mirror of
https://github.com/trapexit/mergerfs.git
synced 2024-12-11 19:53:39 +08:00
428 lines
8.0 KiB
C
428 lines
8.0 KiB
C
/*
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ISC License
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Copyright (c) 2024, Antonio SJ Musumeci <trapexit@spawn.link>
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Permission to use, copy, modify, and/or distribute this software for any
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purpose with or without fee is hereby granted, provided that the above
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copyright notice and this permission notice appear in all copies.
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THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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#define _GNU_SOURCE
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#define _POSIX_C_SOURCE 200809L
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#include <assert.h>
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#include <dlfcn.h>
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#include <stdio.h>
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#include <string.h>
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#include <sys/ioctl.h>
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#include <stdarg.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <unistd.h>
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#include <fcntl.h>
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typedef char IOCTL_BUF[4096];
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#define IOCTL_APP_TYPE 0xDF
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#define IOCTL_FILE_INFO _IOWR(IOCTL_APP_TYPE,0,IOCTL_BUF)
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#define LOAD_FUNC(func) \
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do \
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{ \
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if(!_libc_##func) \
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_libc_##func = (func##_func_t)dlsym(RTLD_NEXT,#func); \
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assert(_libc_##func != NULL); \
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} \
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while(0)
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typedef int (*open_func_t)(const char*, int, ...);
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typedef int (*open64_func_t)(const char*, int, ...);
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typedef int (*openat_func_t)(int, const char*, int, ...);
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typedef int (*openat64_func_t)(int, const char*, int, ...);
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typedef int (*creat_func_t)(const char*, mode_t);
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typedef int (*creat64_func_t)(const char*, mode_t);
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typedef FILE* (*fopen_func_t)(const char*, const char*);
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typedef FILE* (*fopen64_func_t)(const char*, const char*);
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static open_func_t _libc_open = NULL;
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static open64_func_t _libc_open64 = NULL;
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static openat_func_t _libc_openat = NULL;
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static openat64_func_t _libc_openat64 = NULL;
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static fopen_func_t _libc_fopen = NULL;
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static fopen64_func_t _libc_fopen64 = NULL;
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static creat_func_t _libc_creat = NULL;
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static creat64_func_t _libc_creat64 = NULL;
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static
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int
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get_underlying_filepath(int fd_,
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char *filepath_)
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{
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int rv;
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strcpy(filepath_,"fullpath");
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rv = ioctl(fd_,IOCTL_FILE_INFO,filepath_);
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if(rv == -1)
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return -1;
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return rv;
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}
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static
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void
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strip_exec(const char *orig_mode_,
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char *new_mode_)
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{
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size_t i;
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size_t j;
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for(i = j = 0; orig_mode_[i]; i++)
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{
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if(orig_mode_[i] == 'x')
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continue;
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new_mode_[j++] = orig_mode_[i];
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}
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new_mode_[j] = '\0';
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}
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int
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open(const char *pathname_,
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int flags_,
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...)
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{
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int rv;
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int fd;
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mode_t mode;
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struct stat st;
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LOAD_FUNC(open);
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mode = 0;
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if(flags_ & O_CREAT)
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{
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va_list args;
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va_start(args,flags_);
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mode = va_arg(args,mode_t);
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va_end(args);
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}
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fd = _libc_open(pathname_,flags_,mode);
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if(fd == -1)
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return -1;
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if(flags_ & (O_DIRECTORY|O_PATH))
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return fd;
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rv = fstat(fd,&st);
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if(rv == -1)
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return fd;
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if((st.st_mode & S_IFMT) != S_IFREG)
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return fd;
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IOCTL_BUF real_pathname;
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rv = get_underlying_filepath(fd,real_pathname);
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if(rv == -1)
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return fd;
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flags_ &= ~(O_EXCL|O_CREAT);
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rv = _libc_open(real_pathname,flags_,mode);
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if(rv == -1)
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return fd;
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close(fd);
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return rv;
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}
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int
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open64(const char *pathname_,
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int flags_,
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...)
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{
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int rv;
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int fd;
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mode_t mode;
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struct stat st;
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LOAD_FUNC(open64);
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mode = 0;
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if(flags_ & O_CREAT)
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{
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va_list args;
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va_start(args,flags_);
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mode = va_arg(args,mode_t);
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va_end(args);
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}
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fd = _libc_open64(pathname_,flags_,mode);
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if(fd == -1)
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return -1;
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if(flags_ & (O_DIRECTORY|O_PATH))
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return fd;
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rv = fstat(fd,&st);
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if(rv == -1)
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return fd;
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if((st.st_mode & S_IFMT) != S_IFREG)
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return fd;
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IOCTL_BUF real_pathname;
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rv = get_underlying_filepath(fd,real_pathname);
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if(rv == -1)
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return fd;
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flags_ &= ~(O_EXCL|O_CREAT);
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rv = _libc_open64(real_pathname,flags_,mode);
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if(rv == -1)
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return fd;
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close(fd);
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return rv;
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}
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int
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openat(int dirfd_,
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const char *pathname_,
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int flags_,
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...)
