BufWriter has more capacity (8k vs 1k) and doesn't flush the stream after '\n'.
That change helps to reduce the number of syscalls, especially when dealing with text files.
Since BufWriter has a different way of getting number of pending elements than LineWriter -
Pending trait was introduced to deal with that.
Instead of a single source of symbols, now linker keeps a list of DSO (former Library) objects
with their own symbols map. That helps to process R_X86_64_COPY relocations correctly.
For example, if 'a.out' executable with dependencies ['libstdc++.so', 'libc.so'] is being loaded
and 'a.out' uses 'stdout' symbol from 'libc.so', its relocation process goes as follows:
- linker processes relocation entry 'stdout' of type R_X86_64_GLOB_DAT from 'libc.so',
- it goes through object list ['a.out', 'libstdc++.so', 'libc.so'] to find first object
that exports 'stdout' symbol. The symbol is in 'a.out' with the value e.g. '0x404070',
- linker sets 'stdout' symbol GOT entry in 'libc.so' to '0x404070',
....
- linker processes relocation entry 'stdout' of type R_X86_64_COPY from 'a.out',
- it goes through object list excluding 'a.out': ['libstdc++.so', 'libc.so']. The symbol is found in 'libc.so',
- linker copies the 'stdout' symbol content from 'libc.so' to memory at address '0x404070' (in 'a.out' object).
Objects are relocated in reverse order they were loaded. So in the example above, linker starts with relocating
'libc.so' and ends with 'a.out'. It is necessary e.g. when linking with 'libstdc++.so' - there are many
relocations which symbols are found in 'libstdc++.so', so they need to be resolved before their contents are
copied to 'a.out'. That also matches GNU ld.so behavior.
* load TLS segment for executable - while we can skip PT_LOAD for executable,
we still have to load TLS segment.
* set TCB address based on if elf is position independent
When a byte-oriented stream function touches a stream, that stream
should be set to byte-oriented mode if it hasn't been set yet. If
it has been set, the opertion should only succeed if the stream is
already in byte-oriented mode.
Signed-off-by: Wren Turkal <wt@penguintechs.org>
This function is used to set the orientation of a stream to either
byte-oriented or wchar-oriented.
More info on this function is here:
https://man7.org/linux/man-pages/man3/fwide.3p.html
This implementation only impmlemnts the manual switching and does
not yet guard against using a byte-oriented stream with wchar
functions and vice versa. Those step will come in additional
commits.
Signed-off-by: Wren Turkal <wt@penguintechs.org>
Darley Barreto