libctf: lowest-level memory allocation and debug-dumping wrappers
The memory-allocation wrappers are simple things to allow malloc interposition: they are only used inconsistently at present, usually where malloc debugging was required in the past. These provide a default implementation that is environment-variable triggered (initialized on the first call to the libctf creation and file-opening functions, the first functions people will use), and a ctf_setdebug()/ctf_getdebug() pair that allows the caller to explicitly turn debugging off and on. If ctf_setdebug() is called, the automatic setting from an environment variable is skipped. libctf/ * ctf-impl.h: New file. * ctf-subr.c: New file. include/ * ctf-api.h (ctf_setdebug): New. (ctf_getdebug): Likewise.
This commit is contained in:
Nick Alcock
parent
2e94b05630
commit
60da9d9559
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@ -1,3 +1,8 @@
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2019-05-28 Nick Alcock <nick.alcock@oracle.com>
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* ctf-api.h (ctf_setdebug): New.
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(ctf_getdebug): Likewise.
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2019-05-28 Nick Alcock <nick.alcock@oracle.com>
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* ctf-api.h: New file.
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@ -123,6 +123,9 @@ enum
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#define CTF_ADD_ROOT 1 /* Type visible at top-level scope. */
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extern void ctf_setdebug (int debug);
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extern int ctf_getdebug (void);
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#ifdef __cplusplus
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}
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#endif
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@ -0,0 +1,12 @@
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2019-05-28 Nick Alcock <nick.alcock@oracle.com>
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* ctf-impl.h: New file.
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* ctf-subr.c: New file.
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Local Variables:
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mode: change-log
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left-margin: 8
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fill-column: 76
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version-control: never
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End:
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@ -0,0 +1,78 @@
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/* Implementation header.
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Copyright (C) 2019 Free Software Foundation, Inc.
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This file is part of libctf.
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libctf is free software; you can redistribute it and/or modify it under
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the terms of the GNU General Public License as published by the Free
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Software Foundation; either version 3, or (at your option) any later
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version.
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This program is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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See the GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; see the file COPYING. If not see
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<http://www.gnu.org/licenses/>. */
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#ifndef _CTF_IMPL_H
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#define _CTF_IMPL_H
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#include "config.h"
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#include <sys/errno.h>
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#include <ctf-api.h>
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#include <sys/types.h>
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#ifdef __cplusplus
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extern "C"
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{
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#endif
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/* Compiler attributes. */
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#if defined (__GNUC__)
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/* GCC. We assume that all compilers claiming to be GCC support sufficiently
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many GCC attributes that the code below works. If some non-GCC compilers
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masquerading as GCC in fact do not implement these attributes, version checks
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may be required. */
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/* We use the _libctf_*_ pattern to avoid clashes with any future attribute
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macros glibc may introduce, which have names of the pattern
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__attribute_blah__. */
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#define _libctf_printflike_(string_index,first_to_check) \
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__attribute__ ((__format__ (__printf__, (string_index), (first_to_check))))
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#define _libctf_unlikely_(x) __builtin_expect ((x), 0)
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#define _libctf_unused_ __attribute__ ((__unused__))
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#define _libctf_malloc_ __attribute__((__malloc__))
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#endif
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_libctf_malloc_
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extern void *ctf_data_alloc (size_t);
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extern void ctf_data_free (void *, size_t);
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extern void ctf_data_protect (void *, size_t);
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_libctf_malloc_
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extern void *ctf_mmap (size_t length, size_t offset, int fd);
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extern void ctf_munmap (void *, size_t);
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extern ssize_t ctf_pread (int fd, void *buf, ssize_t count, off_t offset);
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_libctf_malloc_
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extern void *ctf_alloc (size_t);
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extern void ctf_free (void *);
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_libctf_printflike_ (1, 2)
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extern void ctf_dprintf (const char *, ...);
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extern void libctf_init_debug (void);
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extern int _libctf_debug; /* debugging messages enabled */
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#ifdef __cplusplus
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}
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#endif
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#endif /* _CTF_IMPL_H */
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@ -0,0 +1,232 @@
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/* Simple subrs.
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Copyright (C) 2019 Free Software Foundation, Inc.
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This file is part of libctf.
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libctf is free software; you can redistribute it and/or modify it under
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the terms of the GNU General Public License as published by the Free
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Software Foundation; either version 3, or (at your option) any later
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version.
