Delete more dead code

libc/calls/unveil.c

@@ -189,6 +189,56 @@ static int unveil_init(void) {
   return 0;
 }
 
+/**
+ * Joins paths, e.g.
+ *
+ *     0    + 0    → 0
+ *     ""   + ""   → ""
+ *     "a"  + 0    → "a"
+ *     "a"  + ""   → "a/"
+ *     0    + "b"  → "b"
+ *     ""   + "b"  → "b"
+ *     "."  + "b"  → "./b"
+ *     "b"  + "."  → "b/."
+ *     "a"  + "b"  → "a/b"
+ *     "a/" + "b"  → "a/b"
+ *     "a"  + "b/" → "a/b/"
+ *     "a"  + "/b" → "/b"
+ *
+ * @return joined path, which may be `buf`, `path`, or `other`, or null
+ *     if (1) `buf` didn't have enough space, or (2) both `path` and
+ *     `other` were null
+ */
+static char *JoinPaths(char *buf, size_t size, const char *path,
+                       const char *other) {
+  size_t pathlen, otherlen;
+  if (!other) return path;
+  if (!path) return other;
+  pathlen = strlen(path);
+  if (!pathlen || *other == '/') {
+    return (/*unconst*/ char *)other;
+  }
+  otherlen = strlen(other);
+  if (path[pathlen - 1] == '/') {
+    if (pathlen + otherlen + 1 <= size) {
+      memmove(buf, path, pathlen);
+      memmove(buf + pathlen, other, otherlen + 1);
+      return buf;
+    } else {
+      return 0;
+    }
+  } else {
+    if (pathlen + 1 + otherlen + 1 <= size) {
+      memmove(buf, path, pathlen);
+      buf[pathlen] = '/';
+      memmove(buf + pathlen + 1, other, otherlen + 1);
+      return buf;
+    } else {
+      return 0;
+    }
+  }
+}
+
 int sys_unveil_linux(const char *path, const char *permissions) {
   int rc;
   const char *dir;
@@ -250,7 +300,7 @@ int sys_unveil_linux(const char *path, const char *permissions) {
         // next = join(dirname(next), link)
         strcpy(b.buf2, next);
         dir = dirname(b.buf2);
-        if ((next = _joinpaths(b.buf3, PATH_MAX, dir, b.lbuf))) {
+        if ((next = JoinPaths(b.buf3, PATH_MAX, dir, b.lbuf))) {
           // next now points to either: buf3, buf2, lbuf, rodata
           strcpy(b.buf4, next);
           next = b.buf4;