I think the error occurs if the input encoding of the file is different from the preferred encoding of your environment. Example: in is UTF-8 $ LANG=de_DE.UTF-8 sed ‘s/.*| //’ < in X Y $ LANG=de_DE.iso88591 sed ‘s/.*| //’ < in X Y UTF-8 can safely be interpreted as ISO-8859-1, you’ll get strange characters but … Read more
I solved my problem a few months ago. Here’s the solution I used. The standard packet-sending API (sock_create, connect, …) cannot be used in a few contexts (interruptions). Using it in the wrong place leads to a KP. The netpoll API is more “low-level” and works in every context. However, there are several conditions : … Read more
Heap and memory management is a facility provided by your C library (likely glibc). It maintains the heap and returns chunks of memory to you every time you do a malloc(). It doesn’t know heap size limit: every time you request more memory than what is available on the heap, it just goes and asks … Read more
You’re running into one surprising difference between i386 and x86_64: they don’t use the same system call mechanism. The correct code is: movq $60, %rax movq $2, %rdi ; not %rbx! syscall Interrupt 0x80 always invokes 32-bit system calls. It’s used to allow 32-bit applications to run on 64-bit systems. For the purposes of learning, … Read more
This pre-commit hook will do the file size check: .git/hooks/pre-commit #!/bin/sh hard_limit=$(git config hooks.filesizehardlimit) soft_limit=$(git config hooks.filesizesoftlimit) : ${hard_limit:=10000000} : ${soft_limit:=500000} list_new_or_modified_files() { git diff –staged –name-status|sed -e ‘/^D/ d; /^D/! s/.\s\+//’ } unmunge() { local result=”${1#\”}” result=”${result%\”}” env echo -e “$result” } check_file_size() { n=0 while read -r munged_filename do f=”$(unmunge “$munged_filename”)” h=$(git ls-files … Read more
No and no. You simply need to be careful and set close-on-exec on all file descriptors you care about. Setting it is easy, though: #include <fcntl.h> fcntl(fd, F_SETFD, fcntl(fd, F_GETFD) | FD_CLOEXEC); #include <unistd.h> /* please don’t do this */ for (i = getdtablesize(); i –> 3;) { if ((flags = fcntl(i, F_GETFD)) != -1) … Read more
From source code, -E is an undocumented option for compatibility with BSD sed. /* Undocumented, for compatibility with BSD sed. */ case ‘E’: case ‘r’: if (extended_regexp_flags) usage(4); extended_regexp_flags = REG_EXTENDED; break; And from manual, -E in BSD sed is used to support extended regular expressions.
You may either call the mount command and parse its output to find the longest common prefix with your path, or use the stat system call to get the device a file resides on and go up the tree until you get to a different device. In Python, stat may be used as follows (untested … Read more
I would strongly disagree with the claim that fopen is prefered over open. It’s impossible to use fopen safely when writing a file in a directory that’s writable by other users due to symlink vulnerabilities/race conditions, since there is no O_EXCL option. If you need to use stdio on POSIX systems, it’s best to use … Read more
You could open() your pipe O_RDONLY | O_NONBLOCK, and if you want the C stream, you can get it with fdopen(). However, there might be a problem with the select() – AFAIK, a pipe fd open for reading that has no writer is always prepared for reading, and read() returns 0, so the select() would … Read more