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Diffstat (limited to 'common/rtfl_tee.c')
| -rw-r--r-- | common/rtfl_tee.c | 249 |
1 files changed, 249 insertions, 0 deletions
diff --git a/common/rtfl_tee.c b/common/rtfl_tee.c new file mode 100644 index 0000000..4911b73 --- /dev/null +++ b/common/rtfl_tee.c @@ -0,0 +1,249 @@ +/* + * RTFL + * + * Copyright 2014 Sebastian Geerken <sgeerken@dillo.org> + * + * This program 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. + * + * This program 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 this program. If not, see <http://www.gnu.org/licenses/>. + */ + +/* + * Like tee(1), this program duplicates a stream; however, it does not + * write the copy to a file, but instead sends it via pipe to another + * program. Example: + * + * $ foo | rtfl-tee bar | qix + * + * Here, the standard output of "foo" is passed to the standard input + * of both "bar" and "qix". + * + * More informations in doc/rtfl.html. + * + * TODO: Something like "echo -n foo | rtfl-tee -b cat" does not work; + * since the line of the first "foo" is never finished, the copy of + * "foo" is never printed. + */ + +#include <unistd.h> +#include <stdio.h> +#include <stdarg.h> +#include <stdlib.h> +#include <errno.h> +#include <string.h> +#include <sys/select.h> + +#define min(a, b) ((a) < (b) ? (a) : (b)) +#define max(a, b) ((a) > (b) ? (a) : (b)) + +static void usrerr (const char *fmt, ...) +{ + va_list args; + va_start (args, fmt); + vfprintf (stderr, fmt, args); + fprintf (stderr, "\n"); + exit (1); +} + +static void syserr (const char *fmt, ...) +{ + va_list args; + va_start (args, fmt); + vfprintf (stderr, fmt, args); + fprintf (stderr, ": %s\n", strerror (errno)); + exit (1); +} + +static ssize_t ewrite(int fd, const void *buf, size_t count) +{ + ssize_t w; + if ((w = write (fd, buf, count)) == -1) + syserr ("write(%d, ...) failed", fd); + return w; +} + +static void writestdout (int orig, char *buf, size_t count) +{ + // Basic idea: "orig" denotes to 0 (stdin of rtfl-tee) or 1 (stdout + // of the called program). "curorig" refers to the origin which is + // currently printed, so than the data from the other origin must + // be buffered. "startline" is set to 1 at the beginning, or iff + // the last printed character was '\n'. (In this case, switching is + // simply possible.) + + static int curorig = 0, startline = 1; + static char obuf[2048]; + static size_t ocount = 0; + + //printf ("\nwritestdout: %d, '%c...' (%d)\n", + // orig, count > 0 ? buf[0] : '.', (int)count); + //printf ("===> curorig = %d, ocount = %d, startline = %d\n", + // curorig, (int)ocount, startline); + + if (count > 0) { + if (orig != curorig) { + if (startline) { + // Simple switching case. + ewrite (1, obuf, ocount); + ocount = 0; + curorig = orig; + ewrite (1, buf, count); + startline = buf[count - 1] == '\n'; + } else { + // Buffer. + size_t odiff = min (count, ocount - sizeof (obuf)); + memcpy (obuf + ocount, buf, odiff); + ocount += odiff; + } + } else { + if (ocount == 0) { + // Nothing buffered: simply print all data. + ewrite (1, buf, count); + startline = buf[count - 1] == '\n'; + } else { + // Only print everything until the last newline character. + // (Note: printing everything until the *first* newline + // character whould make a larger buffer necessary, but, + // on the other hand, preserve better the