Commit Graph

15 Commits

Author SHA1 Message Date
FRIGN 11e2d472bf Add *fshut() functions to properly flush file streams
This has been a known issue for a long time. Example:

printf "word" > /dev/full

wouldn't report there's not enough space on the device.
This is due to the fact that every libc has internal buffers
for stdout which store fragments of written data until they reach
a certain size or on some callback to flush them all at once to the
kernel.
You can force the libc to flush them with fflush(). In case flushing
fails, you can check the return value of fflush() and report an error.

However, previously, sbase didn't have such checks and without fflush(),
the libc silently flushes the buffers on exit without checking the errors.
No offense, but there's no way for the libc to report errors in the exit-
condition.

GNU coreutils solve this by having onexit-callbacks to handle the flushing
and report issues, but they have obvious deficiencies.
After long discussions on IRC, we came to the conclusion that checking the
return value of every io-function would be a bit too much, and having a
general-purpose fclose-wrapper would be the best way to go.

It turned out that fclose() alone is not enough to detect errors. The right
way to do it is to fflush() + check ferror on the fp and then to a fclose().
This is what fshut does and that's how it's done before each return.
The return value is obviously affected, reporting an error in case a flush
or close failed, but also when reading failed for some reason, the error-
state is caught.

the !!( ... + ...) construction is used to call all functions inside the
brackets and not "terminating" on the first.
We want errors to be reported, but there's no reason to stop flushing buffers
when one other file buffer has issues.
Obviously, functionales come before the flush and ret-logic comes after to
prevent early exits as well without reporting warnings if there are any.

One more advantage of fshut() is that it is even able to report errors
on obscure NFS-setups which the other coreutils are unable to detect,
because they only check the return-value of fflush() and fclose(),
not ferror() as well.
2015-04-05 09:13:56 +01:00
FRIGN 93fd817536 Add estrlcat() and estrlcpy()
It has become a common idiom in sbase to check strlcat() and strlcpy()
using

if (strl{cat, cpy}(dst, src, siz) >= siz)
        eprintf("path too long\n");

However, this was not carried out consistently and to this very day,
some tools employed unchecked calls to these functions, effectively
allowing silent truncations to happen, which in turn may lead to
security issues.
To finally put an end to this, the e*-functions detect truncation
automatically and the caller can lean back and enjoy coding without
trouble. :)
2015-03-17 11:24:49 +01:00
FRIGN a76d4943b5 Audit mktemp(1)
1) Unglobalize variables.
2) Sort local variables.
3) Use return instead of exit() in main().
4) Add empty line before return.
2015-03-17 11:01:33 +01:00
FRIGN 31572c8b0e Clean up #includes 2015-02-14 21:12:23 +01:00
FRIGN eee98ed3a4 Fix coding style
It was about damn time. Consistency is very important in such a
big codebase.
2014-11-13 18:08:43 +00:00
sin 0c5b7b9155 Stop using EXIT_{SUCCESS,FAILURE} 2014-10-02 23:46:59 +01:00
sin f5ac08cc04 Only use /tmp if template is a file and not a path 2014-07-04 16:02:15 +01:00
Hiltjo Posthuma eac0f658cf check snprintf error aswell, handle as truncation error
Signed-off-by: Hiltjo Posthuma <hiltjo@codemadness.org>
2014-06-01 18:02:55 +01:00
sin f23409f65a Break long line in mktemp(1) 2014-05-02 21:38:40 +01:00
sin 94e97f19cd No need to use enprintf() with EXIT_FAILURE
eprintf() does just that.
2014-01-30 14:55:26 +00:00
sin db2c54bee6 oops that should have been enprintf() 2014-01-24 16:46:56 +00:00
sin 30620afb6c Check return value of snprintf in mktemp(1) 2014-01-24 16:19:46 +00:00
sin 91a643411d Check for TMPDIR and if set use it 2013-11-14 19:47:22 +00:00
sin 56a62c605f Implement -q support for mktemp(1) 2013-11-13 15:27:41 +00:00
sin 34f7a688cb Add barebones mktemp(1) 2013-11-13 11:06:55 +00:00