From 596271fa71d79e3eec03c7cf6ac76cb026dd8578 Mon Sep 17 00:00:00 2001
From: Doug Zongker <dougz@android.com>
Date: Wed, 29 Apr 2009 16:52:04 -0700
Subject: [PATCH] handle short writes when unzipping files

minzip fails if write() doesn't write all the data in one call.
Apparently this was good enough before, but it causes OTAs to fail all
the time now (maybe due to the recently-submitted kernel)?  Change
code to attempt continuing after short writes.
---
 minzip/Zip.c | 38 +++++++++++++++++++++++++++-----------
 1 file changed, 27 insertions(+), 11 deletions(-)

diff --git a/minzip/Zip.c b/minzip/Zip.c
index 100c833f..ead89939 100644
--- a/minzip/Zip.c
+++ b/minzip/Zip.c
@@ -41,7 +41,7 @@ enum {
     CENSIZ = 20,
     CENLEN = 24,
     CENNAM = 28,
-    CENEXT = 30, 
+    CENEXT = 30,
     CENCOM = 32,
     CENDSK = 34,
     CENATT = 36,
@@ -66,13 +66,13 @@ enum {
 
     LOCSIG = 0x04034b50,      // PK34
     LOCHDR = 30,
-        
+
     LOCVER =  4,
     LOCFLG =  6,
     LOCHOW =  8,
     LOCTIM = 10,
     LOCCRC = 14,
-    LOCSIZ = 18, 
+    LOCSIZ = 18,
     LOCLEN = 22,
     LOCNAM = 26,
     LOCEXT = 28,
@@ -757,7 +757,7 @@ bool mzReadZipEntry(const ZipArchive* pArchive, const ZipEntry* pEntry,
 {
     CopyProcessArgs args;
     bool ret;
-    
+
     args.buf = buf;
     args.bufLen = bufLen;
     ret = mzProcessZipEntryContents(pArchive, pEntry, copyProcessFunction,
@@ -772,13 +772,29 @@ bool mzReadZipEntry(const ZipArchive* pArchive, const ZipEntry* pEntry,
 static bool writeProcessFunction(const unsigned char *data, int dataLen,
         void *fd)
 {
-    ssize_t n = write((int)fd, data, dataLen);
-    if (n != dataLen) {
-        LOGE("Can't write %d bytes (only %ld) from zip file: %s\n",
-                dataLen, n, strerror(errno));
-        return false;
-    }
-    return true;
+    int zeroWrites = 0;
+    ssize_t soFar = 0;
+    do {
+        ssize_t n = write((int)fd, data+soFar, dataLen-soFar);
+        if (n < 0) {
+            LOGE("Error writing %ld bytes from zip file: %s\n",
+                 dataLen-soFar, strerror(errno));
+            return false;
+        } else if (n > 0) {
+            soFar += n;
+            if (soFar == dataLen) return true;
+            if (soFar > dataLen) {
+                LOGE("write overrun?  (%ld bytes instead of %d)\n",
+                     soFar, dataLen);
+                return false;
+            }
+            zeroWrites = 0;
+        } else {
+            ++zeroWrites;
+        }
+    } while (zeroWrites < 5);
+    LOGE("too many consecutive zero-length writes\n");
+    return false;
 }
 
 /*