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![SZEDER Gábor](/assets/img/avatar_default.png)
GCC 8 introduced the new -Wcast-function-type warning, which is implied by -Wextra (which, in turn is enabled in our DEVELOPER flags). When building Git with GCC 8 and this warning enabled on a non-glibc platform [1], one is greeted with a screenful of compiler warnings/errors: compat/obstack.c: In function '_obstack_begin': compat/obstack.c:162:17: error: cast between incompatible function types from 'void * (*)(long int)' to 'struct _obstack_chunk * (*)(void *, long int)' [-Werror=cast-function-type] h->chunkfun = (struct _obstack_chunk * (*)(void *, long)) chunkfun; ^ compat/obstack.c:163:16: error: cast between incompatible function types from 'void (*)(void *)' to 'void (*)(void *, struct _obstack_chunk *)' [-Werror=cast-function-type] h->freefun = (void (*) (void *, struct _obstack_chunk *)) freefun; ^ compat/obstack.c:116:8: error: cast between incompatible function types from 'struct _obstack_chunk * (*)(void *, long int)' to 'struct _obstack_chunk * (*)(long int)' [-Werror=cast-function-type] : (*(struct _obstack_chunk *(*) (long)) (h)->chunkfun) ((size))) ^ compat/obstack.c:168:22: note: in expansion of macro 'CALL_CHUNKFUN' chunk = h->chunk = CALL_CHUNKFUN (h, h -> chunk_size); ^~~~~~~~~~~~~ <snip> 'struct obstack' stores pointers to two functions to allocate and free "chunks", and depending on how obstack is used, these functions take either one parameter (like standard malloc() and free() do; this is how we use it in 'kwset.c') or two parameters. Presumably to reduce memory footprint, a single field is used to store the function pointer for both signatures, and then it's casted to the appropriate signature when the function pointer is accessed. These casts between function pointers with different number of parameters are what trigger those compiler errors. Modify 'struct obstack' to use unions to store function pointers with different signatures, and then use the union member with the appropriate signature when accessing these function pointers. This eliminates the need for those casts, and thus avoids this compiler error. [1] Compiling 'compat/obstack.c' on a platform with glibc is sort of a noop, see the comment before '# define ELIDE_CODE', so this is not an issue on common Linux distros. Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
414 lines
14 KiB
C
414 lines
14 KiB
C
/* obstack.c - subroutines used implicitly by object stack macros
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Copyright (C) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1996, 1997, 1998,
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1999, 2000, 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#include "git-compat-util.h"
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#include <gettext.h>
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#include "obstack.h"
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/* NOTE BEFORE MODIFYING THIS FILE: This version number must be
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incremented whenever callers compiled using an old obstack.h can no
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longer properly call the functions in this obstack.c. */
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#define OBSTACK_INTERFACE_VERSION 1
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/* Comment out all this code if we are using the GNU C Library, and are not
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actually compiling the library itself, and the installed library
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supports the same library interface we do. This code is part of the GNU
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C Library, but also included in many other GNU distributions. Compiling
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and linking in this code is a waste when using the GNU C library
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(especially if it is a shared library). Rather than having every GNU
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program understand `configure --with-gnu-libc' and omit the object
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files, it is simpler to just do this in the source for each such file. */
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#include <stdio.h> /* Random thing to get __GNU_LIBRARY__. */
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#if !defined _LIBC && defined __GNU_LIBRARY__ && __GNU_LIBRARY__ > 1
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# include <gnu-versions.h>
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# if _GNU_OBSTACK_INTERFACE_VERSION == OBSTACK_INTERFACE_VERSION
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# define ELIDE_CODE
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# endif
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#endif
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#include <stddef.h>
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#ifndef ELIDE_CODE
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# if HAVE_INTTYPES_H
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# include <inttypes.h>
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# endif
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# if HAVE_STDINT_H || defined _LIBC
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# include <stdint.h>
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# endif
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/* Determine default alignment. */
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union fooround
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{
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uintmax_t i;
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long double d;
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void *p;
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};
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struct fooalign
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{
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char c;
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union fooround u;
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};
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/* If malloc were really smart, it would round addresses to DEFAULT_ALIGNMENT.
