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copy_file: Add parameter to allow symlinks (#252)
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* copy_file: Add parameter to allow symlinks

This change adds a new parameter `allow_symlinks` to `copy_file` that
allows the action to create a symlink instead of doing an expensive
copy if the execution platform (host) allows it.

Updates #248

* Update docs

* Refactor `is_executable` into attribute

* Fix typo

* s/_impl/_copy_file_impl/
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@Yannic
Yannic committed Jul 10, 2020
1 parent d35e8d7 commit 8f3151f
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Showing 5 changed files with 138 additions and 38 deletions.
21 changes: 20 additions & 1 deletion docs/copy_file_doc.md
View file
@@ -1,7 +1,11 @@
<!-- Generated with Stardoc: http://skydoc.bazel.build -->

<a name="#copy_file"></a>

## copy_file

<pre>
copy_file(<a href="#copy_file-name">name</a>, <a href="#copy_file-src">src</a>, <a href="#copy_file-out">out</a>, <a href="#copy_file-is_executable">is_executable</a>, <a href="#copy_file-kwargs">kwargs</a>)
copy_file(<a href="#copy_file-name">name</a>, <a href="#copy_file-src">src</a>, <a href="#copy_file-out">out</a>, <a href="#copy_file-is_executable">is_executable</a>, <a href="#copy_file-allow_symlink">allow_symlink</a>, <a href="#copy_file-kwargs">kwargs</a>)
</pre>

Copies a file to another location.
Expand Down Expand Up @@ -55,6 +59,21 @@ This rule uses a Bash command on Linux/macOS/non-Windows, and a cmd.exe command
A boolean. Whether to make the output file executable. When
True, the rule's output can be executed using `bazel run` and can be
in the srcs of binary and test rules that require executable sources.
WARNING: If `allow_symlink` is True, `src` must also be executable.
</p>
</td>
</tr>
<tr id="copy_file-allow_symlink">
<td><code>allow_symlink</code></td>
<td>
optional. default is <code>False</code>
<p>
A boolean. Whether to allow symlinking instead of copying.
When False, the output is always a hard copy. When True, the output
*can* be a symlink, but there is no guarantee that a symlink is
created (i.e., at the time of writing, we don't create symlinks on
Windows). Set this to True if you need fast copying and your tools can
handle symlinks (which most UNIX tools can).
</p>
</td>
</tr>
Expand Down
75 changes: 40 additions & 35 deletions rules/private/copy_file_private.bzl
View file
Expand Up @@ -58,45 +58,48 @@ def copy_bash(ctx, src, dst):
use_default_shell_env = True,
)

def _common_impl(ctx, is_executable):
if ctx.attr.is_windows:
copy_cmd(ctx, ctx.file.src, ctx.outputs.out)
def _copy_file_impl(ctx):
if ctx.attr.allow_symlink:
ctx.actions.symlink(
output = ctx.outputs.out,
target_file = ctx.file.src,
is_executable = ctx.attr.is_executable,
)
else:
copy_bash(ctx, ctx.file.src, ctx.outputs.out)
if ctx.attr.is_windows:
copy_cmd(ctx, ctx.file.src, ctx.outputs.out)
else:
copy_bash(ctx, ctx.file.src, ctx.outputs.out)

files = depset(direct = [ctx.outputs.out])
runfiles = ctx.runfiles(files = [ctx.outputs.out])
if is_executable:
if ctx.attr.is_executable:
return [DefaultInfo(files = files, runfiles = runfiles, executable = ctx.outputs.out)]
else:
return [DefaultInfo(files = files, runfiles = runfiles)]

def _impl(ctx):
return _common_impl(ctx, False)

def _ximpl(ctx):
return _common_impl(ctx, True)

_ATTRS = {
"src": attr.label(mandatory = True, allow_single_file = True),
"out": attr.output(mandatory = True),
"is_windows": attr.bool(mandatory = True),
"is_executable": attr.bool(mandatory = True),
"allow_symlink": attr.bool(mandatory = True),
}

_copy_file = rule(
implementation = _impl,
implementation = _copy_file_impl,
provides = [DefaultInfo],
attrs = _ATTRS,
)

_copy_xfile = rule(
implementation = _ximpl,
implementation = _copy_file_impl,
executable = True,
provides = [DefaultInfo],
attrs = _ATTRS,
)

def copy_file(name, src, out, is_executable = False, **kwargs):
def copy_file(name, src, out, is_executable = False, allow_symlink = False, **kwargs):
"""Copies a file to another location.
`native.genrule()` is sometimes used to copy files (often wishing to rename them). The 'copy_file' rule does this with a simpler interface than genrule.
Expand All @@ -111,27 +114,29 @@ def copy_file(name, src, out, is_executable = False, **kwargs):
is_executable: A boolean. Whether to make the output file executable. When
True, the rule's output can be executed using `bazel run` and can be
in the srcs of binary and test rules that require executable sources.
WARNING: If `allow_symlink` is True, `src` must also be executable.
allow_symlink: A boolean. Whether to allow symlinking instead of copying.
When False, the output is always a hard copy. When True, the output
*can* be a symlink, but there is no guarantee that a symlink is
created (i.e., at the time of writing, we don't create symlinks on
Windows). Set this to True if you need fast copying and your tools can
handle symlinks (which most UNIX tools can).
**kwargs: further keyword arguments, e.g. `visibility`
"""

copy_file_impl = _copy_file
if is_executable:
_copy_xfile(
name = name,
src = src,
out = out,
is_windows = select({
"@bazel_tools//src/conditions:host_windows": True,
"//conditions:default": False,
}),
**kwargs
)
else:
_copy_file(
name = name,
src = src,
out = out,
is_windows = select({
"@bazel_tools//src/conditions:host_windows": True,
"//conditions:default": False,
}),
**kwargs
)
copy_file_impl = _copy_xfile

