core: C++-ify membuffer

C-style memory management is a pain and nearly nobody seems to get
it right. Add a C++-version of membuffer that frees the buffer
when it gets out-of-scope. Originally, I was thinking about
conditionally adding a constructor/destructor pair when compiling
with C++. But then decided to create a derived class membufferpp,
because it would be extremely confusing to have behavioral change
when changing a source from from C to C++ or vice-versa.

Also add a comment about the dangers of returned pointer: They
become dangling on changes to the membuffer.

Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>

1 files changed, 0 insertions, 326 deletions

diff --git a/core/membuffer.c b/core/membuffer.c
deleted file mode 100644
index 3b42797e1..000000000
--- a/core/membuffer.c
+++ /dev/null
@@ -1,326 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-#ifdef __clang__
-// Clang has a bug on zero-initialization of C structs.
-#pragma clang diagnostic ignored "-Wmissing-field-initializers"
-#endif
-
-#include <stdarg.h>
-#include <stdlib.h>
-#include <string.h>
-#include <stdio.h>
-
-#include "units.h"
-#include "membuffer.h"
-
-/* Only for internal use */
-static char *detach_buffer(struct membuffer *b)
-{
-	char *result = b->buffer;
-	b->buffer = NULL;
-	b->len = 0;
-	b->alloc = 0;
-	return result;
-}
-
-char *detach_cstring(struct membuffer *b)
-{
-	mb_cstring(b);
-	return detach_buffer(b);
-}
-
-void free_buffer(struct membuffer *b)
-{
-	free(detach_buffer(b));
-}
-
-void flush_buffer(struct membuffer *b, FILE *f)
-{
-	if (b->len) {
-		fwrite(b->buffer, 1, b->len, f);
-		free_buffer(b);
-	}
-}
-
-void strip_mb(struct membuffer *b)
-{
-	while (b->len && isspace(b->buffer[b->len - 1]))
-		b->len--;
-}
-
-/*
- * Running out of memory isn't really an issue these days.
- * So rather than do insane error handling and making the
- * interface very complex, we'll just die. It won't happen
- * unless you're running on a potato.
- */
-static void oom(void)
-{
-	fprintf(stderr, "Out of memory\n");
-	exit(1);
-}
-
-void make_room(struct membuffer *b, unsigned int size)
-{
-	unsigned int needed = b->len + size;
-	if (needed > b->alloc) {
-		char *n;
-		/* round it up to not reallocate all the time.. */
-		needed = needed * 9 / 8 + 1024;
-		n = realloc(b->buffer, needed);
-		if (!n)
-			oom();
-		b->buffer = n;
-		b->alloc = needed;
-	}
-}
-
-const char *mb_cstring(struct membuffer *b)
-{
-	make_room(b, 1);
-	b->buffer[b->len] = 0;
-	return b->buffer;
-}
-
-void put_bytes(struct membuffer *b, const char *str, int len)
-{
-	make_room(b, len);
-	memcpy(b->buffer + b->len, str, len);
-	b->len += len;
-}
-
-void put_string(struct membuffer *b, const char *str)
-{
-	put_bytes(b, str, strlen(str));
-}
-
-void put_vformat(struct membuffer *b, const char *fmt, va_list args)
-{
-	int room = 128;
-
-	for (;;) {
-		int len;
-		va_list copy;
-		char *target;
-
-		make_room(b, room);
-		room = b->alloc - b->len;
-		target = b->buffer + b->len;
-
-		va_copy(copy, args);
-		len = vsnprintf(target, room, fmt, copy);
-		va_end(copy);
-
-		// Buggy C library?
-		if (len < 0) {
-			// We have to just give up at some point
-			if (room > 1000)
-				return;
-
-			// We don't know how big an area we should ask for,
-			// so just expand our allocation by 50%
-			room = room * 3 / 2;
-			continue;
-		}
-
-		if (len < room) {
-			b->len += len;
-			return;
-		}
-
-		room = len + 1;
-	}
-}
-
-/* Silly helper using membuffer */
-char *vformat_string(const char *fmt, va_list args)
-{
-	struct membuffer mb = { 0 };
-	put_vformat(&mb, fmt, args);
-	return detach_cstring(&mb);
-}
-
-char *format_string(const char *fmt, ...)
-{
-	va_list args;
-	char *result;
-
-	va_start(args, fmt);
-	result = vformat_string(fmt, args);
