Bug 189580

Description of problem: 
 
"grep -D skip ..." should skip FIFO, BLK and CHR files, and really shouldn't 
try to open them. 
 
Note also that "grep -d skip" should skip subdirectories, but doesn't. 
 
Version-Release number of selected component (if applicable): 
 
grep-2.5.1-52.2 
 
How reproducible: 
 
100% 
 
Steps to Reproduce: 
0. Become root 
1. mkdir /tmp/x 
2. cd /tmp/x 
3. mknod hdg8 b 34 8 
4. mknod null c 1 3 
5. mkfifo y 
6. strace -eopen grep -D skip -r hello . 
7. CTRL-C when it gets stuck opening the FIFO. 
 
And then: 
9. grep -D skip -r hello . & sleep 3; echo hello >y 
  
Actual results: 
From step 6, the strace shows: 
... 
open("./hdg8", O_RDONLY)                = -1 ENXIO (No such device or address) 
... 
open("./null", O_RDONLY)                = 3 
open("./y", O_RDONLY <unfinished ...> 
 
And from step 9: 
[1] 32746 
grep: ./hdg8: No such device or address 
./y:hello 
[1]+  Exit 2                  grep -D skip -r hello . 
 
Note grep actually read from the FIFO, even though it was supposed to skip it. 
 
Expected results: 
 
grep should not have attempted to open FIFO, character device or block device 
files.  It should also skip socket files according to the manual page and 
grep's --help dump. 
 
Additional info: 
 
grep might be able to use the type information passed by the getdents() system 
call under some circumstances.  This is available through the libc readdir() 
function.  If this information is not available, it should stat the files 
beforehand (fstatat() might be useful in the directory scanning case).  It 
could then potentially dispense with the fstat() it does after opening the 
file. 
 
The main thing, I think, is that it shouldn't attempt to *open* one of these 
special files if -D skip is given to it.