ls command

1 files changed, 143 insertions, 10 deletions

diff --git a/stage3/fs.c b/stage3/fs.c
index d4a325f..5653e4e 100644
--- a/stage3/fs.c
+++ b/stage3/fs.c
@@ -4,29 +4,162 @@
 #include "memory.h"
 #include "heap.h"
 
-str fs_read(str filename)
+#define FS_WALKER(X) bool (X)(str filename, u64 lba, usize fsize, usize fsect, void *varg)
+
+void fs_walk(FS_WALKER(*fun), void *arg)
 {
-	u64 start = (*(u32 *) (0x1000-10-8))/512;
+	u64 lba = (*(u32 *) (0x1000-10-8))/512;
 
 	for (;;) {
-		u8 *info = ata_read_full(start, 1);
+		u8 *info = ata_read_full(lba, 1);
 
 		if (memcmp(info+257, "ustar", 5) != 0) {
 			free(info);
-			return NILS;
+			break;
 		}
 
-		usize fsize;
+		u64 fsize;
 		str_parse_num((str) { 11, (char *) info+124 }, 8, &fsize);
 
 		usize fsect = (fsize+511)/512;
+		str filename = str_intro((char *) info);
 
-		if (memcmp(info, filename.data, filename.len) == 0 && info[filename.len] == '\0') {
-			free(info);
-			return (str) { .len = fsize, .data = ata_read_full(start+1, fsect) };
+		bool done = fun(filename, lba, fsize, fsect, arg);
+
+		free(info);
+		if (done)
+			break;
+
+		lba += 1 + fsect;
+	}
+}
+
+typedef struct {
+	str path;
+	str result;
+} fs_read_arg;
+
+static FS_WALKER(fs_read_walker)
+{
+	fs_read_arg *arg = varg;
+
+	if (str_cmp(filename, arg->path) != 0)
+		return false;
+
+	arg->result = (str) { .len = fsize, .data = ata_read_full(lba+1, fsect) };
+	return true;
+}
+
+str fs_read(str path)
+{
+	fs_read_arg arg = {
+		.path = path,
+		.result = NILS,
+	};
+
+	fs_walk(&fs_read_walker, &arg);
+	return arg.result;
+}
+
+typedef struct {
+	str path;
+	usize cap;
+	dir result;
+} fs_readdir_arg;
+
+static str strip_trail(str x)
+{
+	while (x.len > 0 && x.data[x.len-1] == '/')
+		x.len--;
+	return x;
+}
+
+static FS_WALKER(fs_readdir_walker)
+{
+	(void) lba, (void) fsect;
+	fs_readdir_arg *arg = varg;
+
+	enum {
+		HER_SELF,
+		HER_CHILD,
+		HER_GRANDCHILD,
+	} heritage;
+
+	str entn;
+	str iter = filename;
+
+	bool match = str_start(iter, arg->path);
+	if (!match)
+		return false;
+	iter = str_advance(iter, arg->path.len);
+
+	if (iter.len == 0) {
+		entn = filename;
+		heritage = HER_SELF;
+	} else {
+		if (arg->path.len != 0) {
+			if (iter.data[0] != '/')
+				return false;
+			iter = str_advance(iter, 1);
+		}
+
+		if (iter.len == 0) {
+			entn = strip_trail(filename);
+			heritage = HER_SELF;
 		} else {
-			free(info);
-			start += 1 + fsect;
+			entn = str_walk(&iter, S("/"));
+			if (iter.len == 0)
+				heritage = HER_CHILD;
+			else
+				heritage = HER_GRANDCHILD;
 		}
 	}
+
+	bool is_dir = filename.len == 0 || filename.data[filename.len-1] == '/';
+
+	switch (heritage) {
+		case HER_SELF:
+			if (is_dir)
+				return false;
+
+			__attribute__((fallthrough));
+
+		case HER_CHILD:
+			if (arg->result.len == arg->cap)
+				arg->result.data = realloc(arg->result.data,
+					sizeof(dirent) * (arg->cap = arg->cap ? arg->cap*2 : 1));
+			arg->result.data[arg->result.len++] = (dirent) {
+				.name = str_clone(entn),
+				.size = fsize,
+				.is_dir = is_dir,
+				.children = 0,
+			};
+
+			return heritage == HER_SELF;
+
+		case HER_GRANDCHILD:
+			for (usize i = 0; i < arg->result.len; i++) {
+				dirent *d = &arg->result.data[i];
+				if (str_cmp(d->name, entn) == 0) {
+					d->size += fsize;
+					d->children++;
+					return false;
+				}
+			}
+
+			// orphan. this shouldn't happen
+			return false;
+	};
+}
+
+dir fs_readdir(str path)
+{
+	fs_readdir_arg arg = {
+		.path = strip_trail(path),
+		.cap = 0,
+		.result = { 0, nil },
+	};
+
+	fs_walk(&fs_readdir_walker, &arg);
+	return arg.result;
 }