Re: sendfile syscall offset bug ???

Re: sendfile syscall offset bug ???

[ericonr]

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New comment by ericonr on void-packages repository

https://github.com/void-linux/void-packages/issues/30741#issuecomment-835498277

Comment:
Is this not reproducible with C? What happens if you use sendfile as the function exposed by libc? Does it behave differently with different kernel versions?

Re: sendfile syscall offset bug ???

[Duncaen]

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New comment by Duncaen on void-packages repository

https://github.com/void-linux/void-packages/issues/30741#issuecomment-835791971

Comment:
This has nothing to do with void linux, you are using the syscall wrong. lseek takes off_t and sendfile takes a off_t pointer.

Re: sendfile syscall offset bug ???

[malv-c]

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New comment by malv-c on void-packages repository

https://github.com/void-linux/void-packages/issues/30741#issuecomment-835813595

Comment:
sorry Duncaen
i didn't read the man correctly

Re: sendfile syscall offset bug ???

[Duncaen]

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New comment by Duncaen on void-packages repository

https://github.com/void-linux/void-packages/issues/30741#issuecomment-835791971

Comment:
This has nothing to do with void linux, you are using the syscall wrong. lseek takes off_t and sendfile tasks a off_t pointer.

Re: sendfile syscall offset bug ???

[Duncaen]

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New comment by Duncaen on void-packages repository

https://github.com/void-linux/void-packages/issues/30741#issuecomment-835791971

Comment:
This has nothing to do with void linux, you are using the syscalls wrong. lseek takes off_t and sendfile tasks a off_t pointer.

Re: sendfile syscall offset bug ???

[malv-c]

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New comment by malv-c on void-packages repository

https://github.com/void-linux/void-packages/issues/30741#issuecomment-835765757

Comment:
for small tasks the time c exec is loaded asm exec did the job ...
also to return to code in c may aska long time
and the c lib can put any values where it want
to know it you just have to verify the code
reverify it after compilation
with the hope nothing happen while installing
deal only with kernel problems is less painfull
anyway i can test anything you want ...

Re: sendfile syscall offset bug ???

[malv-c]

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New comment by malv-c on void-packages repository

https://github.com/void-linux/void-packages/issues/30741#issuecomment-835765753

Comment:
for small tasks the time c exec is loaded asm exec did the job ...
also to return to code in c may aska long time
and the c lib can put any values where it want
to know it you just have to verify the code
reverify it after compilation
with the hope nothing happen while installing
deal only with kernel problems is less painfull
anyway i can test anything you want ...

Re: sendfile syscall offset bug ???

[malv-c]

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New comment by malv-c on void-packages repository

https://github.com/void-linux/void-packages/issues/30741#issuecomment-835745838

Comment:
sorry all  you don't know asm
me too i restart it
but i know enough to understand that sendfile off_t refuse the integer lseek one accept
also the exit value and size_t work
[sf.txt](https://github.com/void-linux/void-packages/files/6447150/sf.txt)
commented source of working example for too busy people to change a value in code ;) Duncaen

% strace ./sf3-3 +255 =q sf3.s b*
execve("./sf3-3", ["./sf3-3", "+255", "=q", "sf3.s", "bb", "bh%", "bh0"], 0x7ffc6a137880 /* 42 vars */) = 0
open("q", O_WRONLY|O_CREAT|O_TRUNC|O_LARGEFILE|O_NOATIME, 0777) = 3
open("sf3.s", O_RDONLY)                 = 4
sendfile(3, 4, NULL, 255)               = 255
open("bb", O_RDONLY)                    = 5
sendfile(3, 5, NULL, 255)               = 255
open("bh%", O_RDONLY)                   = 6
sendfile(3, 6, NULL, 255)               = 255
open("bh0", O_RDONLY)                   = 11
sendfile(3, 11, NULL, 255)              = 255
exit_group(0)                           = ?
+++ exited with 0 +++
/tmp
% strace ./sf3-3 ^255 =qf sf3.s b*
execve("./sf3-3", ["./sf3-3", "^255", "=qf", "sf3.s", "bb", "bh%", "bh0"], 0x7ffde3499810 /* 42 vars */) = 0
open("qf", O_WRONLY|O_CREAT|O_TRUNC|O_LARGEFILE|O_NOATIME, 0777) = 3
open("sf3.s", O_RDONLY)                 = 4
sendfile(3, 4, 0xff, 4611686018427387904) = -1 EFAULT (Bad address)
open("bb", O_RDONLY)                    = 5
sendfile(3, 5, 0xff, 4611686018427387904) = -1 EFAULT (Bad address)
open("bh%", O_RDONLY)                   = 6
sendfile(3, 6, 0xff, 4611686018427387904) = -1 EFAULT (Bad address)
open("bh0", O_RDONLY)                   = 11
sendfile(3, 11, 0xff, 4611686018427387904) = -1 EFAULT (Bad address)
exit_group(255)                         = ?
+++ exited with 255 +++


