make -C /lib/modules/5.13.0-37-generic/build M=/home/a1085551/osc10e/ch2 modules
make[1]: Entering directory '/usr/src/linux-headers-5.13.0-37-generic'
CC [M] /home/a1085551/osc10e/ch2/hello.o
/home/a1085551/osc10e/ch2/hello.c: In function ‘proc_init’:
/home/a1085551/osc10e/ch2/hello.c:42:41: error: passing argument 4 of ‘proc_create’ from incompatible pointer type [-Werror=incompatible-pointer-types]
42 | proc_create(PROC_NAME, 0, NULL, &proc_ops);
| ^~~~~~~~~
| |
| struct file_operations *
In file included from /home/a1085551/osc10e/ch2/hello.c:16:
./include/linux/proc_fs.h:110:24: note: expected ‘const struct proc_ops *’ but argument is of type ‘struct file_operations *’
110 | struct proc_dir_entry *proc_create(const char *name, umode_t mode, struct proc_dir_entry *parent, const struct proc_ops *proc_ops);
| ^~~~~~~~~~~
/home/a1085551/osc10e/ch2/hello.c: In function ‘proc_read’:
/home/a1085551/osc10e/ch2/hello.c:89:9: warning: ignoring return value of ‘copy_to_user’, declared with attribute warn_unused_result [-Wunused-result]
89 | copy_to_user(usr_buf, buffer, rv);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
cc1: some warnings being treated as errors
make[2]: *** [scripts/Makefile.build:281: /home/a1085551/osc10e/ch2/hello.o] Error 1
make[1]: *** [Makefile:1879: /home/a1085551/osc10e/ch2] Error 2
make[1]: Leaving directory '/usr/src/linux-headers-5.13.0-37-generic'
make: *** [Makefile:3: all] Error 2
https://github.com/greggagne/osc10e/tree/master/ch2
I try to make the hello kernel module from that link but ended up with this error.
As said in the comments from tsyvarev, in your kernel version "5.13.0-37", the prototype of proc_create() changed. You need to look at the header files of your kernel version. For example, under an Ubuntu distribution, you can find the header file in /usr/src/linux-headers-5.13.0-37-generic/include/linux/proc_fs.h:
$ cat /usr/src/linux-headers-5.13.0-37-generic/include/linux/proc_fs.h
[...]
struct proc_ops {
unsigned int proc_flags;
int (*proc_open)(struct inode *, struct file *);
ssize_t (*proc_read)(struct file *, char __user *, size_t, loff_t *);
ssize_t (*proc_read_iter)(struct kiocb *, struct iov_iter *);
ssize_t (*proc_write)(struct file *, const char __user *, size_t, loff_t *);
/* mandatory unless nonseekable_open() or equivalent is used */
loff_t (*proc_lseek)(struct file *, loff_t, int);
int (*proc_release)(struct inode *, struct file *);
__poll_t (*proc_poll)(struct file *, struct poll_table_struct *);
long (*proc_ioctl)(struct file *, unsigned int, unsigned long);
#ifdef CONFIG_COMPAT
long (*proc_compat_ioctl)(struct file *, unsigned int, unsigned long);
#endif
int (*proc_mmap)(struct file *, struct vm_area_struct *);
unsigned long (*proc_get_unmapped_area)(struct file *, unsigned long, unsigned long, unsigned long, unsigned long);
} __randomize_layout;
[...]
struct proc_dir_entry *proc_create(const char *name, umode_t mode, struct proc_dir_entry *parent, const struct proc_ops *proc_ops);
[...]
Hence, you can modify the source code of hello.c as:
/**
* hello.c
*
* Kernel module that communicates with /proc file system.
*
* The makefile must be modified to compile this program.
* Change the line "simple.o" to "hello.o"
*
* Operating System Concepts - 10th Edition
* Copyright John Wiley & Sons - 2018
*/
#include <linux/init.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/proc_fs.h>
#include <asm/uaccess.h>
#define BUFFER_SIZE 128
#define PROC_NAME "hello"
#define MESSAGE "Hello World\n"
/**
* Function prototypes
*/
static ssize_t proc_read(struct file *file, char *buf, size_t count, loff_t *pos);
static struct proc_ops proc_ops = {
.proc_read = proc_read,
};
/* This function is called when the module is loaded. */
static int proc_init(void)
{
// creates the /proc/hello entry
// the following function call is a wrapper for
// proc_create_data() passing NULL as the last argument
proc_create(PROC_NAME, 0, NULL, &proc_ops);
printk(KERN_INFO "/proc/%s created\n", PROC_NAME);
return 0;
}
/* This function is called when the module is removed. */
static void proc_exit(void) {
// removes the /proc/hello entry
remove_proc_entry(PROC_NAME, NULL);
printk( KERN_INFO "/proc/%s removed\n", PROC_NAME);
}
/**
* This function is called each time the /proc/hello is read.
*
* This function is called repeatedly until it returns 0, so
* there must be logic that ensures it ultimately returns 0
* once it has collected the data that is to go into the
* corresponding /proc file.
*
* params:
*
* file:
* buf: buffer in user space
* count:
* pos:
*/
static ssize_t proc_read(struct file *file, char __user *usr_buf, size_t count, loff_t *pos)
{
int rv = 0;
char buffer[BUFFER_SIZE];
static int completed = 0;
if (completed) {
completed = 0;
return 0;
}
completed = 1;
rv = sprintf(buffer, "Hello World\n");
// copies the contents of buffer to userspace usr_buf
copy_to_user(usr_buf, buffer, rv);
return rv;
}
/* Macros for registering module entry and exit points. */
module_init( proc_init );
module_exit( proc_exit );
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Hello Module");
MODULE_AUTHOR("SGG");
The compilation result is:
$ make
make -C /lib/modules/5.13.0-37-generic/build M=... modules
make[1]: Entering directory '/usr/src/linux-headers-5.13.0-37-generic'
LD [M] /.../hello.ko
BTF [M] /.../hello.ko
Skipping BTF generation for /.../hello.ko due to unavailability of vmlinux
make[1]: Leaving directory '/usr/src/linux-headers-5.13.0-37-generic'
The execution is:
$ sudo insmod hello.ko
$ lsmod | grep hello
hello 16384 0
$ cat /proc/hello
Hello World
I tried with
extern void __NSAutoreleaseNoPool(void* obj);
but that results in an unresolved symbol when linking (not sure what Framework it needs, though).
