From 60da9d955964759b1f52690bff587ad32a198507 Mon Sep 17 00:00:00 2001 From: Nick Alcock Date: Tue, 23 Apr 2019 18:55:27 +0100 Subject: 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. --- include/ChangeLog | 5 ++ include/ctf-api.h | 3 + libctf/ChangeLog | 12 +++ libctf/ctf-impl.h | 78 ++++++++++++++++++ libctf/ctf-subr.c | 232 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 5 files changed, 330 insertions(+) create mode 100644 libctf/ChangeLog create mode 100644 libctf/ctf-impl.h create mode 100644 libctf/ctf-subr.c diff --git a/include/ChangeLog b/include/ChangeLog index 2cd9f49..d113f98 100644 --- a/include/ChangeLog +++ b/include/ChangeLog @@ -1,5 +1,10 @@ 2019-05-28 Nick Alcock + * ctf-api.h (ctf_setdebug): New. + (ctf_getdebug): Likewise. + +2019-05-28 Nick Alcock + * ctf-api.h: New file. 2019-05-28 Nick Alcock diff --git a/include/ctf-api.h b/include/ctf-api.h index 81f6add..8c6b770 100644 --- a/include/ctf-api.h +++ b/include/ctf-api.h @@ -123,6 +123,9 @@ enum #define CTF_ADD_ROOT 1 /* Type visible at top-level scope. */ +extern void ctf_setdebug (int debug); +extern int ctf_getdebug (void); + #ifdef __cplusplus } #endif diff --git a/libctf/ChangeLog b/libctf/ChangeLog new file mode 100644 index 0000000..6a37212 --- /dev/null +++ b/libctf/ChangeLog @@ -0,0 +1,12 @@ +2019-05-28 Nick Alcock + + * ctf-impl.h: New file. + * ctf-subr.c: New file. + + +Local Variables: +mode: change-log +left-margin: 8 +fill-column: 76 +version-control: never +End: diff --git a/libctf/ctf-impl.h b/libctf/ctf-impl.h new file mode 100644 index 0000000..4356a2a --- /dev/null +++ b/libctf/ctf-impl.h @@ -0,0 +1,78 @@ +/* Implementation header. + Copyright (C) 2019 Free Software Foundation, Inc. + + This file is part of libctf. + + libctf is free software; you can redistribute it and/or modify it under + the terms of the GNU General Public License as published by the Free + Software Foundation; either version 3, or (at your option) any later + version. + + This program is distributed in the hope that it will be useful, but + WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. + See the GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program; see the file COPYING. If not see + . */ + +#ifndef _CTF_IMPL_H +#define _CTF_IMPL_H + +#include "config.h" +#include +#include +#include + +#ifdef __cplusplus +extern "C" + { +#endif + +/* Compiler attributes. */ + +#if defined (__GNUC__) + +/* GCC. We assume that all compilers claiming to be GCC support sufficiently + many GCC attributes that the code below works. If some non-GCC compilers + masquerading as GCC in fact do not implement these attributes, version checks + may be required. */ + +/* We use the _libctf_*_ pattern to avoid clashes with any future attribute + macros glibc may introduce, which have names of the pattern + __attribute_blah__. */ + +#define _libctf_printflike_(string_index,first_to_check) \ + __attribute__ ((__format__ (__printf__, (string_index), (first_to_check)))) +#define _libctf_unlikely_(x) __builtin_expect ((x), 0) +#define _libctf_unused_ __attribute__ ((__unused__)) +#define _libctf_malloc_ __attribute__((__malloc__)) + +#endif + +_libctf_malloc_ +extern void *ctf_data_alloc (size_t); +extern void ctf_data_free (void *, size_t); +extern void ctf_data_protect (void *, size_t); + +_libctf_malloc_ +extern void *ctf_mmap (size_t length, size_t offset, int fd); +extern void ctf_munmap (void *, size_t); +extern ssize_t ctf_pread (int fd, void *buf, ssize_t count, off_t offset); + +_libctf_malloc_ +extern void *ctf_alloc (size_t); +extern void ctf_free (void *); + +_libctf_printflike_ (1, 2) +extern void ctf_dprintf (const char *, ...); +extern void libctf_init_debug (void); + +extern int _libctf_debug; /* debugging messages enabled */ + +#ifdef __cplusplus +} +#endif + +#endif /* _CTF_IMPL_H */ diff --git a/libctf/ctf-subr.c b/libctf/ctf-subr.c new file mode 100644 index 0000000..3103e28 --- /dev/null +++ b/libctf/ctf-subr.c @@ -0,0 +1,232 @@ +/* Simple subrs. + Copyright (C) 2019 Free Software Foundation, Inc. + + This file is part of libctf. + + libctf is free