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authorZack Weinberg <zackw@panix.com>2016-11-21 08:16:27 -0500
committerZack Weinberg <zackw@panix.com>2017-02-25 09:47:51 -0500
commit7caa5054afc1754a871333b1539e08a4af79444e (patch)
treea88f80370a89a6a7a2b2e26d3e3f0f51131fef32 /include/features.h
parent4f5a9afffb7f1fdb330b0f8dcca196a439ac07a8 (diff)
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Clean up conditionals for declaration of gets.
gets has the dubious honor of being the only C89 library feature that has been completely removed from the current C and C++ standards. glibc follows suit by not declaring it in _GNU_SOURCE mode either, but it remains present in older compatibility modes. Internally, two test cases need to see stdio.h make the declaration, but all our internal code is of course compiled under _GNU_SOURCE. This is currently kludged by duplicating the gets declaration, fortify wrapper and all, in include/stdio.h. Also, the conditional in the public headers for deciding when to declare gets is complicated and repeated in two places. This patch adds a new macro to features.h that encapsulates the complicated rule for when to declare gets. stdio.h and bits/stdio2.h then simply test __GLIBC_USE (DEPRECATED_GETS), and instead of having a duplicate gets declaration in include/stdio.h, debug/tst-chk1.c and stdio-common/tst-gets.c can force gets to be declared. * include/features.h (__GLIBC_USE_DEPRECATED_GETS): New macro. * libio/stdio.h, libio/bits/stdio2.h: Condition gets on __GLIBC_USE (DEPRECATED_GETS). Update comments to indicate gets was removed from C++ in C++14. * include/stdio.h: Remove redundant declaration of gets. * debug/tst-chk1.c, stdio-common/tst-gets.c: Force gets to be declared, since we are testing it. * stdio-common/Makefile (tst-gets.c): Compile with -Wno-deprecated-declarations. * debug/Makefile (tst-chk1.c, tst-chk2.c, tst-chk3.c, tst-chk4.cc) (tst-chk5.cc, tst-chk6.cc, tst-lfschk1.c, tst-lfschk2.c) (tst-lfschk3.c, tst-lfschk4.cc, tst-lfschk5.cc, tst-lfschk6.cc): Compile with -Wno-deprecated-declarations.
Diffstat (limited to 'include/features.h')
-rw-r--r--include/features.h11
1 files changed, 11 insertions, 0 deletions
diff --git a/include/features.h b/include/features.h
index dc8ae79..7de4089 100644
--- a/include/features.h
+++ b/include/features.h
@@ -136,6 +136,7 @@
#undef __USE_GNU
#undef __USE_FORTIFY_LEVEL
#undef __KERNEL_STRICT_NAMES
+#undef __GLIBC_USE_DEPRECATED_GETS
/* Suppress kernel-name space pollution unless user expressedly asks
for it. */
@@ -383,6 +384,16 @@
# define __USE_FORTIFY_LEVEL 0
#endif
+/* The function 'gets' existed in C89, but is impossible to use
+ safely. It has been removed from ISO C11 and ISO C++14. Note: for
+ compatibility with various implementations of <cstdio>, this test
+ must consider only the value of __cplusplus when compiling C++. */
+#if defined __cplusplus ? __cplusplus >= 201402L : defined __USE_ISOC11
+# define __GLIBC_USE_DEPRECATED_GETS 0
+#else
+# define __GLIBC_USE_DEPRECATED_GETS 1
+#endif
+
/* Get definitions of __STDC_* predefined macros, if the compiler has
not preincluded this header automatically. */
#include <stdc-predef.h>