Issue #20526 has been updated by YO4 (Yoshinao Muramatsu). When a file is opened with `encoding: "bom|utf-8"`, it appears that the fd holds the FTEXT flag as of the point where io_strip_bom() is called. File.write("a.txt", "a\r\n") writes "a\r\r\n". Then rb_io_getbyte is called from io_strip_bom, fill rbuf with crlf conversion via _read(). As a result rbuf holds "\a\r\n". Newline conversion makes this into "a\n" # => [97, 10]. IO#rewind makes this clear. ``` File.write("a.txt", "a\r\n") File.open("a.txt", encoding: "bom|utf-8") {|f| f.read.bytes} # => [97, 10] File.open("a.txt", encoding: "bom|utf-8") {|f| f.rewind; f.read.bytes;} # => [97, 10, 10] File.open("a.txt", encoding: "bom|utf-8", universal_newline: false) {|f| f.rewind; f.read.bytes} # => [97, 13, 13, 10] ``` Strangely, `encoding: "utf-8"` and `encoding: "bom:utf-8"` seem to enable universal newline conversion. This affects newline conversion and the handling of Ctrl-Z character. ``` File.write("a.txt", "a\r\n\x1a\r") File.open("a.txt", encoding: "utf-8") {|f| f.read.bytes} # => [97, 10, 10, 26, 10] File.open("a.txt", "r:utf-8") {|f| f.read.bytes} # => [97, 13, 10] ``` ---------------------------------------- Bug #20526: File.open(encoding: "bom|utf-8") converts "\r\n" to "\n" on Windows https://bugs.ruby-lang.org/issues/20526#change-118604 * Author: kou (Kouhei Sutou) * Status: Open * Assignee: windows * ruby -v: ruby 3.2.2 (2023-03-30 revision e51014f9c0) [x64-mingw-ucrt] * Backport: 3.1: REQUIRED, 3.2: REQUIRED, 3.3: REQUIRED ---------------------------------------- I'm not sure whether this is an intentional behavior or not but it seems that `encoding: "utf-8"` doesn't change newline conversion but `encoding: "bom|utf-8"` changes newline conversion: ```ruby File.write("a.txt", "a\r\n") File.read("a.txt").bytes # => [97, 13, 10] File.open("a.txt", encoding: "utf-8") {|f| f.read.bytes} # => [97, 10, 10] File.open("a.txt", encoding: "bom|utf-8") {|f| f.read.bytes} # => [97, 10] XXX: \r\n -> \n File.open("a.txt", encoding: "bom|utf-8", universal_newline: false) {|f| f.read.bytes} # => [97, 13, 10] ``` Note that the `XXX: ` line in the above codes. Is this an intentional behavior? -- https://bugs.ruby-lang.org/