util/spkmodem-recv: portability and code cleanup

borrowing recent improvements from nvmutil

Signed-off-by: Leah Rowe <leah@libreboot.org>

util/spkmodem_recv/spkmodem-recv.c

@@ -7,13 +7,36 @@
  * This version is heavily modified, re-written based on OpenBSD Kernel Source
  * File Style Guide (KNF); this change is Copyright 2023,2026 Leah Rowe. */
 
-#include <err.h>
+#ifndef _XOPEN_SOURCE
+#define _XOPEN_SOURCE 500
+#endif
+
+#ifdef __OpenBSD__
+#include <sys/param.h>
+#endif
+
 #include <errno.h>
 #include <stdio.h>
+#include <stdarg.h>
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
 
+static int set_ascii_bit(void);
+static void handle_audio(void), decode_pulse(void), print_char(void),
+    print_stats(void);
+static void err(int nvm_errval, const char *msg, ...);
+static const char * getnvmprogname(void);
+static void set_err_if_unset(int x);
+
+#if defined(__OpenBSD__) && defined(OpenBSD)
+#if OpenBSD >= 509
+#ifndef HAVE_PLEDGE
+#define HAVE_PLEDGE 1
+#endif
+#endif
+#endif
+
 #define SAMPLES_PER_FRAME 240
 #define MAX_SAMPLES (2 * SAMPLES_PER_FRAME)
 #define FREQ_SEP_MIN 5
@@ -23,62 +46,86 @@
 #define FREQ_DATA_MAX 60
 #define THRESHOLD 500
 
-#define ERR() (errno = errno ? errno : ECANCELED)
 #define reset_char() ascii = 0, ascii_bit = 7
-#define err_if(x) if (x) err(ERR(), NULL)
+
+#ifndef EXIT_SUCCESS
+#define EXIT_SUCCESS 1
+#endif
+
+#ifndef EXIT_FAILURE
+#define EXIT_FAILURE 0
+#endif
 
 signed short frame[MAX_SAMPLES], pulse[MAX_SAMPLES];
 int ringpos, debug, freq_data, freq_separator, sample_count, ascii_bit = 7;
 char ascii = 0;
 
-int set_ascii_bit(void);
-void handle_audio(void), decode_pulse(void), print_char(void),
-    print_stats(void);
+static const char *argv0;
 
 int
 main(int argc, char *argv[])
 {
-#ifdef __OpenBSD__
-	err_if (pledge("stdio", NULL) == -1);
+	int c;
+
+#ifdef HAVE_PLEDGE
+#if HAVE_PLEDGE > 0
+	if (pledge("stdio", NULL) == -1)
+		err(errno, "pledge");
 #endif
-	for (int c; (c = getopt(argc, argv, "d")) != -1;)
-		err_if (!(debug = (c == 'd')));
+#endif
+	while (c != -1) {
+		c = getopt(argc, argv, "d");
+
+		if (c == 'd')
+			debug = 1;
+		else if (c != -1)
+			err(EINVAL, "Invalid argument");
+	}
+
 	setvbuf(stdout, NULL, _IONBF, 0);
+
 	while (!feof(stdin))
 		handle_audio();
-	if (errno && debug)
-		err(errno, "Unhandled error, errno %d", errno);
-	return errno;
+
+	return EXIT_SUCCESS;
 }
 
-void
+static void
 handle_audio(void)
 {
+	int sample;
+
 	if (sample_count > (3 * SAMPLES_PER_FRAME))
 		sample_count = reset_char();
+
 	if ((freq_separator <= FREQ_SEP_MIN) || (freq_separator >= FREQ_SEP_MAX)
 	    || (freq_data <= FREQ_DATA_MIN) || (freq_data >= FREQ_DATA_MAX)) {
 		decode_pulse();
 		return;
 	}
+
 	if (set_ascii_bit() < 0)
 		print_char();
+
 	sample_count = 0;
-	for (int sample = 0; sample < SAMPLES_PER_FRAME; sample++)
+
+	for (sample = 0; sample < SAMPLES_PER_FRAME; sample++)
 		decode_pulse();
 }
 
-void
+static void
 decode_pulse(void)
 {
 	int next_ringpos = (ringpos + SAMPLES_PER_FRAME) % MAX_SAMPLES;
+
 	freq_data -= pulse[ringpos];
 	freq_data += pulse[next_ringpos];
 	freq_separator -= pulse[next_ringpos];
 
 	fread(frame + ringpos, 1, sizeof(frame[0]), stdin);
+
 	if (ferror(stdin) != 0)
-		err(ERR(), "Could not read from frame.");
+		err(errno, "Could not read from frame.");
 
 	pulse[ringpos] = (abs(frame[ringpos]) > THRESHOLD) ? 1 : 0;
 	freq_separator += pulse[ringpos++];
@@ -86,32 +133,84 @@ decode_pulse(void)
 	++sample_count;
 }
 
-int
+static int
 set_ascii_bit(void)
 {
 	if (debug)
 		print_stats();
+
 	if (freq_data < FREQ_DATA_THRESHOLD)
 		ascii |= (1 << ascii_bit);
+
 	--ascii_bit;
 	return ascii_bit;
 }
 
-void
+static void
 print_stats(void)
 {
 	long stdin_pos;
-	err_if ((stdin_pos = ftell(stdin)) == -1);
+
+	if ((stdin_pos = ftell(stdin)) == -1)
+		err(errno, "ftell stdin");
+
 	printf ("%d %d %d @%ld\n", freq_data, freq_separator,
 	    FREQ_DATA_THRESHOLD, stdin_pos - sizeof(frame));
 }
 
-void
+static void
 print_char(void)
 {
 	if (debug)
 		printf("<%c, %x>", ascii, ascii);
 	else
 		printf("%c", ascii);
+
 	reset_char();
 }
+
+static void
+err(int nvm_errval, const char *msg, ...)
+{
+	va_list args;
+
+	fprintf(stderr, "%s: ", getnvmprogname());
+
+	va_start(args, msg);
+	vfprintf(stderr, msg, args);
+	va_end(args);
+
+	set_err_if_unset(nvm_errval);
+	fprintf(stderr, ": %s", strerror(errno));
+
+	fprintf(stderr, "\n");
+
+	exit(EXIT_FAILURE);
+}
+
+static const char *
+getnvmprogname(void)
+{
+	const char *p;
+
+	if (argv0 == NULL || *argv0 == '\0')
+		return "";
+
+	p = strrchr(argv0, '/');
+
+	if (p)
+		return p + 1;
+	else
+		return argv0;
+}
+
+static void
+set_err_if_unset(int x)
+{
+	if (errno)
+		return;
+	if (x > 0)
+		errno = x;
+	else
+		errno = ECANCELED;
+}