copy_file_impl(
name = name,
src = src,
out = out,
is_windows = select({
"@bazel_tools//src/conditions:host_windows": True,
"//conditions:default": False,
}),
is_executable = is_executable,
allow_symlink = allow_symlink,
**kwargs
)
56 changes: 54 additions & 2 deletions tests/copy_file/BUILD
View file
Expand Up @@ -46,6 +46,7 @@ sh_test(
":file_deps",
# Use DefaultInfo.runfiles from 'copy_gen'.
":copy_gen",
":copy_gen_symlink",
"//tests:unittest.bash",
],
deps = ["@bazel_tools//tools/bash/runfiles"],
Expand All @@ -56,6 +57,7 @@ filegroup(
# Use DefaultInfo.files from 'copy_src'.
srcs = [
":copy_src",
":copy_src_symlink",
],
)

Expand All @@ -64,15 +66,23 @@ filegroup(
genrule(
name = "run_executables",
outs = [
"xsrc-out-symlink.txt",
"xgen-out-symlink.txt",
"xsrc-out.txt",
"xgen-out.txt",
],
cmd = ("$(location :bin_src) > $(location xsrc-out.txt) && " +
"$(location :bin_gen) > $(location xgen-out.txt)"),
cmd = " && ".join([
"$(location :bin_src_symlink) > $(location xsrc-out-symlink.txt)",
"$(location :bin_gen_symlink) > $(location xgen-out-symlink.txt)",
"$(location :bin_src) > $(location xsrc-out.txt)",
"$(location :bin_gen) > $(location xgen-out.txt)",
]),
output_to_bindir = 1,
tools = [
":bin_gen",
":bin_src",
":bin_gen_symlink",
":bin_src_symlink",
],
)

Expand All @@ -82,22 +92,48 @@ sh_binary(
srcs = [":copy_xsrc"],
)

# If 'bin_src' is built, then 'copy_xsrc' made its output executable.
sh_binary(
name = "bin_src_symlink",
srcs = [":copy_xsrc_symlink"],
)

# If 'bin_gen' is built, then 'copy_xgen' made its output executable.
sh_binary(
name = "bin_gen",
srcs = [":copy_xgen"],
)

# If 'bin_gen' is built, then 'copy_xgen' made its output executable.
sh_binary(
name = "bin_gen_symlink",
srcs = [":copy_xgen_symlink"],
)

copy_file(
name = "copy_src",
src = "a.txt",
out = "out/a-out.txt",
)

copy_file(
name = "copy_src_symlink",
src = "a.txt",
out = "out/a-out-symlink.txt",
allow_symlink = True,
)

copy_file(
name = "copy_gen",
src = ":gen",
out = "out/gen-out.txt",
allow_symlink = True,
)

copy_file(
name = "copy_gen_symlink",
src = ":gen",
out = "out/gen-out-symlink.txt",
)

copy_file(
Expand All @@ -107,13 +143,29 @@ copy_file(
is_executable = True,
)

copy_file(
name = "copy_xsrc_symlink",
src = "a_with_exec_bit.txt",
out = "xout/a-out-symlink.sh",
is_executable = True,
allow_symlink = True,
)

copy_file(
name = "copy_xgen",
src = ":gen",
out = "xout/gen-out.sh",
is_executable = True,
)

copy_file(
name = "copy_xgen_symlink",
src = ":gen",
out = "xout/gen-out-symlink.sh",
is_executable = True,
allow_symlink = True,
)

genrule(
name = "gen",
outs = ["b.txt"],
Expand Down
2 changes: 2 additions & 0 deletions tests/copy_file/a_with_exec_bit.txt
View file
@@ -0,0 +1,2 @@
#!/bin/bash
echo aaa
22 changes: 22 additions & 0 deletions tests/copy_file/copy_file_tests.sh
View file
Expand Up @@ -44,20 +44,42 @@ function test_copy_src() {
expect_log '^echo aaa$'
}

function test_copy_src_symlink() {
cat "$(rlocation bazel_skylib/tests/copy_file/out/a-out-symlink.txt)" >"$TEST_log"
expect_log '^#!/bin/bash$'
expect_log '^echo aaa$'
}

function test_copy_gen() {
cat "$(rlocation bazel_skylib/tests/copy_file/out/gen-out.txt)" >"$TEST_log"
expect_log '^#!/bin/bash$'
expect_log '^echo potato$'
}

function test_copy_gen_symlink() {
cat "$(rlocation bazel_skylib/tests/copy_file/out/gen-out-symlink.txt)" >"$TEST_log"
expect_log '^#!/bin/bash$'
expect_log '^echo potato$'
}

function test_copy_xsrc() {
cat "$(rlocation bazel_skylib/tests/copy_file/xsrc-out.txt)" >"$TEST_log"
expect_log '^aaa$'
}

function test_copy_xsrc_symlink() {
cat "$(rlocation bazel_skylib/tests/copy_file/xsrc-out-symlink.txt)" >"$TEST_log"
expect_log '^aaa$'
}

function test_copy_xgen() {
cat "$(rlocation bazel_skylib/tests/copy_file/xgen-out.txt)" >"$TEST_log"
expect_log '^potato$'
}

function test_copy_xgen_symlink() {
cat "$(rlocation bazel_skylib/tests/copy_file/xgen-out-symlink.txt)" >"$TEST_log"
expect_log '^potato$'
}

run_suite "copy_file_tests test suite"

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