fcntl.h doesn't contain all status flag constants
-
31-12-2020 - |
문제
I have been going through header files and I'm not able to find any file with status flag definitions (like O_RDONLY).
Thanks, John
해결책
Summary
If you're on Linux, it should be in /usr/include/bits/fcntl.h
.
#define O_RDONLY 00
You can find it using rgrep
, or ctags
and Vim
, or cpp
, or cwhere
.
rgrep
The simplest way is to use rgrep
, a.k.a. grep -R
.
$ rgrep O_WRONLY .
./X11/Xw32defs.h:# define O_WRONLY _O_WRONLY
./linux/fs.h: * to O_WRONLY and O_RDWR via the strange trick in __dentry_open()
./linux/smbno.h:#define SMB_O_WRONLY 0x0001
./asm-generic/fcntl.h:#define O_WRONLY 00000001
./security/_pam_macros.h: if ((fd = open(_PAM_LOGFILE, O_WRONLY|O_NOFOLLOW|O_APPEND)) != -1) {
./security/_pam_macros.h: if ((fd = open(_PAM_LOGFILE, O_WRONLY|O_APPEND)) != -1) {
./security/_pam_macros.h: if ((fd = open(_PAM_LOGFILE, O_WRONLY|O_NOFOLLOW|O_APPEND)) != -1) {
./security/_pam_macros.h: if ((fd = open(_PAM_LOGFILE, O_WRONLY|O_APPEND)) != -1) {
./bits/fcntl.h:#define O_WRONLY 01
ctags
Or, you could run ctags -R
in /usr/include
and then run vim -t O_WRONLY
.
Or, a bit better, but more typing:
find . /usr/include -name "*.h" |
ctags -f - -L - |
grep "^O_WRONLY " |
cut -d " " -f 1,2,3 |
sed -e 's# /\^# #;s#\$/\;"$##'
cpp
The best way I have found is using cpp
.
Assuming you have a source file called YOUR_SOURCE_FILE with the necessary #include
s, try running:
cpp -dD YOUR_SOURCE_FILE | less
Then search for your #define
, e.g. /O_WRONLY
, then scroll up to find the first file name above it. In this case:
# 27 "/usr/include/bits/fcntl.h" 2 3 4
means that O_WRONLY
is being picked up from /usr/include/bits/fcntl.h
if you include the three header files mentioned in man fcntl
.
cwhere
I have a script called cwhere
to automate running cpp
:
$ cwhere O_WRONLY sys/types.h sys/stat.h fcntl.h
/usr/include/bits/fcntl.h: #define O_WRONLY 01
If desc
is installed, you can just type the name of the function that uses that #define
, e.g.
$ cwhere O_WRONLY 'fcntl()'
/usr/include/bits/fcntl.h: #define O_WRONLY 01