Technorama

An omnibus of tech posts by a Futurologist on software development primarily.

Wednesday 31 July 2024

Plebiscite Greenland only 56,661 population

Greenland risks a plebiscite, that is an influx of more than the current population, who then vote in a referendum for independence from Denmark, where they are an autonomous territory. The Faeroe Islands also have a similar population and risk the same fate.

posted by 東京 # 12:08 0 Comments

Sunday 30 June 2024

Rate limit and CPU limit for Chrome and Firefox

Don't you often notice a lot of minimised windows are using up 60% CPU. Those pages are rotating animations etc.

Whats the solution? Well it's easy enough to do Ctrl+Z and send SIGINT, then on a shell we only need to type "fg", but what for web browsers? It also will work, but maybe things will timeout.

I'd therefore suggest a button on the top bar to rate limit to 1% CPU and 1% network speed (or 1KB sec), that's probably enough to keep connections open and return the computer to usability.

posted by 東京 # 10:29 0 Comments

Monday 6 May 2024

The Next Pandemic

Given we've had coronavirus circulating for thousands of years, and various outbreaks like SARS (2002), MERS (2012) and COVID (2019) it looks like given the global nature of travel we'll have another epidemic like SARS or a pandemic like COVID within a range of 6-10 years, the confidence of this date prediction is not high.

posted by 東京 # 19:25 0 Comments

Thursday 12 October 2023

Secure sandboxes

Seems easy, iPhone keeps getting malware owned by faulty image files.

Sandbox decoders

Run decompressors in a micro sandboxed VM. It it doesn't finish decoding and outputting an uncompressed bitmap file to a ramdrive within one second, just kill the sandbox. Saves being exploited. (Unless the sandbox VM can also be jailbreaked)

Compile the process in the sandbox with AddressSanitizer.

Have a system to automatically upload any coredumps from the sandbox crashes, either then, or after a reboot.

Probably those creating the security exploits will test on real devices a few times before they get a working crack. That gives you chance to get the coredump and backtrace.

posted by 東京 # 13:25 0 Comments

Wednesday 6 September 2023

gcc attribute nonnull considered harmful

gcc function attributes allow optimizer hints, set attribute nonnull and the optimizer will know it is never going to be a nullptr - so it will remove all nullptr checks!

This is often not what is expected by the humble programmer.

posted by 東京 # 23:10 0 Comments

Monday 10 April 2023

Chromium debug build with symbols

Navigate here

Click "Last Modified" heading

Then get the build folder number from the file LAST_CHANGE

posted by 東京 # 20:54 0 Comments

Tuesday 21 February 2023

Custom C/C++ assert example with file line and column information

// -fanalyzer -DNDEBUG -Wno-analyzer-use-of-uninitialized-value

#include <string>
#include <iostream>
#include <string_view>
#include <source_location>

// Pass const std::source_location location = std::source_location::current()
#if NDEBUG
#define myassert(x, s, l)
#else
#define myassert(x, s, l) if(!x)  {printf("%s:%d:%d %s %s\n", l.file_name(), l.line(), l.column(), l.function_name(), s); fflush(stdout); abort();}
#endif

#define TRIGGER_NULLPTR_WARNING 1

std::string make_std_string(const char * const str, const std::source_location location =
               std::source_location::current())
{
    myassert((nullptr != str), "nullptr dereference", location);

#if TRIGGER_NULLPTR_WARNING
    // This line ensures: warning: dereference of NULL '0' [CWE-476] [-Wanalyzer-null-dereference]
    char b = *str; 
#endif

    std::string s(str);
#if TRIGGER_NULLPTR_WARNING
    s[0] = b;
#endif

    return s;
}

int main()
{
    const char * a = NULL;
    std::string result = make_std_string(a);
    std::cout << result;
}

posted by 東京 # 21:39 0 Comments

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