Pushl | Push notification adapter for feeds
kandi X-RAY | Pushl Summary
kandi X-RAY | Pushl Summary
A simple tool that parses content feeds and sends out appropriate push notifications (WebSub, webmention, etc.) when they change. See for the motivation.
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Top functions reviewed by kandi - BETA
- Parse arguments
- Sends a pingback
- Get an item from the cache
- Add headers to kwargs
- Wrapper for POST requests
- Run a pushl
- Process an entry
- Process a new entry
- Run all pending subtasks
- Parse the request result
- Extract text from data
- Sends a request
- Consume a feed
Pushl Key Features
Pushl Examples and Code Snippets
Community Discussions
Trending Discussions on Pushl
QUESTION
I am currently learning assembler for x86 with att syntax. Over the past time I have already written exercise programs without dependencies. Now I wanted to try writing a shared shared-library, as this is what I do in C most of the time.
I thought it may be a good idea to write a simple "test" program, which consists of an, in asm written, test-library and a program, that links to this test-library.
I assembled the library with: as -32 prog.s -o prog.o
and the caller with: as -32 startprog.s -o startprog.o
After I assembled both files, I ran the linker on the library with ld -melf_i386 -fPIE -shared prog.o -o libprog.so
and on the caller ld -melf_i386 startprog.o -L./ -lprog -o startprog
Up to this point everything worked fine. But then I tried to run the program ./startprog
, which causes a Segment violation. I re-ran with gdb
and set _start
as a breakpoint. As soon as I entered r
into gdb, to actually start the execution,
I was greeted with the same SIGSEGV. It seems to occur in the libc
write()
function. At least that is, what I can make of this.
The complete output looks like this:
...ANSWER
Answered 2022-Apr-01 at 11:39As stated in the UPDATE, i've got it working by patching the runtime of the ELF with patchelf --set-interpreter /lib/ld-linux.so.2 startprog
Also as stated, if anyone knows, why it automatically assigned the libc as the runtime, I would be pretty thankful, if they would post the answer. It confuses me to no end any I would like to avoid patching the binary every time.
QUESTION
I try to understand the stack framework by the GAS, and a recursive function assembly case is shown here, as a 32-bit x86 program for Linux:
...ANSWER
Answered 2022-Mar-29 at 21:21The pseudo code was missing a PUSH RET -> PUSH EBP
after the PUSH 1
:
QUESTION
I have a problem with execution of the project compiled in eclipse Version: 2021-12 (4.22.0)
The program is just 2 files:
- function.asm
ANSWER
Answered 2022-Jan-04 at 21:01I've changed the Tool Settings to:
QUESTION
I have this assembly file prog.S :
...ANSWER
Answered 2021-Dec-13 at 08:12The assembler can solve jumping/calling myGlobalFunction
defined in the same section at asm-time, and sometimes it does so, as Peter Cordes investigated.
However, as the function is declared global, it is assumed to be available from other sections, too.
Assembler thinks that your .text
section from the file prog.o
might be statically linkable to other programs at link-time. You are right that in such case other.o
declares myGlobalFunction
as external, the relocation record should be generated into other.o
, and relocation of call myGlobalFunction
in prog.o
is superabundant. Perhaps clang.exe assumes that the symbol myGlobalFunction
is potentially weak and that it could be replaced at link-time with homonymous global symbol defined in someother.o
, also linked together with other.o
and prog.o
.
Call of a global function in the same section could be resolved at compile time. My guess is that Clang defers this to link-time and generates RIP-relative relocation to enable future replacement of the target function from other module.
QUESTION
I'm a newbie to 80386 assembly language. Currently struggling on a school assignment that asks to write a function in assembly language that will be called in a c program.
extern int count(char *string, char c);
I think I have a sense of how this should be done, but still struggling with choosing the right instruction(instruction ends with 'b', 'w' or 'l') and perhaps the "right" register, I know there are some that are reserved to certain purposes.
