[go] net/http: mention io.Seeker requirement in FS documentation

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net/http: mention io.Seeker requirement in FS documentation

Both FileServer and NewFileTransport can try to seek a file, specifically when
MIME type sniffing is performed. This can be somewhat surprising to an
implementer of an fs.FS, as their filesystem will appear to work until a user
tries to access a file with an unrecognized extension (which requires type
sniffing and therefore seeking). With FileServer, this results in a "seeker
can't seek" message, which is not very clear for the developer.

The issue arises because fs.FS does not require Seek, while http.FileSystem
does. Therefore, this change adds a line to the documentation of net/http's
adapter function mentioning the requirement.

Change-Id: Ieb955b7a7f34e2be39dd696cb712513c70100b3a
GitHub-Last-Rev: 319a4d9d5aa2a4718e7bf9514d116f1884f04cf2
GitHub-Pull-Request: golang/go#48781
---
M src/net/http/fs.go
1 file changed, 24 insertions(+), 0 deletions(-)

diff --git a/src/net/http/fs.go b/src/net/http/fs.go
index 57e731e..6aa68c3 100644
--- a/src/net/http/fs.go
+++ b/src/net/http/fs.go
@@ -815,6 +815,8 @@
 
 // FS converts fsys to a FileSystem implementation,
 // for use with FileServer and NewFileTransport.
+// The files provided by fsys must implement io.Seeker
+// for full compatibility with FileServer and NewFileTransport.
 func FS(fsys fs.FS) FileSystem {
 	return ioFS{fsys}
 }

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Gerrit Bot uploaded patch set #2 to this change.

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net/http: mention io.Seeker requirement in FS documentation

net/http: mention io.Seeker requirement in FS documentation

Both FileServer and NewFileTransport can try to seek a file, specifically
when MIME type sniffing is performed. This can be somewhat surprising to an
implementer of an fs.FS, as their filesystem will appear to work until a
user tries to access a file with an unrecognized extension (which requires
type sniffing and therefore seeking). With FileServer, this results in a
"seeker can't seek" message, which is not very clear for the developer.

The issue arises because fs.FS does not require Seek, while http.FileSystem
does. Therefore, this change adds a line to the documentation of net/http's
adapter function mentioning the requirement.

Change-Id: Ieb955b7a7f34e2be39dd696cb712513c70100b3a

GitHub-Last-Rev: 655be81eec59d292fa8a0dd136840a4467c178b5


GitHub-Pull-Request: golang/go#48781
---
M src/net/http/fs.go

1 file changed, 26 insertions(+), 0 deletions(-)

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Gerrit Bot uploaded patch set #3 to this change.

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net/http: mention io.Seeker requirement in FS documentation

Both FileServer and NewFileTransport can try to seek a file, specifically
when MIME type sniffing is performed. This can be somewhat surprising to an
implementer of an fs.FS, as their filesystem will appear to work until a
user tries to access a file with an unrecognized extension (which requires
type sniffing and therefore seeking). With FileServer, this results in a
"seeker can't seek" message, which is not very clear for the developer.

The issue arises because fs.FS does not require Seek, while http.FileSystem
does. Therefore, this change adds a line to the documentation of net/http's
adapter function mentioning the requirement.

Change-Id: Ieb955b7a7f34e2be39dd696cb712513c70100b3a
GitHub-Last-Rev: 655be81eec59d292fa8a0dd136840a4467c178b5
GitHub-Pull-Request: golang/go#48781
---
M src/net/http/fs.go

1 file changed, 24 insertions(+), 0 deletions(-)

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Damien Neil (Gerrit)

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Oct 7, 2021, 3:15:00 PM10/7/21

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Patch set 3:Trust +1

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1 comment:

File src/net/http/fs.go:
- Patch Set #3, Line 819: // for full compatibility with FileServer and NewFileTransport.
  How about just:
  // The files provided by fsys must implement io.Seeker.
  (ServeContent does document that "the content's Seek method must work", but an additional note here seems reasonable.)

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Oct 7, 2021, 11:55:58 PM10/7/21

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Gerrit Bot uploaded patch set #4 to this change.

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net/http: mention io.Seeker requirement in FS documentation

Both FileServer and NewFileTransport can try to seek a file, specifically
when MIME type sniffing is performed. This can be somewhat surprising to an
implementer of an fs.FS, as their filesystem will appear to work until a
user tries to access a file with an unrecognized extension (which requires
type sniffing and therefore seeking). With FileServer, this results in a
"seeker can't seek" message, which is not very clear for the developer.

