precision, argument);
+			}
+			break;
+		}
+		break;
+	} /* switch */
+
+	format[fmt_length] = saved;
+}
+
+/* Handle params for "%*.*f". Negative numbers are ok (compat). */
+static int get_width_prec(const char *str)
+{
+	long v = simple_strtol(str, NULL, 10);
+
+	/* Unlike its Posix counterpart, simple_strtol does not set errno
+	 *
+	 * if (errno) {
+	 *	printf("error invalid number '%s'", str);
+	 *	v = 0;
+	 * }
+	 */
+	return (int)v;
+}
+
+/* Print the text in FORMAT, using ARGV for arguments to any '%' directives.
+ * Return advanced ARGV.
+ */
+static char **print_formatted(struct print_inf *inf, char *f, char **argv, int *conv_err)
+{
+	char *direc_start;          /* Start of % directive.  */
+	unsigned int direc_length;  /* Length of % directive.  */
+	int field_width;            /* Arg to first '*' */
+	int precision;              /* Arg to second '*' */
+	char **saved_argv = argv;
+
+	for (; *f; ++f) {
+		switch (*f) {
+		case '%':
+			direc_start = f++;
+			direc_length = 1;
+			field_width = 0;
+			precision = 0;
+			if (*f == '%') {
+				putchar_str(inf, '%');
+				break;
+			}
+			if (*f == 'b') {
+				if (*argv) {
+					if (print_esc_string(inf, *argv))
+						return saved_argv; /* causes main() to exit */
+					++argv;
+				}
+				break;
+			}
+			if (*f && strchr("-+ #", *f)) {
+				++f;
+				++direc_length;
+			}
+			if (*f == '*') {
+				++f;
+				++direc_length;
+				if (*argv)
+					field_width = get_width_prec(*argv++);
+			} else {
+				while (isdigit(*f)) {
+					++f;
+					++direc_length;
+				}
+			}
+			if (*f == '.') {
+				++f;
+				++direc_length;
+				if (*f == '*') {
+					++f;
+					++direc_length;
+					if (*argv)
+						precision = get_width_prec(*argv++);
+				} else {
+					while (isdigit(*f)) {
+						++f;
+						++direc_length;
+					}
+				}
+			}
+
+			/* Remove "lLhz" size modifiers, repeatedly.
+			 * bash does not like "%lld", but coreutils
+			 * happily takes even "%Llllhhzhhzd"!
+			 * We are permissive like coreutils
+			 */
+			while ((*f | 0x20) == 'l' || *f == 'h' || *f == 'z')
+				overlapping_strcpy(f, f + 1);
+			/* Add "ll" if integer modifier, then print */
+			{
+				static const char format_chars[] = "diouxXcs";
+				char *p = strchr(format_chars, *f);
+				/* needed - try "printf %" without it */
+				if (!p || *f == '\0') {
+					printf("`%s': invalid format\n", direc_start);
+					/* causes main() to exit with error */
+					return saved_argv - 1;
+				}
+				++direc_length;
+				if (p - format_chars <= 5) {
+					/* it is one of "diouxX" */
+					p = malloc(direc_length + 3);
+					if (!p) {
+						/* exit with error */
+						return saved_argv - 1;
+					}
