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Diffstat (limited to 'src/util/dup2_pass_on_exec.c')
| -rw-r--r-- | src/util/dup2_pass_on_exec.c | 64 |
1 files changed, 64 insertions, 0 deletions
diff --git a/src/util/dup2_pass_on_exec.c b/src/util/dup2_pass_on_exec.c new file mode 100644 index 0000000..5286e5b --- /dev/null +++ b/src/util/dup2_pass_on_exec.c @@ -0,0 +1,64 @@ +/*++ +/* NAME +/* dup2_pass_on_exec 1 +/* SUMMARY +/* dup2 close-on-exec behavior test program +/* SYNOPSIS +/* dup2_pass_on_exec +/* DESCRIPTION +/* dup2_pass_on_exec sets the close-on-exec flag on its +/* standard input and then dup2() to duplicate it. +/* Posix-1003.1 specifies in section 6.2.1.2 that dup2(o,n) should behave +/* as: close(n); n = fcntl(o, F_DUPFD, n); as long as o is a valid +/* file-descriptor, n!=o, and 0<=n<=[OPEN_MAX]. +/* Section 6.5.2.2 states that the close-on-exec flag of the result of a +/* successful fcntl(o, F_DUPFD, n) is cleared. +/* +/* At least Ultrix4.3a does not clear the close-on-exec flag of n on +/* dup2(o, n). +/* DIAGNOSTICS +/* Problems are reported to the standard error stream. +/* LICENSE +/* .ad +/* .fi +/* The Secure Mailer license must be distributed with this software. +/* AUTHOR(S) +/* Christian von Roques <roques@pond.sub.org> +/* Forststrasse 71 +/* 76131 Karlsruhe, GERMANY +/*--*/ + +#include <stdio.h> +#include <fcntl.h> +#include <unistd.h> +#include <stdlib.h> + +#define DO(s) if (s < 0) { perror(#s); exit(1); } + +int main(int unused_argc, char **unused_argv) +{ + int res; + + printf("Setting the close-on-exec flag of file-descriptor 0.\n"); + DO(fcntl(0, F_SETFD, 1)); + + printf("Duplicating file-descriptor 0 to 3.\n"); + DO(dup2(0, 3)); + + printf("Testing if the close-on-exec flag of file-descriptor 3 is set.\n"); + DO((res = fcntl(3, F_GETFD, 0))); + if (res & 1) + printf( +"Yes, a newly dup2()ed file-descriptor has the close-on-exec \ +flag cloned.\n\ +THIS VIOLATES Posix1003.1 section 6.2.1.2 or 6.5.2.2!\n\ +You should #define DUP2_DUPS_CLOSE_ON_EXEC in sys_defs.h \ +for your OS.\n"); + else + printf( +"No, a newly dup2()ed file-descriptor has the close-on-exec \ +flag cleared.\n\ +This complies with Posix1003.1 section 6.2.1.2 and 6.5.2.2!\n"); + + return 0; +} |