I also tried
dlsym(RTLD_DEFAULT, "__NSAutoreleaseNoPool")
but that just gives be NULL.
And I tried with _dyld_lookup_and_bind and NSLookupSymbolInImage but they also don't work.
dsymutil and nm both find the symbol, though:
$ dsymutil -s --arch=x86_64
----------------------------------------------------------------------
/System/Library/Frameworks/CoreFoundation.framework/Versions/A/CoreFoundation
----------------------------------------------------------------------
Symbol table for: '/System/Library/Frameworks/CoreFoundation.framework/Versions/A/CoreFoundation' (x86_64)
----------------------------------------------------------------------
Index n_strx n_type n_sect n_desc n_value
======== -------- ------------------ ------ ------ ----------------
[ 0] 00010795 1e (PEXT SECT ) 01 0000 0000000000000000 '__mh_dylib_header'
[ 1] 000107a7 0e ( SECT ) 01 0000 0000000000001c20 '+[NSObject(NSObject) load]'
[ 2] 000107c2 0e ( SECT ) 01 0000 0000000000002630 '___exceptionInit'
[ 3] 000107d3 0e ( SECT ) 01 0000 00000000000029e0 '___CFgetenv'
[ 4] 000107df 0e ( SECT ) 01 0000 0000000000002a50 '___CFBaseInitialize'
...
[ 1923] 0001e820 0e ( SECT ) 01 0000 000000000010ad30 '___NSAutoreleaseNoPool'
...
$ nm -arch x86_64 /System/Library/Frameworks/CoreFoundation.framework/Versions/A/CoreFoundation
...
000000000010ad30 t ___NSAutoreleaseNoPool
...
(That is on MacOSX 10.6. On later MacOSX versions, the symbol really does not seem to exists, at least I cannot find any ref via grep in /usr/lib and /System/Library/Frameworks and also LLDB does not find it. Probably it was removed somehow with ARC.)
So, how can I get that address in my code?
(Related questions: here and here)
(My motivation to do this is here.)
This works:
#include <dlfcn.h>
#include <stdio.h>
#import <Foundation/Foundation.h>
#include <mach-o/dyld.h>
#include <mach-o/nlist.h>
#include <string.h>
#include <assert.h>
// Adapted from:
// https://github.com/0xced/iOS-Artwork-Extractor/blob/master/Classes/FindSymbol.c
// Adapted from MoreAddrToSym / GetFunctionName()
// http://www.opensource.apple.com/source/openmpi/openmpi-8/openmpi/opal/mca/backtrace/darwin/MoreBacktrace/MoreDebugging/MoreAddrToSym.c
void *FindSymbol(const struct mach_header *img, const char *symbol)
{
if ((img == NULL) || (symbol == NULL))
return NULL;
// only 64bit supported
#if defined (__LP64__)
if(img->magic != MH_MAGIC_64)
// we currently only support Intel 64bit
return NULL;
struct mach_header_64 *image = (struct mach_header_64*) img;
struct segment_command_64 *seg_linkedit = NULL;
struct segment_command_64 *seg_text = NULL;
struct symtab_command *symtab = NULL;
unsigned int index;
struct load_command *cmd = (struct load_command*)(image + 1);
for (index = 0; index < image->ncmds; index += 1, cmd = (struct load_command*)((char*)cmd + cmd->cmdsize))
{
switch(cmd->cmd)
{
case LC_SEGMENT_64: {
struct segment_command_64* segcmd = (struct segment_command_64*)cmd;
if (!strcmp(segcmd->segname, SEG_TEXT))
seg_text = segcmd;
else if (!strcmp(segcmd->segname, SEG_LINKEDIT))
seg_linkedit = segcmd;
break;
}
case LC_SYMTAB:
symtab = (struct symtab_command*)cmd;
break;
default:
break;
}
}
if ((seg_text == NULL) || (seg_linkedit == NULL) || (symtab == NULL))
return NULL;
unsigned long vm_slide = (unsigned long)image - (unsigned long)seg_text->vmaddr;
unsigned long file_slide = ((unsigned long)seg_linkedit->vmaddr - (unsigned long)seg_text->vmaddr) - seg_linkedit->fileoff;
struct nlist_64 *symbase = (struct nlist_64*)((unsigned long)image + (symtab->symoff + file_slide));
char *strings = (char*)((unsigned long)image + (symtab->stroff + file_slide));
struct nlist_64 *sym;
for (index = 0, sym = symbase; index < symtab->nsyms; index += 1, sym += 1)
{
if (sym->n_un.n_strx != 0 && !strcmp(symbol, strings + sym->n_un.n_strx))
{
unsigned long address = vm_slide + sym->n_value;
if (sym->n_desc & N_ARM_THUMB_DEF)
return (void*)(address | 1);
else
return (void*)(address);
}
}
#endif
return NULL;
}
typedef void (*NSAutoreleaseNoPoolFunc) (void* obj);
void getNSAutoreleaseNoPool() {
const struct mach_header* img = NSAddImage("/System/Library/Frameworks/CoreFoundation.framework/Versions/A/CoreFoundation", NSADDIMAGE_OPTION_NONE);
NSAutoreleaseNoPoolFunc f = (NSAutoreleaseNoPoolFunc) FindSymbol((struct mach_header*)img, "___NSAutoreleaseNoPool");
printf("func: %p\n", f);
if(f) {
NSObject* foo = [[NSObject alloc] init];
f(foo);
}
}
It gets the same function pointer as within GDB.
Note that you wont see the common NSAutoreleaseNoPool log:
2014-02-18 14:46:26.583 a.out[24989:a0b] *** __NSAutoreleaseNoPool(): Object 0x7fff71154190 of class NSCFString autoreleased with no pool in place - just leaking
The standard backtrace, when that happens, is this:
(gdb) bt
#0 0x00007fff8724bd34 in __NSAutoreleaseNoPool ()
#1 0x00007fff87196e79 in _CFAutoreleasePoolAddObject ()
#2 0x00007fff87196be6 in -[NSObject(NSObject) autorelease] ()
The actual NSLog call is done in _CFAutoreleasePoolAddObject.