The issue arises because fs.FS does not require Seek, while http.FileSystem
does. Therefore, this change adds a line to the documentation of net/http's
adapter function mentioning the requirement.

Change-Id: Ieb955b7a7f34e2be39dd696cb712513c70100b3a

GitHub-Last-Rev: 56d2d41bc9347c45a17db2dfa68dd32b62368d16


GitHub-Pull-Request: golang/go#48781
---
M src/net/http/fs.go

1 file changed, 23 insertions(+), 0 deletions(-)

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Alex Studer (Gerrit)

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Oct 16, 2021, 8:52:16 PM10/16/21

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2 comments:

Patchset:
- Patch Set #4:
  That makes sense to me, done!
File src/net/http/fs.go:

- Patch Set #3, Line 819: // for full compatibility with FileServer and NewFileTransport.

- How about just: […]
  Done

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Damien Neil (Gerrit)

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Oct 19, 2021, 7:24:48 PM10/19/21

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Patch set 4:Run-TryBot +1Code-Review +2Trust +1

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Ian Lance Taylor (Gerrit)

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Oct 19, 2021, 8:03:34 PM10/19/21

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Patch set 4:Trust +1

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Gerrit Bot (Gerrit)

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Oct 20, 2021, 3:18:11 PM10/20/21

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Gerrit Bot uploaded patch set #5 to this change.

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net/http: mention io.Seeker requirement in FS documentation

Both FileServer and NewFileTransport can try to seek a file, specifically
when MIME type sniffing is performed. This can be somewhat surprising to an
implementer of an fs.FS, as their filesystem will appear to work until a
user tries to access a file with an unrecognized extension (which requires
type sniffing and therefore seeking). With FileServer, this results in a
"seeker can't seek" message, which is not very clear for the developer.

The issue arises because fs.FS does not require Seek, while http.FileSystem
does. Therefore, this change adds a line to the documentation of net/http's
adapter function mentioning the requirement.

Change-Id: Ieb955b7a7f34e2be39dd696cb712513c70100b3a

GitHub-Last-Rev: fddccdae36e04fcb87d78b3b03fa4658dbb7d83d


GitHub-Pull-Request: golang/go#48781
---
M src/net/http/fs.go
1 file changed, 23 insertions(+), 0 deletions(-)

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Aug 24, 2022, 10:46:30 AM8/24/22

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Patch set 5:Run-TryBot +1

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Damien Neil (Gerrit)

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net/http: mention io.Seeker requirement in FS documentation

Both FileServer and NewFileTransport can try to seek a file, specifically
when MIME type sniffing is performed. This can be somewhat surprising to an
implementer of an fs.FS, as their filesystem will appear to work until a
user tries to access a file with an unrecognized extension (which requires
type sniffing and therefore seeking). With FileServer, this results in a
"seeker can't seek" message, which is not very clear for the developer.

The issue arises because fs.FS does not require Seek, while http.FileSystem
does. Therefore, this change adds a line to the documentation of net/http's
adapter function mentioning the requirement.

Change-Id: Ieb955b7a7f34e2be39dd696cb712513c70100b3a
GitHub-Last-Rev: fddccdae36e04fcb87d78b3b03fa4658dbb7d83d
GitHub-Pull-Request: golang/go#48781

Reviewed-on: https://go-review.googlesource.com/c/go/+/353874
Reviewed-by: Damien Neil <dn...@google.com>
Auto-Submit: Damien Neil <dn...@google.com>
Run-TryBot: Damien Neil <dn...@google.com>
TryBot-Result: Gopher Robot <go...@golang.org>
Reviewed-by: David Chase <drc...@google.com>
---
M src/net/http/fs.go
1 file changed, 29 insertions(+), 0 deletions(-)

diff --git a/src/net/http/fs.go b/src/net/http/fs.go
index 4f144eb..87caeb7 100644
--- a/src/net/http/fs.go
+++ b/src/net/http/fs.go
@@ -818,6 +818,7 @@


 
 // FS converts fsys to a FileSystem implementation,
 // for use with FileServer and NewFileTransport.

+// The files provided by fsys must implement io.Seeker.


 func FS(fsys fs.FS) FileSystem {
 	return ioFS{fsys}
 }

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