[PATCH 2/2] lua: fix error handling in getpwall and getgrall
Alexander Turenko
alexander.turenko at tarantool.org
Mon Dec 3 18:19:54 MSK 2018
We had discussion with Vladimir and decided to remove errno checks when
a return value does not indicate possibility of an error.
The new patch is at bottom of the email.
WBR, Alexander Turenko.
On Mon, Dec 03, 2018 at 11:33:24AM +0300, Vladimir Davydov wrote:
> On Sun, Dec 02, 2018 at 06:57:32PM +0300, Alexander Turenko wrote:
> > This commit fixes app-tap/pwd.test.lua test. It seems that the problem
> > appears after updating to glibc-2.28.
> >
> > Related to #3766.
> > ---
> > src/lua/pwd.lua | 43 +++++++++++++++++++++++++++++++++++++++----
> > 1 file changed, 39 insertions(+), 4 deletions(-)
> >
> > diff --git a/src/lua/pwd.lua b/src/lua/pwd.lua
> > index 8f17951df..0a6b73395 100644
> > --- a/src/lua/pwd.lua
> > +++ b/src/lua/pwd.lua
> > @@ -158,22 +158,52 @@ local function getpw(uid)
> > return user
> > end
> >
> > +-- It seems glibc developers threat POSIX in the following way.
>
> s/threat/treat
>
Removed the comment at all.
> > +-- {set,get,end}pwent() and {set,get,end}grent() functions can set
> > +-- errno to non-zero value that is not listed in the standard in
> > +-- case of success. Errno should be checked after get{pw,gr}ent
> > +-- only when it returns a non-NULL value.
>
> Why do you need to check for specific error codes then?
>
Discussed it with Vladimir and decided to check only get{pw,gr}ent()
only when they return NULL.
> > +--
> > +-- https://sourceware.org/bugzilla/show_bug.cgi?id=1969
> > +-- https://sourceware.org/bugzilla/show_bug.cgi?id=23737
> > +
> > +local pwent_grent_errno_list = {
> > + errno.EINTR,
> > + errno.EIO,
> > + errno.EMFILE,
> > + errno.ENFILE,
> > +}
> > +
> > +local function is_pwent_grent_errno(e)
> > + for _, v in ipairs(pwent_grent_errno_list) do
> > + if e == v then
> > + return true
> > + end
> > + end
> > + return false
> > +end
> > +
> > local function getpwall()
> > errno(0)
> > ffi.C.setpwent()
> > - if errno() ~= 0 then
> > + if is_pwent_grent_errno(errno()) then
>
> According to the manual setpwent never fails in any visible to the user
> way so why check errno here?
>
It does not stated explicitly in manual pages or POSIX, but it seems to
be in spirit of Unix APIs.
> > return nil
> > end
> > local pws = {}
> > while true do
> > + errno(0)
> > local pw = ffi.C.getpwent()
> > if pw == nil then
> > + if is_pwent_grent_errno(errno()) then
> > + return nil
> > + end
> > break
> > end
> > table.insert(pws, getpw(pw.pw_uid))
> > end
> > + errno(0)
> > ffi.C.endpwent()
> > - if errno() ~= 0 then
> > + if is_pwent_grent_errno(errno()) then
>
> Again, endpwent never fails. May be, remove this check altogether?
>
> Same concerns setgrent and endgrent.
Done.
>
> > return nil
> > end
> > return pws
> > @@ -182,19 +212,24 @@ end
> > local function getgrall()
> > errno(0)
> > ffi.C.setgrent()
> > - if errno() ~= 0 then
> > + if is_pwent_grent_errno(errno()) then
> > return nil
> > end
> > local grs = {}
> > while true do
> > + errno(0)
> > local gr = ffi.C.getgrent()
> > if gr == nil then
> > + if is_pwent_grent_errno(errno()) then
> > + return nil
> > + end
> > break
> > end
> > table.insert(grs, getpw(gr.gr_gid))
> > end
> > + errno(0)
> > ffi.C.endgrent()
> > - if errno() ~= 0 then
> > + if is_pwent_grent_errno(errno()) then
> > return nil
> > end
> > return grs
The new patch
-------------
commit d8a5e29ecfd486a3f998d4a41d8e0bb17463c27d
Author: Alexander Turenko <alexander.turenko at tarantool.org>
Date: Sun Dec 2 17:58:09 2018 +0300
lua: fix error handling in getpwall and getgrall
This commit fixes app-tap/pwd.test.lua test. It seems that the problem
appears after updating to glibc-2.28.
It seems that usual way to handle errors in Unix is to check errno only
when a return value indicates possibility of an error.
Related to #3766.
diff --git a/src/lua/pwd.lua b/src/lua/pwd.lua
index 8f17951df..b2c8e121f 100644
--- a/src/lua/pwd.lua
+++ b/src/lua/pwd.lua
@@ -159,44 +159,37 @@ local function getpw(uid)
end
local function getpwall()
- errno(0)
ffi.C.setpwent()
- if errno() ~= 0 then
- return nil
- end
local pws = {}
while true do
+ errno(0)
local pw = ffi.C.getpwent()
if pw == nil then
+ if errno() ~= 0 then
+ return nil
+ end
break
end
table.insert(pws, getpw(pw.pw_uid))
end
ffi.C.endpwent()
- if errno() ~= 0 then
- return nil
- end
return pws
end
local function getgrall()
- errno(0)
ffi.C.setgrent()
- if errno() ~= 0 then
- return nil
- end
local grs = {}
while true do
local gr = ffi.C.getgrent()
if gr == nil then
+ if errno() ~= 0 then
+ return nil
+ end
break
end
table.insert(grs, getpw(gr.gr_gid))
end
ffi.C.endgrent()
- if errno() ~= 0 then
- return nil
- end
return grs
end
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