Bug 201826 - Calls to nice(2) will fail with errno set to EACCES rather than EPERM
Calls to nice(2) will fail with errno set to EACCES rather than EPERM
Status: CLOSED RAWHIDE
Product: Fedora
Classification: Fedora
Component: glibc (Show other bugs)
5
All Linux
medium Severity medium
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Assigned To: Jakub Jelinek
Brian Brock
:
Depends On:
Blocks:
  Show dependency treegraph
 
Reported: 2006-08-09 00:02 EDT by William Kucharski
Modified: 2007-11-30 17:11 EST (History)
0 users

See Also:
Fixed In Version: 2.4.90-20
Doc Type: Bug Fix
Doc Text:
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Clone Of:
Environment:
Last Closed: 2006-08-15 10:19:45 EDT
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Regression: ---
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oVirt Team: ---
RHEL 7.3 requirements from Atomic Host:
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Description William Kucharski 2006-08-09 00:02:00 EDT
Description of problem:

The man page for nice(2) states:

ERRORS
       EPERM  The  calling  process attempted to increase its priority by sup-
              plying a negative inc but has  insufficient  privileges.   Under
              Linux  the  CAP_SYS_NICE  capability  is required.  (But see the
              discussion of the RLIMIT_NICE resource limit in setrlimit(2).)

However, glibc() converts a call to nice(2) into a call to setpriority(2)
which WILL return with errno set to EACCES.

An strace of the program:

#include <errno.h>

main()
{
        if (nice(-19) < 0)
                printf("%d\n", errno);
}

shows it in reality calls:

setpriority(PRIO_PROCESS, 0, 4294967277) = -1 EACCES (Permission denied)

Version-Release number of selected component (if applicable):

glibc-2.4.8

How reproducible:

Run the test program above.

Steps to Reproduce:
1. Compile the code snippet above
2. Run
3. See incorrect errno set
  
Actual results:

failure with errno set to EACCES

Expected results:

failure with errno set to EPERM

Additional info:

This isn't just a man page error, as if the legacy nice syscall is invoked,
it reacts as documented.

For example, this program:

#include <sys/types.h>
#include <sys/syscall.h>
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <errno.h>

main()
{
        if (nice(-19) < 0)
                printf("%d\n", errno);

        if (syscall(__NR_nice, -19) < 0)
                printf("%d\n", errno);
}

will return:

$ ./a.out
13
1
Comment 1 Jakub Jelinek 2006-08-15 10:19:45 EDT
Fixed in upstream CVS and glibc-2.4.90-20 in rawhide.

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