add opendir, readdir, and stat support for zipos root and directories not explicitly encoded in the zip file

Squashed commit of the following:

commit 793dde99bc71c7a6554b3afba5ddd46b0cfb6ecb
Author: Gavin Hayes <gavin@computoid.com>
Date:   Mon Aug 29 17:27:59 2022 -0400

    add opendir, readdir, and stat support for zipos root and directories not explicitly encoded in the zip file

commit dfc3eeb4db16d21c7b73aae12c7d4707f6286895
Author: Gavin Hayes <gavin@computoid.com>
Date:   Mon Aug 29 00:33:05 2022 -0400

    add root support to __zipos_find

libc/stdio/dirstream.c

@@ -326,6 +326,7 @@ static struct dirent *readdir_impl(DIR *dir) {
   uint8_t *s, *p;
   struct Zipos *zip;
   struct dirent *ent;
+  struct dirent *lastent;
   struct dirent_bsd *bsd;
   struct dirent_netbsd *nbsd;
   struct dirent_openbsd *obsd;
@@ -351,6 +352,20 @@ static struct dirent *readdir_impl(DIR *dir) {
           ent->d_type = S_ISDIR(mode) ? DT_DIR : DT_REG;
           memcpy(ent->d_name, s, ent->d_reclen);
           ent->d_name[ent->d_reclen] = 0;
+        } else {
+          lastent = (struct dirent *)dir->buf;
+          n = p - s;
+          n = MIN(n, 255);
+          if (!lastent->d_ino || (n != lastent->d_reclen) ||
+              memcmp(lastent->d_name, s, n)) {
+            ent = lastent;
+            ent->d_ino++;
+            ent->d_off = -1;
+            ent->d_reclen = n;
+            ent->d_type = DT_DIR;
+            memcpy(ent->d_name, s, ent->d_reclen);
+            ent->d_name[ent->d_reclen] = 0;
+          }
         }
       }
       dir->zip.offset += ZIP_CFILE_HDRSIZE(zip->map + dir->zip.offset);

libc/zipos/find.c

@@ -28,6 +28,9 @@
 ssize_t __zipos_find(struct Zipos *zipos, const struct ZiposUri *name) {
   const char *zname;
   size_t i, n, c, znamesize;
+  if (!name->len) {
+    return 0;
+  }
   c = GetZipCdirOffset(zipos->cdir);
   n = GetZipCdirRecords(zipos->cdir);
   for (i = 0; i < n; ++i, c += ZIP_CFILE_HDRSIZE(zipos->map + c)) {
@@ -38,6 +41,13 @@ ssize_t __zipos_find(struct Zipos *zipos, const struct ZiposUri *name) {
         (name->len + 1 == znamesize && !memcmp(name->path, zname, name->len) &&
          zname[name->len] == '/')) {
       return c;
+    } else if ((name->len < znamesize &&
+                !memcmp(name->path, zname, name->len) &&
+                zname[name->len - 1] == '/') ||
+               (name->len + 1 < znamesize &&
+                !memcmp(name->path, zname, name->len) &&
+                zname[name->len] == '/')) {
+      return 0;
     }
   }
   return -1;

libc/zipos/stat-impl.c

@@ -16,9 +16,10 @@
 │ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
-#include "libc/intrin/safemacros.internal.h"
 #include "libc/calls/struct/stat.h"
+#include "libc/intrin/safemacros.internal.h"
 #include "libc/str/str.h"
+#include "libc/sysv/consts/s.h"
 #include "libc/sysv/errfuns.h"
 #include "libc/zip.h"
 #include "libc/zipos/zipos.internal.h"
@@ -27,14 +28,18 @@ int __zipos_stat_impl(struct Zipos *zipos, size_t cf, struct stat *st) {
   size_t lf;
   if (zipos && st) {
     bzero(st, sizeof(*st));
-    lf = GetZipCfileOffset(zipos->map + cf);
+    if (cf) {
-    st->st_mode = GetZipCfileMode(zipos->map + cf);
+      lf = GetZipCfileOffset(zipos->map + cf);
-    st->st_size = GetZipLfileUncompressedSize(zipos->map + lf);
+      st->st_mode = GetZipCfileMode(zipos->map + cf);
-    st->st_blocks =
+      st->st_size = GetZipLfileUncompressedSize(zipos->map + lf);
-        roundup(GetZipLfileCompressedSize(zipos->map + lf), 512) / 512;
+      st->st_blocks =
-    GetZipCfileTimestamps(zipos->map + cf, &st->st_mtim, &st->st_atim,
+          roundup(GetZipLfileCompressedSize(zipos->map + lf), 512) / 512;
-                          &st->st_ctim, 0);
+      GetZipCfileTimestamps(zipos->map + cf, &st->st_mtim, &st->st_atim,
-    st->st_birthtim = st->st_ctim;
+                            &st->st_ctim, 0);
+      st->st_birthtim = st->st_ctim;
+    } else {
+      st->st_mode = 0444 | S_IFDIR | 0111;
+    }
     return 0;
   } else {
     return einval();