original + // (temporal) order of the lines.) + ssize_t i, nl; + for (nl = -1, i = count - 1; nl == -1 && i >= 0; i--) + if (buf[i] == '\n') nl = i; + + if (nl == -1) { + // No newline: no switch. + ewrite (1, buf, count); + startline = 0; + } else { + // Newline: switch. + ewrite (1, buf, nl + 1); + ewrite (1, obuf, ocount); + startline = obuf[ocount - 1] == '\n'; + ocount = min (sizeof (obuf), count - (nl + 1)); + memcpy (obuf, buf + nl + 1, ocount); + curorig = 1 - curorig; + } + } + } + } +} + +int main (int argc, char *argv[]) +{ + int parent2child[2], child2parent[2], i, offsetcmd, bypass = 0, erroropt = 0; + char *argv2[argc - 1 + 1]; + int done1, done2; + + for (offsetcmd = 1; offsetcmd < argc && argv[offsetcmd][0] == '-'; + offsetcmd++) { + if (argv[offsetcmd][1] == 'b') + bypass = 1; + else if (argv[offsetcmd][1] == '-') { + offsetcmd++; + break; + } else + erroropt = 1; + } + + if (erroropt || offsetcmd >= argc) + usrerr ("Usage: %s [-b] [--] <program> [<program options>]", argv[0]); + + if (pipe (parent2child) == -1) syserr ("pipe failed"); + if (bypass && pipe (child2parent) == -1) syserr ("pipe failed"); + + switch (fork ()) { + case -1: + syserr ("fork failed"); + break; + + case 0: + if (close (parent2child[1]) == -1) + syserr ("close(%d) failed", parent2child[0]); + if (close (0) == -1) syserr ("close(0) failed"); + if (dup2 (parent2child[0], 0) == -1) + syserr ("dup2(%d, 0) failed", parent2child[0]); + if (close (parent2child[0]) == -1) + syserr ("close(%d) failed", parent2child[0]); + + if (bypass) { + if (close (child2parent[0]) == -1) + syserr ("close(%d) failed", child2parent[1]); + if (close (1) == -1) syserr ("close(1) failed"); + if (dup2 (child2parent[1], 1) == -1) + syserr ("dup2(%d, 1) failed", child2parent[1]); + if (close (child2parent[1]) == -1) + syserr ("close(%d) failed", child2parent[1]); + } + + for (i = 0; i < argc - offsetcmd; i++) argv2[i] = argv[i + offsetcmd]; + argv2[argc - offsetcmd] = NULL; + if (execvp (argv2[0], argv2) == -1) + syserr ("execvp(\"%s\", ...) failed", argv2[0]); + break; + + default: + if (close (parent2child[0]) == -1) + syserr ("close(%d) failed", parent2child[0]); + if (bypass && close (child2parent[1]) == -1) + syserr ("close(%d) failed", child2parent[1]); + + done1 = 0; + done2 = !bypass; + while (!done1 || !done2) { + //printf ("==> done1 = %d, done2 = %d\n", done1, done2); + + fd_set set; + FD_ZERO (&set); + + if (!done1) FD_SET (0, &set); + if (!done2) FD_SET (child2parent[0], &set); + + int s = select ((!done2 ? child2parent[0] : 0) + 1, + &set, NULL, NULL, NULL); + + //printf ("==> s = %d\n", s); + + if (s == -1) syserr ("select failed"); + else if (s > 0) { + char buf[2048]; + ssize_t n; + + if (!done1 && FD_ISSET(0, &set)) { + if ((n = read (0, buf, sizeof (buf))) == -1) + syserr ("read failed"); + else if (n == 0) { + if (close (parent2child[1]) == -1) + syserr ("close(%d) failed", parent2child[1]); + done1 = 1; + } else if (n > 0) { + ewrite (parent2child[1], buf, n); + writestdout (0, buf, n); + } + } + + if (!done2 && FD_ISSET (child2parent[0], &set)) { + if ((n = read (child2parent[0], buf, sizeof (buf))) == -1) + syserr ("read failed"); + else if (n == 0) { + if (close (child2parent[0]) == -1) + syserr ("close(%d) failed", child2parent[0]); + done2 = 1; + } else if (n > 0) + writestdout (1, buf, n); + } + } + } + break; + } + + return 0; +} |