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But in fact it might be less smart and round addresses to as much as
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DEFAULT_ROUNDING. So we prepare for it to do that. */
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enum
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{
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DEFAULT_ALIGNMENT = offsetof (struct fooalign, u),
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DEFAULT_ROUNDING = sizeof (union fooround)
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};
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/* When we copy a long block of data, this is the unit to do it with.
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On some machines, copying successive ints does not work;
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in such a case, redefine COPYING_UNIT to `long' (if that works)
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or `char' as a last resort. */
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# ifndef COPYING_UNIT
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# define COPYING_UNIT int
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# endif
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/* The functions allocating more room by calling `obstack_chunk_alloc'
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jump to the handler pointed to by `obstack_alloc_failed_handler'.
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This can be set to a user defined function which should either
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abort gracefully or use longjump - but shouldn't return. This
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variable by default points to the internal function
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`print_and_abort'. */
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static void print_and_abort (void);
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void (*obstack_alloc_failed_handler) (void) = print_and_abort;
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# ifdef _LIBC
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# if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_3_4)
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/* A looong time ago (before 1994, anyway; we're not sure) this global variable
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was used by non-GNU-C macros to avoid multiple evaluation. The GNU C
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library still exports it because somebody might use it. */
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struct obstack *_obstack_compat;
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compat_symbol (libc, _obstack_compat, _obstack, GLIBC_2_0);
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# endif
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# endif
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/* Define a macro that either calls functions with the traditional malloc/free
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calling interface, or calls functions with the mmalloc/mfree interface
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(that adds an extra first argument), based on the state of use_extra_arg.
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For free, do not use ?:, since some compilers, like the MIPS compilers,
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do not allow (expr) ? void : void. */
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# define CALL_CHUNKFUN(h, size) \
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(((h) -> use_extra_arg) \
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? (*(h)->chunkfun.extra) ((h)->extra_arg, (size)) \
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: (*(h)->chunkfun.plain) ((size)))
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# define CALL_FREEFUN(h, old_chunk) \
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do { \
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if ((h) -> use_extra_arg) \
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(*(h)->freefun.extra) ((h)->extra_arg, (old_chunk)); \
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else \
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(*(h)->freefun.plain) ((old_chunk)); \
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} while (0)
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/* Initialize an obstack H for use. Specify chunk size SIZE (0 means default).
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Objects start on multiples of ALIGNMENT (0 means use default).
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CHUNKFUN is the function to use to allocate chunks,
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and FREEFUN the function to free them.
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Return nonzero if successful, calls obstack_alloc_failed_handler if
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allocation fails. */
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int
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_obstack_begin (struct obstack *h,
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int size, int alignment,
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void *(*chunkfun) (long),
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void (*freefun) (void *))
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{
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register struct _obstack_chunk *chunk; /* points to new chunk */
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if (alignment == 0)
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alignment = DEFAULT_ALIGNMENT;
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if (size == 0)
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/* Default size is what GNU malloc can fit in a 4096-byte block. */
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{
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/* 12 is sizeof (mhead) and 4 is EXTRA from GNU malloc.
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Use the values for range checking, because if range checking is off,
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the extra bytes won't be missed terribly, but if range checking is on
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and we used a larger request, a whole extra 4096 bytes would be
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allocated.
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These number are irrelevant to the new GNU malloc. I suspect it is
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less sensitive to the size of the request. */
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int extra = ((((12 + DEFAULT_ROUNDING - 1) & ~(DEFAULT_ROUNDING - 1))
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+ 4 + DEFAULT_ROUNDING - 1)
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& ~(DEFAULT_ROUNDING - 1));
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size = 4096 - extra;
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}
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h->chunkfun.plain = chunkfun;
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h->freefun.plain = freefun;
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h->chunk_size = size;
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h->alignment_mask = alignment - 1;
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h->use_extra_arg = 0;
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chunk = h->chunk = CALL_CHUNKFUN (h, h -> chunk_size);
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if (!chunk)
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(*obstack_alloc_failed_handler) ();
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h->next_free = h->object_base = __PTR_ALIGN ((char *) chunk, chunk->contents,
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alignment - 1);
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h->chunk_limit = chunk->limit
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= (char *) chunk + h->chunk_size;
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chunk->prev = NULL;
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/* The initial chunk now contains no empty object. */
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h->maybe_empty_object = 0;
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h->alloc_failed = 0;
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return 1;
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}
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int
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_obstack_begin_1 (struct obstack *h, int size, int alignment,
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void *(*chunkfun) (void *, long),
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void (*freefun) (void *, void *),
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void *arg)
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{
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register struct _obstack_chunk *chunk; /* points to new chunk */
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if (alignment == 0)
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alignment = DEFAULT_ALIGNMENT;
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if (size == 0)
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/* Default size is what GNU malloc can fit in a 4096-byte block. */
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{
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/* 12 is sizeof (mhead) and 4 is EXTRA from GNU malloc.