A note about __NSAutoreleaseNoPool, from Foundation/NSDebug.h:
/**************** Autorelease pool debugging ****************/
// Functions used as interesting breakpoints in a debugger
// void __NSAutoreleaseNoPool(void *object);
// Called to log the "Object X of class Y autoreleased with no
// pool in place - just leaking" message. If an environment
// variable named "NSAutoreleaseHaltOnNoPool" is set with string
// value "YES", the function will automatically break in the
// debugger (or terminate the process).
// void __NSAutoreleaseFreedObject(void *freedObject);
// Called when a previously freed object would be released
// by an autorelease pool. If an environment variable named
// "NSAutoreleaseHaltOnFreedObject" is set with string value
// "YES", the function will automatically break in the debugger
// (or terminate the process).
So, if you want to debug such cases, either start up GDB and issue b __NSAutoreleaseNoPool to setup the breakpoint on this function. Or do an export NSAutoreleaseHaltOnNoPool=1 in your shell.
__NSAutoreleaseNoPool is pretty simple:
(gdb) disassemble
Dump of assembler code for function __NSAutoreleaseNoPool:
0x00007fff8724bd30 <__NSAutoreleaseNoPool+0>: push %rbp
0x00007fff8724bd31 <__NSAutoreleaseNoPool+1>: mov %rsp,%rbp
0x00007fff8724bd34 <__NSAutoreleaseNoPool+4>: nop
0x00007fff8724bd35 <__NSAutoreleaseNoPool+5>: nopl 0x0(%rax)
0x00007fff8724bd39 <__NSAutoreleaseNoPool+9>: lea 0x2ced8(%rip),%rdi # 0x7fff87278c18 <__PRETTY_FUNCTION__.27904+480>
0x00007fff8724bd40 <__NSAutoreleaseNoPool+16>: callq 0x7fff871439e0 <__CFgetenv>
0x00007fff8724bd45 <__NSAutoreleaseNoPool+21>: test %rax,%rax
0x00007fff8724bd48 <__NSAutoreleaseNoPool+24>: je 0x7fff8724bd55 <__NSAutoreleaseNoPool+37>
0x00007fff8724bd4a <__NSAutoreleaseNoPool+26>: movzbl (%rax),%eax
0x00007fff8724bd4d <__NSAutoreleaseNoPool+29>: cmp $0x59,%al
0x00007fff8724bd4f <__NSAutoreleaseNoPool+31>: je 0x7fff8724bd60 <__NSAutoreleaseNoPool+48>
0x00007fff8724bd51 <__NSAutoreleaseNoPool+33>: cmp $0x79,%al
0x00007fff8724bd53 <__NSAutoreleaseNoPool+35>: je 0x7fff8724bd60 <__NSAutoreleaseNoPool+48>
0x00007fff8724bd55 <__NSAutoreleaseNoPool+37>: leaveq
0x00007fff8724bd56 <__NSAutoreleaseNoPool+38>: retq
0x00007fff8724bd57 <__NSAutoreleaseNoPool+39>: nopw 0x0(%rax,%rax,1)
0x00007fff8724bd60 <__NSAutoreleaseNoPool+48>: int3
0x00007fff8724bd61 <__NSAutoreleaseNoPool+49>: callq 0x7fff872609c2 <dyld_stub_getpid>
0x00007fff8724bd66 <__NSAutoreleaseNoPool+54>: mov %eax,%edi
0x00007fff8724bd68 <__NSAutoreleaseNoPool+56>: mov $0x9,%esi
0x00007fff8724bd6d <__NSAutoreleaseNoPool+61>: leaveq
0x00007fff8724bd6e <__NSAutoreleaseNoPool+62>: jmpq 0x7fff87260a16 <dyld_stub_kill>
0x00007fff8724bd73 <__NSAutoreleaseNoPool+67>: nopw 0x0(%rax,%rax,1)
0x00007fff8724bd79 <__NSAutoreleaseNoPool+73>: nopl 0x0(%rax)
End of assembler dump.
For a practical example, see demo_NSAutoreleaseNoPool.mm.
Is there a command-line tool that will take a symbolic errno such as EINVAL and print the corresponding string, Invalid argument?
I would like to avoid having to find that EINVAL is value 22 on my system and then using$ perror 22.
Ideally I could write something like
$ errorcommand EINVAL
Invalid argument
$
AFAIK, there isn't a standard tool that does the job. At one level, it wouldn't be particularly hard to write one - the messiest parts are finding the correct file to parse (is is often, but by no means always, /usr/include/sys/errno.h) and then taking the data from that to do the mapping of names to numbers. I have not found a system that uses enum values rather than #define values, but it is probably only a matter of time. It is also a moot point whether to generate a triple consisting of token number (EINTR, etc), token name ("EINTR", etc) and error message ("Interrupted system call", etc), or whether to use just the number and name and leave it to 'strerror()' to supply the message.
As I said, it isn't particularly hard. I already had a program called 'errno' that accepted pure numeric values and printed the corresponding error messages:
$ errno 1:10 20
1: Operation not permitted
2: No such file or directory
3: No such process
4: Interrupted system call
5: Input/output error
6: Device not configured
7: Argument list too long
8: Exec format error
9: Bad file descriptor
10: No child processes
20: Not a directory
$
I've written a Perl script and hacked the program to handle symbolic error numbers too:
$ errno 1:4 EINTR ENOTDIR
1 (EPERM): Operation not permitted
2 (ENOENT): No such file or directory
3 (ESRCH): No such process
4 (EINTR): Interrupted system call
EINTR (4): Interrupted system call
ENOTDIR (20): Not a directory
$
It does not handle ranges of symbolic error numbers (exercise for the reader).
