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authorTuncer Ayaz <[email protected]>2010-01-15 17:42:09 +0100
committerTuncer Ayaz <[email protected]>2010-01-18 18:13:03 +0100
commitecd339d1b4225627ecb371ed66d43139766fd4a8 (patch)
treece7e27deeb76f2b34ca48f85fd2fb050f3be846c
parente9adb6d0ef8426dec1f8f3211cabb49fc4464c01 (diff)
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Don't return a false {error,eexist} in filelib:ensure_dir/1
This is about the non-atomicity of filelib:ensure_dir/1. When using filelib:ensure_dir/1 from multiple processes to create the same path or parts of the same directory structure (which happens with rebar's worker processes) it happens quite a lot that between a file:read_file_info/1 and file:make_dir/1 one of the other procs has already created the directory we want to create. mkdir(1) says one of the following for -p depending on which Unix like system you're on: "no error if existing" "no error will be reported if a directory given as an operand already exists" I've seen more than one Erlang project where the return value of ensure_dir/1 is ignored completely. To eliminate the race condition, call file:make_dir/1 without first testing whether the directory exists. If it succeeds everything is fine. Otherwise, if the error code is {error,eexists}, check whether the directory exists. If it does, everything is fine; if not, return {error,eexist} (which indicates that there exists a regular file with the same name, or (more unlikely) that another process removed the directory after the call to file:make_dir/1). Signed-off-by: Tuncer Ayaz <[email protected]>
-rw-r--r--lib/stdlib/src/filelib.erl12
1 files changed, 11 insertions, 1 deletions
diff --git a/lib/stdlib/src/filelib.erl b/lib/stdlib/src/filelib.erl
index d65588f0d1..3acc40ea20 100644
--- a/lib/stdlib/src/filelib.erl
+++ b/lib/stdlib/src/filelib.erl
@@ -228,7 +228,17 @@ ensure_dir(F) ->
ok;
false ->
ensure_dir(Dir),
- file:make_dir(Dir)
+ case file:make_dir(Dir) of
+ {error,eexist}=EExist ->
+ case do_is_dir(Dir, file) of
+ true ->
+ ok;
+ false ->
+ EExist
+ end;
+ Err ->
+ Err
+ end
end.