1 files changed, 129 insertions, 0 deletions
diff --git a/src/libc/fs/dirinject.c b/src/libc/fs/dirinject.c
new file mode 100644
index 0000000..9b08756
--- /dev/null
+++ b/src/libc/fs/dirinject.c
@@ -0,0 +1,129 @@
+#include <assert.h>
+#include <camellia/fs/dir.h>
+#include <camellia/fs/misc.h>
+#include <camellia/syscalls.h>
+#include <errno.h>
+#include <string.h>
+#include <sys/param.h>
+#include <unistd.h>
+
+typedef struct Handle {
+	int delegate;
+	int plen;
+	char path[];
+} Handle;
+
+static int
+dir_seglen(const char *path)
+{
+	/* if path contains /, return its position + 1
+	 * otherwise, return strlen */
+	int len = 0;
+	while (path[len]) {
+		if (path[len] == '/') {
+			len++;
+			break;
+		}
+		len++;
+	}
+	return len;
+}
+
+static int
+find_injects(const char *injects[], const char *path, int plen, struct dirbuild *db)
+{
+	// TODO deduplicate
+	const char *inj;
+	int matches = 0;
+	assert(plen >= 1);
+	assert(path[plen-1] == '/');
+
+	while ((inj = *injects++)) {
+		int ilen = strlen(inj);
+		if (plen < ilen && memcmp(path, inj, plen) == 0) {
+			if (db) {
+				/* inj[plen-1] == '/' */
+				const char *ent = inj + plen;
+				dir_appendl(db, ent, dir_seglen(ent));
+			}
+			matches++;
+		}
+	}
+	return matches;
+}
+
+void
+fs_dirinject2(const char *injects[])
+{
+	const size_t buflen = 4096;
+	char *buf = malloc(buflen);
+	if (!buf) exit(1);
+
+	for (;;) {
+		struct ufs_request req;
+		hid_t reqh = _sys_fs_wait(buf, buflen, &req);
+		if (reqh < 0) break;
+		Handle *hndl = req.id;
+		switch (req.op) {
+		case VFSOP_OPEN: {
+			if (buf[req.len - 1] == '/') {
+				if (find_injects(injects, buf, req.len, NULL) > 0) {
+					/* opening a directory that we're injecting into */
+					hndl = malloc(sizeof(Handle) + req.len);
+					if (hndl == NULL) {
+						_sys_fs_respond(reqh, NULL, -EGENERIC, 0);
+						break;
+					}
+					/* ignore errors from _sys_open */
+					hndl->delegate = _sys_open(buf, req.len, req.flags);
+					hndl->plen = req.len;
+					memcpy(hndl->path, buf, hndl->plen);
+					_sys_fs_respond(reqh, hndl, 0, 0);
+					break;
+				}
+			}
+			/* default behaviour */
+			forward_open(reqh, buf, req.len, req.flags);
+			break;
+		}
+
+		case VFSOP_CLOSE: {
+			if (hndl->delegate >= 0) {
+				close(hndl->delegate);
+			}
+			free(hndl);
+			_sys_fs_respond(reqh, NULL, 0, 0);
+			break;
+		}
+
+		case VFSOP_READ:
+		case VFSOP_GETSIZE: {
+			struct dirbuild db;
+			char *target = NULL;
+			if (req.op == VFSOP_READ) {
+				target = buf;
+			}
+			req.capacity = MIN(req.capacity, buflen);
+
+			dir_start(&db, req.offset, target, req.capacity);
+			find_injects(injects, hndl->path, hndl->plen, &db);
+			if (hndl->delegate >= 0) {
+				dir_append_from(&db, hndl->delegate);
+			}
+			_sys_fs_respond(reqh, target, dir_finish(&db), 0);
+			break;
+		}
+
+		default: {
+			_sys_fs_respond(reqh, NULL, -1, 0);
+			break;
+		}
+		}
+	}
+	exit(0);
+}
+
+void
+fs_dirinject(const char *path) {
+	fs_dirinject2((const char*[]){ path, NULL });
+}