Is the “number of items actually written” guaranteed to have written every item in its entirety?.Is the “number of items actually read/written” guaranteed to be the number of items that can be read/written (until either EOF or I/O error)?.If sizeof(*ptr) * nitems overflows, what happens?.In fread(): If sizeof(*ptr) is greater than the entire file, what happens?.So there are the following edge cases that are interesting: Read(2), write(2), fopen(3), getc(3), putc(3), gets(3), puts(3), printf(3), scanf(3) DIAGNOSTICSįread and fwrite return 0 upon end of file or error. It returns the number of items actually written. It returns the number of items actually read.įwrite appends at most nitems of data of the type of *ptr beginning at ptr to the named output stream. Here’s what it reads:įread, fwrite – buffered binary input/output SYNOPSISįwrite(ptr, sizeof(*ptr), nitems, stream)įread reads, into a block beginning at ptr, nitems of data of the type of *ptr from the named input stream. Modern-day man pages for those functions are equally terse, though, so this is not exactly a novelty of age. The man page for fread() and fwrite() is rather terse. I will first display the man page, then ask the questions I want to answer, then look at the implementation and finally use that gained knowledge to answer the questions. It was common historical practice not to declare functions in headers, just see crypt(3) as an example. Is a short read or write “normal” in the sense that I should normally expect it? While this makes no answer about modern-day operating systems, a look at V7 may enlighten me about what the historical precedent is.Īs an aside: It’s worth noting that the stdio.h functions are some of the few that require a header. Something that’s always bothered me about the stdio.h primitives fread() and fwrite() are their weak guarantees about what they actually do. Introductionĭid I say I’m done with UNIX Seventh Edition (V7)? How silly of me of course I’m not. Isn’t compatibility great? Posted in 68000, AT&T Unix, disk images, m68k, SYSV, unix | 2 Replies Philip Pemberton’s 3B1 emulator moved Since the 3B1 uses a non standard format, if you want to use FAT 360kb disks from a PC emulator then you’ll need “freebee-9sec-O2.exe”. For anyone wanting to install the 3B1 Unix, you’ll want “freebee-10sec-O2.exe”. There are two executables, for normies, tourists, and people only wanting to witness the fun it doesn’t matter which one you use. So here, you are, freebee based on build d3c9486 of freebee. While so many like to think that the ‘Unix’ business is booming, it really only boomed once AT&T exited the market until Linux had started to gain enough mindshare post 1.0… Which also included 68000 support, although aimed for the the stronger 68030/68040’s.Īnyways I’m sure you didn’t come here for my ramblings about the 68000 instead you want an easy to run package to click and GO! Not that it mattered all that much for AT&T as they started to establish themselves as the new defacto go to UNIX vendor they quickly abandoned the market leaving the Unix PC, and 3B2’s to die off. But such was the Unix microprocessor revolution of the era, it’s crazy to think the mighty SUN-2 is also on the same level of performance, although SUN would at least go the way of the 68020 before giving up on the 68k for SPARC.Įven though the 68000 lacked the ability to recover from bus faults, allowing a better path to UNIX with the 68010, OEM’s still brought their own MMU technology to flesh it out, leading to divergent systems. Although even in emulation it’s incredibly slow. I have to say, having never played with an AT&T Unix PC, it’s kind neat with this windowing non X11 UI. Again super thanks to shadyjesse for finding and fixing the larger issues, and philpem for his great emulator, freebee! So 1970’s
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |