user/ext2fs: basic ext2 read support

2 files changed, 149 insertions, 0 deletions

diff --git a/src/user/app/ext2fs/ext2 b/src/user/app/ext2fs/ext2
new file mode 160000
+Subproject 8db7b4fbb2429b504d7c711dae89d917de16bed
diff --git a/src/user/app/ext2fs/main.c b/src/user/app/ext2fs/main.c
new file mode 100644
index 0000000..24d1ab0
--- /dev/null
+++ b/src/user/app/ext2fs/main.c
@@ -0,0 +1,149 @@
+#include "ext2/ex_cache.h"
+#include "ext2/ext2.h"
+#include <camellia/flags.h>
+#include <camellia/syscalls.h>
+#include <err.h>
+#include <errno.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <user/lib/fs/dir.h>
+#include <user/lib/fs/misc.h>
+
+struct handle {
+	uint32_t n;
+	bool dir;
+};
+
+static int my_read(void *fp, void *buf, size_t len, size_t off);
+static int my_write(void *fp, const void *buf, size_t len, size_t off);
+
+static int
+my_read(void *fp, void *buf, size_t len, size_t off)
+{
+	if (fseek(fp, off, SEEK_SET) < 0) {
+		return -1;
+	} else if (fread(buf, len, 1, fp) == 1) {
+		return 0;
+	} else {
+		return -1;
+	}
+}
+
+static int
+my_write(void *fp, const void *buf, size_t len, size_t off)
+{
+	if (fseek(fp, off, SEEK_SET) < 0) {
+		return -1;
+	} else if (fwrite(buf, len, 1, fp) == 1) {
+		return 0;
+	} else {
+		return -1;
+	}
+}
+
+int
+main(int argc, char **argv)
+{
+	if (argc < 2) errx(1, "bad usage");
+	// TODO pread/pwrite for normal handles
+	FILE *disk = fopen(argv[1], "rw");
+	if (!disk) err(1, "couldn't open '%s'", argv[1]);
+
+	struct e2device *dev = exc_init(my_read, my_write, (void*)disk);
+	if (!dev) errx(1, "exc_init failed");
+	struct ext2 *fs = ext2_opendev(dev, exc_req, exc_drop);
+	if (!fs) errx(1, "ext2_opendev failed");
+
+	const size_t buflen = 4096;
+	char *buf = malloc(buflen);
+	struct ufs_request req;
+	for (;;) {
+		handle_t reqh = ufs_wait(buf, buflen, &req);
+		struct handle *h = req.id;
+		if (reqh < 0) break;
+
+		switch (req.op) {
+		case VFSOP_OPEN:
+			bool is_dir = req.len == 0 || buf[req.len-1] == '/';
+			uint32_t n = ext2c_walk(fs, buf, req.len);
+			if (n == 0) {
+				_syscall_fs_respond(reqh, NULL, -ENOENT, 0);
+				break;
+			}
+
+			struct ext2d_inode *inode = ext2_req_inode(fs, n);
+			if (!inode) {
+				_syscall_fs_respond(reqh, NULL, -ENOENT, 0);
+				break;
+			}
+			int type = (inode->perms >> 12) & 0xF;
+			ext2_dropreq(fs, inode, false);
+
+			if ((type == 0x8 && is_dir) || (type == 0x4 && !is_dir)) {
+				_syscall_fs_respond(reqh, NULL, -ENOENT, 0);
+				break;
+			} else if (type != 0x8 && type != 0x4) {
+				_syscall_fs_respond(reqh, NULL, -ENOSYS, 0);
+				break;
+			}
+
+			h = malloc(sizeof *h);
+			if (!h) {
+				_syscall_fs_respond(reqh, NULL, -1, 0);
+				break;
+			}
+
+			h->n = n;
+			h->dir = is_dir;
+			_syscall_fs_respond(reqh, h, 0, 0);
+			break;
+		case VFSOP_READ:
+			if (!h->dir) {
+				void *b = ext2_req_file(fs, h->n, &req.capacity, req.offset);
+				if (b) {
+					_syscall_fs_respond(reqh, b, req.capacity, 0);
+					ext2_dropreq(fs, b, false);
+				} else {
+					_syscall_fs_respond(reqh, NULL, -1, 0);
+				}
+			} else {
+				struct dirbuild db;
+				char namebuf[257];
+				if (req.capacity > buflen)
+					req.capacity = buflen;
+				dir_start(&db, req.offset, buf, buflen);
+				for (struct ext2_diriter iter = {0}; ext2_diriter(&iter, fs, h->n); ) {
+					if (iter.ent->namelen_lower == 1 && iter.ent->name[0] == '.') {
+						continue;
+					}
+					if (iter.ent->namelen_lower == 2
+						&& iter.ent->name[0] == '.'
+						&& iter.ent->name[1] == '.')
+					{
+						continue;
+					}
+					if (iter.ent->type == 2) { /* dir */
+						memcpy(namebuf, iter.ent->name, iter.ent->namelen_lower);
+						namebuf[iter.ent->namelen_lower] = '/';
+						dir_appendl(&db, namebuf, iter.ent->namelen_lower + 1);
+					} else {
+						dir_appendl(&db, iter.ent->name, iter.ent->namelen_lower);
+					}
+				}
+				_syscall_fs_respond(reqh, buf, dir_finish(&db), 0);
+			}
+			break;
+		case VFSOP_CLOSE:
+			free(h);
+			_syscall_fs_respond(reqh, NULL, -1, 0);
+			break;
+		default:
+			_syscall_fs_respond(reqh, NULL, -1, 0);
+			break;
+		}
+	}
+
+	return 1;
+}