英文:
Getting errno after a write operation
问题
我有以下的Go代码，它最终会填满磁盘并因为ENOSPC而失败（只是一个概念验证）。我如何从os.Write返回的err中确定它确实是因为ENOSPC而失败的（所以我需要在写操作之后获取errno的方法）？
package main
import (
"log"
"os"
)
func main() {
fd, _ := os.Create("dump.txt")
defer fd.Close()
for {
buf := make([]byte, 1024)
_, err := fd.Write(buf)
if err != nil {
log.Fatalf("%T %v", err, err)
}
}
}
编辑：根据@FUZxxl的建议更新了程序：
package main
import (
"log"
"os"
"syscall"
)
func main() {
fd, _ := os.Create("dump.txt")
defer fd.Close()
for {
buf := make([]byte, 1024)
_, err := fd.Write(buf)
if err != nil {
log.Printf("%T %v\n", err, err)
errno, ok := err.(syscall.Errno)
if ok {
log.Println("type assert ok")
if errno == syscall.ENOSPC {
log.Println("got ENOSPC")
}
} else {
log.Println("type assert not ok")
}
break
}
}
}
然而，我没有得到预期的结果。以下是输出：
2015/02/15 10:13:27 *os.PathError write dump.txt: no space left on device
2015/02/15 10:13:27 type assert not ok
英文:
I have the following Go code which will eventually fill the disk and fail with ENOSPC (just a proof of concept). How can I determine from the err returned by os.Write that it indeed failed because of ENOSPC (so I need a way to grab errno after the write operation) ?
package main
import (
"log"
"os"
)
func main() {
fd, _ := os.Create("dump.txt")
defer fd.Close()
for {
buf := make([]byte, 1024)
_, err := fd.Write(buf)
if err != nil {
log.Fatalf("%T %v", err, err)
}
}
}
EDIT: Updated the program as @FUZxxl suggested:
package main
import (
"log"
"os"
"syscall"
)
func main() {
fd, _ := os.Create("dump.txt")
defer fd.Close()
for {
buf := make([]byte, 1024)
_, err := fd.Write(buf)
if err != nil {
log.Printf("%T %v\n", err, err)
errno, ok := err.(syscall.Errno)
if ok {
log.Println("type assert ok")
if errno == syscall.ENOSPC {
log.Println("got ENOSPC")
}
} else {
log.Println("type assert not ok")
}
break
}
}
}
However, I'm not getting the expected result. Here is the output:
2015/02/15 10:13:27 *os.PathError write dump.txt: no space left on device
2015/02/15 10:13:27 type assert not ok
答案1
得分: 5
文件操作通常会返回一个*os.PathError类型的错误；将err转换为os.PathError类型，并使用Err字段来检查底层原因，就像这样：
patherr, ok := err.(*os.PathError)
if ok && patherr.Err == syscall.ENOSPC {
log.Println("磁盘空间不足！")
}
英文:
File operations generally return an *os.PathError; cast err to os.PathError and use the Err field to examine the underlying cause, like this:
patherr, ok := err.(*os.PathError)
if ok && patherr.Err == syscall.ENOSPC {
log.Println("Out of disk space!")
}
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