...ANSWER
Answered 2021-Oct-21 at 20:49I do not program in assembler so I asked gcc to compile it for me:
QUESTION
First I tried opening a file with fopen function and print content of the file using fprint function but it was just printing a bunch of symbols to the terminal.
After a while I realized that it does not take pointer to a stream as argument and above mentioned behaviour was expected. It was printing the actual pointer value. putc or puts function also does not seem to take a pointer to the file I/O stream as an argument.
My best guess right now is I have to access the buffer fopen function created somehow! But I have no idea how or if it is possible. To sum it all up I am absolutely stuck right now.
The ultimate goal here is to get input from STDIN and/or a file do some processing on the text(eg: lowercase to uppercase) and output the result to STDOUT and/or a file. I figured If I am able to get the answer to above mentioned problem then It should help with the ultimate goal maybe.
PS: Let me know If the question can be improved in any way. Thank you.
Maybe the following code will help to get a better understanding of what I am trying to say.
...ANSWER
Answered 2021-Aug-19 at 13:46You need to first read from the file using fread
or fgets
or some other function and then write what you read to standard output. There is no shortcut to directly print the contents of one file.
QUESTION
I'm going through a book named Programming from the ground up by Jonathan Bratlett. This book teaches assembly language for x86 processors and the linux operating system using GCC toolset.
In unit 7 which teaches about error handling, you are asked to modify an existing program to add a recovery mechanism for the program that allows it to read from STDIN if it cannot open the standard file already hard coded in the program.
The problem here is that user entered filename from the STDIN is appended with \n at the end by default. So the program does not find the file to read from.
I have to replace the \n with 0 manually in the program for it to work. And it does not feel like the proper way to handle this situation. How do I go about solving this problem properly?
PS: This is my first time asking a question here. Please let me know If I can improve the question in any way. Thank you.
Here is the code:
...ANSWER
Answered 2021-Aug-17 at 15:35It's normal to need to manually handle newlines in terminal / file input. read
system calls just give you access to the raw byte stream, no parsing.
That's why it's normal to take filenames from command-line args (like cat foo.txt
), rather than a list of files from stdin.
And why in Unix shell programming, you definitely want to avoid parsing filenames out of a text stream: https://unix.stackexchange.com/questions/128985/why-not-parse-ls-and-what-to-do-instead - and why things like find -print0
and xargs -0
to use \0
as a separator exist.
\n
is a legal character that can appear in filenames, so the only way to safely/unambiguously parse filenames from stdin is to separate them with the one byte that can't appear in filenames, 0
, the C string terminator. (Or to use some kind of format with explicit lengths, so you'd know the next 123 characters were all filename regardless of what they were.)
For a single filename, you could also expect the user to end their input at the end of the filename, e.g. submitting TTY input by pressing the EOF character (control-D by default, run stty
to show terminal modes).
Then you can directly use the result of read()
into an already-zeroed buffer as a C string. (Except that still doesn't fully let you handle newlines in filenames with the terminal not in raw mode; the user typing a newline would cause the terminal input to be submitted, i.e. read()
would return. However, the user can work around that by using control-V to make the next character "literal", letting them hit ^V enter to type a literal newline without submitting input with the TTY in "cooked" canonical mode. Try it yourself typing into cat
or strace cat
on a terminal, along with what happens when you type control-D on a non-empty line (read returns non-zero), vs. on an empty line (or after a previous control-D) to make read return zero, i.e. EOF)
QUESTION
Assembly language program to read in a (three-or-more-digit) positive integer as a string and convert the string to the actual value of the integer.
Specifically, create a subroutine to read in a number. Treat this as a string, though it will be composed of digits. Also, create a subroutine to convert a string of digits to an integer.
Do not have to test for input where someone thought i8xc was an integer.
I am doing it like this. Please help.
...ANSWER
Answered 2021-Aug-08 at 18:28Proper interaction with operating system is missing.
