diff options
Diffstat (limited to 'erts')
| -rw-r--r-- | erts/doc/src/erlang.xml | 53 | ||||
| -rw-r--r-- | erts/emulator/beam/erl_bif_binary.c | 3 |
2 files changed, 55 insertions, 1 deletions
diff --git a/erts/doc/src/erlang.xml b/erts/doc/src/erlang.xml index cd9bb85f5c..e90160dfd7 100644 --- a/erts/doc/src/erlang.xml +++ b/erts/doc/src/erlang.xml @@ -253,6 +253,54 @@ iolist() = [char() | binary() | iolist()] </desc> </func> <func> + <name>binary_part(Subject, PosLen) -> binary()</name> + <fsummary>Extracts a part of a binary</fsummary> + <type> + <v>Subject = binary()</v> + <v>PosLen = {Start,Length}</v> + <v>Start = int()</v> + <v>Length = int()</v> + </type> + <desc> + <p>Extracts the part of the binary described by <c>PosLen</c>.</p> + + <p>Negative length can be used to extract bytes at the end of a binary:</p> + +<code> +1> Bin = <<1,2,3,4,5,6,7,8,9,10>>. +2> binary_part(Bin,{byte_size(Bin), -5)). +<<6,7,8,9,10>> +</code> + + <p>If <c>PosLen</c> in any way references outside the binary, a <c>badarg</c> exception is raised.</p> + + <p><c>Start</c> is zero-based, i.e:</p> +<code> +1> Bin = <<1,2,3>> +2> binary_part(Bin,{0,2}). +<<1,2>> +</code> + + <p>See the STDLIB module <c>binary</c> for details about the <c>PosLen</c> semantics.</p> + + <p>Allowed in guard tests.</p> + </desc> + </func> + <func> + <name>binary_part(Subject, Start, Length) -> binary()</name> + <fsummary>Extracts a part of a binary</fsummary> + <type> + <v>Subject = binary()</v> + <v>Start = int()</v> + <v>Length = int()</v> + </type> + <desc> + <p>The same as <c>binary_part(Subject, {Pos, Len})</c>.</p> + + <p>Allowed in guard tests.</p> + </desc> + </func> + <func> <name>binary_to_atom(Binary, Encoding) -> atom()</name> <fsummary>Convert from text representation to an atom</fsummary> <type> @@ -318,6 +366,11 @@ iolist() = [char() | binary() | iolist()] corresponding to the bytes from position <c>Start</c> to position <c>Stop</c> in <c>Binary</c>. Positions in the binary are numbered starting from 1.</p> + + <note><p>This functions indexing style of using one-based indices for + binaries is deprecated. New code should use the functions in + the STDLIB module <c>binary</c> instead. They consequently + use the same (zero-based) style of indexing.</p></note> </desc> </func> <func> diff --git a/erts/emulator/beam/erl_bif_binary.c b/erts/emulator/beam/erl_bif_binary.c index 0a40e28474..3e8480324c 100644 --- a/erts/emulator/beam/erl_bif_binary.c +++ b/erts/emulator/beam/erl_bif_binary.c @@ -2369,7 +2369,8 @@ static BIF_RETTYPE do_binary_copy(Process *p, Eterm bin, Eterm en) goto badarg; } if (!n) { - goto badarg; + Eterm res_term = erts_new_heap_binary(p,NULL,0,&bytes); + BIF_RET(res_term); } ERTS_GET_BINARY_BYTES(bin,bytes,bit_offs,bit_size); if (bit_size != 0) { |