Where is std::ostream::gcount()???

[flat gate]

Literally fwrite() shows you the number of bytes which were written successfully???

[subtle berry]

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[sonic owl]

What does it mean

[flat gate]

it says it in the post

[quiet cedar]

check the streambuf directly if you wanna mimic it

use sputn, rdbuf that spits back to the count of chars written

or, for file streams, grab tellp before and after you write

substract to get the diff.. assuming its seekable

[flat gate]

meh

[flat gate]

how do you access this thing in a
std::ofstream writer("f.txt");
?

[quiet cedar]

there is no direct gcount for output

thats input territory

but to get how many bytes actually hit the file grab the streambuf and use sputn

[sonic owl]

gcount means get count

[flat gate]

so you mean

char rawData[1024];
init(&rawData);
size_t bytesWritten = f.rdbuf()->sputn(rawData, sizeof(rawData));

this?

[dark wharf]

what for do you need the count in particular? a write either succeeds, i.e., writes as much as you told it to write, or it fails?

[flat gate]

if a pipe has 30 bytes available out of 4096 total capacity, and I forcefully write 1024 bytes in it, will it successfully write the first 30 bytes, and then I need to manually issue a second write and then block (that is exactly what pipe() linux man page says), or will it block without writing 30 bytes? that's why

check my last post about popen, I gave up and used fwrite

[dark wharf]

k ^^

[flat gate]

oh and, due to fopen's internal buffer and flushing, a.k.a. write(1, buff, dataLen) runs, GOD knows when, this gets more complicated

[dark wharf]

yeah. tbh, I'd just use the plain posix functions for stuff like pipes.

[flat gate]

ye, good thing I know the raw system calls lmao

!solved

[subtle berry]

Thank you and let us know if you have any more questions!

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[flat gate]

oh and,
my beloved strace
can reveal black box binaries' write() calls to stdout fd 1