alx‭

Is it valid to partly allocate an object, as long as you only use the allocated part of it? #include <stdio.h> #include <stdlib.h> struct s { int i[100]; }; int main(void) {...

1 answer  ·  posted 2mo ago by alx‭  ·  last activity 2mo ago by Lundin‭

What does it mean that we can use memcmp(3) on invalid values? ISO C allows comparing an invalid value through memcmp(3), because it doesn't read the value, but rather its representation, and "rea...

2 answers  ·  posted 1mo ago by alx‭  ·  last activity 1mo ago by Lundin‭

Let's consider the following code: const char a[][4] = {"aa", "aaa"}; const char *b[] = {"bb", "bbb"}; const char *const c[] = {"cc", "ccc"}; For shared libraries, both b and c arrays require...

0 answers  ·  posted 10mo ago by alx‭  ·  edited 9mo ago by alx‭

I was directed a few days ago to a post about a string copy function, which IMO improves the commonly known string copy functions, including strlcpy(3BSD), strlcat(3BSD), and strscpy(9). It define...

2 answers  ·  posted 1y ago by alx‭  ·  last activity 3mo ago by alx‭

Is it legal ISO C to declare a function as noreturn with a non-void return type (but of course not actually returning)? As far as I can read from the standard, it seems legal. Example: noreturn ...

1 answer  ·  posted 1y ago by alx‭  ·  edited 1y ago by alx‭

How can we use git-send-email(1) to sign patches (emails) with the gpg(1) keyring? I've heard it can be done, but couldn't find anything in the git-send-email(1) documentation nor in a web search.

2 answers  ·  posted 10mo ago by alx‭  ·  last activity 9mo ago by alx‭

Is -isystem/path/to/sys/includes a standard compiler option, or is it a compiler extension implemented by gcc, clang, and maybe other compilers? Can I rely on its availability? I couldn't find th...

1 answer  ·  posted 11mo ago by alx‭  ·  last activity 11mo ago by InfiniteDissent‭

How to write a macro that discards the const qualifier, for any type? I hope some combination of typeof and a cast will do, but haven't found the combination. I tried this, without luck: #define...

2 answers  ·  posted 10mo ago by alx‭  ·  last activity 5mo ago by alx‭

I'd like to assert that some code can be optimized out, and is not present in the final binary object. #define CONSTANT 0 #if (!CONSTANT) [[landmine_A]] #endif static int foo(void); void...

1 answer  ·  posted 9mo ago by alx‭  ·  last activity 9mo ago by alx‭

Let's analyze this code, assuming an architecture where the alignment of int64_t is the same as that of double: void bar(double *f, int64_t *j) { *(int64_t *)f = *j; } void foo(void) ...

1 answer  ·  posted 2mo ago by alx‭  ·  edited 2mo ago by Lundin‭

It can't be done with git-send-email(1), but there's a tool that integrates with it, and is very simple to use: patatt(1). Install the tool: $ sudo apt-get install patatt And then for each rep...

posted 9mo ago by alx‭  ·  edited 9mo ago by alx‭

Calling an undefined function will have that behavior at link time: landmine.c: #ifndef CONSTANT #define CONSTANT 0 #endif #define assert_not_in_binary_if(e) do \ { \ if (e) \ undefi...

posted 9mo ago by alx‭  ·  edited 9mo ago by alx‭

I developed this macro (using GNU C) similar to C++'s const_cast(). #define const_cast(t, p) \ ({ ...

posted 5mo ago by alx‭  ·  edited 5mo ago by alx‭

After addressing @Lundin 's suggestions: Implemented in terms of libc functions for performance. const correctness style improvements I have a few more that I realized after trying to repla...

posted 4mo ago by alx‭  ·  edited 3mo ago by alx‭