- Gdb dup2. and "open" "dup2" "close" are library functions To force the unmount, you can kill the offending process (or try kill -SIGTERM), but that would close the smb connection (even though some of the files it has open do not need to be If you would like to create a patcher, I recommend dup2 patcher. 解説 gdbの call コマンドではCの関数が呼び出せる。 まずopenで差し替え先ファイルを開く。引数の66は O_CREAT|O_RDWR。ファイルディスクリプタが $1 に入る 次にdup2で dup2和dup的区别就是可以用newfd参数指定新描述符的数值，如果newfd已经打开，则先将其关闭。如果newfd等于oldfd，则dup2返回newfd, 而不关闭它。 I want to create a simple tool (with C) which can do this tiny subset of gdb s features: Attach to an already running program (with PID) Inject instructions into it like this: dup2 (open for those not familiar with gdb , "attach" "call" "detach" are gdb commands . Currently C and C++ languages are The dup2 () system call performs the same task as dup (), but instead of using the lowest-numbered unused file descriptor, it uses the file descriptor number specified in newfd. debug 1 gef hijack-fd 2 /tmp/stderr. 文章浏览阅读1. get information with "help attach" inside a gdb prompt . However, bash doesn’t provide any direct metho The answer is (quoting) : attach to the process in question using gdb, and run: p dup2 (open ("/dev/null", 0), 1) (for stdout redirection) p dup2 (open ("/dev/null", 0), 2) (for stderr redirection) Something went wrong with call dup2() then, it should have duplicated the fd for "myprog. Via dup2, stderr is overwritten with this new file. sh 我目前正在打印gdb中变量的内容，如下所示：(gdb) call printf("%s",buffer)缓冲区包含一个很大的字符串，我想将其重定向到文件而不是屏幕。在gdb中启用logging功能在这里没有帮 Online GDB is online compiler and debugger for C/C++. txt' as fd #4 ─────────────────────────────── Exception raised The dup2 () system call performs the same task as dup (), but instead of using the lowest-numbered unused file descriptor, it uses the file descriptor number specified in newfd. and "open" "dup2" "close" are library functions 有时通过SecureCRT或者Putty远程ssh到主机上执行某个进程，因长时间没有交互导致ssh断链，此时该进程由init进程收留。该进程的输出也就无法获得了。 这种情况下，可以利 56 0x0000555555554860 in dup2@plt () 57 0x0000555555554860 <dup2@plt+0>: ff 25 ca 07 20 00 jmpq *0x2007ca(%rip) 58 x 0x555555755030 59 0x555555755030: 0x55554866 60 (gdb) disas As a GDB method has been presented, I will draw attention to other methods which are generally easier with other software to alter the program. When working in Linux, it’s very common to use redirections. Once you have your new executable, compare the old and new for differences in the raw hex, and then specify the • If oldfd is a valid file descriptor, and newfd has the same value as oldfd, then dup2 () does nothing, and returns newfd. I have an idea, but don't know what kind of flaws it has: using gdb, open /dev/null with O_WRONLY (edit: an comment suggested O_PATH as a better alternative), then dup2 to close We would like to show you a description here but the site won’t allow us. Hopper Disassembler (Linux, OS X) Move the cursor to the instruction to be modified, 退出gdb即可 此时可以看到指定的log文件已经创建了，通过 ls -l /proc/<pid>/fd/ 可以看到标准输出已经重定向到指定文件了。 原理就是通过gdb向程序插入代码并执行，dup2可以实现 Mac OS X-compatible GDB script (requires dup2 and open to be cast) - background. Using gcc/g++ as compiler and gdb as debugger. You can compile, run and debug code with gdb online. You should still be able to fix this if you redo gdb and call I want to create a simple tool (with C) which can do this tiny subset of gdbs features: Attach to an already running program (with PID) Inject instructions into it like this: dup2 (open ("/tmp/ Via open, the file you want to redirect to is created. dup3 ()dup3 () is the same as dup2 (), except that: • The caller can force the gdb -p $! # invoke gdb and attach the process by its PID # (conveniently stored in $! by our last couple commands) # In GDB we can actually execute C code # against the running process. $ gdb =ls gef start gef gef config gef. For example, we can run a program and silence the output that it generates when we execute it. The compile code gdb command will compile some arbitrary C code and run the for those not familiar with gdb , "attach" "call" "detach" are gdb commands . stdout" over fd 1 rather than making a new fd 5. txt [+] Opened '/tmp/stderr. 4k次。有时通过SecureCRT或者Putty远程ssh到主机上执行某个进程，因长时间没有交互导致ssh断链，此时该进程由init进程收留。该进程的输出也就无法获得了。 linux系統編程之文件與IO（八）：文件描述符相關操作-dup,dup2,fcntl 本節目標： 1,文件共享 打開文件內核數據結構 一個進程兩次打開同一個文件 兩個進程打開同一個文件 2,複製文件描述符（dup 将标准输入重定向到标准输出（dup2 (STDIN_FILENO,STDOUT_FILENO)）是一个特殊的操作，它的实际用途取决于具体场景，但大多数情况下这种直接重定向可能没有实际意义，甚 . trdqn kize imqvz bnjqf vmzdv shepkyc zwyqq oplh woxxvvm yoe