generrno.pl
#!/usr/bin/perl -w
#
# #(#)$Id: generrno.pl,v 1.1 2010/02/07 18:39:18 jleffler Exp jleffler $
#
# Generate table of error number constants from given file(s)
use strict;
my %symlist;
my $maxsymlen = 0;
my $maxmsglen = 0;
while (<>)
{
next unless m%^\s*#\s*define\s+(E[A-Z0-9a-z]+)\s+(\d+)\s*/\*\s*([A-Za-z].*\S)\s*\*/%;
$symlist{$1} = { number => $2, message => $3 };
$maxsymlen = length($1) if length($1) > $maxsymlen;
$maxmsglen = length($3) if length($3) > $maxmsglen;
}
my $format = sprintf " { %%-%ds %%-%ds %%-5s %%-%ds },\n", $maxsymlen + 3, $maxsymlen + 1, $maxmsglen + 2;
foreach my $key (sort keys %symlist)
{
my $name = qq{"$key",};
my $symbol = qq{$key,};
my $number = qq{$symlist{$key}->{number},};
my $message = qq{"$symlist{$key}->{message}"};
printf $format, $name, $symbol, $number, $message;
}
errno.c
/*
#(#)File: $RCSfile: errno.c,v $
#(#)Version: $Revision: 2.2 $
#(#)Last changed: $Date: 2010/02/07 19:22:37 $
#(#)Purpose: Print messages corresponding to errno values or name
#(#)Author: J Leffler
#(#)Copyright: (C) JLSS 2003,2005,2008,2010
*/
/*TABSTOP=4*/
#define MAIN_PROGRAM
/* Need O/S specific messages as well as POSIX messages */
//#if __STDC_VERSION__ >= 199901L
//#define _XOPEN_SOURCE 600
//#else
//#define _XOPEN_SOURCE 500
//#endif /* __STDC_VERSION__ */
#include <ctype.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h> /* getopt() on MacOS X 10.2 */
#include "stderr.h"
#include "range.h"
typedef struct err_info
{
const char *errsym; /* Error symbol - "EINTR" */
int errnum; /* Error number - EINTR */
int errdef; /* Error define - 4 */
const char *errmsg; /* Error message - Interrupted system call */
} err_info;
/*
** Generate generrno.h using:
** perl generrno.pl /usr/include/sys/errno.h > generrno.h
** NB: list must be sorted alphabetically on symbol name
*/
static const err_info err_msgs[] =
{
#include "generrno.h"
};
static const char usestr[] = "[-qV] [--] lo[:hi] ...";
#define DIM(x) (sizeof(x)/sizeof(*(x)))
static const err_info *err_nums[DIM(err_msgs)];
#ifndef lint
/* Prevent over-aggressive optimizers from eliminating ID string */
const char jlss_id_errno_c[] = "#(#)$Id: errno.c,v 2.2 2010/02/07 19:22:37 jleffler Exp $";
#endif /* lint */
static int cmp_err_number(const void *v1, const void *v2)
{
int e1 = (*((const err_info * const *)v1))->errnum;
int e2 = (*((const err_info * const *)v2))->errnum;
return(e1 - e2);
}
static void map_numbers(void)
{
int i;
for (i = 0; i < DIM(err_msgs); i++)
err_nums[i] = &err_msgs[i];
qsort(err_nums, DIM(err_nums), sizeof(*err_nums), cmp_err_number);
}
static const char *err_symbol(int num)
{
const char *sym = "<UNKNOWN>";
err_info lookfor = { 0, num, 0, 0 };
err_info *lookptr = &lookfor;
const err_info **found = bsearch(&lookptr, err_nums, DIM(err_nums), sizeof(*err_nums), cmp_err_number);
if (found != 0)
sym = (*found)->errsym;
return(sym);
}
static int cmp_err_symbol(const void *v1, const void *v2)
{
const char *s1 = ((const err_info *)v1)->errsym;
const char *s2 = ((const err_info *)v2)->errsym;
return(strcmp(s1, s2));
}
static int pr_string_errno(const char *arg, int qflag)
{
int estat = EXIT_SUCCESS;
err_info lookfor = { arg, 0, 0, 0 };
const err_info *found = bsearch(&lookfor, err_msgs, DIM(err_msgs), sizeof(*err_msgs), cmp_err_symbol);
if (found == 0)
{
err_remark("unrecognized symbol %s\n", arg);
estat = EXIT_FAILURE;
}
else if (qflag == 0)
printf("%s (%d): %s\n", arg, found->errnum, found->errmsg);
return(estat);
}
static int pr_number_errno(const char *arg, int qflag)
{
int estat = EXIT_SUCCESS;
long lo;
long hi;
const char *endp;
long msg;
endp = numeric_range(arg, &lo, &hi);
if (endp == arg)
err_remark("Invalid range specified (%s) - should be lo[:hi]\n", arg);
else if (*endp != '\0')
err_remark("Non-numeric character (%c) after range '%s'\n",
(isprint((unsigned char)*endp) ? *endp : '?'), arg);
else
{
for (msg = lo; msg <= hi; msg++)
{
char *msgtxt = strerror(msg);
if (msgtxt == 0)
{
err_remark("no message for errno = %ld\n", msg);
estat = EXIT_FAILURE;
}
else if (qflag == 0)
printf("%ld (%s): %s\n", msg, err_symbol(msg), msgtxt);
}
}
return(estat);
}
static int pr_errno(char *arg, int qflag)
{
int estat;
if (isalpha(*arg))
estat = pr_string_errno(arg, qflag);
else
estat = pr_number_errno(arg, qflag);
return(estat);
}
int main(int argc, char **argv)
{
int i;
int opt;
int nstat;
int estat = EXIT_SUCCESS;
int qflag = 0;
int nflag = 0;
err_setarg0(argv[0]);
map_numbers();
while ((opt = getopt(argc, argv, "qV0:1:2:3:4:5:6:7:8:9:")) != EOF)
{
switch (opt)
{
case 'q':
qflag = 1;
break;
case 'V':
err_version("ERRNO", "$Revision: 2.2 $ ($Date: 2010/02/07 19:22:37 $)");
break;
case '0':
case '1':
case '2':
case '3':
case '4':
case '5':
case '6':
case '7':
case '8':
case '9':
/* GETOPT() is probably not the right tool for this job! */
nstat = pr_errno(optarg-2, qflag);
if (estat == EXIT_SUCCESS)
estat = nstat;
nflag = 1;
break;
default:
err_usage(usestr);
break;
}
}
if (optind >= argc && nflag == 0)
err_usage(usestr);
for (i = optind; i < argc; i++)
{
nstat = pr_errno(argv[i], qflag);
if (estat == EXIT_SUCCESS)
estat = nstat;
}
return(estat);
}
The code needs some supporting files - stderr.h, range.h, range2.c and stderrmin.c (a simpler version of the stderr.c I normally use, which has extra bells and whistles for handling syslog and writing to file descriptors instead of file pointers.).
