Re: There is a problem when I compile the case with -lcrypt

[Cui Bixuan <cuibixuan at huawei dot com>]

On 2015/9/4 17:40, Andreas Schwab wrote:

>>
>> I don't know why? Is this a problem?
> 
> The value of errno is unspecified except after a function call that is
> documented to set errno _and_ that function call returned a failure
> condition.  Additionally, some functions like strtol are documented to
> not modify errno if they return sucessfully.  If you want to check for
> failure for such a function you need to set errno to zero before the
> call.
> 
Thank you for your explanation :-).

And there is another question, the testcase,
test.c:

#include <sys/types.h>
#include <sys/time.h>
#include <sys/resource.h>

#include <err.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

static int      getafile(void);

static int
getafile(void)
{
        int fd;

        char temp[] = "/tmp/dup2XXXXXXXXX";
        if ((fd = mkstemp(temp)) < 0)
                err(1, "mkstemp");
        remove(temp);
        if (ftruncate(fd, 1024) != 0)
                err(1, "ftruncate");
        return (fd);
}

int
main(int argc, char *argv[])
{
        struct rlimit rlp;
        int orgfd, fd1, fd2, test = 0;

        orgfd = getafile();

        /* If dup(2) ever work? */
        if ((fd1 = dup(orgfd)) < 0)
                err(1, "dup");
        printf("ok %d - dup(2) works\n", ++test);

        if ((fd2 = fcntl(fd1, F_DUPFD)) < 0)
                err(1, "fcntl(F_DUPFD)");
        printf("ok %d - fcntl(F_DUPFD) works\n", ++test);

        printf("pass\n");
        return (0);
}

Compile and run it:
aarch64-linux-gnu-gcc test.c -o test -lpthread

./test
ok 1 - dup(2) works
test: fcntl(F_DUPFD): Invalid argument

I can find the error by 'strace ./test':
...
write(1, "ok 1 - dup(2) works\n", 20ok 1 - dup(2) works
)   = 20
fcntl(4, F_DUPFD, 547995340800)         = -1 EINVAL (Invalid argument)
write(2, "test: ", 6test: )                   = 6
write(2, "fcntl(F_DUPFD)", 14fcntl(F_DUPFD))          = 14
write(2, ": ", 2: )                       = 2
write(2, "Invalid argument\n", 17Invalid argument
)      = 17
exit_group(1)                           = ?
+++ exited with 1 +++



then:
aarch64-linux-gnu-gcc test.c -o test

./test
ok 1 - dup(2) works
ok 2 - fcntl(F_DUPFD) works
pass


And If we add comment to 'printf("ok %d - dup(2) works\n", ++test);' , like this:
        /* If dup(2) ever work? */
        if ((fd1 = dup(orgfd)) < 0)
                err(1, "dup");
//      printf("ok %d - dup(2) works\n", ++test);

        if ((fd2 = fcntl(fd1, F_DUPFD)) < 0)
                err(1, "fcntl(F_DUPFD)");
        printf("ok %d - fcntl(F_DUPFD) works\n", ++test);

compile and run:
aarch64-linux-gnu-gcc test.c -o test -lpthread

./test
ok 1 - fcntl(F_DUPFD) works
pass

Hope you can help me.
> Andreas.
>