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Diffstat (limited to '')
| -rw-r--r-- | examples/loadables/fdflags.c | 374 |
1 files changed, 374 insertions, 0 deletions
diff --git a/examples/loadables/fdflags.c b/examples/loadables/fdflags.c new file mode 100644 index 0000000..9f2d089 --- /dev/null +++ b/examples/loadables/fdflags.c @@ -0,0 +1,374 @@ +/* Loadable builtin to get and set file descriptor flags. */ + +/* See Makefile for compilation details. */ + +/* + Copyright (C) 2017-2022 Free Software Foundation, Inc. + + This file is part of GNU Bash. + Bash is free software: you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation, either version 3 of the License, or + (at your option) any later version. + + Bash is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with Bash. If not, see <http://www.gnu.org/licenses/>. +*/ + +#include <config.h> + +#if defined (HAVE_UNISTD_H) +# include <unistd.h> +#endif +#include <fcntl.h> +#include <errno.h> +#include "bashansi.h" +#include <stdio.h> + +#include "loadables.h" + +#ifndef FD_CLOEXEC +# define FD_CLOEXEC 1 +#endif + +static const struct +{ + const char *name; + int value; +} file_flags[] = +{ +#ifdef O_APPEND + { "append", O_APPEND }, +#else +# define O_APPEND 0 +#endif +#ifdef O_ASYNC + { "async", O_ASYNC }, +#else +# define O_ASYNC 0 +#endif +#ifdef O_SYNC + { "sync", O_SYNC }, +#else +# define O_SYNC 0 +#endif +#ifdef O_NONBLOCK + { "nonblock", O_NONBLOCK }, +#else +# define O_NONBLOCK 0 +#endif +#ifdef O_FSYNC + { "fsync", O_FSYNC }, +#else +# define O_FSYNC 0 +#endif +#ifdef O_DSYNC + { "dsync", O_DSYNC }, +#else +# define O_DSYNC 0 +#endif +#ifdef O_RSYNC + { "rsync", O_RSYNC }, +#else +# define O_RSYNC 0 +#endif +#ifdef O_ALT_IO + { "altio", O_ALT_IO }, +#else +# define O_ALT_IO 0 +#endif +#ifdef O_DIRECT + { "direct", O_DIRECT }, +#else +# define O_DIRECT 0 +#endif +#ifdef O_NOATIME + { "noatime", O_NOATIME }, +#else +# define O_NOATIME 0 +#endif +#ifdef O_NOSIGPIPE + { "nosigpipe", O_NOSIGPIPE }, +#else +# define O_NOSIGPIPE 0 +#endif + +#ifndef O_CLOEXEC +# define ALLFLAGS (O_APPEND|O_ASYNC|O_SYNC|O_NONBLOCK|O_FSYNC|O_DSYNC|\ + O_RSYNC|O_ALT_IO|O_DIRECT|O_NOATIME|O_NOSIGPIPE) + +/* An unused bit in the file status flags word we can use to pass around the + state of close-on-exec. */ +# define O_CLOEXEC ((~ALLFLAGS) ^ ((~ALLFLAGS) & ((~ALLFLAGS) - 1))) +#endif + +#ifdef O_CLOEXEC + { "cloexec", O_CLOEXEC }, +#endif +}; + +#define N_FLAGS (sizeof (file_flags) / sizeof (file_flags[0])) + +#ifndef errno +extern int errno; +#endif + +/* FIX THIS */ +static int +getallflags () +{ + int i, allflags; + + for (i = allflags = 0; i < N_FLAGS; i++) + allflags |= file_flags[i].value; + return allflags; +} + +static int +getflags(int fd, int p) +{ + int c, f; + int allflags; + + if ((c = fcntl(fd, F_GETFD)) == -1) + { + if (p) + builtin_error("can't get status for fd %d: %s", fd, strerror(errno)); + return -1; + } + + if ((f = fcntl(fd, F_GETFL)) == -1) + { + if (p) + builtin_error("Can't get flags for fd %d: %s", fd, strerror(errno)); + return -1; + } + + if (c) + f |= O_CLOEXEC; + + return f & getallflags(); +} + +static void +printone(int fd, int p, int verbose) +{ + int f; + size_t i; + + if ((f = getflags(fd, p)) == -1) + return; + + printf ("%d:", fd); + + for (i = 0; i < N_FLAGS; i++) + { + if (f & file_flags[i].value) + { + printf ("%s%s", verbose ? "+" : "", file_flags[i].name); + f &= ~file_flags[i].value; + } + else if (verbose) + printf ( "-%s", file_flags[i].name); + else + continue; + + if (f || (verbose && i != N_FLAGS - 1)) + putchar (','); + } + printf ("\n"); +} + +static int +parseflags(char *s, int *p, int *n) +{ + int f, *v; + size_t i; + + f = 0; + *p = *n = 0; + + for (s = strtok(s, ","); s; s = strtok(NULL, ",")) + { + switch (*s) + { + case '+': + v = p; + s++; + break; + case '-': + v = n; + s++; + break; + default: + v = &f; + break; + } + + for (i = 0; i < N_FLAGS; i++) + if (strcmp(s, file_flags[i].name) == 0) + { + *v |= file_flags[i].value; + break; + } + if (i == N_FLAGS) + builtin_error("invalid flag `%s'", s); + } + + return f; +} + +static void +setone(int fd, char *v, int verbose) +{ + int f, n, pos, neg, cloexec; + + f = getflags(fd, 1); + if (f == -1) + return; + + parseflags(v, &pos, &neg); + + cloexec = -1; + + if ((pos & O_CLOEXEC) && (f & O_CLOEXEC) == 0) + cloexec = FD_CLOEXEC; + if ((neg & O_CLOEXEC) && (f & O_CLOEXEC)) + cloexec = 0; + + if (cloexec != -1 && fcntl(fd, F_SETFD, cloexec) == -1) + builtin_error("can't set status for fd %d: %s", fd, strerror(errno)); + + pos &= ~O_CLOEXEC; + neg &= ~O_CLOEXEC; + f &= ~O_CLOEXEC; + + n = f; + n |= pos; + n &= ~neg; + + if (n != f && fcntl(fd, F_SETFL, n) == -1) + builtin_error("can't set flags for fd %d: %s", fd, strerror(errno)); +} + +static int +getmaxfd () +{ + int maxfd, ignore; + +#ifdef F_MAXFD + maxfd = fcntl (0, F_MAXFD); + if (maxfd > 0) + return maxfd; +#endif + + maxfd = getdtablesize (); + if (maxfd <= 0) + maxfd = HIGH_FD_MAX; + for (maxfd--; maxfd > 0; maxfd--) + if (fcntl (maxfd, F_GETFD, &ignore) != -1) + break; + + return maxfd; +} + +int +fdflags_builtin (WORD_LIST *list) +{ + int opt, maxfd, i, num, verbose, setflag; + char *setspec; + WORD_LIST *l; + intmax_t inum; + + setflag = verbose = 0; + reset_internal_getopt (); + while ((opt = internal_getopt (list, "s:v")) != -1) + { + switch (opt) + { + case 's': + setflag = 1; + setspec = list_optarg; + break; + case 'v': + verbose = 1; + break; + CASE_HELPOPT; + default: + builtin_usage (); + return (EX_USAGE); + } + + } + list = loptend; + + /* Maybe we could provide some default here, but we don't yet. */ + if (list == 0 && setflag) + return (EXECUTION_SUCCESS); + + if (list == 0) + { + maxfd = getmaxfd (); + if (maxfd < 0) + { + builtin_error ("can't get max fd: %s", strerror (errno)); + return (EXECUTION_FAILURE); + } + for (i = 0; i < maxfd; i++) + printone (i, 0, verbose); + return (EXECUTION_SUCCESS); + } + + opt = EXECUTION_SUCCESS; + for (l = list; l; l = l->next) + { + if (legal_number (l->word->word, &inum) == 0 || inum < 0) + { + builtin_error ("%s: invalid file descriptor", l->word->word); + opt = EXECUTION_FAILURE; + continue; + } + num = inum; /* truncate to int */ + if (setflag) + setone (num, setspec, verbose); + else + printone (num, 1, verbose); + } + + return (opt); +} + +char *fdflags_doc[] = +{ + "Display and modify file descriptor flags.", + "", + "Display or, if the -s option is supplied, set flags for each file", + "descriptor supplied as an argument. If the -v option is supplied,", + "the display is verbose, including each settable option name in the", + "form of a string such as that accepted by the -s option.", + "", + "The -s option accepts a string with a list of flag names, each preceded", + "by a `+' (set) or `-' (unset). Those changes are applied to each file", + "descriptor supplied as an argument.", + "", + "If no file descriptor arguments are supplied, the displayed information", + "consists of the status of flags for each of the shell's open files.", + (char *)NULL +}; + +/* The standard structure describing a builtin command. bash keeps an array + of these structures. The flags must include BUILTIN_ENABLED so the + builtin can be used. */ +struct builtin fdflags_struct = { + "fdflags", /* builtin name */ + fdflags_builtin, /* function implementing the builtin */ + BUILTIN_ENABLED, /* initial flags for builtin */ + fdflags_doc, /* array of long documentation strings. */ + "fdflags [-v] [-s flags_string] [fd ...]", /* usage synopsis; becomes short_doc */ + 0 /* reserved for internal use */ +}; |