lbmk/util/libreboot-utils/lib/string.c

/* SPDX-License-Identifier: MIT
 * Copyright (c) 2026 Leah Rowe <leah@libreboot.org>
 *
 * String functions
 */

#include <sys/types.h>
#include <sys/stat.h>

#include <errno.h>
#include <stdarg.h>
#include <stddef.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>

#include "../include/common.h"

/* scmp() - strict string comparison
 *
 * strict string comparison
 * similar to strncmp, but null and
 * unterminated inputs do not produce
 * a return value; on error, errno is
 * set and -1 is returned.
 *
 * the real return value is stored in
 * the 4th argument by pointer.
 *
 * the value at rval pointer is set,
 * only upon success. callers should
 * check the return value accordingly.
 */

int
scmp(const char *a,
    const char *b,
    size_t maxlen,
    int *rval)
{
	size_t ch;
	unsigned char ac;
	unsigned char bc;

	if (a == NULL ||
	    b == NULL ||
	    rval == NULL) {

		errno = EFAULT;
		return -1;
	}

	for (ch = 0; ch < maxlen; ch++) {

		ac = (unsigned char)a[ch];
		bc = (unsigned char)b[ch];

		if (ac != bc) {
			*rval = ac - bc;
			return 0;
		}

		if (ac == '\0') {
			*rval = 0;
			return 0;
		}
	}

	/* block unterminated strings */
	errno = EFAULT;
	return -1;
}

/* slen() - strict strict length
 *
 * strict string length calculation
 * similar to strnlen, but null and
 * unterminated inputs do not produce
 * a return value; on error, errno is
 * set and -1 is returned.
 *
 * the real return value is stored in
 * the 3rd argument by pointer.
 *
 * the value at rval pointer is set,
 * only upon success. callers should
 * check the return value accordingly.
 */

int
slen(const char *s,
    size_t maxlen,
    size_t *rval)
{
	size_t ch;

	if (s == NULL ||
	    rval == NULL) {

		errno = EFAULT;
		return -1;
	}

	for (ch = 0;
	    ch < maxlen && s[ch] != '\0';
	    ch++);

	if (ch == maxlen) {
		/* unterminated */
		errno = EFAULT;
		return -1;
	}

	*rval = ch;
	return 0;
}

/* the one for nvmutil state is in state.c */
/* this one just exits */
void
err_no_cleanup(int nvm_errval, const char *msg, ...)
{
	va_list args;
	int saved_errno = errno;
	const char *p;

#if defined(__OpenBSD__) && defined(OpenBSD)
#if (OpenBSD) >= 509
	if (pledge("stdio", NULL) == -1)
		fprintf(stderr, "pledge failure during exit");
#endif
#endif
	if (!errno)
		saved_errno = errno = ECANCELED;

	if ((p = getnvmprogname()) != NULL)
		fprintf(stderr, "%s: ", p);

	va_start(args, msg);
	vfprintf(stderr, msg, args);
	va_end(args);

	fprintf(stderr, ": %s\n", strerror(errno));

	exit(EXIT_FAILURE);
}

const char *
getnvmprogname(void)
{
	static char *rval = NULL;
	static char *p;	
	static int setname = 0;

	if (!setname) {
		if ((rval = lbgetprogname(NULL)) == NULL)
			return NULL;

		p = strrchr(rval, '/');
		if (p)
			rval = p + 1;

		setname = 1;
	}

	return rval;
}

/* singleton. if string not null,
   sets the string. after set,
   will not set anymore. either
   way, returns the string
 */
char *
lbgetprogname(char *argv0)
{
	static int setname = 0;
	static char *progname = NULL;
	size_t len;

	if (!setname) {
		if (if_err(argv0 == NULL || *argv0 == '\0', EFAULT) ||
		    slen(argv0, 4096, &len) < 0 ||
		    (progname = malloc(len + 1)) == NULL)
			return NULL;

		memcpy(progname, argv0, len + 1);
		setname = 1;
	}

	return progname;
}