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Use the values for range checking, because if range checking is off,
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the extra bytes won't be missed terribly, but if range checking is on
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and we used a larger request, a whole extra 4096 bytes would be
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allocated.
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These number are irrelevant to the new GNU malloc. I suspect it is
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less sensitive to the size of the request. */
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int extra = ((((12 + DEFAULT_ROUNDING - 1) & ~(DEFAULT_ROUNDING - 1))
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+ 4 + DEFAULT_ROUNDING - 1)
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& ~(DEFAULT_ROUNDING - 1));
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size = 4096 - extra;
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}
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h->chunkfun.extra = (struct _obstack_chunk * (*)(void *,long)) chunkfun;
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h->freefun.extra = (void (*) (void *, struct _obstack_chunk *)) freefun;
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h->chunk_size = size;
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h->alignment_mask = alignment - 1;
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h->extra_arg = arg;
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h->use_extra_arg = 1;
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chunk = h->chunk = CALL_CHUNKFUN (h, h -> chunk_size);
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if (!chunk)
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(*obstack_alloc_failed_handler) ();
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h->next_free = h->object_base = __PTR_ALIGN ((char *) chunk, chunk->contents,
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alignment - 1);
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h->chunk_limit = chunk->limit
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= (char *) chunk + h->chunk_size;
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chunk->prev = NULL;
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/* The initial chunk now contains no empty object. */
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h->maybe_empty_object = 0;
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h->alloc_failed = 0;
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return 1;
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}
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/* Allocate a new current chunk for the obstack *H
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on the assumption that LENGTH bytes need to be added
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to the current object, or a new object of length LENGTH allocated.
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Copies any partial object from the end of the old chunk
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to the beginning of the new one. */
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void
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_obstack_newchunk (struct obstack *h, int length)
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{
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register struct _obstack_chunk *old_chunk = h->chunk;
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register struct _obstack_chunk *new_chunk;
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register long new_size;
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register long obj_size = h->next_free - h->object_base;
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register long i;
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long already;
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char *object_base;
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/* Compute size for new chunk. */
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new_size = (obj_size + length) + (obj_size >> 3) + h->alignment_mask + 100;
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if (new_size < h->chunk_size)
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new_size = h->chunk_size;
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/* Allocate and initialize the new chunk. */
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new_chunk = CALL_CHUNKFUN (h, new_size);
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if (!new_chunk)
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(*obstack_alloc_failed_handler) ();
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h->chunk = new_chunk;
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new_chunk->prev = old_chunk;
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new_chunk->limit = h->chunk_limit = (char *) new_chunk + new_size;
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/* Compute an aligned object_base in the new chunk */
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object_base =
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__PTR_ALIGN ((char *) new_chunk, new_chunk->contents, h->alignment_mask);
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/* Move the existing object to the new chunk.
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Word at a time is fast and is safe if the object
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is sufficiently aligned. */
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if (h->alignment_mask + 1 >= DEFAULT_ALIGNMENT)
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{
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for (i = obj_size / sizeof (COPYING_UNIT) - 1;
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i >= 0; i--)
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((COPYING_UNIT *)object_base)[i]
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= ((COPYING_UNIT *)h->object_base)[i];
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/* We used to copy the odd few remaining bytes as one extra COPYING_UNIT,
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but that can cross a page boundary on a machine
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which does not do strict alignment for COPYING_UNITS. */
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already = obj_size / sizeof (COPYING_UNIT) * sizeof (COPYING_UNIT);
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}
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else
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already = 0;
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/* Copy remaining bytes one by one. */
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for (i = already; i < obj_size; i++)
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object_base[i] = h->object_base[i];
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/* If the object just copied was the only data in OLD_CHUNK,
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free that chunk and remove it from the chain.