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This program is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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See the GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; see the file COPYING. If not see
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<http://www.gnu.org/licenses/>. */
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#include <ctf-impl.h>
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#ifdef HAVE_MMAP
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#include <sys/mman.h>
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#endif
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#include <sys/types.h>
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#include <stdarg.h>
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#include <string.h>
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#include <unistd.h>
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static size_t _PAGESIZE _libctf_unused_;
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int _libctf_debug = 0; /* Debugging messages enabled. */
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_libctf_malloc_ void *
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ctf_data_alloc (size_t size)
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{
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void *ret;
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#ifdef HAVE_MMAP
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if (_PAGESIZE == 0)
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_PAGESIZE = sysconf(_SC_PAGESIZE);
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if (size > _PAGESIZE)
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{
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ret = mmap (NULL, size, PROT_READ | PROT_WRITE,
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MAP_PRIVATE | MAP_ANON, -1, 0);
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if (ret == MAP_FAILED)
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ret = NULL;
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}
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else
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ret = calloc (1, size);
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#else
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ret = calloc (1, size);
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#endif
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return ret;
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}
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void
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ctf_data_free (void *buf, size_t size _libctf_unused_)
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{
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#ifdef HAVE_MMAP
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/* Must be the same as the check in ctf_data_alloc(). */
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if (size > _PAGESIZE)
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(void) munmap (buf, size);
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else
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free (buf);
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#else
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free (buf);
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#endif
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}
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/* Private, read-only mmap from a file, with fallback to copying.
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No handling of page-offset issues at all: the caller must allow for that. */
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_libctf_malloc_ void *
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ctf_mmap (size_t length, size_t offset, int fd)
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{
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void *data;
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#ifdef HAVE_MMAP
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data = mmap (NULL, length, PROT_READ, MAP_PRIVATE, fd, offset);
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if (data == MAP_FAILED)
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data = NULL;
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#else
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if ((data = malloc (length)) != NULL)
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{
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if (ctf_pread (fd, data, length, offset) <= 0)
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{
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free (data);
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data = NULL;
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}
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}
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#endif
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return data;
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}
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void
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ctf_munmap (void *buf, size_t length _libctf_unused_)
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{
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#ifdef HAVE_MMAP
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(void) munmap (buf, length);
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#else
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free (buf);
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#endif
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}
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void
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ctf_data_protect (void *buf, size_t size)
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{
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#ifdef HAVE_MMAP
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/* Must be the same as the check in ctf_data_alloc(). */
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if (size > _PAGESIZE)
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(void) mprotect (buf, size, PROT_READ);
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#endif
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}
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_libctf_malloc_ void *
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ctf_alloc (size_t size)
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{
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return (malloc (size));
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}
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void
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ctf_free (void *buf)
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{
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free (buf);
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}
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ssize_t
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ctf_pread (int fd, void *buf, ssize_t count, off_t offset)
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{
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ssize_t len;
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size_t acc = 0;
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char *data = (char *) buf;
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#ifdef HAVE_PREAD
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while (count > 0)
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{
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errno = 0;
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if (((len = pread (fd, data, count, offset)) < 0) &&
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errno != EINTR)
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return len;
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if (errno == EINTR)
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continue;
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acc += len;
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if (len == 0) /* EOF. */
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return acc;
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count -= len;
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offset += len;
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data += len;
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}
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return acc;
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#else
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off_t orig_off;
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if ((orig_off = lseek (fd, 0, SEEK_CUR)) < 0)
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return -1;
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if ((lseek (fd, offset, SEEK_SET)) < 0)
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return -1;
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while (count > 0)
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{
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errno = 0;
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if (((len = read (fd, data, count)) < 0) &&
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errno != EINTR)
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return len;
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if (errno == EINTR)
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continue;
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acc += len;
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if (len == 0) /* EOF. */
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break;
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count -= len;
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data += len;
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}
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if ((lseek (fd, orig_off, SEEK_SET)) < 0)
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return -1; /* offset is smashed. */
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#endif
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return acc;
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}
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const char *
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ctf_strerror (int err)
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{
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return (const char *) (strerror (err));
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}
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void
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libctf_init_debug (void)
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{
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static int inited;
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if (!inited)
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{
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_libctf_debug = getenv ("LIBCTF_DEBUG") != NULL;
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inited = 1;
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}
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}
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void ctf_setdebug (int debug)
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{
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/* Ensure that libctf_init_debug() has been called, so that we don't get our
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debugging-on-or-off smashed by the next call. */
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libctf_init_debug();
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_libctf_debug = debug;
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ctf_dprintf ("CTF debugging set to %i\n", debug);
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}
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int ctf_getdebug (void)
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{
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return _libctf_debug;
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}
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_libctf_printflike_ (1, 2)
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void ctf_dprintf (const char *format, ...)
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{
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if (_libctf_debug)
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{
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va_list alist;
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va_start (alist, format);
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fflush (stdout);
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(void) fputs ("libctf DEBUG: ", stderr);
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(void) vfprintf (stderr, format, alist);
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va_end (alist);
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}
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}
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