The existing documentation of WriteFile does not make it clear for
non-native English speakers that it will not change the permissions if
the file already exists before.
Fixes#35711
Change-Id: If861c3e3700957fc9ac3d5313351c57d399d3f58
Reviewed-on: https://go-review.googlesource.com/c/go/+/218417
Reviewed-by: Rob Pike <r@golang.org>
- CopyN: 5 creates ambiguity with respect to whitespace and upperbound
- TeeReader less boilerplate and displays a common usage of it
- SectionReader_* all sections unified to 5:17 for clarity
- SectionReader_Seek uses io.Copy to stdout like other examples
- Seeker_Seek remove useless prints
- Pipe print reader like other examples
Updates #36417
Change-Id: Ibd01761d5a5786cdb1ea934f7a98f8302430c8a5
GitHub-Last-Rev: 4c17f9a8e3
GitHub-Pull-Request: golang/go#38379
Reviewed-on: https://go-review.googlesource.com/c/go/+/227868
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Offered as an alternative to CL 221380, which was more
tutorial than necessary.
Update #37344
Change-Id: Ide673b0b97983c2c2319a9311dc3d0a10567e6c4
Reviewed-on: https://go-review.googlesource.com/c/go/+/223097
Reviewed-by: Ian Lance Taylor <iant@golang.org>
After golang.org/cl/210124, I wondered if the same error had gone
unnoticed elsewhere. I quickly spotted another dozen mistakes after
reading through the output of:
git grep '\<[Aa]n [bcdfgjklmnpqrtvwyz][a-z]'
Many results are false positives for acronyms like "an mtime", since
it's pronounced "an em-time". However, the total amount of output isn't
that large given how simple the grep pattern is.
Change-Id: Iaa2ca69e42f4587a9e3137d6c5ed758887906ca6
Reviewed-on: https://go-review.googlesource.com/c/go/+/210678
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Zach Jones <zachj1@gmail.com>
Reviewed-by: Robert Griesemer <gri@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Note that ioutil.WriteFile's perm argument is the value before the
umask is applied.
Fixes#35835
Change-Id: I61cd9c88bced3be52b616d86e060cd3fd912ab1f
Change-Id: I61cd9c88bced3be52b616d86e060cd3fd912ab1f
GitHub-Last-Rev: 0069abb7c5
GitHub-Pull-Request: golang/go#35836
Reviewed-on: https://go-review.googlesource.com/c/go/+/208838
Reviewed-by: Ian Lance Taylor <iant@golang.org>
On Windows, os.Chmod and syscall.Chmod toggle the FILE_ATTRIBUTES_
READONLY flag depending on the permission bits. That's a bit odd but I
guess some compromises were made at some point and this is what was
chosen to map to a Unix concept that Windows doesn't really have in the
same way. That's fine. However, the logic used in Chmod was forgotten
from os.Open and syscall.Open, which then manifested itself in various
places, most recently, go modules' read-only behavior.
This makes syscall.Open consistent with syscall.Chmod and adds a test
for the permission _behavior_ using ioutil. By testing the behavior
instead of explicitly testing for the attribute bits we care about, we
make sure this doesn't regress in unforeseen ways in the future, as well
as ensuring the test works on platforms other than Windows.
In the process, we fix some tests that never worked and relied on broken
behavior, as well as tests that were disabled on Windows due to the
broken behavior and had TODO notes.
Fixes#35033
Change-Id: I6f7cf54517cbe5f6b1678d1c24f2ab337edcc7f7
Reviewed-on: https://go-review.googlesource.com/c/go/+/202439
Run-TryBot: Jason A. Donenfeld <Jason@zx2c4.com>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
Reviewed-by: Alex Brainman <alex.brainman@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Document that if either src implements the WriteTo interface
or if dst implements the ReaderFrom interface, then
buf will not be used.
Fixes#32276
Change-Id: Id0a69c90e255e694e7ec9f79ffe4d8391441e59e
GitHub-Last-Rev: 750e7e86d5
GitHub-Pull-Request: golang/go#32279
Reviewed-on: https://go-review.googlesource.com/c/go/+/179137
Reviewed-by: Emmanuel Odeke <emm.odeke@gmail.com>
Allow TempDir to create directories with predictable
prefixes and suffixes, separated by the last "*", for example:
"prefix*suffix"
will now expand to
"prefix" + <RANDOM_VALUE> + "suffix"
RELNOTE=yes
Fixes#33805.
Change-Id: I85fa73ae6a684ce820d1810c82a60765eb9c4a42
Reviewed-on: https://go-review.googlesource.com/c/go/+/198488
Run-TryBot: Emmanuel Odeke <emm.odeke@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
The current implementation allows multiple calls `Close` and `CloseWithError` in every side of the pipe, as a result, the original error can be overwritten.
