util.c

/* See LICENSE file for copyright and license details. */
#include <errno.h>
#include <stdarg.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "util.h"

char *argv0;

static void
verr(const char *fmt, va_list ap)
{
	if (argv0 && strncmp(fmt, "usage", sizeof("usage") - 1)) {
		fprintf(stderr, "%s: ", argv0);
	}

	vfprintf(stderr, fmt, ap);

	if (fmt[0] && fmt[strlen(fmt) - 1] == ':') {
		fputc(' ', stderr);
		perror(NULL);
	} else {
		fputc('\n', stderr);
	}
}

void
warn(const char *fmt, ...)
{
	va_list ap;

	va_start(ap, fmt);
	verr(fmt, ap);
	va_end(ap);
}

void
die(const char *fmt, ...)
{
	va_list ap;

	va_start(ap, fmt);
	verr(fmt, ap);
	va_end(ap);

	exit(1);
}

static int
evsnprintf(char *str, size_t size, const char *fmt, va_list ap)
{
	int ret;

	ret = vsnprintf(str, size, fmt, ap);

	if (ret < 0) {
		warn("vsnprintf:");
		return -1;
	} else if ((size_t)ret >= size) {
		warn("vsnprintf: Output truncated");
		return -1;
	}

	return ret;
}

int
esnprintf(char *str, size_t size, const char *fmt, ...)
{
	va_list ap;
	int ret;

	va_start(ap, fmt);
	ret = evsnprintf(str, size, fmt, ap);
	va_end(ap);

	return ret;
}

const char *
bprintf(const char *fmt, ...)
{
	va_list ap;
	int ret;

	va_start(ap, fmt);
	ret = evsnprintf(buf, sizeof(buf), fmt, ap);
	va_end(ap);

	return (ret < 0) ? NULL : buf;
}

const char *
fmt_human(uintmax_t num, int base)
{
	double scaled;
	size_t i, prefixlen;
	const char **prefix;
	const char *prefix_1000[] = { "", "k", "M", "G", "T", "P", "E", "Z",
	                              "Y" };
	const char *prefix_1024[] = { "", "Ki", "Mi", "Gi", "Ti", "Pi", "Ei",
	                              "Zi", "Yi" };

	switch (base) {
	case 1000:
		prefix = prefix_1000;
		prefixlen = LEN(prefix_1000);
		break;
	case 1024:
		prefix = prefix_1024;
		prefixlen = LEN(prefix_1024);
		break;
	default:
		warn("fmt_human: Invalid base");
		return NULL;
	}

	scaled = num;
	for (i = 0; i < prefixlen && scaled >= base; i++) {
		scaled /= base;
	}

	return bprintf("%.1f %s", scaled, prefix[i]);
}

int
pscanf(const char *path, const char *fmt, ...)
{
	FILE *fp;
	va_list ap;
	int n;

	if (!(fp = fopen(path, "r"))) {
		warn("fopen '%s':", path);
		return -1;
	}
	va_start(ap, fmt);
	n = vfscanf(fp, fmt, ap);
	va_end(ap);
	fclose(fp);

	return (n == EOF) ? -1 : n;
}