hush/procps/lsof.c
Thomas De Schampheleire 879f008a8f lsof: correct check for symbolic link
Busybox lsof used the d_type field of a 'struct dirent' to verify whether the
entry is a symbolic link. This field, however, is not portable. On at least
one board [1] I have seen, that field is 0, and the check fails even though
the entry is a link.

The explicit check for a symbolic link is really only needed to skip the
default directory entries '.' and '..'. The directory /proc/<pid>/fd/
should not contain anything else but these two and symbolic links.
With these assumptions, this patch replaces the explicit link check with a
basic check for '.' and '..' (and any hidden file). In the unlikely case that
there are other file types, xmalloc_readlink() will return NULL, and we can
skip the entry.

[1] A MIPS-based board with glibc 2.9, Linux 2.6.32.27.

Signed-off-by: Thomas De Schampheleire <thomas.de.schampheleire@gmail.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2013-06-27 03:44:46 +02:00

80 lines
2.6 KiB
C

/* vi: set sw=4 ts=4: */
/*
* Mini lsof implementation for busybox
*
* Copyright (C) 2012 by Sven Oliver 'SvOlli' Moll <svolli@svolli.de>
*
* Licensed under GPLv2, see file LICENSE in this source tree.
*/
//config:config LSOF
//config: bool "lsof"
//config: default y
//config: help
//config: Show open files in the format of:
//config: PID <TAB> /path/to/executable <TAB> /path/to/opened/file
//applet:IF_LSOF(APPLET(lsof, BB_DIR_USR_BIN, BB_SUID_DROP))
//kbuild:lib-$(CONFIG_LSOF) += lsof.o
//usage:#define lsof_trivial_usage
//usage: ""
//usage:#define lsof_full_usage "\n\n"
//usage: "Show all open files"
#include "libbb.h"
/*
* Examples of "standard" lsof output:
*
* COMMAND PID USER FD TYPE DEVICE SIZE NODE NAME
* init 1 root cwd DIR 8,5 4096 2 /
* init 1 root rtd DIR 8,5 4096 2 /
* init 1 root txt REG 8,5 872400 63408 /app/busybox-1.19.2/busybox
* rpc.portm 1064 root mem REG 8,5 43494 47451 /app/glibc-2.11/lib/libnss_files-2.11.so
* rpc.portm 1064 root 3u IPv4 2178 UDP *:111
* rpc.portm 1064 root 4u IPv4 1244 TCP *:111 (LISTEN)
* runsvdir 1116 root 0r CHR 1,3 1214 /dev/null
* runsvdir 1116 root 1w CHR 1,3 1214 /dev/null
* runsvdir 1116 root 2w CHR 1,3 1214 /dev/null
* runsvdir 1116 root 3r DIR 8,6 1560 58359 /.local/var/service
* gpm 1128 root 4u unix 0xffff88007c09ccc0 1302 /dev/gpmctl
*/
int lsof_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int lsof_main(int argc UNUSED_PARAM, char **argv UNUSED_PARAM)
{
procps_status_t *proc = NULL;
while ((proc = procps_scan(proc, PSSCAN_PID|PSSCAN_EXE)) != NULL) {
char name[sizeof("/proc/%u/fd/0123456789") + sizeof(int)*3];
unsigned baseofs;
DIR *d_fd;
char *fdlink;
struct dirent *entry;
if (getpid() == proc->pid)
continue;
baseofs = sprintf(name, "/proc/%u/fd/", proc->pid);
d_fd = opendir(name);
if (d_fd) {
while ((entry = readdir(d_fd)) != NULL) {
/* Skip entries '.' and '..' (and any hidden file) */
if (entry->d_name[0] == '.')
continue;
safe_strncpy(name + baseofs, entry->d_name, 10);
if ((fdlink = xmalloc_readlink(name)) != NULL) {
printf("%d\t%s\t%s\n", proc->pid, proc->exe, fdlink);
free(fdlink);
}
}
closedir(d_fd);
}
}
return EXIT_SUCCESS;
}