From a808b3e738540011abce6fefd5f87d3031fcf266 Mon Sep 17 00:00:00 2001
From: Justine Tunney <jtunney@gmail.com>
Date: Thu, 23 Feb 2023 06:24:49 -0800
Subject: [PATCH] Serialize ZipOS handle IO across threads

---
 Makefile                    | 10 +++++-----
 libc/zipos/free.c           |  2 ++
 libc/zipos/lseek.c          |  3 +++
 libc/zipos/open.c           |  1 +
 libc/zipos/read.c           |  5 ++++-
 libc/zipos/zipos.internal.h |  2 ++
 libc/zipos/zipos.mk         |  1 +
 7 files changed, 18 insertions(+), 6 deletions(-)

diff --git a/Makefile b/Makefile
index b804fa929..4f831034b 100644
--- a/Makefile
+++ b/Makefile
@@ -134,11 +134,11 @@ include libc/crt/crt.mk				# │  You can issue system calls
 include third_party/nsync/nsync.mk		# │
 include third_party/dlmalloc/dlmalloc.mk	#─┘
 include libc/mem/mem.mk				#─┐
-include libc/zipos/zipos.mk			# ├──DYNAMIC RUNTIME
-include third_party/gdtoa/gdtoa.mk		# │  You can now use stdio
-include libc/time/time.mk			# │  You can finally call malloc()
-include third_party/nsync/mem/mem.mk		# │
-include libc/thread/thread.mk			# │
+include third_party/gdtoa/gdtoa.mk		# ├──DYNAMIC RUNTIME
+include third_party/nsync/mem/mem.mk		# │  You can now use stdio
+include libc/thread/thread.mk			# │  You can finally call malloc()
+include libc/zipos/zipos.mk			# │
+include libc/time/time.mk			# │
 include libc/stdio/stdio.mk			# │
 include third_party/libcxx/libcxx.mk		# │
 include net/net.mk				# │
diff --git a/libc/zipos/free.c b/libc/zipos/free.c
index 512a71eba..2b2c18b3e 100644
--- a/libc/zipos/free.c
+++ b/libc/zipos/free.c
@@ -21,6 +21,7 @@
 #include "libc/intrin/asancodes.h"
 #include "libc/intrin/cmpxchg.h"
 #include "libc/str/str.h"
+#include "libc/thread/thread.h"
 #include "libc/zipos/zipos.internal.h"
 
 void __zipos_free(struct Zipos *z, struct ZiposHandle *h) {
@@ -28,6 +29,7 @@ void __zipos_free(struct Zipos *z, struct ZiposHandle *h) {
     __asan_poison((char *)h + sizeof(struct ZiposHandle),
                   h->mapsize - sizeof(struct ZiposHandle), kAsanHeapFree);
   }
+  pthread_mutex_destroy(&h->lock);
   __zipos_lock();
   do h->next = z->freelist;
   while (!_cmpxchg(&z->freelist, h->next, h));
diff --git a/libc/zipos/lseek.c b/libc/zipos/lseek.c
index 352dec699..34fb4f35d 100644
--- a/libc/zipos/lseek.c
+++ b/libc/zipos/lseek.c
@@ -18,6 +18,7 @@
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/calls/calls.h"
 #include "libc/sysv/errfuns.h"
+#include "libc/thread/thread.h"
 #include "libc/zip.h"
 #include "libc/zipos/zipos.internal.h"
 
@@ -31,6 +32,7 @@
  */
 int64_t __zipos_lseek(struct ZiposHandle *h, int64_t offset, unsigned whence) {
   int64_t rc;
+  pthread_mutex_lock(&h->lock);
   switch (whence) {
     case SEEK_SET:
       rc = offset;
@@ -50,5 +52,6 @@ int64_t __zipos_lseek(struct ZiposHandle *h, int64_t offset, unsigned whence) {
   } else {
     rc = einval();
   }
+  pthread_mutex_unlock(&h->lock);
   return rc;
 }
diff --git a/libc/zipos/open.c b/libc/zipos/open.c
index 930e5d285..61b71d1ec 100644
--- a/libc/zipos/open.c
+++ b/libc/zipos/open.c
@@ -90,6 +90,7 @@ StartOver:
   if (h) {
     h->size = size;
     h->mapsize = mapsize;
+    pthread_mutex_init(&h->lock, 0);
   }
   return h;
 }
diff --git a/libc/zipos/read.c b/libc/zipos/read.c
index 3cfd5d025..472a8007f 100644
--- a/libc/zipos/read.c
+++ b/libc/zipos/read.c
@@ -17,9 +17,10 @@
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/assert.h"
-#include "libc/intrin/safemacros.internal.h"
 #include "libc/calls/struct/iovec.h"
+#include "libc/intrin/safemacros.internal.h"
 #include "libc/str/str.h"
+#include "libc/thread/thread.h"
 #include "libc/zip.h"
 #include "libc/zipos/zipos.internal.h"
 
@@ -39,11 +40,13 @@ static size_t GetIovSize(const struct iovec *iov, size_t iovlen) {
 ssize_t __zipos_read(struct ZiposHandle *h, const struct iovec *iov,
                      size_t iovlen, ssize_t opt_offset) {
   size_t i, b, x, y;
+  pthread_mutex_lock(&h->lock);
   x = y = opt_offset != -1 ? opt_offset : h->pos;
   for (i = 0; i < iovlen && y < h->size; ++i, y += b) {
     b = min(iov[i].iov_len, h->size - y);
     if (b) memcpy(iov[i].iov_base, h->mem + y, b);
   }
   if (opt_offset == -1) h->pos = y;
+  pthread_mutex_unlock(&h->lock);
   return y - x;
 }
diff --git a/libc/zipos/zipos.internal.h b/libc/zipos/zipos.internal.h
index a77a911ab..661d098ec 100644
--- a/libc/zipos/zipos.internal.h
+++ b/libc/zipos/zipos.internal.h
@@ -1,6 +1,7 @@
 #ifndef COSMOPOLITAN_LIBC_ZIPOS_ZIPOS_H_
 #define COSMOPOLITAN_LIBC_ZIPOS_ZIPOS_H_
 #include "libc/intrin/nopl.internal.h"
+#include "libc/thread/thread.h"
 #include "libc/thread/tls.h"
 #if !(__ASSEMBLER__ + __LINKER__ + 0)
 COSMOPOLITAN_C_START_
@@ -15,6 +16,7 @@ struct ZiposUri {
 
 struct ZiposHandle {
   struct ZiposHandle *next;
+  pthread_mutex_t lock;
   size_t size;    /* byte length of `mem` */
   size_t mapsize; /* total size of this struct */
   size_t pos;     /* read/write byte offset state */
diff --git a/libc/zipos/zipos.mk b/libc/zipos/zipos.mk
index 0632b4a0d..66ae43e7c 100644
--- a/libc/zipos/zipos.mk
+++ b/libc/zipos/zipos.mk
@@ -34,6 +34,7 @@ LIBC_ZIPOS_A_DIRECTDEPS =				\
 	LIBC_FMT					\
 	LIBC_RUNTIME					\
 	LIBC_SYSV					\
+	LIBC_THREAD					\
 	LIBC_STR					\
 	LIBC_INTRIN					\
 	LIBC_STUBS					\