C ++将char *的ASCII字符转换为Unix文件名

Question

I have a char* which only contains ASCII characters (decimal: 32-126). I'm searching for a c++ function which escapes (add a backslash before the character) characters that have special meanings in the unix filesystem like '/' or '.'. I want to open the file with fopen later.

I'm not sure, if manually replacing would be a good option. I don't know all characters with special meanings. I also don't know if '?' or '*' would work with fopen.

Answer 1

Actually Unix (or more specific the SuS) disallows only the byte values '/' and '\\0' in file names. Everything else actually is fair game. The exact (in the sense that they're immediately following and followed by a '/') strings "." and ".." are reserved to relative path access, but they are very well valid in a Unix path.

And of course any number and sequence of '.' is perfectly allowed in a Unix filename, as long as another character other than '/' or '\\0' is part of the filename. Yes, newline, any control character, they're all perfectly valid Unix filenames.

Of course the file system you're using may have a different idea about what's permissible, but you were just asking about Unix.

Update:

Oh and it should be noted, that Unix doesn't specify dome "parse" method for filenames. Which essentially means, a filename is treated as a binary blob key into a key→value database. It also means, that there's no such thing as "escaping" for Unix filenames.

Answer 2

POSIX filenames don't have a concept of escape characters. There is no way to have a slash as an element of a filename (when the system renders filenames using Unicode you may be able to create a filename which looks as if it contains a slash, though). I think all other printable characters are just fine although using special characters like * and ? in filename will probably cause problems when people try use them from a shell.