| 1 | /*- |
| 2 | * Copyright (c) 1990 The Regents of the University of California. |
| 3 | * All rights reserved. |
| 4 | * |
| 5 | * This code is derived from software contributed to Berkeley by |
| 6 | * Chris Torek. |
| 7 | * |
| 8 | * %sccs.include.redist.c% |
| 9 | */ |
| 10 | |
| 11 | #if defined(LIBC_SCCS) && !defined(lint) |
| 12 | static char sccsid[] = "@(#)findfp.c 5.10 (Berkeley) %G%"; |
| 13 | #endif /* LIBC_SCCS and not lint */ |
| 14 | |
| 15 | #include <unistd.h> |
| 16 | #include <stdio.h> |
| 17 | #include <errno.h> |
| 18 | #include <stdlib.h> |
| 19 | #include <string.h> |
| 20 | #include "local.h" |
| 21 | #include "glue.h" |
| 22 | |
| 23 | int __sdidinit; |
| 24 | |
| 25 | #define NSTATIC 20 /* stdin + stdout + stderr + the usual */ |
| 26 | #define NDYNAMIC 10 /* add ten more whenever necessary */ |
| 27 | |
| 28 | #define std(flags, file) \ |
| 29 | {0,0,0,flags,file,{0},0,__sF+file,__sclose,__sread,__sseek,__swrite} |
| 30 | /* p r w flags file _bf z cookie close read seek write */ |
| 31 | |
| 32 | static FILE usual[NSTATIC - 3]; /* the usual */ |
| 33 | static struct glue uglue = { 0, NSTATIC - 3, usual }; |
| 34 | |
| 35 | FILE __sF[3] = { |
| 36 | std(__SRD, STDIN_FILENO), /* stdin */ |
| 37 | std(__SWR, STDOUT_FILENO), /* stdout */ |
| 38 | std(__SWR|__SNBF, STDERR_FILENO) /* stderr */ |
| 39 | }; |
| 40 | struct glue __sglue = { &uglue, 3, __sF }; |
| 41 | |
| 42 | static struct glue * |
| 43 | moreglue(n) |
| 44 | register int n; |
| 45 | { |
| 46 | register struct glue *g; |
| 47 | register FILE *p; |
| 48 | static FILE empty; |
| 49 | |
| 50 | g = (struct glue *)malloc(sizeof(*g) + n * sizeof(FILE)); |
| 51 | if (g == NULL) |
| 52 | return (NULL); |
| 53 | p = (FILE *)(g + 1); |
| 54 | g->next = NULL; |
| 55 | g->niobs = n; |
| 56 | g->iobs = p; |
| 57 | while (--n >= 0) |
| 58 | *p++ = empty; |
| 59 | return (g); |
| 60 | } |
| 61 | |
| 62 | /* |
| 63 | * Find a free FILE for fopen et al. |
| 64 | */ |
| 65 | FILE * |
| 66 | __sfp() |
| 67 | { |
| 68 | register FILE *fp; |
| 69 | register int n; |
| 70 | register struct glue *g; |
| 71 | |
| 72 | if (!__sdidinit) |
| 73 | __sinit(); |
| 74 | for (g = &__sglue;; g = g->next) { |
| 75 | for (fp = g->iobs, n = g->niobs; --n >= 0; fp++) |
| 76 | if (fp->_flags == 0) |
| 77 | goto found; |
| 78 | if (g->next == NULL && (g->next = moreglue(NDYNAMIC)) == NULL) |
| 79 | break; |
| 80 | } |
| 81 | return (NULL); |
| 82 | found: |
| 83 | fp->_flags = 1; /* reserve this slot; caller sets real flags */ |
| 84 | fp->_p = NULL; /* no current pointer */ |
| 85 | fp->_w = 0; /* nothing to read or write */ |
| 86 | fp->_r = 0; |
| 87 | fp->_bf._base = NULL; /* no buffer */ |
| 88 | fp->_bf._size = 0; |
| 89 | fp->_lbfsize = 0; /* not line buffered */ |
| 90 | fp->_file = -1; /* no file */ |
| 91 | /* fp->_cookie = <any>; */ /* caller sets cookie, _read/_write etc */ |
| 92 | fp->_ub._base = NULL; /* no ungetc buffer */ |
| 93 | fp->_ub._size = 0; |
| 94 | fp->_lb._base = NULL; /* no line buffer */ |
| 95 | fp->_lb._size = 0; |
| 96 | return (fp); |
| 97 | } |
| 98 | |
| 99 | /* |
| 100 | * XXX. Force immediate allocation of internal memory. Not used by stdio, |
| 101 | * but documented historically for certain applications. Bad applications. |
| 102 | */ |
| 103 | f_prealloc() |
| 104 | { |
| 105 | int n = getdtablesize() - NSTATIC + 20; /* 20 for slop */ |
| 106 | register struct glue *g; |
| 107 | |
| 108 | for (g = &__sglue; (n -= g->niobs) > 0 && g->next; g = g->next) |
| 109 | /* void */; |
| 110 | if (n > 0) |
| 111 | g->next = moreglue(n); |
| 112 | } |
| 113 | |
| 114 | /* |
| 115 | * exit() calls _cleanup() through *__cleanup, set whenever we |
| 116 | * open or buffer a file. This chicanery is done so that programs |
| 117 | * that do not use stdio need not link it all in. |
| 118 | * |
| 119 | * The name `_cleanup' is, alas, fairly well known outside stdio. |
| 120 | */ |
| 121 | void |
| 122 | _cleanup() |
| 123 | { |
| 124 | /* (void) _fwalk(fclose); */ |
| 125 | (void) _fwalk(__sflush); /* `cheating' */ |
| 126 | } |
| 127 | |
| 128 | /* |
| 129 | * __sinit() is called whenever stdio's internal variables must be set up. |
| 130 | */ |
| 131 | void |
| 132 | __sinit() |
| 133 | { |
| 134 | /* make sure we clean up on exit */ |
| 135 | __cleanup = _cleanup; /* conservative */ |
| 136 | __sdidinit = 1; |
| 137 | } |