This CL fixes this behavior adding an error existence check on `atomicError` type
and keeping the first error still available.
Fixes#24283
Change-Id: Iefe8f758aeb775309424365f8177511062514150
GitHub-Last-Rev: b559540d7a
GitHub-Pull-Request: golang/go#33239
Reviewed-on: https://go-review.googlesource.com/c/go/+/187197
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
Run-TryBot: Joe Tsai <thebrokentoaster@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
And start using it elsewhere in the standard library, removing the
copies in the process.
While at it, rewrite the io.WriteString godoc to be more clear, since it
can now make reference to the defined interface.
Fixes#27946.
Change-Id: Id5ba223c09c19e5fb49815bd3b1bd3254fc786f3
Reviewed-on: https://go-review.googlesource.com/c/139457
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Users of TempFile need to be able to supply the suffix, especially
when using operating systems that give semantic meaning to the
filename extension such as Windows. Renaming the file to include
an extension after the fact is insufficient as it could lead to
race conditions.
If the string given to TempFile includes a "*", the random string
replaces the "*". For example "myname.*.bat" will result in a random
filename such as "myname.123456.bat". If no "*' is included the
old behavior is retained, and the random digits are appended to the
end.
If multiple "*" are included, the final one is replaced, thus
permitting a pathological programmer to create filenames such as
"foo*.123456.bat" but not "foo.123456.*.bat"
Fixes#4896
Change-Id: Iae7f0980b4de6d7d31b87c8c3c3d40767b283c1f
Reviewed-on: https://go-review.googlesource.com/105675
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Add a note that if an error is returned after having read
at least the minimum no. of bytes, the error is set to nil.
Fixes#20477
Change-Id: I75ba5ee967be3ff80249e40d459da4afeeb53463
Reviewed-on: https://go-review.googlesource.com/102459
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
CL 60630 claimed to and did “improve performance of CopyN”
but in doing so introduced a second copy of the I/O copying loop.
This code is subtle and easy to get wrong and the last thing we
need is of two copies that can drift out of sync. Even the newly
introduced copy contains various subtle changes that are not
obviously semantically equivalent to the original. (They probably
are, but it's not obvious.)
Although the CL description does not explain further what the
important optimization was, it appears that the most critical
one was not allocating a 32kB buffer for CopyN(w, r, 512).
This CL deletes the forked copy of copy and instead applies
the buffer size restriction optimization directly to copy itself.
CL 60630 reported:
name old time/op new time/op delta
CopyNSmall-4 5.09µs ± 1% 2.25µs ±86% -55.91% (p=0.000 n=11+14)
CopyNLarge-4 114µs ±73% 121µs ±72% ~ (p=0.701 n=14+14)
Starting with that CL as the baseline, this CL does not change a ton:
name old time/op new time/op delta
CopyNSmall-8 370ns ± 1% 411ns ± 1% +11.18% (p=0.000 n=16+14)
CopyNLarge-8 18.2µs ± 1% 18.3µs ± 1% +0.63% (p=0.000 n=19+20)
It does give up a small amount of the win of 60630 but preserves
the bulk of it, with the benefit that we will not need to debug these
two copies drifting out of sync in the future.
Change-Id: I05b1a5a7115390c5867847cba606b75d513eb2e2
Reviewed-on: https://go-review.googlesource.com/78122
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
MultiWriter(w1, w2) only writes to w2 if w1.Write succeeds.
I did not know this, and it was not documented.
Document and test.
Change-Id: Idec2e8444d5a7aca0b95d07814a28daa454eb1d3
Reviewed-on: https://go-review.googlesource.com/78123
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Usage of atomic.Value has a subtle requirement that the
value be of the same concrete type. In prior usage, the intention
was to consistently store a value of the error type.
Since error is an interface, the underlying concrete can differ.
Fix this by creating a type-safe abstraction over atomic.Value
that wraps errors in a struct{error} type to ensure consistent types.
Change-Id: Ica74f2daba15e4cff48d2b4f830d2cb51c608fb6
Reviewed-on: https://go-review.googlesource.com/75594
Run-TryBot: Joe Tsai <thebrokentoaster@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Replace any nested Writer that is a MultiWriter with its associated
Writers.
Fixes#22431
Change-Id: Ida7c4c83926363c1780689e216cf0c5241a5b8eb
Reviewed-on: https://go-review.googlesource.com/73470
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
In the distant past, Pipe was implemented with channels and a
long running pipe.run goroutine (see CL 994043).
This approach of having all communication serialized through the
run method was error prone giving Pipe a history of deadlocks
and race conditions.
