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path: root/src/stdio/__fdopen.c
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2014-02-07in fdopen, avoid setting O_APPEND flag if it's already setRich Felker-1/+2
this saves a syscall in the case where the underlying open already took place with O_APPEND, which is common because fopen with append modes sets O_APPEND at the time of open before passing the file descriptor to __fdopen.
2014-02-07fix ftello result for append streams with unflushed outputRich Felker-0/+1
when there is unflushed output, ftello (and ftell) compute the logical stream position as the underlying file descriptor's offset plus an adjustment for the amount of buffered data. however, this can give the wrong result for append-mode streams where the unflushed writes should adjust the logical position to be at the end of the file, as if a seek to end-of-file takes place before the write. the solution turns out to be a simple trick: when ftello (indirectly) calls lseek to determine the current file offset, use SEEK_END instead of SEEK_CUR if the stream is append-mode and there's unwritten buffered data. the ISO C rules regarding switching between reading and writing for a stream opened in an update mode, along with the POSIX rules regarding switching "active handles", conveniently leave undefined the hypothetical usage cases where this fix might lead to observably incorrect offsets. the bug being fixed was discovered via the test case for glibc issue
2012-11-08clean up stdio_impl.hRich Felker-0/+6
this header evolved to facilitate the extremely lazy practice of omitting explicit includes of the necessary headers in individual stdio source files; not only was this sloppy, but it also increased build time. now, stdio_impl.h is only including the headers it needs for its own use; any further headers needed by source files are included directly where needed.
2012-09-29add 'e' modifier (close-on-exec) to fopen and fdopenRich Felker-2/+4
this feature will be in the next version of POSIX, and can be used internally immediately. there are many internal uses of fopen where close-on-exec is needed to fix bugs.
2012-06-17fdopen should set errno when it fails due to invalid mode stringRich Felker-1/+4
2011-07-30add proper fuxed-based locking for stdioRich Felker-3/+5
previously, stdio used spinlocks, which would be unacceptable if we ever add support for thread priorities, and which yielded pathologically bad performance if an application attempted to use flockfile on a key file as a major/primary locking mechanism. i had held off on making this change for fear that it would hurt performance in the non-threaded case, but actually support for recursive locking had already inflicted that cost. by having the internal locking functions store a flag indicating whether they need to perform unlocking, rather than using the actual recursive lock counter, i was able to combine the conditionals at unlock time, eliminating any additional cost, and also avoid a nasty corner case where a huge number of calls to ftrylockfile could cause deadlock later at the point of internal locking. this commit also fixes some issues with usage of pthread_self conflicting with __attribute__((const)) which resulted in crashes with some compiler versions/optimizations, mainly in flockfile prior to pthread_create.
2011-04-17debloat: use __syscall instead of syscall where possibleRich Felker-2/+2
don't waste time (and significant code size due to function call overhead!) setting errno when the result of a syscall does not matter or when it can't fail.
2011-04-15avoid setting errno when checking for ttyRich Felker-1/+1
setting errno here is completely valid, but some programs, notably busybox printf, assume that errno will not be set during output and treat this as an error condition. in any case, skipping it slightly reduces code size and saves time.
2011-03-20global cleanup to use the new syscall interfaceRich Felker-3/+3
2011-02-12initial check-in, version 0.5.0v0.5.0Rich Felker-0/+52