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/*
* Oracle Linux DTrace.
* Copyright (c) 2025, Oracle and/or its affiliates. All rights reserved.
* Licensed under the Universal Permissive License v 1.0 as shown at
* http://oss.oracle.com/licenses/upl.
*/
/*
* NAME
* errno.d - list and count the system calls with a non-zero errno value
*
* SYNOPSIS
* sudo dtrace -s errno.d
*
* DESCRIPTION
* Trace every system call that returns a non-zero value in errno.
* Show the name of the function, the value of errno and how often
* this function returned a non-zero value for errno.
*
* NOTES
* - The script needs to be terminated with ctrl-C. In case the
* script is running in the background, get it to run in the
* foreground first by using the fg command and then use ctrl-C
* to terminate the process. Otherwise, typing in ctrl-C will do.
*
* - The value of errno is available upon the return from the system call.
*
* - To present the results in a compact form, we use an aggregation
* called syscalls. Otherwise we may get several screens with the
* information. Plus that we then can't easily count the functions.
*
* - Although the results of an aggregation are automatically
* printed when the tracing terminates, in this case, we want to
* control the format of the output. This is why the results are
* printed using printa() in the END probe
*/
/*
* Store the information in an aggregation called syscalls.
* Use the predicate to only allow non-zero errno values that are
* within the range for errno.
*/
syscall:::return
/ errno > 0 && errno <= ERANGE /
{
@syscalls[probefunc,errno] = count();
}
/*
* The printf() line prints the header of the table to follow.
*/
END
{
printf("%20s %5s %5s\n\n","syscall","errno","count");
printa("%20s %5d %@5d\n",@syscalls);
}
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