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Annotation of coherent/a/usr/man/MULTI/open, revision 1.1

1.1     ! root        1: 
        !             2: 
        !             3: open()                 COHERENT System Call                open()
        !             4: 
        !             5: 
        !             6: 
        !             7: 
        !             8: Open a file
        !             9: 
        !            10: iinntt ooppeenn(_f_i_l_e, _t_y_p_e) cchhaarr *_f_i_l_e; iinntt _t_y_p_e;
        !            11: 
        !            12: open opens  a file  to receive  data, or to  have its  data read.
        !            13: When it  opens file, open  returns a file descriptor,  which is a
        !            14: small, positive integer  that identifies the open file for subse-
        !            15: quent calls to read, write, close, dup, or dup2.  type determines
        !            16: how the file is opened, as follows:
        !            17: 
        !            18: 
        !            19:              00       Read only
        !            20:              11       Write
        !            21:              22       Read and write
        !            22: 
        !            23: 
        !            24: After file is opened, reading or writing begins at byte 0.
        !            25: 
        !            26: ***** Example *****
        !            27: 
        !            28: This example copies the file named in argv[1] to the one named in
        !            29: argv[2] by using COHERENT system calls.  It demonstrates the sys-
        !            30: tem calls open, close, read, write, and creat.
        !            31: 
        !            32: 
        !            33: #include <stdio.h>
        !            34: #define BUFSIZE (20*512)
        !            35: char buf[BUFSIZE];
        !            36: 
        !            37: 
        !            38: 
        !            39: void fatal(s)
        !            40: char *s;
        !            41: {
        !            42:         fprintf(stderr, "copy: %s\n", s);
        !            43:         exit(1);
        !            44: }
        !            45: 
        !            46: 
        !            47: 
        !            48: main(argc, argv)
        !            49: int argc; char *argv[];
        !            50: {
        !            51:         register int ifd, ofd;
        !            52:         register unsigned int n;
        !            53: 
        !            54: 
        !            55: 
        !            56:         if (argc != 3)
        !            57:                 fatal("Usage: copy source destination");
        !            58:         if ((ifd = open(argv[1], 0)) == -1)
        !            59:                 fatal("cannot open input file");
        !            60:         if ((ofd = creat(argv[2], 0666)) == -1)
        !            61:                 fatal("cannot open output file");
        !            62: 
        !            63: 
        !            64: COHERENT Lexicon                                           Page 1
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        !            68: 
        !            69: open()                 COHERENT System Call                open()
        !            70: 
        !            71: 
        !            72: 
        !            73: 
        !            74: 
        !            75: 
        !            76:         while ((n = read(ifd, buf, BUFSIZE)) != 0) {
        !            77:                 if (n == -1)
        !            78:                         fatal("read error");
        !            79:                 if (write(ofd, buf, n) != n)
        !            80:                         fatal("write error");
        !            81:         }
        !            82: 
        !            83: 
        !            84: 
        !            85:         if (close(ifd) == -1 || close(ofd) == -1)
        !            86:                 fatal("cannot close");
        !            87:         exit(0);
        !            88: }
        !            89: 
        !            90: 
        !            91: ***** See Also *****
        !            92: 
        !            93: COHERENT system calls, fopen()
        !            94: 
        !            95: ***** Diagnostics *****
        !            96: 
        !            97: open returns  -1 if the file is nonexistent,  if the caller lacks
        !            98: permission, or if a system resource is exhausted.
        !            99: 
        !           100: ***** Notes *****
        !           101: 
        !           102: open is  a low-level call that passes  data directly to COHERENT.
        !           103: It  should not  be mixed  with high-level  calls, such  as fread,
        !           104: fwrite, or fopen.
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        !           130: COHERENT Lexicon                                           Page 2
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