stderr.h
/*
#(#)File: $RCSfile: stderr.h,v $
#(#)Version: $Revision: 9.2 $
#(#)Last changed: $Date: 2009/03/06 06:52:26 $
#(#)Purpose: Header file for standard error functions
#(#)Author: J Leffler
#(#)Copyright: (C) JLSS 1989-93,1996-99,2003,2005-09
#(#)Product: :PRODUCT:
*/
#ifndef STDERR_H
#define STDERR_H
#ifdef MAIN_PROGRAM
#ifndef lint
/* Prevent over-aggressive optimizers from eliminating ID string */
const char jlss_id_stderr_h[] = "#(#)$Id: stderr.h,v 9.2 2009/03/06 06:52:26 jleffler Exp $";
#endif /* lint */
#endif
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif /* HAVE_CONFIG_H */
#include <stdio.h>
#include <stdarg.h>
#ifdef __GNUC__
#define PRINTFLIKE(n,m) __attribute__((format(printf,n,m)))
#define NORETURN() __attribute__((noreturn))
#else
#define PRINTFLIKE(n,m) /* If only */
#define NORETURN() /* If only */
#endif /* __GNUC__ */
/* -- Definitions for error handling */
enum { ERR_STAT = 1 }; /* Default exit status */
enum { ERR_DEFAULT = 0x0000 }; /* Default flag */
enum { ERR_NOFLUSH = 0x0001 }; /* Do not flush open files */
enum { ERR_EXIT = 0x0004 }; /* Exit -- do not return */
enum { ERR_ABORT = 0x0008 }; /* Abort -- do not return */
enum { ERR_STAMP = 0x0020 }; /* Timestamp messages */
enum { ERR_NOARG0 = 0x0040 }; /* Do not print arg0 prefix */
enum { ERR_PID = 0x0080 }; /* Include pid=nnnnn info */
enum { ERR_ERRNO = 0x0100 }; /* Include system error */
#ifdef USE_STDERR_SYSLOG
/* Definitions related to using syslog */
enum { ERR_LOG_EMERG = 0x01000 }; /* system is unusable */
enum { ERR_LOG_ALERT = 0x02000 }; /* action must be taken immediately */
enum { ERR_LOG_CRIT = 0x04000 }; /* critical conditions */
enum { ERR_LOG_ERR = 0x08000 }; /* error conditions */
enum { ERR_LOG_WARNING = 0x10000 }; /* warning conditions */
enum { ERR_LOG_NOTICE = 0x20000 }; /* normal but signification condition */
enum { ERR_LOG_INFO = 0x40000 }; /* informational */
enum { ERR_LOG_DEBUG = 0x80000 }; /* debug-level messages */
enum { ERR_LOG_LEVEL_HI = ERR_LOG_EMERG|ERR_LOG_ALERT|ERR_LOG_CRIT|ERR_LOG_ERR };
enum { ERR_LOG_LEVEL_LO = ERR_LOG_WARNING|ERR_LOG_NOTICE|ERR_LOG_INFO|ERR_LOG_DEBUG };
enum { ERR_LOG_LEVEL = ERR_LOG_LEVEL_HI|ERR_LOG_LEVEL_LO };
#endif /* USE_STDERR_SYSLOG */
/* -- Standard combinations of flags */
enum { ERR_REM = ERR_DEFAULT };
enum { ERR_ERR = ERR_EXIT };
enum { ERR_ABT = ERR_ABORT };
enum { ERR_LOG = ERR_STAMP|ERR_PID };
enum { ERR_SYSREM = ERR_REM|ERR_ERRNO };
enum { ERR_SYSERR = ERR_ERR|ERR_ERRNO };
/* -- Maximum recorded length of argv[0]; extra is truncated */
enum { ERR_MAXLEN_ARGV0 = 63 };
/* -- Global definitions */
extern const char err_format1[]; /* "%s\n" - for one string argument */
extern const char err_format2[]; /* "%s %s\n" - for two string arguments */
extern const char *err_getarg0(void);
extern void err_setarg0(const char *argv0);
extern FILE *err_stderr(FILE *fp);
extern const char *err_rcs_string(const char *s, char *buffer, size_t buflen);
extern void err_abort(const char *format, ...) PRINTFLIKE(1,2) NORETURN();
extern void err_error(const char *format, ...) PRINTFLIKE(1,2) NORETURN();
extern void err_error1(const char *s1) NORETURN();
extern void err_error2(const char *s1, const char *s2) NORETURN();
extern void err_help(const char *use_str, const char *hlp_str) NORETURN();
extern void err_helplist(const char *use_str, const char * const *help_list) NORETURN();
extern void err_internal(const char *function, const char *msg) NORETURN();
extern void err_logmsg(FILE *fp, int flags, int estat, const char *format, ...) PRINTFLIKE(4,5);
extern void err_print(int flags, int estat, const char *format, va_list args);
extern void err_printversion(const char *program, const char *verinfo);
extern void err_remark(const char *format, ...) PRINTFLIKE(1,2);
extern void err_remark1(const char *s1);
extern void err_remark2(const char *s1, const char *s2);
extern void err_report(int flags, int estat, const char *format, ...) PRINTFLIKE(3,4);
extern void err_syserr(const char *format, ...) PRINTFLIKE(1,2) NORETURN();
extern void err_syserr1(const char *s1) NORETURN();
extern void err_syserr2(const char *s1, const char *s2) NORETURN();
extern void err_sysrem(const char *format, ...) PRINTFLIKE(1,2);
extern void err_sysrem1(const char *s1);
extern void err_sysrem2(const char *s1, const char *s2);
extern void err_usage(const char *usestr) NORETURN();
extern void err_version(const char *program, const char *verinfo) NORETURN();
extern int err_getlogopts(void); /* Get default log options */
extern int err_setlogopts(int new_opts); /* Set default log options */
#ifdef USE_STDERR_FILEDESC
extern int err_use_fd(int fd); /* Use file descriptor */
#endif /* USE_STDERR_FILEDESC */
#ifdef USE_STDERR_SYSLOG
/* In case of doubt, use zero for both logopts and facility */
extern int err_use_syslog(int logopts, int facility); /* Configure/use syslog() */