In the end:
you pushed the result but the following addl $8, %esp
invalidates the pushed value and the final ret
incorrectly leads the instruction flow to whatever garbage was in the memory pointed by SS:ESP+4
at the program entry.
When you increase the stack pointer, you cannot rely that data below ESP will survive.
Your program does not interact with its user, if you want it to print something, use system function to write.
QUESTION
I am currently writing a bit of x86
assembly code and linking it with glibc using as
and ld
.
ANSWER
Answered 2021-Jul-20 at 21:18strcat(str3, str1)
concatenates str1
onto the end of str3
by copying the bytes of str1
into memory starting at the terminating null byte of str3
. So the terminating null of str3
gets overwritten by the character '\n'
, and a new terminating null is written to the following byte. But guess what: the byte immediately following the terminating null of str3
is the first byte of str4
. So you've just overwritten the first byte of str4
with a null byte. Hence it behaves like an empty string when you go to print it later.
You could add an extra byte of space between each of your strings to avoid this. But more broadly, it isn't really sensible for a writeLine
function to modify the string it is passed, so a better plan would be to redesign it so it doesn't need to do that. For instance, you could write the passed string with one call to puts
(which already appends a newline), and if you want an additional newline, make a separate call to putc
.
QUESTION
I'm confused a little with my book, take a look at this:
...ANSWER
Answered 2021-Jul-07 at 19:43The return address is a pointer to code that is pushed onto the stack by the caller, typically by a call
instruction. Since that is pushed by the caller, that value (and any others pushed by the caller) are necessarily on the stack before the first machine code instruction of f
runs. The convention requires that the return address is the top thing on the stack upon (the control flow) transition from caller to callee.
So, just before the start of f
there's return address on the stack. The return address is sometimes called linkage in older texts. It is a parameter passed by the caller that the callee uses to know where to return. Passing the return address as a parameter for the callee to use allows the function (here f
) to be called from many different places (at many different depths of the call chain), and always return to its caller, no matter who that is.
The return address and rbp are different. We cannot say how rbp is used by the caller here b/c we don't see the caller. However, the rbp register is required — by the calling convention — to retain its original value upon return from callee to caller. Thus, since this callee chooses to modify the rbp value (for no apparent reason, though), it is necessary to also restore the original rbp value before returning, which it does.
It is called an old rbp b/c at the time of transition from caller to callee, the rbp value belongs to someone higher up in the call stack, and is not the rbp value that pertains to f
(but rather to f
s callers).
We can't say what is in rbp that belongs to the callers, however, f
, chooses to use rbp as a pointer to data, specifically stack data (it doesn't use it though).
- Is return address actually the value of rbp the very first time we entered main's frame?
No. rbp is generally used as a pointer to the stack, called a frame pointer, it is separate from the return address.
- If so, why it's not called old rbp as others? what's if f calls another function should we call it return address or rbp?
If f
calls another function there will be at least 2 return addresses on the stack. rbp is another matter, and if main
and f
use a frame pointer (and f
calls another function) then there will be at least one frame pointer (main
s as f
put it there) on the stack as well.
- return address is the return address for main and has nothing to do with f() right?
We can't say from this snippet that main
called f
. f
should be callable by virtually any caller. If main
did call f
then the return address represents the dynamic linkage of main
calling f
. It would be ok, for example, for main
to call f
from two different places in main
s implementation. At each different call site in main
, a different code address would be passed to f
as the return address, and f
would use the passed return address parameter to dynamically return to the proper caller & call site.
Suggest you try a small example and single step in the debugger. Keep an eye on stack pushes (and the value pushed) & pops and watch the control flow transition from caller to callee and all the way back again.
Community Discussions, Code Snippets contain sources that include Stack Exchange Network
Vulnerabilities
No vulnerabilities reported
Install Pushl
Anything with a class of h-entry
An <article> tag
Anything with a class of entry
You can install it using pip with e.g.:.
In my setup, I have pushl installed in my website's pipenv:.
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