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{
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int rv;
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int fd;
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mode_t mode;
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struct stat st;
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LOAD_FUNC(openat);
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mode = 0;
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if(flags_ & O_CREAT)
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{
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va_list args;
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va_start(args,flags_);
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mode = va_arg(args,mode_t);
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va_end(args);
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}
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fd = _libc_openat(dirfd_,pathname_,flags_,mode);
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if(fd == -1)
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return -1;
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if(flags_ & (O_DIRECTORY|O_PATH))
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return fd;
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rv = fstat(fd,&st);
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if(rv == -1)
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return fd;
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if((st.st_mode & S_IFMT) != S_IFREG)
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return fd;
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IOCTL_BUF real_pathname;
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rv = get_underlying_filepath(fd,real_pathname);
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if(rv == -1)
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return fd;
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flags_ &= ~(O_EXCL|O_CREAT);
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rv = _libc_openat(dirfd_,real_pathname,flags_,mode);
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if(rv == -1)
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return fd;
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close(fd);
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return rv;
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}
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int
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openat64(int dirfd_,
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const char *pathname_,
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int flags_,
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...)
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{
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int rv;
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int fd;
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mode_t mode;
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struct stat st;
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LOAD_FUNC(openat64);
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mode = 0;
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if(flags_ & O_CREAT)
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{
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va_list args;
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va_start(args,flags_);
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mode = va_arg(args,mode_t);
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va_end(args);
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}
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fd = _libc_openat64(dirfd_,pathname_,flags_,mode);
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if(fd == -1)
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return -1;
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if(flags_ & (O_DIRECTORY|O_PATH))
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return fd;
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rv = fstat(fd,&st);
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if(rv == -1)
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return fd;
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if((st.st_mode & S_IFMT) != S_IFREG)
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return fd;
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IOCTL_BUF real_pathname;
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rv = get_underlying_filepath(fd,real_pathname);
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if(rv == -1)
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return fd;
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flags_ &= ~(O_EXCL|O_CREAT);
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rv = _libc_openat64(dirfd_,real_pathname,flags_,mode);
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if(rv == -1)
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return fd;
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close(fd);
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return rv;
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}
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FILE*
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fopen(const char *pathname_,
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const char *mode_)
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{
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int fd;
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int rv;
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FILE *f;
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FILE *f2;
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struct stat st;
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LOAD_FUNC(fopen);
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f = _libc_fopen(pathname_,mode_);
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if(f == NULL)
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return NULL;
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fd = fileno(f);
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if(fd == -1)
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return f;
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rv = fstat(fd,&st);
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if(rv == -1)
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return f;
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if((st.st_mode & S_IFMT) != S_IFREG)
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return f;
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IOCTL_BUF real_pathname;
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rv = get_underlying_filepath(fd,real_pathname);
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if(rv == -1)
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return f;
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char new_mode[64];
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strip_exec(mode_,new_mode);
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f2 = _libc_fopen(real_pathname,new_mode);
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if(f2 == NULL)
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return f;
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fclose(f);
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return f2;
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}
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FILE*
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fopen64(const char *pathname_,
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const char *mode_)
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{
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int fd;
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int rv;
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FILE *f;
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FILE *f2;
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struct stat st;
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LOAD_FUNC(fopen64);
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f = _libc_fopen64(pathname_,mode_);
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if(f == NULL)
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return NULL;
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fd = fileno(f);
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if(fd == -1)
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return f;
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rv = fstat(fd,&st);
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if(rv == -1)
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return f;
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if((st.st_mode & S_IFMT) != S_IFREG)
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return f;
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IOCTL_BUF real_pathname;
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rv = get_underlying_filepath(fd,real_pathname);
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if(rv == -1)
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return f;
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char new_mode[64];
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strip_exec(mode_,new_mode);
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f2 = _libc_fopen64(real_pathname,new_mode);
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if(f2 == NULL)
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return f;
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fclose(f);
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return f2;
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}
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int
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creat(const char *pathname_,
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mode_t mode_)
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{
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int fd;
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int rv;
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LOAD_FUNC(creat);
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fd = _libc_creat(pathname_,mode_);
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if(fd == -1)
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return -1;
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IOCTL_BUF real_pathname;
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rv = get_underlying_filepath(fd,real_pathname);
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if(rv == -1)
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return fd;
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rv = _libc_creat(real_pathname,mode_);
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if(rv == -1)
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return fd;
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close(fd);
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return rv;
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}
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int
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creat64(const char *pathname_,
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mode_t mode_)
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{
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int fd;
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int rv;
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LOAD_FUNC(creat64);
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fd = _libc_creat64(pathname_,mode_);
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if(fd == -1)
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return -1;
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IOCTL_BUF real_pathname;
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rv = get_underlying_filepath(fd,real_pathname);
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if(rv == -1)
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return fd;
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rv = _libc_creat64(real_pathname,mode_);
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if(rv == -1)
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return fd;
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close(fd);
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return rv;
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}
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