#endif /* USE_STDERR_SYSLOG */
/*
** JL 2003-07-31: Security Note.
** Question: given that err_remark("abc\n") and err_remark1("abc")
** produce the same output, when should you use err_remark1()
** instead of err_remark()?
** Answer 1: trivia - when you can't put the newline in the string.
** Answer 2: security - when the argument contains user input and could,
** therefore, contain conversion specifiers, etc. The code in
** err_remark() does not (and cannot) verify that you have
** passed correct arguments for the conversion specifiers in
** the format string.
** Answer 3: inertia - when migrating code that uses remark().
**
** Generalizing: when you use a function that has 'const char *format'
** in the prototype above, make sure your code is fully in charge of the
** format string to avoid security lapses. Do not allow the user to
** provide that string unless you stringently check it beforehand.
*/
#endif /* STDERR_H */
range.h
/*
#(#)File: $RCSfile: range.h,v $
#(#)Version: $Revision: 1.8 $
#(#)Last changed: $Date: 2008/02/11 07:39:36 $
#(#)Purpose: Declaration of range parsing functions
#(#)Author: J Leffler
#(#)Copyright: (C) JLSS 1997,2005,2007-08
#(#)Product: :PRODUCT:
*/
/*TABSTOP=4*/
#ifndef RANGE_H
#define RANGE_H
#ifdef MAIN_PROGRAM
#ifndef lint
/* Prevent over-aggressive optimizers from eliminating ID string */
const char jlss_id_range_h[] = "#(#)$Id: range.h,v 1.8 2008/02/11 07:39:36 jleffler Exp $";
#endif /* lint */
#endif /* MAIN_PROGRAM */
/*
** parse_range(): parse range of non-negative numbers.
**
** Given a string, parse_range() returns the lo and hi values corresponding
** to the range specified by the string. For example:
** Input: Low High
** 23 23 23
** 23-25 23 25
** 23- 23 0
** -23 0 23
** Any delimiter other than '-' before or after a number terminates the
** scan, but commas are skipped. Returns pointer to character after
** last character parsed (which may or may not be '\0') if successful.
** Otherwise, returns null.
**
** Idiomatic use:
**
** const char *ptr = source_string;
** const char *nxt;
** while ((nxt = parse_range(ptr, &lo, &hi)) != 0)
** {
** if (nxt == ptr)
** err_error("invalid range string (%s)\n", source_string);
** use_range(lo, hi);
** ptr = nxt;
** }
*/
extern const char *parse_range(const char *str, long *lo, long *hi);
/*
** numeric_range(): parse range of numbers, positive or negative.
**
** Input: Low High
** 23 23 23
** -23 -23 -23
** 23:25 23 25
** 23..25 23 25
** -23..-25 -25 -23
** -23..25 -23 25
** 23..-25 -25 23
** Returns pointer to '\0' at end of string if OK, sets *lo and *hi,
** and guarantees *lo <= *hi.
** Otherwise, returns pointer to start of string and does not set *lo or *hi.
**
** Idiomatic use:
**
** const char *ptr = source_string;
** const char *nxt;
** while ((nxt = numeric_range(ptr, &lo, &hi)) != 0)
** {
** if (nxt == ptr)
** err_error("invalid range string (%s)\n", source_string);
** use_range(lo, hi);
** ptr = nxt;
** }
*/
extern const char *numeric_range(const char *str, long *lo, long *hi);
#endif /* RANGE_H */
range2.c
/*
#(#)File: $RCSfile: range2.c,v $
#(#)Version: $Revision: 1.8 $
#(#)Last changed: $Date: 2008/02/11 08:44:50 $
#(#)Purpose: Decode string into range of integers.
#(#)Author: J Leffler
#(#)Copyright: (C) JLSS 1997,2002,2005,2007-08
#(#)Product: :PRODUCT:
*/
/*TABSTOP=4*/
/*
** Parse number ranges, dealing with positive and negative values,
** and ranges separated by either colon or double-dot.
**
** Input: Low High
** 23 23 23
** -23 -23 -23
** 23:25 23 25
** 23..25 23 25
** -23..-25 -25 -23
** -23..25 -23 25
** 23..-25 -25 23
** -23..+25 -23 25
** Any other delimiter after number (or before number) terminates
** input. NB: a leading colon (or dot) is not a valid range. If
** there is a format error, the returned pointer points to the
** start of the string (and lo and hi are unchanged). If there is
** no error, then the returned pointer points to the ASCII NUL at
** the end of the string.
*/
#include "range.h"
#include <stdlib.h>
#ifndef lint
/* Prevent over-aggressive optimizers from eliminating ID string */
const char jlss_id_range2_c[] = "#(#)$Id: range2.c,v 1.8 2008/02/11 08:44:50 jleffler Exp $";
#endif /* lint */
/*
** Parse numeric range.
** Return pointer to trailing '\0' if OK, else pointer to input string
*/
const char *numeric_range(const char *str, long *lo, long *hi)
{
const char *s = str;
char *t;
long l;
long h;
l = strtol(s, &t, 10);
if (*t == '\0')
{
/* Just one number */
*lo = *hi = l;
return(t);
}
if (*t == ':')
t += 1;
else if (t[0] == '.' && t[1] == '.')
t += 2;
else
{
/* Format error */
return(str);
}
h = strtol(t, &t, 10);
if (*t != '\0')
{
/* Format error */
return(str);
}
if (h < l)
{
long x = h;
h = l;
l = x;
}
*lo = l;
*hi = h;
return(t);
}
#ifdef TEST
#include <stdio.h>
#include "stderr.h"
int main(int argc, char **argv)
{
int i;
long lo;
long hi;
const char *t;
const char *s;
err_setarg0(argv[0]);
if (argc <= 1)
err_usage("range [...]");
for (i = 1; i < argc; i++)
{
t = argv[i];
if (t != 0 && *t != '\0')
{
printf("Parse: %15s (addr = 0x%08lX) ", t, (unsigned long)t);
fflush(stdout);
s = numeric_range(t, &lo, &hi);
printf("Range: %2ld -> %2ld (addr = 0x%08lX; trailer = <<%s>>)\n", lo, hi, (unsigned long)s, s);
fflush(stdout);
}
}
return(0);
}
#endif /* TEST */
stderrmin.c
This is about 400 lines, instead of about 700 lines. Yes, it is overkill for this program; I don't use it only in this program.