+					memcpy(p, direc_start, direc_length);
+					p[direc_length + 1] = p[direc_length - 1];
+					p[direc_length - 1] = 'l';
+					p[direc_length] = 'l';
+					//bb_error_msg("<%s>", p);
+					direc_length += 2;
+					direc_start = p;
+				} else {
+					p = NULL;
+				}
+				if (*argv) {
+					print_direc(inf, direc_start, direc_length,
+						    field_width, precision, *argv++);
+				} else {
+					print_direc(inf, direc_start, direc_length,
+						    field_width, precision, "");
+				}
+				*conv_err |= errno;
+				free(p);
+			}
+			break;
+		case '\\':
+			if (*++f == 'c')
+				return saved_argv; /* causes main() to exit */
+			putchar_str(inf, process_escape_sequence((const char **)&f));
+			f--;
+			break;
+		default:
+			putchar_str(inf, *f);
+		}
+	}
+
+	return argv;
+}
+
+/**
+ * printf_setexpr() - Implements the setexpr <name> fmt <format> command
+ *
+ * This function implements the format string evaluation for the
+ * setexpr <name> fmt <format> <value> command.
+ *
+ * @str: Output string of the evaluated expression
+ * @size: Length of @str buffer
+ * @argc: Number of arguments
+ * @argv: Argument list
+ * @return: 0 if OK, 1 on error
+ */
+int printf_setexpr(char *str, size_t size, int argc, char *const *argv)
+{
+	int conv_err;
+	char *format;
+	char **argv2;
+	struct print_inf inf = {
+		.str = str,
+		.size = size,
+		.offset = 0,
+		.error = 0,
+	};
+
+	if (!str || !size)
+		return 1;
+
+	inf.str[0] = '\0';
+
+	format = argv[0];
+	argv2 = (char **)argv + 1;
+
+	conv_err = 0;
+	argv = argv2;
+	/* In case any print_str call raises an error inf.error will be
+	 * set after print_formatted returns.
+	 */
+	argv2 = print_formatted(&inf, format, (char **)argv, &conv_err);
+
+	/* coreutils compat (bash doesn't do this):
+	 *if (*argv)
+	 *	fprintf(stderr, "excess args ignored");
+	 */
+
+	return (argv2 < argv) || /* if true, print_formatted errored out */
+		conv_err || /* print_formatted saw invalid number */
+		inf.error;  /* print_str reported error */
+}
diff --git a/cmd/printf.h b/cmd/printf.h
new file mode 100644
index 0000000..dcaff6d
--- /dev/null
+++ b/cmd/printf.h
@@ -0,0 +1,8 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+
+#ifndef __PRINTF_H
+#define __PRINTF_H
+
+int printf_setexpr(char *str, size_t size, int argc, char *const *argv);
+
+#endif
diff --git a/cmd/setexpr.c b/cmd/setexpr.c
index e828be3..1eb67e2 100644
--- a/cmd/setexpr.c
+++ b/cmd/setexpr.c
@@ -11,11 +11,15 @@
 #include <common.h>
 #include <config.h>
 #include <command.h>
+#include <ctype.h>
 #include <env.h>
 #include <log.h>
 #include <malloc.h>
 #include <mapmem.h>
 #include <linux/sizes.h>
+#include "printf.h"
+
+#define MAX_STR_LEN 128
 