-	va_end(args);
-	return result;
-}
-
-void put_format(struct membuffer *b, const char *fmt, ...)
-{
-	va_list args;
-
-	va_start(args, fmt);
-	put_vformat(b, fmt, args);
-	va_end(args);
-}
-
-void put_format_loc(struct membuffer *b, const char *fmt, ...)
-{
-	va_list args;
-
-	va_start(args, fmt);
-	put_vformat_loc(b, fmt, args);
-	va_end(args);
-}
-
-void put_milli(struct membuffer *b, const char *pre, int value, const char *post)
-{
-	int i;
-	char buf[4];
-	const char *sign = "";
-	unsigned v;
-
-	v = value;
-	if (value < 0) {
-		sign = "-";
-		v = -value;
-	}
-	for (i = 2; i >= 0; i--) {
-		buf[i] = (v % 10) + '0';
-		v /= 10;
-	}
-	buf[3] = 0;
-	if (buf[2] == '0') {
-		buf[2] = 0;
-		if (buf[1] == '0')
-			buf[1] = 0;
-	}
-
-	put_format(b, "%s%s%u.%s%s", pre, sign, v, buf, post);
-}
-
-void put_temperature(struct membuffer *b, temperature_t temp, const char *pre, const char *post)
-{
-	if (temp.mkelvin)
-		put_milli(b, pre, temp.mkelvin - ZERO_C_IN_MKELVIN, post);
-}
-
-void put_depth(struct membuffer *b, depth_t depth, const char *pre, const char *post)
-{
-	if (depth.mm)
-		put_milli(b, pre, depth.mm, post);
-}
-
-void put_duration(struct membuffer *b, duration_t duration, const char *pre, const char *post)
-{
-	if (duration.seconds)
-		put_format(b, "%s%u:%02u%s", pre, FRACTION(duration.seconds, 60), post);
-}
-
-void put_pressure(struct membuffer *b, pressure_t pressure, const char *pre, const char *post)
-{
-	if (pressure.mbar)
-		put_milli(b, pre, pressure.mbar, post);
-}
-
-void put_salinity(struct membuffer *b, int salinity, const char *pre, const char *post)
-{
-	if (salinity)
-		put_format(b, "%s%d%s", pre, salinity / 10, post);
-}
-
-void put_degrees(struct membuffer *b, degrees_t value, const char *pre, const char *post)
-{
-	int udeg = value.udeg;
-	const char *sign = "";
-
-	if (udeg < 0) {
-		udeg = -udeg;
-		sign = "-";
-	}
-	put_format(b, "%s%s%u.%06u%s", pre, sign, FRACTION(udeg, 1000000), post);
-}
-
-void put_location(struct membuffer *b, const location_t *loc, const char *pre, const char *post)
-{
-	if (has_location(loc)) {
-		put_degrees(b, loc->lat, pre, " ");
-		put_degrees(b, loc->lon, "", post);
-	}
-}
-
-void put_quoted(struct membuffer *b, const char *text, int is_attribute, int is_html)
-{
-	const char *p = text;
-
-	for (;text;) {
-		const char *escape;
-
-		switch (*p++) {
-		default:
-			continue;
-		case 0:
-			escape = NULL;
-			break;
-		case 1 ... 8:
-		case 11:
-		case 12:
-		case 14 ... 31:
-			escape = "?";
-			break;
-		case '<':
-			escape = "&lt;";
-			break;
-		case '>':
-			escape = "&gt;";
-			break;
-		case '&':
-			escape = "&amp;";
-			break;
-		case '\'':
-			if (!is_attribute)
-				continue;
-			escape = "&apos;";
-			break;
-		case '\"':
-			if (!is_attribute)
-				continue;
-			escape = "&quot;";
-			break;
-		case '\n':
-			if (!is_html)
-				continue;
-			else
-				escape = "<br>";
-		}
-		put_bytes(b, text, (p - text - 1));
-		if (!escape)
-			break;
-		put_string(b, escape);
-		text = p;
-	}
-}
-
-char *add_to_string_va(char *old, const char *fmt, va_list args)
-{
-	char *res;
-	struct membuffer o = { 0 }, n = { 0 };
-	put_vformat(&n, fmt, args);
-	put_format(&o, "%s\n%s", old ?: "", mb_cstring(&n));
-	res = strdup(mb_cstring(&o));
-	free_buffer(&o);
-	free_buffer(&n);
-	free((void *)old);
-	return res;
-}
-
-/* this is a convenience function that cleverly adds text to a string, using our membuffer
- * infrastructure.
- * WARNING - this will free(old), the intended pattern is
- * string = add_to_string(string, fmt, ...)
- */
-char *add_to_string(char *old, const char *fmt, ...)
-{
-	char *res;
-	va_list args;
-
-	va_start(args, fmt);
-	res = add_to_string_va(old, fmt, args);
-	va_end(args);
-	return res;
-}