% strace ./sf3 +63 :q qq qqa qqs qqw
execve("./sf3", ["./sf3", "+63", ":q", "qq", "qqa", "qqs", "qqw"], 0x7ffeaec3d830 /* 42 vars */) = 0
open("q", O_RDONLY)                     = 3
open("qq", O_WRONLY|O_CREAT|O_TRUNC|O_LARGEFILE|O_NOATIME, 0777) = 4
sendfile(4, 3, NULL, 63)                = 63
open("qqa", O_WRONLY|O_CREAT|O_TRUNC|O_LARGEFILE|O_NOATIME, 0777) = 5
lseek(3, 0, SEEK_SET)                   = 0
sendfile(5, 3, NULL, 63)                = 63
open("qqs", O_WRONLY|O_CREAT|O_TRUNC|O_LARGEFILE|O_NOATIME, 0777) = 6
lseek(3, 0, SEEK_SET)                   = 0
sendfile(6, 3, NULL, 63)                = 63
open("qqw", O_WRONLY|O_CREAT|O_TRUNC|O_LARGEFILE|O_NOATIME, 0777) = 11
lseek(3, 0, SEEK_SET)                   = 0
sendfile(11, 3, NULL, 63)               = 63
exit_group(0)                           = ?
+++ exited with 0 +++
/tmp
% strace ./sf3 ^63 :q qq qqa qqs qqw
execve("./sf3", ["./sf3", "^63", ":q", "qq", "qqa", "qqs", "qqw"], 0x7ffcf6c22ce0 /* 42 vars */) = 0
open("q", O_RDONLY)                     = 3
open("qq", O_WRONLY|O_CREAT|O_TRUNC|O_LARGEFILE|O_NOATIME, 0777) = 4
sendfile(4, 3, 0x3f, 4611686018427387904) = -1 EFAULT (Bad address)
open("qqa", O_WRONLY|O_CREAT|O_TRUNC|O_LARGEFILE|O_NOATIME, 0777) = 5
lseek(3, 63, SEEK_SET)                  = 63
sendfile(5, 3, 0x3f, 4611686018427387904) = -1 EFAULT (Bad address)
open("qqs", O_WRONLY|O_CREAT|O_TRUNC|O_LARGEFILE|O_NOATIME, 0777) = 6
lseek(3, 63, SEEK_SET)                  = 63
sendfile(6, 3, 0x3f, 4611686018427387904) = -1 EFAULT (Bad address)
open("qqw", O_WRONLY|O_CREAT|O_TRUNC|O_LARGEFILE|O_NOATIME, 0777) = 11
lseek(3, 63, SEEK_SET)                  = 63
sendfile(11, 3, 0x3f, 4611686018427387904) = -1 EFAULT (Bad address)
exit_group(63)                          = ?
+++ exited with 63 +++


% strace ./sf3 ^63 b*
execve("./sf3", ["./sf3", "^63", "bb", "bh%", "bh0"], 0x7ffff06f9d30 /* 42 vars */) = 0
open("bb", O_RDONLY)                    = 3
fcntl(1, F_SETFL, O_RDONLY)             = 0
sendfile(1, 3, 0x3f, 4611686018427387904) = -1 EFAULT (Bad address)
open("bh%", O_RDONLY)                   = 4
sendfile(1, 4, 0x3f, 4611686018427387904) = -1 EFAULT (Bad address)
open("bh0", O_RDONLY)                   = 5
sendfile(1, 5, 0x3f, 4611686018427387904) = -1 EFAULT (Bad address)
exit_group(63)                          = ?
+++ exited with 63 +++
/tmp
% strace ./sf3 +63 b*
execve("./sf3", ["./sf3", "+63", "bb", "bh%", "bh0"], 0x7fff8f955ab0 /* 42 vars */) = 0
open("bb", O_RDONLY)                    = 3
fcntl(1, F_SETFL, O_RDONLY)             = 0
sendfile(1, 3, NULL, 63export HISTCONTROL=ignoredups:erasedups
shopt -s histreedit his)                = 63
open("bh%", O_RDONLY)                   = 4
sendfile(1, 4, NULL, 63AE ri
M
man tr
ll /bin/tr 
gcl https://github.com/coreutils/cor)                = 63
open("bh0", O_RDONLY)                   = 5
sendfile(1, 5, NULL, 63./sbx  -z 
alsactl store
alsamixer 
create_ap --help |more
ee /)                = 63
exit_group(0)                           = ?
+++ exited with 0 +++