After the introduction of sync.Cond, the implementation was rewritten
(see CL 4252057) to use condition variables and avoid the
long running pipe.run goroutine. While this implementation is superior
to the previous one, this implementation is strange in that the
p.data field is always set immediately prior to signaling the other
goroutine with Cond.Signal, effectively making the combination of the
two a channel-like operation. Inferior to a channel, however, this still
requires explicit locking around the p.data field.
The data+rwait can be effectively be replaced by a "chan []byte" to
inform a reader that there is data available.
The data+wwait can be effectively be replaced by a "chan int" to
inform a writer of how many bytes were read.
This implementation is a simplified from net.Pipe in CL 37402.
Change-Id: Ia5b26320b0525934fd87a3b69a091c787167f5aa
Reviewed-on: https://go-review.googlesource.com/65330
Run-TryBot: Joe Tsai <thebrokentoaster@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Bryan Mills <bcmills@google.com>
When we added a Stat call to determine the initial buffer size in
https://golang.org/cl/163069, we included an arbitrary 1e9-byte limit
"just in case". That interacts badly with power-of-2 resizing in
*bytes.Buffer: it causes buffers reading from very large files to
consume up to twice the necessary space.
The documentation for (os.FileInfo).Size says that it reports "length
in bytes for regular files; system-dependent for others", but the
"system dependent" cases overwhelmingly return either a small number
(e.g., the length of the target path for a symlink) or a non-positive
number (e.g., for a file in /proc under Linux). It should be
appropriate to use the number reported by Size as an approximate lower
bound, even if it is large.
fixes#21455
Change-Id: I609c72519b7b87428c24d0b22db46eede30e0e54
Reviewed-on: https://go-review.googlesource.com/55870
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Change-Id: I24374accf48d43edf4bf27ea6ba2245ddca558ad
Reviewed-on: https://go-review.googlesource.com/50910
Reviewed-by: Giovanni Bajo <rasky@develer.com>
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
Run-TryBot: Joe Tsai <thebrokentoaster@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
While there's an example for SectionReader.Seek, if someone is
seeking documentation specifically about Seeker.Seek, they may
not immediately find the SectionReader example. Offset and whence
may not be entirely intuitive to new developers either, so include
examples of both positive/negative offsets and SeekStart/SeekEnd.
Change-Id: I5b7442ccf683d9706e9261c11bc0ea31a1ac21d4
Reviewed-on: https://go-review.googlesource.com/48873
Reviewed-by: Kevin Burke <kev@inburke.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Document that the byte value returned by ReadByte() is meaningless
if its error != nil. Because io.Reader and io.ByteReader are similar in
name, this CL aims to clear up any ambiguity surrounding the returned
values, particularly where io.Reader is allowed to return both a
non-zero number of valid bytes and err == EOF.
Fixes#20825
Change-Id: I3a23c18c80c471c0caae3b4d2f6f8e547da0bed9
Reviewed-on: https://go-review.googlesource.com/46950
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TestMultiReaderFlatten determines the call depth by counting PCs
returned by runtime.Callers. With inlining, this is incorrect because
a PC can represent multiple calls. Furthermore, runtime.Callers might
return an additional "skip" PC, which does not represent a real call.
This modifies the test to use CallersFrames to determine the call depth.
Now the test passes with -l=4.
Change-Id: I284f3b1e0b2d194bd08c230c616914503e5a370d
Reviewed-on: https://go-review.googlesource.com/40990
Run-TryBot: David Lazar <lazard@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
The first part of this test tries to confirm that we can't create
a TempFile in a non-existent directory, but does not ensure that
the non-existent directory really does not exist. Instead, let's
create an empty temp directory, and use a non-existent subdir of
that.
Change-Id: I176f14ed5f5a2d7a8c29d8f6949755db69d7dbb6
Reviewed-on: https://go-review.googlesource.com/40914
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This ensures there isn't a live reference to buf1 on our stack
when MultiReader is inlined.
Fixes#18819.
Change-Id: I96a8cdc1ffad8f8a10c0ddcbf0299005f3176b61
Reviewed-on: https://go-review.googlesource.com/35931
Run-TryBot: David Lazar <lazard@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
Reviewed-by: Russ Cox <rsc@golang.org>
Since commit cc62bed0 (CL 994043) the pipe deadlock when doing
Read+Close or Write+Close on same end was fixed, alas with test for
Read+Close case only.
Then commit 6d6f3381 (CL 4252057) made a thinko: in the writer path
p.werr is checked for != nil and then err is set but there is no break
from waiting loop unlike break is there in similar condition for reader.
Together with having only Read+Close case tested that made it to leave
reintroduced Write+Close deadlock unnoticed.
Fix it.
Implicitly this also fixes net.Pipe to conform to semantic of net.Conn
interface where Close is documented to unblock any blocked Read or Write
operations.