/*
#(#)File: $RCSfile: stderrmin.c,v $
#(#)Version: $Revision: 9.6 $
#(#)Last changed: $Date: 2009/03/02 20:27:38 $
#(#)Purpose: Minimal implementation of error reporting routines
#(#)Author: J Leffler
#(#)Copyright: (C) JLSS 1988-91,1996-99,2001,2003,2005-09
#(#)Product: :PRODUCT:
*/
/*TABSTOP=4*/
#undef STDERR_EXTENDED
#include "stderr.h"
#include <assert.h>
#include <ctype.h>
#include <errno.h>
#include <string.h>
#include <stdlib.h>
#include <stdarg.h>
#include <time.h>
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#else
extern int getpid(void);
#endif /* HAVE_UNISTD_H */
enum { MAX_MSGLEN = 2048 };
/* Global format strings */
const char err_format1[] = "%s\n";
const char err_format2[] = "%s %s\n";
static const char def_format[] = "%Y-%m-%d %H:%M:%S";
static const char *tm_format = def_format;
static char arg0[ERR_MAXLEN_ARGV0+1] = "**undefined**";
/* Permitted default error flags */
enum { ERR_LOGOPTS = ERR_NOFLUSH | ERR_EXIT | ERR_ABORT | ERR_STAMP |
ERR_NOARG0 | ERR_PID | ERR_ERRNO };
static int err_flags = 0; /* Default error flags (ERR_STAMP, ERR_PID, etc) */
static FILE *errout = 0;
/*
** err_???_print() functions are named systematically, and are all static.
**
** err_[ev][crx][fn]_print():
** -- e takes ellipsis argument
** -- v takes va_list argument
** -- c conditionally exits
** -- r returns (no exit)
** -- x exits (no return)
** -- f takes file pointer
** -- n no file pointer (use errout)
**
** NB: no-return and printf-like can only be attached to declarations, not definitions.
*/
static void err_vxf_print(FILE *fp, int flags, int estat, const char *format, va_list args)
NORETURN();
static void err_vxn_print(int flags, int estat, const char *format, va_list args)
NORETURN();
static void err_exn_print(int flags, int estat, const char *format, ...)
NORETURN() PRINTFLIKE(3,4);
static void err_terminate(int flags, int estat) NORETURN();
#ifndef lint
/* Prevent over-aggressive optimizers from eliminating ID string */
const char jlss_id_stderrmin_c[] = "#(#)$Id: stderrmin.c,v 9.6 2009/03/02 20:27:38 jleffler Exp $";
#endif /* lint */
/*
** Set default log options, returning old value.
** Setting ERR_EXIT and ERR_ABORT is permitted but not recommended.
*/
int err_setlogopts(int new_opts)
{
int old_opts = err_flags;
err_flags = new_opts & ERR_LOGOPTS;
return(old_opts);
}
/* Return default log options */
int err_getlogopts(void)
{
return(err_flags);
}
/* Change the definition of 'stderr', reporting on the old one too */
/* NB: using err_stderr((FILE *)0) simply reports the current 'stderr' */
FILE *(err_stderr)(FILE *newerr)
{
FILE *old;
if (errout == 0)
errout = stderr;
old = errout;
if (newerr != 0)
errout = newerr;
return(old);
}
/* Return stored basename of command */
const char *(err_getarg0)(void)
{
return(arg0);
}
/* Store basename of command, excluding trailing slashes */
void (err_setarg0)(const char *argv0)
{
/* Ignore three pathological program names -- NULL, "/" and "" */
if (argv0 != 0 && *argv0 != '\0' && (*argv0 != '/' || *(argv0 + 1) != '\0'))
{
const char *cp;
size_t nbytes = sizeof(arg0) - 1;
if ((cp = strrchr(argv0, '/')) == 0)
{
/* Basename of file only */
cp = argv0;
}
else if (*(cp + 1) != '\0')
{
/* Regular pathname containing slashes but not trailing slashes */
cp++;
}
else
{
/* Skip backwards over trailing slashes */
const char *ep = cp;
while (ep > argv0 && *ep == '/')
ep--;
/* Skip backwards over non-slashes */
cp = ep;
while (cp > argv0 && *cp != '/')
cp--;
assert(ep >= cp);
cp++;
nbytes = (size_t)(ep - cp) + 1;
if (nbytes > sizeof(arg0) - 1)
nbytes = sizeof(arg0) - 1;
}
strncpy(arg0, cp, nbytes);
arg0[nbytes] = '\0';
}
}
const char *(err_rcs_string)(const char *s2, char *buffer, size_t buflen)
{
const char *src = s2;
char *dst = buffer;
char *end = buffer + buflen - 1;
/*
** Bother RCS! We've probably been given something like:
** "$Revision: 9.6 $ ($Date: 2009/03/02 20:27:38 $)"
** We only want to emit "7.5 (2001/08/11 06:25:48)".
** Skip the components between '$' and ': ', copy up to ' $',
** repeating as necessary. And we have to test for overflow!
** Also work with the unexpanded forms of keywords ($Keyword$).
** Never needed this with SCCS!
*/
while (*src != '\0' && dst < end)
{
while (*src != '\0' && *src != '$')
{
*dst++ = *src++;
if (dst >= end)
break;
}
if (*src == '$')
src++;
while (*src != '\0' && *src != ':' && *src != '$')
src++;
if (*src == '\0')
break;
if (*src == '$')
{
/* Unexpanded keyword '$Keyword$' notation */
src++;
continue;
}
if (*src == ':')
src++;
if (*src == ' ')
src++;
while (*src != '\0' && *src != '$')
{
/* Map / in 2009/02/15 to dash */
/* Heuristic - maps slashes surrounded by digits to dashes */
char c = *src++;
if (c == '/' && isdigit(*src) && isdigit(*(src-2)))
c = '-';
*dst++ = c;
if (dst >= end)
break;
}
if (*src == '$')
{
if (*(dst-1) == ' ')
dst--;
src++;
}
}
*dst = '\0';
return(buffer);
}
/* Format a time string for now (using ISO8601 format) */
/* Allow for future settable time format with tm_format */
static char *err_time(char *buffer, size_t buflen)
{
time_t now;
struct tm *tp;
now = time((time_t *)0);
tp = localtime(&now);
strftime(buffer, buflen, tm_format, tp);
return(buffer);
}
/* Most fundamental (and flexible) error message printing routine - always returns */
static
At least for Ubuntu (12.04 and later, to my certain knowledge), there's an errno utility you can easily install via apt-get install moreutils. (Thanks to #kevinoid and #leo for the update.)
