commit 76df02f86b9746e139fd9fc934a70e3a21bbc557
author Dieter Baron <dillo@nih.at> Tue Sep 28 12:52:18 2021 +0200
committer Dieter Baron <dillo@nih.at> Tue Sep 28 12:53:56 2021 +0200
tree a4db4d639bec7f6e540f42697a6f71fe0103855a
parent 99e54f56bd671ec3a252e44ea1386fec80098931

Use fchmod when available to avoid race condition.

Spotted by CodeQL.

CMakeLists.txt

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 2fb8716..76bc9c1 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -102,6 +102,7 @@
 check_function_exists(clonefile HAVE_CLONEFILE)
 check_function_exists(explicit_bzero HAVE_EXPLICIT_BZERO)
 check_function_exists(explicit_memset HAVE_EXPLICIT_MEMSET)
+check_function_exists(fchmod HAVE_FCHMOD)
 check_function_exists(fileno HAVE_FILENO)
 check_function_exists(fseeko HAVE_FSEEKO)
 check_function_exists(ftello HAVE_FTELLO)

cmake-config.h.in

diff --git a/cmake-config.h.in b/cmake-config.h.in
index 544adbd..abd8e1b 100644
--- a/cmake-config.h.in
+++ b/cmake-config.h.in
@@ -23,6 +23,7 @@
 #cmakedefine HAVE_CRYPTO
 #cmakedefine HAVE_FICLONERANGE
 #cmakedefine HAVE_FILENO
+#cmakedefine HAVE_FCHMOD
 #cmakedefine HAVE_FSEEKO
 #cmakedefine HAVE_FTELLO
 #cmakedefine HAVE_GETPROGNAME

lib/zip_mkstempm.c

diff --git a/lib/zip_mkstempm.c b/lib/zip_mkstempm.c
index ccdd62a..ede5142 100644
--- a/lib/zip_mkstempm.c
+++ b/lib/zip_mkstempm.c
@@ -82,7 +82,11 @@
         if ((fd = open(path, O_CREAT | O_EXCL | O_RDWR | O_CLOEXEC, mode == -1 ? 0666 : (mode_t)mode)) >= 0) {
             if (mode != -1) {
                 /* open() honors umask(), which we don't want in this case */
+#ifdef HAVE_FCHMOD
+                (void)fchmod(fd, (mode_t)mode);
+#else
                 (void)chmod(path, (mode_t)mode);
+#endif
             }
             return fd;
         }