 /**
  * struct expr_arg: Holds an argument to an expression
@@ -370,15 +374,16 @@ static int do_setexpr(struct cmd_tbl *cmdtp, int flag, int argc,
 	int w;
 
 	/*
-	 * We take 3, 5, or 6 arguments:
+	 * We take 3, 5, or 6 arguments, except fmt operation, which
+	 * takes 4 to 8 arguments (limited by _maxargs):
 	 * 3 : setexpr name value
 	 * 5 : setexpr name val1 op val2
 	 *     setexpr name [g]sub r s
 	 * 6 : setexpr name [g]sub r s t
+	 *     setexpr name fmt format [val1] [val2] [val3] [val4]
 	 */
 
-	/* > 6 already tested by max command args */
-	if ((argc < 3) || (argc == 4))
+	if (argc < 3)
 		return CMD_RET_USAGE;
 
 	w = cmd_get_data_size(argv[0], 4);
@@ -386,6 +391,24 @@ static int do_setexpr(struct cmd_tbl *cmdtp, int flag, int argc,
 	if (get_arg(argv[2], w, &aval))
 		return CMD_RET_FAILURE;
 
+	/* format string assignment: "setexpr name fmt %d value" */
+	if (strcmp(argv[2], "fmt") == 0 && IS_ENABLED(CONFIG_CMD_SETEXPR_FMT)) {
+		char str[MAX_STR_LEN];
+		int result;
+
+		if (argc == 3)
+			return CMD_RET_USAGE;
+
+		result = printf_setexpr(str, sizeof(str), argc - 3, &argv[3]);
+		if (result)
+			return result;
+
+		return env_set(argv[1], str);
+	}
+
+	if (argc == 4 || argc > 6)
+		return CMD_RET_USAGE;
+
 	/* plain assignment: "setexpr name value" */
 	if (argc == 3) {
 		if (w == CMD_DATA_SIZE_STR) {
@@ -495,7 +518,7 @@ static int do_setexpr(struct cmd_tbl *cmdtp, int flag, int argc,
 }
 
