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libjio/bindings/preload/libjio_preload.c  view on Meta::CPAN

/*
 * libjio C preloader
 * Alberto Bertogli (albertito@blitiri.com.ar)
 *
 * This generates a shared object that, when prelinked, can be used to make an
 * existing application to use libjio for UNIX I/O.
 * It's not nice or pretty, and does some nasty tricks to work both with and
 * without LFS. I don't think it builds or works without glibc.
 */


#include <unistd.h>
#include <string.h>
#include <stdlib.h>
#include <stdarg.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/uio.h>
#include <dlfcn.h>

/* we don't build this with LFS, however, it's essential that the proper
 * environment is set for libjio's loading; otherwise we would mess the ABI
 * up */
typedef long long off64_t;
#define _FILE_OFFSET_BITS 64
#define off_t off64_t
#include <libjio.h>
#undef off_t
#undef _FILE_OFFSET_BITS


/* maximum number of simultaneous open file descriptors we support */
#define MAXFD (4096 * 2)

/* recursion counter, per-thread */
static int __thread called = 0;


/* C library functions, filled via the dynamic loader */
static void *libc;

static int (*c_open)(const char *pathname, int flags, mode_t mode);
static int (*c_open64)(const char *pathname, int flags, mode_t mode);
static int (*c_close)(int fd);
static int (*c_unlink)(const char *pathname);
static ssize_t (*c_read)(int fd, void *buf, size_t count);
static ssize_t (*c_pread)(int fd, void *buf, size_t count, off_t offset);
static ssize_t (*c_pread64)(int fd, void *buf, size_t count, off64_t offset);
static ssize_t (*c_readv)(int fd, const struct iovec *vector, int count);
static ssize_t (*c_write)(int fd, const void *buf, size_t count);
static ssize_t (*c_pwrite)(int fd, const void *buf, size_t count, off_t offset);
static ssize_t (*c_pwrite64)(int fd, const void *buf, size_t count, off64_t offset);
static ssize_t (*c_writev)(int fd, const struct iovec *vector, int count);
static int (*c_ftruncate)(int fd, off_t length);
static int (*c_ftruncate64)(int fd, off64_t length);
static off_t (*c_lseek)(int fd, off_t offset, int whence);
static off64_t (*c_lseek64)(int fd, off64_t offset, int whence);
static int (*c_fsync)(int fd);
static int (*c_dup)(int oldfd);
static int (*c_dup2)(int oldfd, int newfd);


/* file descriptor table, to translate fds to jfs */
struct fd_entry {
	int fd;