1 files changed, 276 insertions, 0 deletions
diff --git a/lib/io_dirfd.c b/lib/io_dirfd.c
new file mode 100644
index 0000000..252658c
--- /dev/null
+++ b/lib/io_dirfd.c
@@ -0,0 +1,276 @@
+// SPDX-License-Identifier: LGPL-3.0-or-later
+
+#define _GNU_SOURCE
+#include <hkvs.h>
+
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/file.h>
+#include <sys/mman.h>
+#include <sys/random.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+typedef struct hkvs_dirfd hkvs_dirfd;
+struct hkvs_dirfd {
+	hkvs_io base;
+	int fd;
+	uint64_t create_fi;
+};
+
+static const char *const base32 = "ABCDEFGHIJKLMNOPQRSTUVWXTZ234567";
+
+HKVS_INLINE bool hkvs_dirfd_check_size(size_t size) {
+	return (size_t)(off64_t)size == size && (off64_t)size >= 0;
+}
+
+static void hkvs_dirfd_name(char *name, uint64_t fi) {
+	name[0] = 'd';
+	name[1] = 'a';
+	name[2] = 't';
+	name[3] = 'a';
+	name[4] = '.';
+	name[18] = 0;
+	{
+		uint64_t val = fi;
+		for(size_t i = 0; i < 13; i++) {
+			name[17 - i] = base32[val % 32];
+			val /= 32;
+		}
+	}
+}
+
+static void hkvs_dirfd_destroy(hkvs_io *iov) {
+	hkvs_dirfd *io = (hkvs_dirfd*)iov;
+	(void) close(io->fd);
+	free(io);
+}
+
+static int hkvs_dirfd_random(hkvs_io *iov, char *buf, size_t n) {
+	(void)iov;
+	while(n) {
+		ssize_t r = getrandom(buf, n, 0);
+		if(r < 0) return -errno;
+		size_t k = (size_t)r;
+		buf += k;
+		n -= k;
+	}
+	return 0;
+}
+
+static int hkvs_dirfd_open(hkvs_io *iov, uint64_t fi, char **pmem, size_t *psize) {
+	hkvs_dirfd *io = (hkvs_dirfd*)iov;
+
+	int r;
+	if(fi == 0) {
+		r = openat(io->fd, "main", O_RDWR | O_CREAT | O_CLOEXEC, 0666);
+	} else {
+		char name[32];
+		hkvs_dirfd_name(name, fi);
+		r = openat(io->fd, name, O_RDWR | O_CLOEXEC, 0666);
+	}
+	if(r < 0) return -errno;
+	int fd = r;
+
+	off64_t fsize = lseek64(fd, 0, SEEK_END);
+	size_t size = (size_t)fsize;
+	if((off64_t)size != fsize) {
+		r = -EFBIG;
+		goto end;
+	}
+
+	void *addr;
+	if(size == 0) {
+		addr = NULL;
+	} else {
+		addr = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
+		if(addr == MAP_FAILED) {
+			r = -errno;
+			goto end;
+		}
+	}
+
+	*psize = size;
+	*pmem = addr;
+	r = 0;
+
+end:
+	close(fd);
+	return r;
+}
+
+static int hkvs_dirfd_create(hkvs_io *iov, uint64_t *pfi, char **pmem, size_t size) {
+	hkvs_dirfd *io = (hkvs_dirfd*)iov;
+	uint64_t fi = io->create_fi;
+	if(fi == 0) abort();
+
+	if(!hkvs_dirfd_check_size(size)) return -EFBIG;
+
+	int fd;
+	char name[32];
+	hkvs_dirfd_name(name, fi);
+	while(true) {
+		int r = openat(io->fd, name, O_RDWR | O_CREAT | O_EXCL | O_CLOEXEC, 0666);
+		if(r >= 0) {
+			fd = r;
+			break;
+		}
+		r = errno;
+		if(r != EEXIST) return -r;
+		fi++;
+		uint64_t val = fi;
+		char *p = name + 17;
+		while(true) {
+			*p = base32[val % 32];
+			if(val % 32 != 0) break;