 U_BOOT_CMD(
-	setexpr, 6, 0, do_setexpr,
+	setexpr, 8, 0, do_setexpr,
 	"set environment variable as the result of eval expression",
 	"[.b, .w, .l, .s] name [*]value1 <op> [*]value2\n"
 	"    - set environment variable 'name' to the result of the evaluated\n"
@@ -505,6 +528,12 @@ U_BOOT_CMD(
 	"      memory addresses (*)\n"
 	"setexpr[.b, .w, .l] name [*]value\n"
 	"    - load a value into a variable"
+#ifdef CONFIG_CMD_SETEXPR_FMT
+	"\n"
+	"setexpr name fmt <format> [value1] [value2] [value3] [value4]\n"
+	"    - set environment variable 'name' to the result of the bash like\n"
+	"      format string evaluation of value."
+#endif
 #ifdef CONFIG_REGEX
 	"\n"
 	"setexpr name gsub r s [t]\n"
diff --git a/configs/sandbox_defconfig b/configs/sandbox_defconfig
index 96c9f61..bcd82f7 100644
--- a/configs/sandbox_defconfig
+++ b/configs/sandbox_defconfig
@@ -71,6 +71,7 @@ CONFIG_CMD_REMOTEPROC=y
 CONFIG_CMD_SPI=y
 CONFIG_CMD_USB=y
 CONFIG_CMD_AXI=y
+CONFIG_CMD_SETEXPR_FMT=y
 CONFIG_CMD_AB_SELECT=y
 CONFIG_BOOTP_DNS2=y
 CONFIG_CMD_PCAP=y
diff --git a/doc/usage/index.rst b/doc/usage/index.rst
index 40b796a..719b2c9 100644
--- a/doc/usage/index.rst
+++ b/doc/usage/index.rst
@@ -43,6 +43,7 @@ Shell commands
    reset
    sbi
    scp03
+   setexpr
    size
    true
    ums
diff --git a/doc/usage/setexpr.rst b/doc/usage/setexpr.rst
new file mode 100644
index 0000000..2e511b1
--- /dev/null
+++ b/doc/usage/setexpr.rst
@@ -0,0 +1,148 @@
+.. SPDX-License-Identifier: GPL-2.0+
+
+setexpr command
+===============
+
+Synopsis
+--------
+
+::
+
+    setexpr[.b, .w, .l .s] <name> [*]<value> <op> [*]<value2>
+    setexpr[.b, .w, .l] <name> [*]<value>
+    setexpr <name> fmt <format> [value]...
+    setexpr <name> gsub r s [t]
+    setexpr <name> sub r s [t]
+
+Description
+-----------
+
+The setexpr command is used to set an environment variable to the result
+of an evaluation.
+
+setexpr[.b, .w, .l .s] <name> [*]<value> <op> [*]<value2>
+     Set environment variable <name> to the result of the evaluated
+     expression specified by <op>.
+
+setexpr[.b, .w, .l] name [*]value
+     Load <value> into environment variable <name>
+
+setexpr name fmt <format> value
+     Set environment variable <name> to the result of the C like
+     format string <format> evaluation of <value>.
+
+setexpr name gsub <r> <s> [<t>]
+     For each substring matching the regular expression <r> in the
+     string <t>, substitute the string <s>.
+     The result is assigned to <name>.
+     If <t> is not supplied, use the old value of <name>.
+
+setexpr name sub <r> <s> [<t>]
+     Just like gsub(), but replace only the first matching substring
+
+The setexpr command takes the following arguments:
+
+format
+    This parameter contains a C or Bash like format string.
+    The number of arguments is limited to 4.
+    The following format types are supported:
+
+    c
+        single character
+    d, i
+        decimal value
+    o
+        octal value
+    s
+        string
+    u
+        unsigned decimal value
+    x, X
+        hexadecimal value
+    '%'
+        no conversion, instead a % character will be written
+
+    Backslash escapes:
+
+    \" = double quote
+    \\ = backslash
+    \a = alert (bell)
+    \b = backspace
+    \c = produce no further output
+    \f = form feed
+    \n = new line
+    \r = carriage return
+    \t = horizontal tab
+    \v = vertical tab
+    \NNN = octal number (NNN is 0 to 3 digits)
+
+name
+    The name of the environment variable to be set
+
+op
+    '|'
+        name = value | value2
+    '&'
+        name = value & value2
+    '+'
+        name = value + value2
+        (This is the only operator supported for strings.
+	It acts as concatenation operator on strings)
+    '^'
+        name = value ^ value2
+    '-'
+        name = value - value2
+    '*'
+        name = value * value2
+    '/'
+        name = value / value2
+    '%'
+        name = value % value2
+
+r
+    Regular expression
+
+s
+    Substitution string
+
+t
+    string
+
+value
+    Can either be an integer value, a string.
+    If the pointer prefix '*' is given value is treated as memory address.
+
+value2
+    See value
+
+Example
+-------
+
+::
+
+    => setexpr foo fmt %d 0x100
+    => echo $foo
+    256
+    =>
+
+    => setexpr foo fmt 0x%08x 63
+    => echo $foo
+    0x00000063
+    =>
+
+    => setexpr foo fmt %%%o 8
+    => echo $foo
+    %10
+    =>
+
+Configuration
+-------------
+
+The setexpr gsub and sub operations are only available if CONFIG_REGEX=y.
+
+Return value
+------------
+
+The return value $? is set to 0 (true) if the operation was successful.
+
+If an error occurs, the return value $? is set to 1 (false).
diff --git a/include/vsprintf.h b/include/vsprintf.h
index 2290083..4016de6 100644
--- a/include/vsprintf.h
+++ b/include/vsprintf.h
@@ -41,6 +41,7 @@ int strict_strtoul(const char *cp, unsigned int base, unsigned long *res);
 unsigned long long simple_strtoull(const char *cp, char **endp,
 					unsigned int base);
 long simple_strtol(const char *cp, char **endp, unsigned int base);
+long long simple_strtoll(const char *cp, char **endp, unsigned int base);
 
