libvips crash when saving JPEGs

main.c

#include <stdio.h>
#include <math.h>
#include <vips/vips.h>
#include <stdlib.h>
#include <glib-object.h>

gboolean use_copy_hack = FALSE;
gboolean save_original = FALSE;

void process(VipsImage* src);

int main(int argc, char **argv) {
	if (argc != 3) {
		printf(
"Demonstrates crash when saving a particular JPEG with libvips:\n"
"	%s <save original> <use copy>\n"
"\n"
"	<save original>: + to save the original, - to skip\n"
"	<use copy>: + to use vips_copy(), - to use vips_extract_area()\n"
"\n"
"These cases crash:\n"
"	%s - +\n"
"	%s + +\n"
"	%s + -\n", argv[0], argv[0], argv[0], argv[0]);
		return 1;
	}

	if (argv[1][0] == '+') {
		printf("Will save original.\n");
		save_original = TRUE;
	} else {
		printf("Skipping saving original.\n");
	}

	if (argv[2][0] == '-') {
		printf("Using vips_extract_area() in place of vips_copy().\n");
		use_copy_hack = TRUE;
	} else {
		printf("Using vips_copy().\n");
	}

	FILE *f = fopen("source.jpg", "rb");
	fseek(f, 0, SEEK_END);
	long fsize = ftell(f);
	fseek(f, 0, SEEK_SET);

	char *buffer = malloc(fsize + 1);
	fread(buffer, fsize, 1, f);
	fclose(f);

	VipsImage *img;

	if (!(img = vips_image_new_from_buffer(buffer, fsize, NULL, NULL))) {
		printf("Failed to load file: %s\n", vips_error_buffer());
		vips_error_clear();
	}

	if (save_original) {
		printf("Saving source image.\n");
		vips_jpegsave(img, "tmp.jpg", NULL);
	}

	for (int i = 0; i < 8; i++) {
		printf("Starting conversion %d\n", i);
		process(img);
	}

	vips_thread_shutdown();

	return 0;
}

void process(VipsImage* src) {
	VipsImage *dupe = NULL;

	if (use_copy_hack) {
		if (vips_extract_area(src, &dupe, 0, 0, src->Xsize, src->Ysize, NULL) != 0) {
			printf("Failed to use hack to copy image: %s\n", vips_error_buffer());
			return;
		}
	} else {
		if (vips_copy(src, &dupe, NULL) != 0) {
			printf("Failed to copy image: %s\n", vips_error_buffer());
			return;
		}
	}

	size_t length = 0;
	void *buffer = NULL;
	int result = vips_jpegsave_buffer(dupe, &buffer, &length, NULL);

	if (result != 0) {
		printf("Failed to write JPEG: %s\n", vips_error_buffer());
		return;
	}

	g_free(buffer);
}