+			val /= 32;
+			p--;
+		}
+	}
+
+	io->create_fi = fi + 1;
+
+	int r = ftruncate64(fd, (off64_t)size);
+	if(r < 0) {
+		r = -errno;
+		goto fail;
+		return r;
+	}
+
+	void *addr;
+	if(size == 0) {
+		addr = NULL;
+	} else {
+		addr = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
+		if(addr == MAP_FAILED) {
+			r = -errno;
+			goto fail;
+		}
+	}
+
+	*pfi = fi;
+	*pmem = addr;
+	r = 0;
+
+end:
+	close(fd);
+	return r;
+
+fail:
+	(void) unlinkat(io->fd, name, 0);
+	goto end;
+}
+
+static void hkvs_dirfd_close(hkvs_io *iov, uint64_t fi, char *pmem, size_t size) {
+	(void)iov;
+	(void)fi;
+
+	if(size == 0) return;
+
+	int r = munmap(pmem, size);
+	if(r < 0) {
+		r = errno;
+		// TODO
+		(void) r;
+		abort();
+	}
+}
+
+static int hkvs_dirfd_resize(hkvs_io *iov, uint64_t fi, char **pmem, size_t old_size, size_t new_size) {
+	hkvs_dirfd *io = (hkvs_dirfd*)iov;
+
+	if(!hkvs_dirfd_check_size(new_size)) return -EFBIG;
+
+	int r;
+	if(fi == 0) {
+		r = openat(io->fd, "main", O_RDWR | O_CREAT | O_CLOEXEC, 0666);
+	} else {
+		char name[32];
+		hkvs_dirfd_name(name, fi);
+		r = openat(io->fd, name, O_RDWR | O_CLOEXEC, 0666);
+	}
+	if(r < 0) return -errno;
+	int fd = r;
+
+	void *addr = *pmem;
+	if(new_size > old_size) {
+		r = ftruncate64(fd, (off64_t)new_size);
+		if(r < 0) goto fail;
+
+		if(addr) {
+			addr = mremap(addr, old_size, new_size, MREMAP_MAYMOVE);
+		} else {
+			addr = mmap(NULL, new_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
+		}
+		if(addr == MAP_FAILED) {
+			r = -errno;
+			(void) ftruncate64(fd, (off64_t)old_size);
+			goto end;
+		}
+		*pmem = addr;
+	} else if(new_size > old_size) {
+		if(new_size == 0) {
+			munmap(addr, old_size);
+			addr = NULL;
+		} else {
+			addr = mremap(addr, old_size, new_size, MREMAP_MAYMOVE);
+			if(addr == MAP_FAILED) goto fail;
+		}
+
+		r = ftruncate64(fd, (off64_t)old_size);
+		if(r < 0) {
+			// TODO
+			(void) r;
+		}
+
+		*pmem = addr;
+	}
+
+	r = 0;
+
+end:
+	close(fd);
+	return r;
+
+fail:
+	r = -errno;
+	goto end;
+}
+
+static void hkvs_dirfd_unlink(hkvs_io *iov, uint64_t fi) {
+	hkvs_dirfd *io = (hkvs_dirfd*)iov;
+
+	if(fi == 0) abort();
+
+	char name[32];
+	hkvs_dirfd_name(name, fi);
+	int r = unlinkat(io->fd, name, 0);
+	if(r < 0) {
+		r = errno;
+		// TODO
+		(void) r;
+	} else {
+		if(fi < io->create_fi) {
+			io->create_fi = fi;
+		}
+	}
+}
+
+hkvs_io *hkvs_io_new_unsafe_dirfd(int fd) {
+	hkvs_dirfd *io = malloc(sizeof(*io));
+	if(!io) return NULL;
+	io->base = (hkvs_io){
+		.destroy = &hkvs_dirfd_destroy,
+		.random = &hkvs_dirfd_random,
+		.open = &hkvs_dirfd_open,
+		.create = &hkvs_dirfd_create,
+		.resize = &hkvs_dirfd_resize,
+		.close = &hkvs_dirfd_close,
+		.unlink = &hkvs_dirfd_unlink,
+	};
+	io->fd = fd;
+	io->create_fi = 1;
+	return &io->base;
+}