 /**
  * trailing_strtol() - extract a trailing integer from a string
diff --git a/lib/strto.c b/lib/strto.c
index c00bb58..f8b53d8 100644
--- a/lib/strto.c
+++ b/lib/strto.c
@@ -143,6 +143,14 @@ unsigned long long simple_strtoull(const char *cp, char **endp,
 	return result;
 }
 
+long long simple_strtoll(const char *cp, char **endp, unsigned int base)
+{
+	if (*cp == '-')
+		return -simple_strtoull(cp + 1, endp, base);
+
+	return simple_strtoull(cp, endp, base);
+}
+
 long trailing_strtoln(const char *str, const char *end)
 {
 	const char *p;
diff --git a/test/cmd/setexpr.c b/test/cmd/setexpr.c
index 08b6e6e..0dc94f7 100644
--- a/test/cmd/setexpr.c
+++ b/test/cmd/setexpr.c
@@ -386,6 +386,90 @@ static int setexpr_test_str_long(struct unit_test_state *uts)
 }
 SETEXPR_TEST(setexpr_test_str_long, UT_TESTF_CONSOLE_REC);
 
+#ifdef CONFIG_CMD_SETEXPR_FMT
+/* Test 'setexpr' command with simply setting integers */
+static int setexpr_test_fmt(struct unit_test_state *uts)
+{
+	u8 *buf;
+
+	buf = map_sysmem(0, BUF_SIZE);
+	memset(buf, '\xff', BUF_SIZE);
+
+	/* Test decimal conversion */
+	ut_assertok(run_command("setexpr fred fmt %d 0xff", 0));
+	ut_asserteq_str("255", env_get("fred"));
+	/* Test hexadecimal conversion with 0x prefix and 4 digits */
+	ut_assertok(run_command("setexpr fred fmt 0x%04x 257", 0));
+	ut_asserteq_str("0x0257", env_get("fred"));
+	/* Test octal conversion with % prefix */
+	ut_assertok(run_command("setexpr fred fmt %%%o 8", 0));
+	ut_asserteq_str("%10", env_get("fred"));
+	/* Test argument surrounded by %% */
+	ut_assertok(run_command("setexpr fred fmt %%%x%% 0xff", 0));
+	ut_asserteq_str("%ff%", env_get("fred"));
+	/* Test escape sequence */
+	ut_assertok(run_command("setexpr fred fmt \"hello\\040world\"", 0));
+	ut_asserteq_str("hello world", env_get("fred"));
+	/* Test %b with string containing octal escape sequence */
+	ut_assertok(run_command("setexpr fred fmt oh%bno \137", 0));
+	ut_asserteq_str("oh_no", env_get("fred"));
+	/* Test %b with string containing \c escape sequence */
+	ut_assertok(run_command("setexpr fred fmt hello%bworld \"\\c\"", 0));
+	ut_asserteq_str("hello", env_get("fred"));
+	/* Test multiple arguments referencing environment varialbes */
+	ut_assertok(run_command("setenv a eff", 0));
+	ut_assertok(run_command("setenv b hello", 0));
+	ut_assertok(run_command("setenv c 0x63", 0));
+	ut_assertok(run_command("setenv d world", 0));
+	ut_assertok(run_command("setexpr fred fmt \"0x%08x-%s-%d-%s\" $a $b $c $d", 0));
+	ut_asserteq_str("0x00000eff-hello-99-world", env_get("fred"));
+	/* Test with two format specifiers, but only one argument */
+	ut_assertok(run_command("setexpr fred fmt %d_%x 100", 0));
+	ut_asserteq_str("256_0", env_get("fred"));
+	/* Test maximum string length */
+	ut_assertok(run_command("setexpr fred fmt \"%0127d\" 7b", 0));
+	ut_asserteq_str("0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000123", env_get("fred"));
+	/* Test maximum unsigned integer size */
+	ut_assertok(run_command("setexpr fred fmt %u ffffffffffffffff", 0));
+	ut_asserteq_str("18446744073709551615", env_get("fred"));
+	/* Test maximum positive integer size */
+	ut_assertok(run_command("setexpr fred fmt %d 7fffffffffffffff", 0));
+	ut_asserteq_str("9223372036854775807", env_get("fred"));
+	/* Test maximum negative integer size */
+	ut_assertok(run_command("setexpr fred fmt %d 8000000000000000", 0));
+	ut_asserteq_str("-9223372036854775808", env_get("fred"));
+	/* Test minimum negative integer size */
+	ut_assertok(run_command("setexpr fred fmt %d ffffffffffffffff", 0));
+	ut_asserteq_str("-1", env_get("fred"));
+	/* Test signed value with + sign */
+	ut_assertok(run_command("setexpr fred fmt %d +5", 0));
+	ut_asserteq_str("5", env_get("fred"));
+	/* Test signed value with - sign */
+	ut_assertok(run_command("setexpr fred fmt %d -4", 0));
+	ut_asserteq_str("-4", env_get("fred"));
+	/* Test unsigned value with + sign */
+	ut_assertok(run_command("setexpr fred fmt %u +3", 0));
+	ut_asserteq_str("3", env_get("fred"));
+	/* Test unsigned value with - sign */
+	ut_assertok(run_command("setexpr fred fmt %x -2", 0));
+	ut_asserteq_str("fffffffffffffffe", env_get("fred"));
+	/* Error test with missing format specifier */
+	ut_asserteq(1, run_command("setexpr fred fmd hello 0xff", 0));
+	/* Error test with invalid format type */
+	ut_asserteq(1, run_command("setexpr fred fmt %a 0xff", 0));
+	/* Error test with incomplete format specifier */
+	ut_asserteq(1, run_command("setexpr fred fmt hello% bf", 0));
+	/* Error exceeding maximum string length */
+	ut_asserteq(1, run_command("setexpr fred fmt \"%0128d\" 456", 0));
+
+	unmap_sysmem(buf);
+
+	return 0;
+}
+
+SETEXPR_TEST(setexpr_test_fmt, UT_TESTF_CONSOLE_REC);
+#endif
+
 int do_ut_setexpr(struct cmd_tbl *cmdtp, int flag, int argc, char *const argv[])
 {
 	struct unit_test *tests = UNIT_TEST_SUITE_START(setexpr_test);