software; you can redistribute it and/or modify it under + the terms of the GNU General Public License as published by the Free + Software Foundation; either version 3, or (at your option) any later + version. + + This program is distributed in the hope that it will be useful, but + WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. + See the GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program; see the file COPYING. If not see + . */ + +#include +#ifdef HAVE_MMAP +#include +#endif +#include +#include +#include +#include + +static size_t _PAGESIZE _libctf_unused_; +int _libctf_debug = 0; /* Debugging messages enabled. */ + +_libctf_malloc_ void * +ctf_data_alloc (size_t size) +{ + void *ret; + +#ifdef HAVE_MMAP + if (_PAGESIZE == 0) + _PAGESIZE = sysconf(_SC_PAGESIZE); + + if (size > _PAGESIZE) + { + ret = mmap (NULL, size, PROT_READ | PROT_WRITE, + MAP_PRIVATE | MAP_ANON, -1, 0); + if (ret == MAP_FAILED) + ret = NULL; + } + else + ret = calloc (1, size); +#else + ret = calloc (1, size); +#endif + return ret; +} + +void +ctf_data_free (void *buf, size_t size _libctf_unused_) +{ +#ifdef HAVE_MMAP + /* Must be the same as the check in ctf_data_alloc(). */ + + if (size > _PAGESIZE) + (void) munmap (buf, size); + else + free (buf); +#else + free (buf); +#endif +} + +/* Private, read-only mmap from a file, with fallback to copying. + + No handling of page-offset issues at all: the caller must allow for that. */ + +_libctf_malloc_ void * +ctf_mmap (size_t length, size_t offset, int fd) +{ + void *data; + +#ifdef HAVE_MMAP + data = mmap (NULL, length, PROT_READ, MAP_PRIVATE, fd, offset); + if (data == MAP_FAILED) + data = NULL; +#else + if ((data = malloc (length)) != NULL) + { + if (ctf_pread (fd, data, length, offset) <= 0) + { + free (data); + data = NULL; + } + } +#endif + return data; +} + +void +ctf_munmap (void *buf, size_t length _libctf_unused_) +{ +#ifdef HAVE_MMAP + (void) munmap (buf, length); +#else + free (buf); +#endif +} + +void +ctf_data_protect (void *buf, size_t size) +{ +#ifdef HAVE_MMAP + /* Must be the same as the check in ctf_data_alloc(). */ + + if (size > _PAGESIZE) + (void) mprotect (buf, size, PROT_READ); +#endif +} + +_libctf_malloc_ void * +ctf_alloc (size_t size) +{ + return (malloc (size)); +} + +void +ctf_free (void *buf) +{ + free (buf); +} + +ssize_t +ctf_pread (int fd, void *buf, ssize_t count, off_t offset) +{ + ssize_t len; + size_t acc = 0; + char *data = (char *) buf; + +#ifdef HAVE_PREAD + while (count > 0) + { + errno = 0; + if (((len = pread (fd, data, count, offset)) < 0) && + errno != EINTR) + return len; + if (errno == EINTR) + continue; + + acc += len; + if (len == 0) /* EOF. */ + return acc; + + count -= len; + offset += len; + data += len; + } + return acc; +#else + off_t orig_off; + + if ((orig_off = lseek (fd, 0, SEEK_CUR)) < 0) + return -1; + if ((lseek (fd, offset, SEEK_SET)) < 0) + return -1; + + while (count > 0) + { + errno = 0; + if (((len = read (fd, data, count)) < 0) && + errno != EINTR) + return len; + if (errno == EINTR) + continue; + + acc += len; + if (len == 0) /* EOF. */ + break; + + count -= len; + data += len; + } + if ((lseek (fd, orig_off, SEEK_SET)) < 0) + return -1; /* offset is smashed. */ +#endif + + return acc; +} + +const char * +ctf_strerror (int err) +{ + return (const char *) (strerror (err)); +} + +void +libctf_init_debug (void) +{ + static int inited; + if (!inited) + { + _libctf_debug = getenv ("LIBCTF_DEBUG") != NULL; + inited = 1; + } +} + +void ctf_setdebug (int debug) +{ + /* Ensure that libctf_init_debug() has been called, so that we don't get our + debugging-on-or-off smashed by the next call. */ + + libctf_init_debug(); + _libctf_debug = debug; + ctf_dprintf ("CTF debugging set to %i\n", debug); +} + +int ctf_getdebug (void) +{ + return _libctf_debug; +} + +_libctf_printflike_ (1, 2) +void ctf_dprintf (const char *format, ...) +{ + if (_libctf_debug) + { + va_list alist; + + va_start (alist, format); + fflush (stdout); + (void) fputs ("libctf DEBUG: ", stderr); + (void) vfprintf (stderr, format, alist); + va_end (alist); + } +} -- cgit v1.1