test/libc/calls/stat_test.c

@@ -64,6 +64,10 @@ TEST(stat, zipos) {
              stat("/zip/.python/test/"
                   "tokenize_tests-latin1-coding-cookie-and-utf8-bom-sig.txt",
                   &st));
+  EXPECT_SYS(0, 0, stat("/zip", &st));
+  EXPECT_SYS(0, 0, stat("/zip/", &st));
+  EXPECT_SYS(0, 0, stat("/zip/.python", &st));
+  EXPECT_SYS(0, 0, stat("/zip/.python/", &st));
 }
 
 static long Stat(const char *path, struct stat *st) {

test/libc/stdio/dirstream_test.c

@@ -20,9 +20,9 @@
 #include "libc/calls/struct/dirent.h"
 #include "libc/dce.h"
 #include "libc/errno.h"
-#include "libc/stdio/rand.h"
 #include "libc/runtime/gc.internal.h"
 #include "libc/runtime/runtime.h"
+#include "libc/stdio/rand.h"
 #include "libc/str/str.h"
 #include "libc/sysv/consts/dt.h"
 #include "libc/testlib/testlib.h"
@@ -57,6 +57,35 @@ TEST(opendir, enotdir) {
   ASSERT_SYS(ENOTDIR, NULL, opendir("yo/there"));
 }
 
+TEST(opendir, zipTest_fake) {
+  ASSERT_NE(NULL, (dir = opendir("/zip")));
+  EXPECT_NE(NULL, (ent = readdir(dir)));
+  EXPECT_STREQ("echo", ent->d_name);
+  EXPECT_NE(NULL, (ent = readdir(dir)));
+  EXPECT_STREQ("usr", ent->d_name);
+  EXPECT_EQ(NULL, (ent = readdir(dir)));
+  EXPECT_EQ(0, closedir(dir));
+  ASSERT_NE(NULL, (dir = opendir("/zip/")));
+  EXPECT_NE(NULL, (ent = readdir(dir)));
+  EXPECT_STREQ("echo", ent->d_name);
+  EXPECT_NE(NULL, (ent = readdir(dir)));
+  EXPECT_STREQ("usr", ent->d_name);
+  EXPECT_EQ(NULL, (ent = readdir(dir)));
+  EXPECT_EQ(0, closedir(dir));
+  ASSERT_NE(NULL, (dir = opendir("/zip/usr")));
+  EXPECT_NE(NULL, (ent = readdir(dir)));
+  EXPECT_STREQ("share", ent->d_name);
+  EXPECT_EQ(NULL, (ent = readdir(dir)));
+  EXPECT_EQ(0, closedir(dir));
+  ASSERT_NE(NULL, (dir = opendir("/zip/usr/")));
+  EXPECT_NE(NULL, (ent = readdir(dir)));
+  EXPECT_STREQ("share", ent->d_name);
+  EXPECT_EQ(NULL, (ent = readdir(dir)));
+  EXPECT_EQ(0, closedir(dir));
+  EXPECT_EQ(NULL, (dir = opendir("/zip/us")));
+  EXPECT_EQ(NULL, (dir = opendir("/zip/us/")));
+}
+
 TEST(dirstream, testDots) {
   int hasdot = 0;
   int hasdotdot = 0;