On Fri, Nov 08, 2019 at 06:13:53PM +0200, Eli Zaretskii wrote: >>>> Libc functions are free to call other functions internally, >>>> and such internal calls may fail where the outer level call >>>> does not fail. So even if a libc function does not return >>>> an error, errno can have changed. >>> >>> That would be a bug in libc, I think. Its functions should save and >>> restore errno if other functions they call error out without causing >>> the calling function to fail. >> >> Here is the POSIX man page: >> >> ... >> The value in errno is significant only when the return value of the >> call indicated an error (i.e., -1 from most system calls; -1 or NULL >> from most library functions); a function that succeeds is allowed to >> change errno. > > Thanks, but AFAIU this says the same as I did: if a function succeeds, > it should not modify errno.
I think your understanding of the English language differs from mine. Did you read the line "a function that succeeds is allowed to change errno"?
