user: implement a minimal `find`

1 files changed, 66 insertions, 0 deletions

diff --git a/src/user/app/find/find.c b/src/user/app/find/find.c
new file mode 100644
index 0000000..502a190
--- /dev/null
+++ b/src/user/app/find/find.c
@@ -0,0 +1,66 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define eprintf(fmt, ...) fprintf(stderr, "find: "fmt"\n" __VA_OPT__(,) __VA_ARGS__)
+
+void recurse(char *path) {
+	FILE *f = fopen(path, "r");
+	const int buf_len = 4096;
+	char *buf;
+
+	if (!f) {
+		eprintf("couldn't open %s", path);
+		return;
+	}
+
+	buf = malloc(buf_len);
+	for (;;) {
+		int len = fread(buf, 1, buf_len, f);
+		int pos = 0;
+		if (len <= 0) break;
+		while (pos < len) {
+			if (buf[pos] == '\0') {
+				eprintf("%s has an empty entry, bailing", path);
+				break;
+			}
+			const char *end = memchr(buf + pos, 0, len - pos);
+			if (!end) {
+				eprintf("buf overflowed, unimplemented"); // TODO
+				break;
+			}
+			printf("%s%s\n", path, buf + pos);
+
+			size_t entrylen = end - (buf + pos) + 1;
+			if (end[-1] == '/') {
+				// append onto end of the current path
+				// TODO no overflow check
+				char *pend = path + strlen(path);
+				memcpy(pend, buf + pos, entrylen);
+				recurse(path);
+				*pend = '\0';
+			}
+			pos += entrylen;
+		}
+	}
+	fclose(f);
+	free(buf);
+}
+
+void find(const char *path) {
+	// TODO export PATH_MAX
+	char *buf = malloc(4096);
+	memcpy(buf, path, strlen(path)+1);
+	recurse(buf);
+	free(buf);
+}
+
+int main(int argc, char **argv) {
+	if (argc < 2) {
+		recurse("/");
+	} else {
+		for (int i = 1; i < argc; i++)
+			recurse(argv[i]);
+	}
+	return 0;
+}