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But not if that chunk might contain an empty object. */
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if (! h->maybe_empty_object
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&& (h->object_base
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== __PTR_ALIGN ((char *) old_chunk, old_chunk->contents,
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h->alignment_mask)))
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{
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new_chunk->prev = old_chunk->prev;
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CALL_FREEFUN (h, old_chunk);
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}
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h->object_base = object_base;
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h->next_free = h->object_base + obj_size;
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/* The new chunk certainly contains no empty object yet. */
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h->maybe_empty_object = 0;
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}
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# ifdef _LIBC
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libc_hidden_def (_obstack_newchunk)
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# endif
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/* Return nonzero if object OBJ has been allocated from obstack H.
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This is here for debugging.
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If you use it in a program, you are probably losing. */
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/* Suppress -Wmissing-prototypes warning. We don't want to declare this in
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obstack.h because it is just for debugging. */
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int _obstack_allocated_p (struct obstack *h, void *obj);
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int
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_obstack_allocated_p (struct obstack *h, void *obj)
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{
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register struct _obstack_chunk *lp; /* below addr of any objects in this chunk */
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register struct _obstack_chunk *plp; /* point to previous chunk if any */
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lp = (h)->chunk;
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/* We use >= rather than > since the object cannot be exactly at
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the beginning of the chunk but might be an empty object exactly
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at the end of an adjacent chunk. */
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while (lp != NULL && ((void *) lp >= obj || (void *) (lp)->limit < obj))
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{
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plp = lp->prev;
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lp = plp;
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}
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return lp != NULL;
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}
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/* Free objects in obstack H, including OBJ and everything allocate
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more recently than OBJ. If OBJ is zero, free everything in H. */
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# undef obstack_free
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void
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obstack_free (struct obstack *h, void *obj)
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{
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register struct _obstack_chunk *lp; /* below addr of any objects in this chunk */
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register struct _obstack_chunk *plp; /* point to previous chunk if any */
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lp = h->chunk;
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/* We use >= because there cannot be an object at the beginning of a chunk.
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But there can be an empty object at that address
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at the end of another chunk. */
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while (lp != NULL && ((void *) lp >= obj || (void *) (lp)->limit < obj))
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{
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plp = lp->prev;
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CALL_FREEFUN (h, lp);
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lp = plp;
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/* If we switch chunks, we can't tell whether the new current
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chunk contains an empty object, so assume that it may. */
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h->maybe_empty_object = 1;
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}
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if (lp)
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{
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h->object_base = h->next_free = (char *) (obj);
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h->chunk_limit = lp->limit;
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h->chunk = lp;
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}
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else if (obj != NULL)
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/* obj is not in any of the chunks! */
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abort ();
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}
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# ifdef _LIBC
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/* Older versions of libc used a function _obstack_free intended to be
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called by non-GCC compilers. */
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strong_alias (obstack_free, _obstack_free)
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# endif
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int
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_obstack_memory_used (struct obstack *h)
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{
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register struct _obstack_chunk* lp;
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register int nbytes = 0;
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for (lp = h->chunk; lp != NULL; lp = lp->prev)
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{
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nbytes += lp->limit - (char *) lp;
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}
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return nbytes;
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}
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# ifdef _LIBC
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# include <libio/iolibio.h>
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# endif
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# ifndef __attribute__
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/* This feature is available in gcc versions 2.5 and later. */
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# if __GNUC__ < 2 || (__GNUC__ == 2 && __GNUC_MINOR__ < 5)
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# define __attribute__(Spec) /* empty */
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# endif
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# endif
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static void
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print_and_abort (void)
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{
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/* Don't change any of these strings. Yes, it would be possible to add
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the newline to the string and use fputs or so. But this must not
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happen because the "memory exhausted" message appears in other places
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like this and the translation should be reused instead of creating
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a very similar string which requires a separate translation. */
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# ifdef _LIBC
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(void) __fxprintf (NULL, "%s\n", _("memory exhausted"));
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# else
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fprintf (stderr, "%s\n", _("memory exhausted"));
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# endif
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exit (1);
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}
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#endif /* !ELIDE_CODE */
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