No test added to net/ since net.Pipe tests are "Assuming that the
underlying io.Pipe implementation is solid and we're just testing the
net wrapping". The test added in this patch should be enough to cover
the breakage.
Fixes#18401
Updates #18170
Change-Id: I9e9460b3fd7d220bbe60b726accf86f352aed8d4
Reviewed-on: https://go-review.googlesource.com/34637
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
Specify that that LimitedReader returns EOF when the underlying
R returns EOF even if bytes remaining, N > 0.
Fixes#18271
Change-Id: I990a7135f1d31488d535238ae061d42ee96bacb7
Reviewed-on: https://go-review.googlesource.com/34249
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
The combination of two prior CLs can cause panics:
* CL/17873: make chained multiReader Read more efficient
* CL/28533: make MultiReader nil exhausted Readers for earlier GC
The first CL allows MultiReader to "inherit" another MultiReader's list of Readers
for efficiency reasons. This is problematic when combined with the
later CL since that can set prior Readers in that list to nil for GC reasons.
This causes panics when two MultiReaders are used together (even synchronously).
To fix this, rather than setting consumed Readers as nil, we set them with
a special eofReader that always returns EOF.
Fixes#18232
Change-Id: I2a9357ab217e3d54d38ea9022d18e4d14f4182d3
Reviewed-on: https://go-review.googlesource.com/34140
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
I avoided anywhere in the compiler or things which might be used by
the compiler in the future, since they need to build with Go 1.4.
I also avoided anywhere where there was no benefit to changing it.
I probably missed some.
Updates #16721
Change-Id: Ib3c895ff475c6dec2d4322393faaf8cb6a6d4956
Reviewed-on: https://go-review.googlesource.com/30250
TryBot-Result: Gobot Gobot <gobot@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Andrew Gerrand <adg@golang.org>
Fixes#14196
Change-Id: Ife7950289ac6adbcfc4d0f2fce31f20bc2657858
Reviewed-on: https://go-review.googlesource.com/28772
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
No test because the language spec makes no promises in this area.
Fixes#16983
Change-Id: I1a6aa7ff87dd14aa27e8400040a6f6fc908aa1fd
Reviewed-on: https://go-review.googlesource.com/28533
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
If an io.Reader returned (non-zero, EOF), MultiReader would yield
bytes forever.
This bug has existed before Go 1 (!!), introduced in the original
MultiReader implementation in https://golang.org/cl/1764043 and also
survived basically the only update to this code since then
(https://golang.org/cl/17873, git rev ccdca832c), which was added in
Go 1.7.
This just bit me when writing a test for some unrelated code.
Fixes#16795
Change-Id: I36e6a701269793935d19a47ac12f67b07179fbff
Reviewed-on: https://go-review.googlesource.com/27397
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
The documentation previously used C style enumerations: 0, 1, 2.
While this is pretty much universally correct, it does not help a user
become aware of the existence of the SeekStart, SeekCurrent, and SeekEnd
constants. Thus, we should use them in the documentation to direct people's
attention to them.
Updates #6885
Change-Id: I44b5e78d41601c68a0a1c96428c853df53981d52
Reviewed-on: https://go-review.googlesource.com/23551
Reviewed-by: Andrew Gerrand <adg@golang.org>
It's not clear we want to enshrine an io interface in which Size cannot
return an error. Because this requires more thought before committing
to the API, remove from Go 1.7.
Fixes#15818.
Change-Id: Ic4138ffb0e033030145a12d33f78078350a8381f
Reviewed-on: https://go-review.googlesource.com/23392
Reviewed-by: Austin Clements <austin@google.com>
Run-TryBot: Russ Cox <rsc@golang.org>
before this change, when io.MultiReader was called many times but contain few
underlying readers, calls to Read were unnecessarily expensive.
Fixes#13558
Change-Id: I3ec4e88c7b50c075b148331fb1b7348a5840adbe
Reviewed-on: https://go-review.googlesource.com/17873
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
joshuabezaleel
Eric
Brad Fitzpatrick
Rob Pike
Constantin Konstantinidis
Davor Kapsa
Ian Lance Taylor
Daniel Martí
Mostyn Bramley-Moore
Lars Lehtonen
Jason A. Donenfeld
sandyskies
Emmanuel T Odeke
jsign
Jordi Martin
Derek Phan
G. Hussain Chinoy
Author Name
Tom Limoncelli
Agniva De Sarker
Russ Cox
Joe Tsai
Michael Fraenkel
Albert Nigmatzianov
Bryan C. Mills
Guilherme Rezende
Vitor De Mario
Greg Poirier
smasher164
David Lazar
Kirill Smelkov
Anmol Sethi
andrew werner