flag: integer overflow in intValue.Set and uintValue.Set

[perillo]

Please answer these questions before submitting your issue. Thanks!

What did you do?

I set a command line flag of type flag.Int, but with a value greater then 2^31 - 1 on 32 bit systems the underlying value is set to 0, instead of reporting an error.

Here is a sample program:
https://play.golang.org/p/F7YNWJWt29

flag.Uint has the same problem.

What did you expect to see?

The program should exit with an error status and message.

What did you see instead?

The program prints

n is  0

System details

go version go1.8 linux/amd64
GOARCH="amd64"
GOBIN="/home/manlio/.local/bin"
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/home/manlio/.local/lib/go:/home/manlio/code/src/go"
GORACE=""
GOROOT="/usr/lib/go"
GOTOOLDIR="/usr/lib/go/pkg/tool/linux_amd64"
GCCGO="gccgo"
CC="gcc"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build498162815=/tmp/go-build -gno-record-gcc-switches"
CXX="g++"
CGO_ENABLED="1"
PKG_CONFIG="pkg-config"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
GOROOT/bin/go version: go version go1.8 linux/amd64
GOROOT/bin/go tool compile -V: compile version go1.8 X:framepointer
uname -sr: Linux 4.9.9-1-ARCH
/usr/lib/libc.so.6: GNU C Library (GNU libc) stable release version 2.24, by Roland McGrath et al.
gdb --version: GNU gdb (GDB) 7.12.1

[griesemer]

As an aside, your example program has a bug: You need to add the "-number" string to the os.Args list as in: https://play.golang.org/p/k5yxZB7XmV .

Yet, still, the issue is present.

[griesemer]

The code works correctly if you use flag.Int64 instead: https://play.golang.org/p/odbmwqKO3_ . Also, I believe you can define the how errors are handled explicitly: https://golang.org/pkg/flag/#ErrorHandling. So this may actually be working as intended.

[ianlancetaylor]

@griesemer I don't think it is working as intended. The Set method has an error return, and it returns an error when the string can not be parsed or when the value is out of range of an int64. I think it should also be used when the value is out of range of an intValue.

[perillo]

On Tue, Feb 21, 2017 at 11:16 PM, Robert Griesemer ***@***.*** > wrote: The code works correctly if you use flag.Int64 instead: https://play.golang.org/p/odbmwqKO3_ .

The problem is that intValue calls strconv.ParseInt(s, 0, 64). It should call, instead, strconv.ParseInt(s, 0, strconv.IntSize) See the discussion at https://groups.google.com/forum/#!topic/golang-nuts/6rf8xh45m64

…

Also, I believe you can define the how errors are handled explicitly: https://golang.org/pkg/flag/#ErrorHandling. So this may actually be working as intended. — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#19230 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AF7dgGsflt_PNtDhFM5YNbXEY5LGrX3Eks5re2JAgaJpZM4MH6YT> .

[gopherbot]

CL https://golang.org/cl/38419 mentions this issue.