Re: bin/41837

[Stathis Kamperis <ekamperi%gmail.com@localhost>]

The following reply was made to PR bin/41837; it has been noted by GNATS.

From: Stathis Kamperis <ekamperi%gmail.com@localhost>
To: gnats-bugs%netbsd.org@localhost
Cc: 
Subject: Re: bin/41837
Date: Sat, 8 Aug 2009 22:52:38 +0300

 #include <assert.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>     /* strcmp() */
 
 int main(void)
 {
        /*
         * If TMP_MAX is defined, use that unless it exceeds 2000.
         * We do this because the implementation may support some
         * astronomically large value and blow up the memory limits.
         * E.g., in DragonFly it equals 308915776. But, even if
         * TMP_MAX isn't that large, it still needs to be kept low,
         * because later on when we check if the generated strings are
         * unique, we use a nested loop which is of O(n^2) complexity.
         * And we want the test to complete in reasonable amount of time.
         */
 #ifdef TMP_MAX
        size_t N = TMP_MAX > 2000 ? 2000 : TMP_MAX;
 #else
        size_t N = 25;          /* Lowest possible value for TMP_MAX. */
 #endif
        char **files;
        size_t i, j;
 
        /*
         * Allocate memory for file paths.
         * We could use a variable-sized array, but let's stick for now
         * to the C89.
         */
        files = malloc(N * sizeof(char *));
        assert(files != NULL);
 
        /* Generate the file paths. */
        for (i = 0; i < N; i++) {
                files[i] = tempnam("/tmp", "file");
                assert(files[i] != NULL);
        }
 
        /*
         * Make sure that all generated paths start with our directory,
         * and contain our prefix.
         */
        for (i = 0; i < N; i++) {
                assert(strncmp(files[i], "/tmp/", 5) == 0);
                assert(strncmp(files[i] + 5, "file", 4) == 0);
        }
 
        /*
         * If the implementation uses tmpnam() internally, we are still
         * guaranteed at least {TMP_MAX} unique filenames. But, to be
         * honest, there's no explicit statement for the case where
         * tempnam() doesn't use tmpnam(). Anyway, tmpfile() shares the
         * same limit as tmpnam(), so it's reasonable to assume that
         * tempnam() does the same as well.
         */
        for (i = 0; i < N-1; i++)
                for (j = i+1; j < N; j++)
                        assert(strcmp(files[i], files[j]) != 0);
 
        /* We are done -- free resouces. */
        for (i = 0; i < N; i++)
                free(files[i]);
        free(files);
 
        printf("passed\n");
 
        return (EXIT_SUCCESS);
 }