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086542fb5b
shgetc sets up to be able to perform an "unget" operation without the
caller having to remember and pass back the character value, and for
this purpose used a conditional store idiom:
if (f->rpos[-1] != c) f->rpos[-1] = c
to make it safe to use with non-writable buffers (setup by the
sh_fromstring macro or __string_read with sscanf).
however, validity of this depends on the buffer space at rpos[-1]
being initialized, which is not the case under some conditions
(including at least unbuffered files and fmemopen ones).
whenever data was read "through the buffer", the desired character
value is already in place and does not need to be written. thus,
rather than testing for the absence of the value, we can test for
rpos<=buf, indicating that the last character read could not have come
from the buffer, and thereby that we have a "real" buffer (possibly of
zero length) with writable pushback (UNGET bytes) below it.
musl libc
musl, pronounced like the word "mussel", is an MIT-licensed
implementation of the standard C library targetting the Linux syscall
API, suitable for use in a wide range of deployment environments. musl
offers efficient static and dynamic linking support, lightweight code
and low runtime overhead, strong fail-safe guarantees under correct
usage, and correctness in the sense of standards conformance and
safety. musl is built on the principle that these goals are best
achieved through simple code that is easy to understand and maintain.
The 1.1 release series for musl features coverage for all interfaces
defined in ISO C99 and POSIX 2008 base, along with a number of
non-standardized interfaces for compatibility with Linux, BSD, and
glibc functionality.
For basic installation instructions, see the included INSTALL file.
Information on full musl-targeted compiler toolchains, system
bootstrapping, and Linux distributions built on musl can be found on
the project website:
http://www.musl-libc.org/