$ errno 98
EADDRINUSE 98 Address already in use
$ errno EINVAL
EINVAL 22 Invalid argument
This works on Ubuntu 9.04:
user#host:~$ grep EINVAL /usr/include/asm-generic/errno*.h
/usr/include/asm-generic/errno-base.h:#define EINVAL 22 /* Invalid argument */
You can also try a Python script:
import errno
from os import strerror
from sys import argv
print strerror(errno.__dict__[argv[1]]
The function
strerror()
Is possibly what you're looking for, but I don't know of a command that exposes that to any shell offhand.
MKS exposes the command line strerror
Tried
grep EINVAL /usr/include/sys/errno.h
and seen what comes back?
#! /bin/bash -f
errorDir="/usr/include/asm-generic"
strError="$1"
numericVal=awk -v pat="$strError" '$0 ~ pat{print $3}' $errorDir/errno-base.h $errorDir/errno.h
perror $numericVal
Caution: As this script uses the location of ERROR MACROS,this might not be portable although it works on my system.
Rob Wells is partially correct. Unfortunately /usr/include/asm/errno.h is nonstandard. You really need to grep /usr/include/errno.h and /usr/include/*/errno.h.
To make this errorcommand, try adding this to your .bashrc file:
function errorcommand
{
grep "${1}" /usr/include/errno.h /usr/include/*/errno.h
}
Which works like this:
Rob Wells is partially correct. Unfortunately /usr/include/asm/errno.h is nonstandard. You really need to grep /usr/include/errno.h and /usr/include/*/errno.h.
To make this errorcommand, try adding this to your .bashrc file:
function errorcommand
{
grep "${1}" /usr/include/errno.h /usr/include/*/errno.h
}
Which works like this:
$ errorcommand EINV
/usr/include/sys/errno.h:#define EINVAL 22 /* Invalid argument */
$
A compact bash script that exactly does what you want:
#!/bin/bash -f
file="/tmp/prog$$.c"
out="/tmp/prog$$"
if [ $# -ne 1 ]
then
echo "Usage: $0 ERROR-NO"
exit 1
fi
echo "#include <stdio.h>" >> $file
echo "#include <errno.h>" >> $file
echo "int main(){" >> $file
echo "printf(\"$1:%s\n\",strerror($1));" >> $file
echo "}" >> $file
gcc $file -o $out &> /dev/null
if [ $? == "0" ]
then
$out
rm -f $out
else
echo "Syntax Error: $1 Unknown"
fi
# cleanup the file
rm -f $file
On my corporate box /usr/include wasn't available. So I put this portable simple solution (if you have Python) into my init files. You can torture it into a one-liner if you wish:
function strerror () {
python -c "import os, errno; print(os.strerror(errno.$1))"
}
There's no standard utility to do this. I believe your best bet is to write such a utility yourself. Use strerror() to print the associated error message.
For people that want a quick, on-liner:
find /usr/include/ -name errno*.h -exec grep ERRNO {} +
e.g.
[x#localhost]$ find /usr/include/ -name errno*.h -exec grep EINVAL {} +
/usr/include/asm-generic/errno-base.h:#define EINVAL 22 /* Invalid argument */
[x#localhost]$ find /usr/include/ -name errno*.h -exec grep 111 {} +
/usr/include/asm-generic/errno.h:#define ECONNREFUSED 111 /* Connection refused */
Here is a short C++ program that handles both numeric and symbolic errors. Given the option -l as its very first argument, it lists all known error symbols and then exits. Otherwise iterates over all arguments and prints the error text, and nothing else, for each argument.
There is nothing much here that has not been mentioned earlier, but it does it all in a single source file, not counting table.h, which is generated.
To build:
./table.sh > table.h
g++ -O2 -Wall -W -Wextra -o errno errno.cc
The program is in C, except for the C++ iteration in list_and_exit().
errno.cc
# include <string.h>
# include <stdio.h>
# include <stdlib.h>
# include <errno.h>
# include <ctype.h>
struct ErrSym {
char const *name;
unsigned char value; // 0..255
};
static ErrSym const es[] = {
# include "table.h"
};
static int cmp(char const *a, ErrSym const *b) {
return strcmp(a, b->name);
}
static ErrSym const *find_by_name(char *needle) {
typedef int (*IVV)(void const *, void const *);
static int const n = (sizeof es / sizeof *es);
return (ErrSym*)bsearch(needle, es, n,
sizeof *es, (IVV)cmp);
}
static void list_and_exit() {
for (auto &e : es)
printf("%3d %-15s %s\n",
e.value, e.name, strerror(e.value));
exit(0);
}
static void handle_arg(char *arg) {
if (isdigit(arg[0]))
printf("%s\n", strerror(atoi(arg)));
else if (ErrSym const *p = find_by_name(arg))
printf("%s\n", strerror(p->value));
else
printf("Unknown error symbol: %s\n", arg);
}
int main(int argc, char *argv[]) {
if (argc > 1 && 0 == strcmp("-l", argv[1]))
list_and_exit();
for (int i = 1; i < argc; i++)
handle_arg(argv[i]);
return 0;
}
With the assumption that error numbers are less than 256, ErrSym.value is defined as unsigned char, so that the compiler can warn about values that are out of range.
To generate table.h, the trick (as mentioned in a comment above) is to use the C compiler and the preprocessor.
table.sh
#!/bin/bash
trap 'rm -f tmp.c' EXIT
echo '#include <errno.h>' > tmp.c
#
# -E Run the preprocessor only
# -dM At end, dump preprocessor symbols
# According to documentation, but not tested, these
# options should work also with clang and Intel's icc.
gcc -E -dM tmp.c | ./table.pl | sort
table.pl
#!/usr/bin/perl -n
#
# Convert '#define EACCES 13' to '{ "EACCES", 13 },'
# Skip lines that do not match
#
# By happy concidence, all names beginning
# with E are error numbers
#
next unless (/^#define +(E\S+) +(\S+)/);
$_ = sprintf("{%-18s %10s},\n", qq{"$1",}, $2);
s/, /, /; # Remove excess whitespace
print;
The output from errno -l is sorted by error symbol. Say errno -l | sort to sort by error number.