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/*
* Copyright (C) 2017-2020, Thomas Maier-Komor
*
* This is the source code of mbuffer.
*
* This program 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 of the License, 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. If not, see <http://www.gnu.org/licenses/>.
*/
#include "mbconf.h"
#include <assert.h>
#include <dlfcn.h>
#include <errno.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <unistd.h>
#define EXPAND(A) A ## 1
#define ISEMPTY(A) EXPAND(A)
#define STRINGIFY(x) #x
#define TOSTRING(x) STRINGIFY(x)
#if ISEMPTY(LIBC_FSTAT)
#undef LIBC_FSTAT
#define LIBC_FSTAT fstat
#endif
ssize_t (*d_open)(const char *path, int oflag, ...) = 0;
ssize_t (*d_read)(int filedes, void *buf, size_t nbyte) = 0;
int (*d_fxstat)(int ver, int fd, struct stat *st) = 0;
int (*d_fstat)(int fd, struct stat *st) = 0;
static ssize_t Fd = -1;
static size_t BSize = 0;
static const char *IDEV = "";
static int HadZero = 0;
static int Debug = 0;
int LIBC_OPEN(const char *path, int oflag, ...)
{
if (d_open == 0) {
const char *d = getenv("IDEV_DEBUG");
if (d)
Debug = strtol(d,0,0);
d_open = (ssize_t (*)(const char *,int,...)) dlsym(RTLD_NEXT,TOSTRING(LIBC_OPEN));
fprintf(stderr,"idev.so: d_open = %p\n",d_open);
fflush(stderr);
const char *idev = getenv("IDEV");
if (idev)
IDEV = idev;
}
assert(d_open);
int fd;
if (oflag & O_CREAT) {
va_list val;
va_start(val,oflag);
int mode = va_arg(val,int);
va_end(val);
fd = d_open(path, oflag, mode);
} else {
fd = d_open(path, oflag);
}
fprintf(stderr,"idev.so: open(%s,0x%x,...) = %d (IDEV='%s')\n",path,oflag,fd,IDEV);
if (strcmp(path, getenv("IDEV")) == 0) {
fprintf(stderr,"idev.so: FD = %d\n",fd);
fflush(stderr);
Fd = fd;
HadZero = 0;
}
return fd;
}
ssize_t LIBC_READ(int fd, void *buf, size_t s)
{
if (d_read == 0) {
const char *d = getenv("IDEV_DEBUG");
if (d)
Debug = strtol(d,0,0);
d_read = (ssize_t (*)(int,void*,size_t)) dlsym(RTLD_NEXT, "read");
if (Debug)
fprintf(stderr,"idev.so: d_read = %p\n",d_read);
}
assert(d_read);
if (fd != Fd)
return d_read(fd,buf,s);
assert(HadZero == 0);
if (BSize == 0)
BSize = strtol(getenv("BSIZE"),0,0);
if (s < BSize) {
if (Debug) {
fprintf(stderr,"idev.so: read(%d,%p,%llu<%llu) = ENOMEM\n",fd,buf,(long long unsigned)s,(long long unsigned)BSize);
fflush(stderr);
}
errno = ENOMEM;
return -1;
}
int n = d_read(fd,buf,s);
if (n == 0)
HadZero = 1;
return n;
}
int __fxstat(int ver, int fd, struct stat *st)
{
if (d_fxstat == 0) {
const char *d = getenv("IDEV_DEBUG");
if (d)
Debug = strtol(d,0,0);
d_fxstat = (int (*)(int,int,struct stat *)) dlsym(RTLD_NEXT, "__fxstat");
if (Debug)
fprintf(stderr,"idev.so: d_fstat = %p\n",d_fxstat);
}
if (Debug)
fprintf(stderr,"idev.so: __fxstat(%d,%d,%p)\n",ver,fd,st);
assert(d_fxstat);
int r = d_fxstat(ver,fd,st);
if (fd == Fd) {
if (BSize == 0)
BSize = strtol(getenv("BSIZE"),0,0);
if (Debug) {
fprintf(stderr,"idev.so: blksize set to %llu\n",(long long unsigned)BSize);
fflush(stderr);
}
st->st_blksize = BSize;
st->st_mode &= ~S_IFMT;
st->st_mode |= S_IFCHR;
}
return r;
}
int fstat(int fd, struct stat *st)
{
if (d_fstat == 0) {
const char *d = getenv("IDEV_DEBUG");
if (d)
Debug = strtol(d,0,0);
d_fstat = (int (*)(int,struct stat *)) dlsym(RTLD_NEXT, TOSTRING(LIBC_FSTAT));
if (Debug)
fprintf(stderr,"idev.so: d_fstat = %p\n",d_fstat);
}
if (Debug)
fprintf(stderr,"idev.so: fstat(%d,%p)\n",fd,st);
assert(d_fstat);
int r = d_fstat(fd,st);
if (fd == Fd) {
if (BSize == 0)
BSize = strtol(getenv("BSIZE"),0,0);
if (Debug) {
fprintf(stderr,"idev.so: blksize set to %llu\n",(long long unsigned)BSize);
fflush(stderr);
}
st->st_blksize = BSize;
st->st_mode &= ~S_IFMT;
st->st_mode |= S_IFCHR;
}
return r;
}
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