From 279be2015b4af98200b4d6b3e32c1b0155f51cd2 Mon Sep 17 00:00:00 2001
From: Sean Purcell <me@seanp.xyz>
Date: Thu, 6 Apr 2017 12:56:40 -0700
Subject: [PATCH 1/3] Let zstd overwrite read-only files

---
 programs/fileio.c | 47 +++++++++++++++++++++++++++++++++++------------
 1 file changed, 35 insertions(+), 12 deletions(-)

diff --git a/programs/fileio.c b/programs/fileio.c
index 78fb9a26..b384c3c2 100644
--- a/programs/fileio.c
+++ b/programs/fileio.c
@@ -31,6 +31,11 @@
 #include <time.h>       /* clock */
 #include <errno.h>      /* errno */
 
+#if defined (_MSC_VER)
+#  include <sys/stat.h>
+#  include <io.h>
+#endif
+
 #include "mem.h"
 #include "fileio.h"
 #define ZSTD_STATIC_LINKING_ONLY   /* ZSTD_magicNumber, ZSTD_frameHeaderSize_max */
@@ -188,6 +193,18 @@ void FIO_setOverlapLog(unsigned overlapLog){
 /*-*************************************
 *  Functions
 ***************************************/
+/** FIO_remove() :
+ * @result : Unlink `fileName`, even if it's read-only */
+static int FIO_remove(const char* path)
+{
+#if defined(_WIN32) || defined(WIN32)
+    /* windows doesn't allow remove read-only files, so try to make it
+     * writable first */
+    chmod(path, _S_IWRITE);
+#endif
+    return remove(path);
+}
+
 /** FIO_openSrcFile() :
  * condition : `dstFileName` must be non-NULL.
  * @result : FILE* to `dstFileName`, or NULL if it fails */
@@ -230,23 +247,29 @@ static FILE* FIO_openDstFile(const char* dstFileName)
         if (g_sparseFileSupport == 1) {
             g_sparseFileSupport = ZSTD_SPARSE_DEFAULT;
         }
-        if (!g_overwrite && strcmp (dstFileName, nulmark)) {  /* Check if destination file already exists */
+        if (strcmp (dstFileName, nulmark)) {  /* Check if destination file already exists */
             f = fopen( dstFileName, "rb" );
             if (f != 0) {  /* dest file exists, prompt for overwrite authorization */
                 fclose(f);
-                if (g_displayLevel <= 1) {
-                    /* No interaction possible */
-                    DISPLAY("zstd: %s already exists; not overwritten  \n", dstFileName);
-                    return NULL;
-                }
-                DISPLAY("zstd: %s already exists; do you wish to overwrite (y/N) ? ", dstFileName);
-                {   int ch = getchar();
-                    if ((ch!='Y') && (ch!='y')) {
-                        DISPLAY("    not overwritten  \n");
+                if (!g_overwrite) {
+                    if (g_displayLevel <= 1) {
+                        /* No interaction possible */
+                        DISPLAY("zstd: %s already exists; not overwritten  \n", dstFileName);
                         return NULL;
                     }
-                    while ((ch!=EOF) && (ch!='\n')) ch = getchar();  /* flush rest of input line */
-        }   }   }
+                    DISPLAY("zstd: %s already exists; do you wish to overwrite (y/N) ? ", dstFileName);
+                    {   int ch = getchar();
+                        if ((ch!='Y') && (ch!='y')) {
+                            DISPLAY("    not overwritten  \n");
+                            return NULL;
+                        }
+                        while ((ch!=EOF) && (ch!='\n')) ch = getchar();  /* flush rest of input line */
+                    }
+                }
+
+                /* need to unlink */
+                FIO_remove(dstFileName);
+        }   }
         f = fopen( dstFileName, "wb" );
         if (f==NULL) DISPLAYLEVEL(1, "zstd: %s: %s\n", dstFileName, strerror(errno));
     }

From 9da11c6aaecff37e2b167f1e5d1e5c1463689f9a Mon Sep 17 00:00:00 2001
From: Sean Purcell <me@seanp.xyz>
Date: Thu, 6 Apr 2017 12:58:49 -0700
Subject: [PATCH 2/3] Add test for overwriting read-only

---
 tests/playTests.sh | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/tests/playTests.sh b/tests/playTests.sh
index 5abbb14e..5409d9aa 100755
--- a/tests/playTests.sh
+++ b/tests/playTests.sh
@@ -109,6 +109,13 @@ $ZSTD -q tmp && die "overwrite check failed!"
 $ECHO "test : force overwrite"
 $ZSTD -q -f tmp
 $ZSTD -q --force tmp
+$ECHO "test : overwrite readonly file"
+$ECHO foo > tmpro.zst
+$ECHO foo > tmpro
+chmod 400 tmpro.zst
+$ZSTD -q --force tmpro || die "failed to overwrite read-only file"
+chmod 600 tmpro.zst
+rm tmpro tmpro.zst
 $ECHO "test : file removal"
 $ZSTD -f --rm tmp
 ls tmp && die "tmp should no longer be present"

From 1652172b2d11e87ef26ad04a0406428cd13be3c1 Mon Sep 17 00:00:00 2001
From: Sean Purcell <me@seanp.xyz>
Date: Thu, 6 Apr 2017 17:06:30 -0700
Subject: [PATCH 3/3] Add refuse to overwrite test and fix format

---
 tests/playTests.sh | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/tests/playTests.sh b/tests/playTests.sh
index 5409d9aa..266bbd91 100755
--- a/tests/playTests.sh
+++ b/tests/playTests.sh
@@ -110,12 +110,13 @@ $ECHO "test : force overwrite"
 $ZSTD -q -f tmp
 $ZSTD -q --force tmp
 $ECHO "test : overwrite readonly file"
+rm -f tmpro tmpro.zst
 $ECHO foo > tmpro.zst
 $ECHO foo > tmpro
 chmod 400 tmpro.zst
-$ZSTD -q --force tmpro || die "failed to overwrite read-only file"
-chmod 600 tmpro.zst
-rm tmpro tmpro.zst
+$ZSTD -q tmpro && die "should have refused to overwrite read-only file"
+$ZSTD -q -f tmpro
+rm -f tmpro tmpro.zst
 $ECHO "test : file removal"
 $ZSTD -f --rm tmp
 ls tmp && die "tmp should no longer be present"