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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-06 01:46:30 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-06 01:46:30 +0000 |
commit | b5896ba9f6047e7031e2bdee0622d543e11a6734 (patch) | |
tree | fd7b460593a2fee1be579bec5697e6d887ea3421 /src/util/fifo_rdwr_bug.c | |
parent | Initial commit. (diff) | |
download | postfix-2f07919848e7bd4a084699d26e8821e3a00696d9.tar.xz postfix-2f07919848e7bd4a084699d26e8821e3a00696d9.zip |
Adding upstream version 3.4.23.upstream/3.4.23upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'src/util/fifo_rdwr_bug.c')
-rw-r--r-- | src/util/fifo_rdwr_bug.c | 89 |
1 files changed, 89 insertions, 0 deletions
diff --git a/src/util/fifo_rdwr_bug.c b/src/util/fifo_rdwr_bug.c new file mode 100644 index 0000000..2486876 --- /dev/null +++ b/src/util/fifo_rdwr_bug.c @@ -0,0 +1,89 @@ +/*++ +/* NAME +/* fifo_rdwr_bug 1 +/* SUMMARY +/* fifo server test program +/* SYNOPSIS +/* fifo_rdwr_bug +/* DESCRIPTION +/* fifo_rdwr_bug creates a FIFO and opens it read-write mode. +/* On BSD/OS 3.1 select() will report that the FIFO is readable +/* even before any data is written to it. Doing an actual read +/* causes the read to block; a non-blocking read fails. +/* DIAGNOSTICS +/* Problems are reported to the standard error stream. +/* LICENSE +/* .ad +/* .fi +/* The Secure Mailer license must be distributed with this software. +/* AUTHOR(S) +/* Wietse Venema +/* IBM T.J. Watson Research +/* P.O. Box 704 +/* Yorktown Heights, NY 10598, USA +/*--*/ + +#include <sys_defs.h> +#include <sys/time.h> +#include <sys/param.h> +#include <sys/stat.h> +#include <stdio.h> +#include <fcntl.h> +#include <signal.h> +#include <unistd.h> +#include <stdlib.h> +#include <string.h> + +#define FIFO_PATH "test-fifo" +#define perrorexit(s) { perror(s); exit(1); } + +static void cleanup(void) +{ + printf("Removing fifo %s...\n", FIFO_PATH); + if (unlink(FIFO_PATH)) + perrorexit("unlink"); + printf("Done.\n"); +} + +int main(int unused_argc, char **unused_argv) +{ + struct timeval tv; + fd_set read_fds; + fd_set except_fds; + int fd; + + (void) unlink(FIFO_PATH); + + printf("Creating fifo %s...\n", FIFO_PATH); + if (mkfifo(FIFO_PATH, 0600) < 0) + perrorexit("mkfifo"); + + printf("Opening fifo %s, read-write mode...\n", FIFO_PATH); + if ((fd = open(FIFO_PATH, O_RDWR, 0)) < 0) { + perror("open"); + cleanup(); + exit(1); + } + printf("Selecting the fifo for readability...\n"); + FD_ZERO(&read_fds); + FD_SET(fd, &read_fds); + FD_ZERO(&except_fds); + FD_SET(fd, &except_fds); + tv.tv_sec = 1; + tv.tv_usec = 0; + + switch (select(fd + 1, &read_fds, (fd_set *) 0, &except_fds, &tv)) { + case -1: + perrorexit("select"); + default: + if (FD_ISSET(fd, &read_fds)) { + printf("Opening a fifo read-write makes it readable!!\n"); + break; + } + case 0: + printf("The fifo is not readable, as it should be.\n"); + break; + } + cleanup(); + exit(0); +} |