All the main logic has been moved to functions on the Decoder struct and the package level functions merely construct and use a global detector that is protected by a mutex so that is is safe for concurrent use. This will solve #20

NOTE: previously I had added TypeByFileHandle so that detection can be done on a *os.File, but this had troubles on linux, so I removed it.

The magicmime library uses a global variable to hold the file descriptor associated with the libmagic database. This is not safe for use across mutliple goroutines. This pull-request makes it possible to use a libmagic file-description in unsynchronized and synchronized modes.

This pull-request changes the Open function API signature to add a parameter indicating the synchronization mode (SYNCHRONIZED or UNSYNCHRONIZED), and returns a pointer to a struct (type MimeDB) that keeps a reference to the libmagic file descriptor and mutex (if synchronized).

The TypeByBuffer, TypeByFile, and Close functions are now receiver functions that operate on the new MimeDB struct type. If the Open function was called with SYNCHRONIZED SyncMode then these functions will use a mutex to coordinate calls to the libmagic library.

I solved the multiple definitions issue by changing the package of example_test.go to magicmime.

After that I noticed TestMissingFile started panicking on Travis and saw that the mimetype DB was not set up. Interestingly, on OS X and the Linux vm I have tested it on, it doesn't panic.

Maybe it should never panic and the version of Travis is outdated / panics, but I haven't had the time to verify it.

The last commit adds Coveralls to your project, if you want it. If you decide to do it, first you have to add your project on Coveralls, then go to rakyll/magicmime Travis' settings and add environment variable COVERALLS_REPO_TOKEN with the token value you got on Coveralls. If you don't, just don't merge it :)

This closes #17.

When I try to download this package using go get github.com/rakyll/magicmime I get an error saying

# github.com/rakyll/magicmime
../../rakyll/magicmime/magicmime.go:28:11: fatal error: 'magic.h' file not found
 #include <magic.h>
          ^
1 error generated.

What could be the possible reason for this error?

Hey @rakyll,

just wondering...

have you figured out a way to make it work with Travis?

I have tried with https://github.com/henvic/magicmime/commit/d917cf88fca4ef77448f3196c87db5039d27ad44

but it doesn't work out https://travis-ci.org/henvic/magicmime/builds/83209266

due to multiple definitions, but I don't get how it is happening. On my machine it works just fine.

Hello @rakyll !

Is it possible to cut (semantic) version tags for magicmime? it would be easier to track it with dep.

Thank you for you work on the project.

The changes are, in the order of importance:

1. On CentOS, the package name is file-devel not libmagic-dev.
2. As it was done for Mac OS X, add the actual commands to install needed package.
3. Add Fedora and RHEL next to CentOS.
4. Mention this comes from 'file' tool.
5. It's 'package' not 'packages'.

Hi

I get cannot open; magic mime db is already open after my vscode crashed during tests and it obviously didn't close the db. However I cannot get it working again. If I ignore the error that it's already open, when I run magicmime.Close() I get invalid memory address or nil pointer dereference.

EDIT: this is still broken after rebooting

Currently, Open sequence doesn't handle the case where magic_setflags and magic_load fails. We need to close magic and free the underlying resources.

Also, we must document that Close must be called once user is done with magic.

The example in example_test.go has memeroy leak.

package main

import (
    "fmt"

    "github.com/rakyll/magicmime"
)

func main() {
    mm, err := magicmime.New(magicmime.MAGIC_MIME_TYPE | magicmime.MAGIC_SYMLINK | magicmime.MAGIC_ERROR)
    if err != nil {
        panic(err)
    }
   defer mm.Close()
    filepath := "/bin/ls"

    mimetype, err := mm.TypeByFile(filepath)
    if err != nil {
        fmt.Printf("Something went wrong: %s", err)
        return
    }

    fmt.Printf("%s -> %s\n", filepath, mimetype)
}

Take special attention for defer mm.Close()

I am attempting to install Pistol, and I am running into an error involving magic mime.

https://github.com/doronbehar/pistol/issues/76

The error states:

imports github.com/rakyll/magicmime: build constraints exclude all Go files in /home/user/go/bin/pkg/mod/github.com/rakyll/[email protected]

This is a new one for both me and the developer of pistol, and after doing some digging, an issue was discovered in the golang repository that mentions a potential solution to the issue by ensuring package main is used to denote the main script of the package.

https://github.com/golang/go/issues/24068#issuecomment-497928701

I attempted the suggested resolution, which created another error, because there is no main function in the source code.

So I am inquiring about a workaround that would allow me to use magicmime to install pistol.

Previously, passing an empty []byte paniced when trying to get a pointer to the first element. Since the slice is empty, that resulted in a index out of range runtime error.

*** Error in `./app': free(): invalid next size (fast): 0x00007f79400b5140 ***

======= Backtrace: =========
/lib64/libc.so.6(+0x7c503)[0x7f7971af5503]
/usr/lib64/libmagic.so.1(file_vprintf+0x6c)[0x7f797247330c]
/usr/lib64/libmagic.so.1(file_printf+0x87)[0x7f79724733e7]
/usr/lib64/libmagic.so.1(file_trycdf+0x4c7)[0x7f7972477157]
/usr/lib64/libmagic.so.1(file_buffer+0x1c6)[0x7f7972473726]
/usr/lib64/libmagic.so.1(magic_buffer+0x31)[0x7f7972467b61]
./app(_cgo_f7c060554b06_Cfunc_magic_buffer+0x1f)[0x8093df]
./app[0x459c60]

I'm using magicmime with multiple goroutines but with a mutex around magicmime.TypeByBuffer(blob)