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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-05-06 01:46:30 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-05-06 01:46:30 +0000
commitb5896ba9f6047e7031e2bdee0622d543e11a6734 (patch)
treefd7b460593a2fee1be579bec5697e6d887ea3421 /src/util/fifo_rdwr_bug.c
parentInitial commit. (diff)
downloadpostfix-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.c89
1 files changed, 89 insertions, 0 deletions
diff --git a/src/util/fifo_rdwr_bug.c b/src/util/fifo_rdwr_bug.c
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+++ b/src/util/fifo_rdwr_bug.c
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+/*++
+/* 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);
+}